title:
XMM-Newton observations of the supernova remnant RX J0852.0-4622/GRO
  J0852-4642

abstract:
  RX J0852.0-4622 is a shell type supernova remnant with a power law spectrum
in the south-eastern corner of the Vela supernova remnant. We report XMM-Newton
observations of three fields centered on the rim of the remnant and confirm the
power law shape of the spectra with no prominent emission lines as previously
obtained with ASCA. The emission line feature at ~4.1 keV indicated in the
ASCA/SIS spectrum of the northern field is detected and found in the southern
and western fields, as well, with a total significance of slightly more than 4
sigmas. The line position is improved and the feature is centered on 4.45 +/-
0.05 keV. We suggest this line feature to be emission from Ti and Sc. The
measured X-ray flux is consistent with the Ti gamma-ray flux previously
measured with COMPTEL. We discuss various physical processes which may lead to
the creation of these lines, and we discuss the implications for the progenitor
and the supernova type.


title:
Comments on the size of the simulation box in cosmological N-Body
  simulations

abstract:
  N-Body simulations are a very important tool in the study of formation of
large scale structures. Much of the progress in understanding the physics of
high redshift universe and comparison with observations would not have been
possible without N-Body simulations. Given the importance of this tool, it is
essential to understand its limitations as ignoring the limitations can easily
lead to interesting but unreliable results. In this paper we study the
limitations arising out of the finite size of simulation volume. This finite
size implies that modes larger than the size of the simulation volume are
ignored and a truncated power spectrum is simulated. If the simulation volume
is large enough then the mass in collapsed haloes expected from the full power
spectrum and from the truncated power spectrum should match. We propose a
quantitative measure based on this approach that allows us to compute the
minimum box size for an N-Body simulation. We find that the required box size
for simulations of LCDM model at high redshifts is much larger than is
typically used. We can also use this approach to quantify the effect of
perturbations at large scales for power law models and we find that if we fix
the scale of non-linearity, the required box size becomes very large as the
index becomes small. The appropriate box size computed using this approach is
also an appropriate choice for the transition scale when tools like MAP (Tormen
and Bertschinger, 1996) that add the contribution of the missing power are
used.


title: Stellar velocity dispersion in NLS1 galaxies

abstract:
  Several authors recently explored the Black-Hole mass (M_BH) vs. stellar
velocity dispersion (sigma_*) relationship for Narrow Line Seyfert 1 galaxies
(NLS1s). Their results are more or less in agreement and seem to indicate that
NLS1s fill the region below the fit obtained by Tremaine et al. (2002), showing
a range of sigma_* similar to that of Seyfert 1 galaxies, and a lower M_BH.
Until now the [O III] width has been used in place of the stellar velocity
dispersion, but some indications begin to arise against the effectiveness of
the gaseous kinematics in representing the bulge potential at least in NLS1s.
Bian & Zhao (2004) stressed the urgency to produce true sigma_* measurements.
Here we present new stellar velocity dispersions obtained through direct
measurements of the Ca II absorption triplet (~ 8550 A) in the nuclei of 8 NLS1
galaxies. The resulting sigma_* values and a comparison with sigma_[O III]
confirm our suspects (see Botte et al. 2004) that [O III] typically
overestimates the stellar velocity dispersion and demonstrate that NLS1s follow
the M_BH-sigma_* relation as Seyfert 1, quasars and non-active galaxies.


title: The extra-planar neutral gas in the edge-on spiral galaxy NGC 891

abstract:
  We present neutral hydrogen observations of the nearby edge-on spiral galaxy
NGC891 which show extended extra-planar emission up to distances of 15 kpc from
the plane. 3D modeling of the galaxy shows that this emission comes from halo
gas rotating more slowly than the gas in the disk.We derive the rotation curves
of the gas above the plane and find a gradient in rotation velocity of -15
km/s/kpc. We also present preliminary results of a galactic fountain model
applied to NGC891.


title: Stability of the mixed phase in hybrid stars

abstract:
  The transition from hadronic matter to quark matter in the core of neutron
stars is likely to be associated with the appearance of a mixed phase, leading
to a smooth variation of the star density profile. We discuss the results of a
systematic study of the properties of the mixed pase upon Coulomb and surface
effects. A state of the art nonrelativistic equation of state of nuclear matter
has been used for the low density phase, while quark matter has been described
within the MIT bag model, including the effect of perturbative one-gluon
exchange interactions. The implications for neutron star structure are
discussed.


title: Hydrodynamics of Internal Shocks in Relativistic Outflows

abstract:
  We study the hydrodynamical effects of two colliding shells, adopted to model
internal shocks in various relativistic outflows such as gamma-ray bursts and
blazars. We find that the density profiles are significantly affected by the
propagation of rarefaction waves. A split-feature appears at the contact
discontinuity of the two shells. The shell spreading with a few ten percent of
the speed of light is also shown to be a notable aspect. The conversion
efficiency of the bulk kinetic energy to internal one shows deviations from the
widely-used inelastic two-point-mass-collision model. Observational
implications are also shortly discussed.


title: Contribution of microlensing to X-ray variability of distant QSOs

abstract:
  We consider a contribution of microlensing to the X-ray variability of
high-redshifted QSOs. Cosmologically distributed gravitational microlenses
could be localized in galaxies (or even in bulge or halo of gravitational
macrolenses) or could be distributed in a uniform way. We have analyzed both
cases of such distributions. We found that the optical depth for gravitational
microlensing caused by cosmologically distributed deflectors could be
significant and could reach $10^{-2} - 0.1$ at $z\sim 2$. This means that
cosmologically distributed deflectors may contribute significantlly to the
X-ray variability of high-redshifted QSOs ($z>2$). Considering that the upper
limit of the optical depth ($\tau\sim 0.1$) corresponds to the case where dark
matter forms cosmologically distributed deflectors, observations of the X-ray
variations of unlensed QSOs can be used for the estimation of the dark matter
fraction of microlenses.


title:
The European Large Area ISO Survey VIII: 90-micron final analysis and
  source counts

abstract:
  We present a re--analysis of the European Large Area ISO Survey (ELAIS) 90mum
observations carried out with ISOPHOT, an instrument on board the ESA's
Infrared Space Observatory (ISO). With more than 12 sq. deg., the ELAIS survey
is the largest area covered by ISO in a single program and is about one order
of magnitude deeper than the IRAS 100mum survey. The data analysis is presented
and was mainly performed with the Phot Interactive Analysis software but using
the pairwise method of Stickel et al. (2003) for signal processing from ERD
(Edited Raw Data) to SCP (Signal per Chopper Plateau). The ELAIS 90mum
catalogue contains 229 reliable sources with fluxes larger than 70 mJy and is
available at www.blackwell-synergy.com. Number counts are presented and show an
excess above the no-evolution model prediction. This confirms the strong
evolution detected at shorter(15mum) and longer (170mum) wavelengths in other
ISO surveys. The ELAIS counts are in agreement with previous works at 90mum and
in particular with the deeper counts extracted from the Lockman hole
observations. Comparison with recent evolutionary models show that the models
of Franceschini et al. and Guiderdoni et al. which includes a
heavily-extinguished population of galaxies give the best fit to the data.
Deeper observations are nevertheless required to better discriminate between
the model predictions in the far-infrared and are scheduled with the Spitzer
Space Telescope which already started operating and will also be performed by
ASTRO-F.


title:
Dust attenuation and star formation in the nearby universe: the
  ultraviolet and far-infrared points of view

abstract:
  We make use of the on-going All Imaging Survey of the UV GALEX satellite
cross-correlated with the IRAS all sky survey to build samples of galaxies
trully selected in far-infrared or in ultraviolet. We discuss the amount of
dust attenuation and the star formation rates for these galaxies and compare
the properties of the galaxies selected in FIR or in UV.


title:
What can we learn about black-hole formation from black-hole X-ray
  binaries?

abstract:
  I discuss the effect of the formation of a black hole on a (close) binary and
show some of the current constraints that the observed properties of black hole
X-ray binaries put on the formation of black holes. In particular I discuss the
evidence for and against asymmetric kicks imparted on the black hole at
formation and find contradicting answers, as there seems to be evidence for
kick for individual systems and from the Galactic $z$-distribution of black
hole X-ray binaries, but not from their line-of-sight velocities.


title:
Magnetic Field Generation and electron acceleration in Collisionless
  Shocks

abstract:
  Using a three dimensional relativistic particle-in-cell code we have
performed numerical experiments of plasma shells colliding at relativistic
velocities. Such scenarios are found in many astrophysical objects e.g. the
relativistic outflow from gamma ray bursts, active galactic nuclei jets and
supernova remnants. We show how a Weibel-like two-stream instability is capable
of generating small-scale magnetic filaments with strength up to percents of
equipartition. Such field topology is ideal for the generation of jitter
radiation as opposed to synchrotron radiation. We also explain how the field
generating mechanism involves acceleration of electrons to power law
distributions (N(E)~E^(-p))through a non-Fermi acceleration mechanism. The
results add to our understanding of collisionless shocks.


title: Starbursts in the Far-Ultraviolet

abstract:
  Starbursts are a significant component of the present-day universe, and offer
unique laboratories for studying the processes that have regulated the
formation and evolution of galaxies and the intergalactic medium. The
combination of large aperture size, medium-to-high spectral resolution, and
access to the feature-rich far-ultraviolet band make FUSE a uniquely valuable
tool for studying starbursts. In this paper, I summarize several of FUSE's
``greatest hits'' for starbursts.


title: Two-Component Jet Models of Gamma-Ray Burst Sources

abstract:
  Recent observational and theoretical studies have raised the possibility that
the collimated outflows in gamma-ray burst (GRB) sources have two distinct
components: a narrow (opening half-angle $\theta_{\rm n}$), highly relativistic
(initial Lorentz factor $\eta_\rmn \gtrsim 10^2$) outflow, from which the
$\gamma$-ray emission originates, and a wider ($\theta_{\rm w} \lesssim 3
\theta_{\rm n}$), moderately relativistic ($\eta_{\rm w}\sim 10$) surrounding
flow. Using a simple synchrotron emission model, we calculate the R-band
afterglow lightcurves expected in this scenario and derive algebraic
expressions for the flux ratios of the emission from the two jet components at
the main transition times in the lightcurve. We apply this model to GRB
sources, for explaining the structure of afterglows and source energetics, as
well as to X-ray flash sources, which we interpret as GRB jets viewed at an
angle $\theta_{\rm obs} > \theta_{\rm n}$. Finally, we argue that a
neutron-rich hydromagnetic outflow may naturally give rise to repeated
brightening episodes in the afterglow lightcurve as observed in GRB 021004 and
GRB 030329.


title:
A highly-ionized absorber in the X-ray binary 4U 1323-62: a new
  explanation for the dipping phenomenon

abstract:
  We report the detection of narrow Fe XXV and Fe XXVI X-ray absorption lines
at 6.68 +/- 0.04 keV and 6.97 +/- 0.05 keV in the persistent emission of the
dipping low-mass X-ray binary 4U 1323-62 during a 2003 January XMM-Newton
observation. These features are superposed on a broad emission feature centered
on 6.6 {+0.1}{-0.2} keV. During dipping intervals the equivalent width of the
Fe XXV feature increases while that of the Fe XXVI feature decreases,
consistent with the presence of less strongly ionized material in the
line-of-sight. As observed previously, the changes in the 1.0-10 keV spectrum
during dips are inconsistent with a simple increase in absorption by cool
material. However, the changes in both the absorption features and the
continuum can be modeled by variations in the properties of an ionized
absorber. No partial covering of any component of the spectrum, and hence no
extended corona, are required. From persistent to deep dipping the
photo-ionization parameter, Xi, expressed in erg cm s^{-1}, decreases from
log(Xi) of 3.9 +/- 0.1 to log(Xi) of 3.13 +/- 0.07, while the equivalent
hydrogen column density of the ionized absorber increases from (3.8 +/- 0.4)
10^{22} atoms cm^{-2} to (37 +/- 2) 10^{22} atoms cm^{-2}. Since highly-ionized
absorption features are seen from many other dip sources, this mechanism may
also explain the overall changes in X-ray spectrum observed during dipping
intervals from these systems.


title:
The H-alpha Galaxy Survey II. Extinction and NII corrections to H-alpha
  fluxes

abstract:
  We study the two main corrections generally applied to narrow-band H-alpha
fluxes from galaxies in order to convert them to star formation rates, namely
for NII contamination and for extinction internal to the galaxy. From an
imaging study using narrow-band filters, we find the NII and H-alpha emission
to be differently distributed. In most disk star formation regions the NII
fraction is small, whereas some galaxies display a diffuse central component
which can be dominated by NII emission. We consider explanations for variations
in the NII/H-alpha ratio, including metallicity variations and different
excitation mechanisms. We then estimate the extinction towards star formation
regions in spiral galaxies, firstly using Br-gamma/H-alpha line ratios. We find
that extinction values are larger in galaxy nuclei than in disks, and that
there is no evidence for heavily dust-embedded regions emerging in the near-IR.
We use optical emission line data from the literature to show only a moderate
dependence of extinction on inclination, consistent with broad-band photometric
studies; typical extinctions are smaller for late-type dwarfs than for spiral
types. Finally, we show that the application of type-dependent extinction
corrections significantly improves the agreement between star formation rates
from H-alpha and IRAS fluxes. This agreement argues against star formation in
normal galaxies being dominated by heavily dust-embedded components.


title: The radio spectrum of a quiescent stellar mass black hole

abstract:
  Observations of V404 Cyg performed with the Westerbork Synthesis Radio
Telescope at four frequencies, over the interval 1.4-8.4 GHz, have provided us
with the first broadband radio spectrum of a `quiescent' stellar mass black
hole. The measured mean flux density is of 0.35 mJy, with a spectral index
alpha=+ 0.09\pm0.19$ (such that S_nu \propto nu^{alpha}). Synchrotron emission
from an inhomogeneous partially self-absorbed outflow of plasma accounts for
the flat/inverted radio spectrum, in analogy with hard state black hole X-ray
binaries, indicating that a steady jet is being produced between a few 10^{-6}
and a few per cent of the Eddington X-ray luminosity.


title:
Gravitational lens under perturbations: Symmetry of perturbing
  potentials with invariant caustics

abstract:
  When the gravitational lensing potential can be approximated by that of
circularly symmetric system affected by weak perturbations, it is found that
the shape of the resulting (tangential) caustics is entirely specified by the
local azimuthal behaviour of the affecting perturbations. This provides a
common mathematical groundwork for understanding problems such as the
close-wide (d <-> 1/d) separation degeneracy of binary lens microlensing
lightcurves and the shear-ellipticity degeneracy of quadruple image lens
modelling.


title:
Precision radial velocities of double-lined spectroscopic binaries with
  an iodine absorption cell

abstract:
  A spectroscopic technique employing an iodine absorption cell (I_2) to
superimpose a reference spectrum onto a stellar spectrum is currently the most
widely adopted approach to obtain precision radial velocities of solar-type
stars. It has been used to detect ~80 extrasolar planets out of ~130 know. Yet
in its original version, it only allows us to measure precise radial velocities
of single stars. In this paper, we present a novel method employing an I_2
absorption cell that enables us to accurately determine radial velocities of
both components of double-lined binaries. Our preliminary results based on the
data from the Keck I telescope and HIRES spectrograph demonstrate that 20-30
m/s radial velocity precision can be routinely obtained for "early" type
binaries (F3-F8). For later type binaries, the precision reaches ~10 m/s. We
discuss applications of the technique to stellar astronomy and searches for
extrasolar planets in binary systems. In particular, we combine the
interferometric data collected with the Palomar Testbed Interferometer with our
preliminary precision velocities of the spectroscopic double-lined binary HD
4676 to demonstrate that with such a combination one can routinely obtain
masses of the binary components accurate at least at the level of 1.0%.


title: Polarized dust emission of magnetized molecular cloud cores

abstract:
  We compute polarization maps for molecular cloud cores modeled as magnetized
singular isothermal toroids, under the assumption that the emitting dust grains
are aspherical and aligned with the large-scale magnetic field. We show that,
depending on the inclination of the toroid with the line-of-sight, the bending
of the magnetic field lines resulting from the need to counteract the inward
pull of gravity naturally produces a depolarization effect toward the centre of
the map. We compute the decrease of polarization degree with increasing
intensity for different viewing angles and frequencies, and we show that an
outward increasing temperature gradient, as expected in starless cores heated
by the external radiation field, enhances the decrease of polarization. We
compare our results with recent observations, and we conclude that this
geometrical effect, together with other mechanisms of depolarization, may
significantly contribute to the decrease of polarization degrees with intensity
observed in the majority of molecular cloud cores. Finally, we consider the
dependence of the polarization degree on the dust temperature gradient
predicted for externally heated clouds, and we briefly comment on the limits of
the Chandrasekhar-Fermi formula to estimate the magnetic field strength in
molecular cloud cores.


title:
Evolution strategies applied to the problem of line profile
  decomposition in QSO spectra

abstract:
  We describe the decomposition of QSO absorption line ensembles applying an
evolutionary forward modelling technique. The modelling is optimized using an
evolution strategy (ES) based on a novel concept of completely derandomized
self-adaption. The algorithm is described in detail. Its global optimization
performance in decomposing a series of simulated test spectra is compared to
that of classical deterministic algorithms. Our comparison demonstrates that
the ES is a highly competitive algorithm capable to calculate the optimal
decomposition without requiring any particular initialization.


title: Optimizing the yield of Sunyaev-Zel'dovich cluster surveys

abstract:
  We consider the optimum depth of a cluster survey selected using the
Sunyaev-Zel'dovich effect. By using simple models for the evolution of the
cluster mass function and detailed modeling for a variety of observational
techniques, we show that the optimum survey yield is achieved when the average
size of the clusters selected is close to the size of the telescope beam. For a
total power measurement, we compute the optimum noise threshold per beam as a
function of the beam size and then discuss how our results can be used in more
general situations. As a by-product we gain some insight into what is the most
advantageous instrumental set-up. In the case of beam switching observations
one is not severely limited if one manages to set the noise threshold close to
the point which corresponds to the optimum yield. By defining a particular
reference configuration, we show how our results can be applied to
interferometer observations. Considering a variety of alternative scenarios, we
discuss how robust our conclusions are to modifications in the cluster model
and cosmological parameters. The precise optimum is particularly sensitive to
the amplitude of fluctuations and the profile of the gas in the cluster.


title: Eclipsing Binaries in the Young LMC Cluster NGC 1850

abstract:
  I present light curves for two detached eclipsing binary stars in the region
of the LMC cluster NGC 1850, which is possibly a young globular cluster still
in formation. One, a likely spectral type O star, is a newly detected eclipsing
binary in the region of the very young subcluster NGC 1850A. This binary is
among a small number of highly massive O-type stars in binary systems found in
LMC clusters. These two eclipsing binaries are the first discovered in the well
studied NGC 1850, and the O-type star is the first eclisping binary found in
NGC 1850A. Light curves for two NGC 1850 region Cepheid variables are also
shown. Discovering two eclipsing binaries in the young globlular-like cluster
NGC 1850 is discussed in terms of the importance of the binary fraction to
globular cluster evolution.


title: CMB temperature and polarisation pseudo-Cl estimators and covariances

abstract:
  We develop the pseudo-Cl method for reconstructing the Cosmic Microwave
Background (CMB) temperature and polarization auto- and cross-power spectra,
and estimate the pseudo-Cl covariance matrix for a realistic experiment on the
cut sky. We calculate the full coupling equations for all six possible CMB
power spectra, relating the observed pseudo-Cl's to the underlying all-sky
Cl's, and test the reconstruction on both full-sky and cut-sky simulated CMB
data sets. In particular we consider the reconstruction of the Cl from upcoming
ground-based polarization experiments covering areas of a few hundred sq.
degrees and find that the method is fast, unbiased and performs well over a
wide range of multipoles from l=2 to l=2500. We then calculate the full
covariance matrix between the modes of the pseudo-temperature and polarization
power spectra, assuming that the underlying CMB fields are Gaussian randomly
distributed. The complexity of the covariance matrix prohibits its rapid
calculation, required for parameter estimation. Hence we present an
approximation for the covariance matrix in terms of convolutions of the
underlying power spectra. The coupling matrices in these expressions can be
estimated by fitting to numerical simulations, circumventing direct and slow
calculation, and further, inaccurate analytic approximations. We show that
these coupling matrices are mostly independent of cosmology, and that the full
covariance matrix for all six pseudo-Cl power spectra can be quickly and
accurately calculated for any given cosmological model using this method. We
compare these semi-analytic covariance matrices against simulations and find
good agreement, the accuracy of which depends mainly on survey area and the
range of cosmological parameters considered.


title: Neutrino Emission from Ungapped Quark Matter

abstract:
  We study neutrino emission from a normal, ungapped, quark phase in the core
of a compact star. Neutrino emission from non-interacting quark matter leads to
an emissivity that scales as $\epsilon\sim T^7$. We show that the emissivity is
enhanced by a combination of Fermi liquid and non-Fermi liquid effects. Fermi
liquid effects lead to an emissivity that scales as $\epsilon\sim \alpha_s
T^6$, as originally shown by Iwamoto. We demonstrate that non-Fermi liquid
effects further enhance the rate, leading to $\epsilon\sim \alpha_s^3
T^6\log(m/T)^2$, where $m$ is the electric screening scale and $m\gg T$ under
the conditions found in compact stars. We show, however, that combined with
non-Fermi liquid effects in the specific heat the enhancement in the emissivity
only leads to a modest reduction in the temperature of the star at late times.
Our results confirm existing bounds on the presence of ungapped quark matter in
compact stars. We also discuss neutrino emission from superconducting phases
with ungapped fermionic excitations.


title: The Rise of the s-Process in the Galaxy

abstract:
  From newly-obtained high-resolution, high signal-to-noise ratio spectra the
abundances of the elements La and Eu have been determined over the stellar
metallicity range -3<[Fe/H]<+0.3 in 159 giant and dwarf stars. Lanthanum is
predominantly made by the s-process in the solar system, while Eu owes most of
its solar system abundance to the r-process. The changing ratio of these
elements in stars over a wide metallicity range traces the changing
contributions of these two processes to the Galactic abundance mix. Large
s-process abundances can be the result of mass transfer from very evolved
stars, so to identify these cases, we also report carbon abundances in our
metal-poor stars. Results indicate that the s-process may be active as early as
[Fe/H]=-2.6, alalthough we also find that some stars as metal-rich as [Fe/H]=-1
show no strong indication of s-process enrichment. There is a significant
spread in the level of s-process enrichment even at solar metallicity.


title:
Neutrino Scattering, Absorption and Annihilation above the accretion
  disks of Gamma Ray Bursts

abstract:
  The central engine that drives gamma ray burst (GRB) explosions may derive
from the ability of electrons/positrons and nucleons to tap into the momentum
and energy from the large neutrino luminosity emitted by an accretion disk
surrounding a black hole. This transfer of momentum and energy occurs due to
neutrino absorption, scattering, and annihilation and the non-spherical
geometry of the source both increases the annihilation efficiency and, close to
the black hole, directs the momentum transfer towards the disk axis. We present
annihilation efficiencies and the momentum/energy transfers for a number of
accretion disk models and compute the critical densities of infalling material
below which the transfer of neutrino momentum/energy will lead to an explosion.
Models in which the neutrinos and antineutrinos become trapped within the disk
have noticeably different momentum and energy deposition structure compared to
thin disk models that may lead to significant differences in the explosion
dynamics.


title: Long Period Variables in the LMC: Results from MACHO and 2MASS

abstract:
  We use the eight year light-curve database from the MACHO (MAssive Compact
Halo Objects) project together with infrared colors and magnitudes from 2MASS
(the Two Micron All Sky Survey) to identify a sample of 22,000 long period
variables in the Large Magellanic Cloud (referred to hereafter as LMC LPVs). A
period-luminosity diagram of these stars reveals six well-defined sequences, in
substantial agreement with previous analyses of samples from OGLE (Optical
Gravitational Lensing Experiment). In our analysis we identify analogues to
galactic LPVs in the LMC LPV sample. We find that carbon-dominated AGB stars
populate only two of the sequences, one of which includes the Mira variables.
The high-luminosity end of the same two sequences are also the location of the
only stars with $J-K_s > 2$, indicating that they are enshrouded in dust. The
unknown mechanism that drives the variability of stars in the longest period
produces different morphology in the period-luminosity diagram as compared to
the shortest period sequences, which are thought to be caused by pulsation. In
particular, the longest period sequence extends to lower luminosity RGB stars
and the luminosity function does not peak among the AGB stars. We point out
several features which will constrain new models of the period-luminosity
sequences.


title:
High Resolution, Long - Slit Spectroscopy of VY CMa: The Evidence for
  Localized High Mass Loss Events

abstract:
  High spatial and spectral resolution spectroscopy of the OH/IR supergiant VY
CMa and its circumstellar ejecta reveals evidence for high mass loss events
from localized regions on the star occurring over the past 1000 years. The
reflected absorption lines and the extremely strong K I emission lines show a
complex pattern of velocities in the ejecta. We show that the large, dusty NW
arc, expanding at 50 km/sec with respect to the embedded star, is kinematically
distinct from the surrounding nebulosity and was ejected about 400 years ago.
Other large, more filamentary loops were probably expelled as much as 800 to
1000 years ago while knots and small arcs close to the star resulted from more
recent events 100 to 200 years ago. The more diffuse, uniformly distributed gas
and dust is surprisingly stationary with little or no velocity relative to the
star. This is not what we would expect for the circumstellar material from an
evolved red supergiant with a long history of mass loss. We therefore suggest
that the high mass loss rate for VY CMa is a measure of the mass carried out by
these specific ejections accompanied by streams or flows of gas through low
density regions in the dust envelope. VY CMa may thus be our most extreme
example of stellar activity, but our results also bring into question the
evolutionary state of this famous star. In a separate Appendix, we discuss the
origin of the very strong K I and other rare emission lines in its spectrum.


title: Discovery of a New Low-Latitude Milky Way Globular Cluster using GLIMPSE

abstract:
  Spitzer Space Telescope imaging as part of the Galactic Legacy Mid-Plane
Survey Extraordinaire (GLIMPSE) reveals a previously unidentified low-latitude
rich star cluster near l=31.3 degrees, b=-0.1 degrees. Near-infrared JHK'
photometry from the Wyoming Infrared Observatory indicates an extinction of A_V
~ 15+/-3 mag for cluster members. Analysis of 13CO features along the same
sightline suggests a probable kinematic distance of 3.1 -- 5.2 kpc. The new
cluster has an angular diameter of ~1-2 pc, a total magnitude m_{K_0}=2.1
corrected for extinction, and a luminosity of M_K ~ -10.3 at 3.1 kpc. In
contrast to young massive Galactic clusters with ages <100 Myr, the new cluster
has no significant radio emission. Comparison to theoretical K-band luminosity
functions indicates an age of at least several Gyr and a mass of at least 10^5
solar masses. Unlike known old open clusters, this new cluster lies in the
inner Galaxy at R_{GC} ~ 6.1 kpc. We designate this object ``GLIMPSE-C01'' and
classify it as a Milky Way globular cluster passing through the Galactic disk.
We also identify a region of star formation and fan-shaped outflows from young
stellar objects in the same field as the cluster. The cluster's passage through
the Galactic molecular layer may have triggered this star formation activity.


title:
The contribution to the perihelion advanced of Mercury arising out of
  the dependence of mass on gravitational potential

abstract:
  The effect of general relativistic prediction of the dependence of mass on
gravitational potential on the dynamics of a planet moving around the sun is
shown to have a negative contribution of 14.326 arcsec/century towards the
overall non-Newtonian perihelion advance of Mercury.


title:
Wide band X-ray Imager (WXI) and Soft Gamma-ray Detector (SGD) for the
  NeXT Mission

abstract:
  The NeXT mission has been proposed to study high-energy non-thermal phenomena
in the universe. The high-energy response of the super mirror will enable us to
perform the first sensitive imaging observations up to 80 keV. The focal plane
detector, which combines a fully depleted X-ray CCD and a pixellated CdTe
detector, will provide spectra and images in the wide energy range from 0.5 keV
to 80 keV. In the soft gamma-ray band up to ~1 MeV, a narrow field-of-view
Compton gamma-ray telescope utilizing several tens of layers of thin Si or CdTe
detector will provide precise spectra with much higher sensitivity than present
instruments. The continuum sensitivity will reach several times 10^(-8)
photons/s/keV/cm^(2) in the hard X-ray region and a few times10^(-7)
photons/s/keV/cm^(2) in the soft gamma-ray region.


title: Hydrogen Burning on Magnetar Surfaces

abstract:
  We compute the rate of diffusive nuclear burning for hydrogen on the surface
of a "magnetar" (Soft Gamma-Ray Repeater or Anomalous X-Ray Pulsar). We find
that hydrogen at the photosphere will be burned on an extremely rapid timescale
of hours to years, depending on composition of the underlying material.
Improving on our previous studies, we explore the effect of a maximally thick
"inert" helium layer, previously thought to slow down the burning rate. Since
hydrogen diffuses faster in helium than through heavier elements, we find this
helium buffer actually increases the burning rate for magnetars. We compute
simple analytic scalings of the burning rate with temperature and magnetic
field for a range of core temperature. We conclude that magnetar photospheres
are very unlikely to contain hydrogen. This motivates theoretical work on heavy
element atmospheres that are needed to measure effective temperature from the
observed thermal emission and constrains models of AXPs that rely on magnetar
cooling through thick light element envelopes.


title:
SparsePak: A Formatted Fiber Field-Unit for The WIYN Telescope Bench
  Spectrograph. II. On-Sky Performance

abstract:
  We present a performance analysis of SparsePak and the WIYN Bench
Spectrograph for precision studies of stellar and ionized gas kinematics of
external galaxies. We focus on spectrograph configurations with echelle and
low-order gratings yielding spectral resolutions of ~10000 between 500-900nm.
These configurations are of general relevance to the spectrograph performance.
Benchmarks include spectral resolution, sampling, vignetting, scattered light,
and an estimate of the system absolute throughput. Comparisons are made to
other, existing, fiber feeds on the WIYN Bench Spectrograph. Vignetting and
relative throughput are found to agree with a geometric model of the optical
system. An aperture-correction protocol for spectrophotometric standard-star
calibrations has been established using independent WIYN imaging data and the
unique capabilities of the SparsePak fiber array. The WIYN
point-spread-function is well-fit by a Moffat profile with a constant power-law
outer slope of index -4.4. We use SparsePak commissioning data to debunk a
long-standing myth concerning sky-subtraction with fibers: By properly treating
the multi-fiber data as a ``long-slit'' it is possible to achieve precision sky
subtraction with a signal-to-noise performance as good or better than
conventional long-slit spectroscopy. No beam-switching is required, and hence
the method is efficient. Finally, we give several examples of science
measurements which SparsePak now makes routine. These include H$\alpha$
velocity fields of low surface-brightness disks, gas and stellar
velocity-fields of nearly face-on disks, and stellar absorption-line profiles
of galaxy disks at spectral resolutions of ~24,000.


title: Physics of Outflows: the Binary Protostar L1551 IRS5 and its Jets

abstract:
  Recent observations of the deeply embedded L1551 IRS5 system permit the
detailed examination of the properties of both the stellar binary and the
binary jet. For the individual components of the stellar binary, we determine
their masses, mass accretion rates, effective temperatures and luminosities.
For the atomic wind/jet flow, we determine the mass loss rate, yielding
observationally determined values of the ratio of the mass loss to the mass
accretion rate, f. For the X-ray emitting region in the northern jet, we have
obtained the jet-velocity and derive the extinction and the densities on
different spatial scales. Examining the observational evidence within the
framework of the x-wind theory leads us to conclude that these models are
indeed potentially able to account for the observational data for this deeply
embedded source.


title: Extracting clean supernova spectra

abstract:
  We use a new technique to extract the spectrum of a supernova from that of
the contaminating background of its host galaxy, and apply it to the specific
case of high-redshift Type Ia supernova (SN Ia) spectroscopy. The algorithm is
based on a two-channel iterative technique employing the Richardson-Lucy
restoration method and is implemented in the IRAF code 'specinholucy'. We run
the code both on simulated (SN Ia at z=0.5 embedded in a bright host galaxy)
and observed (SNe Ia at various phases up to z=0.236) data taken with VLT+FORS1
and show the advantages of using such a deconvolution technique in comparison
with less elaborate methods. This paper is motivated by the need for optimal
supernova spectroscopic data reduction in order to make meaningful comparisons
between the low and high-redshift SN Ia samples. This may reveal subtle
evolutionary and systematic effects that could depend on redshift and bias the
cosmological results derived from comparisons of local and high-z SNe Ia in
recent years. We describe the various aspects of the extraction in some detail
as guidelines for the first-time user and present an optimal observing strategy
for successful implementation of this method in future high-z SN Ia
spectroscopic follow-up programmes.


title: Compact stars in the standard model - and beyond

abstract:
  In the context of the standard model of particle physics, there is a definite
upper limit to the density of stable compact stars. However, if there is a
deeper layer of constituents, below that of quarks and leptons, stability may
be re-established far beyond this limiting density and a new class of compact
stars could exist. These objects would cause gravitational lensing of white
dwarfs and gamma-ray bursts, which might be observable as a diffraction pattern
in the spectrum. Such observations could provide means for obtaining new clues
about the fundamental particles and the origin of cold dark matter.


title:
Combined constraints on Cardassian models from supernovae, CMB and
  large-scale structure observations

abstract:
  We confront Cardassian models with recent observational data. These models
can be viewed either as purely phenomenological modifications of the Friedmann
equation, or as arising from cosmic fluids with non-standard properties. In the
first case, we find that the models are consistent with the data for a wide
range of parameters but no significant preference over the Lambda-CDM model is
found. In the latter case we find that the fact that the sound speed is
non-zero in these models makes them inconsistent with the galaxy power spectrum
from the Sloan Digital Sky Survey.


title:
Uncertainties of Antiproton and Positron Spectra from B/C Data and
  mSUGRA Contributions for Clumpy Halos

abstract:
  We have studied the variation of $e^+$ and $\bar p$ top of the atmosphere
spectra due to the parameters uncertainties of the Milky Way geometry,
propagation models and cross sections. We have used the B/C data and Galprop
code for propagation analysis. We have also derived the uncertainty bands for
subFe/Fe ratio, H and He. Finally we have considered a neutralino induced
component in the mSUGRA framework. We conclude that even in the case of
diffusion convection model for the standard propagation, where secondary
spectra gives a good fit of the data, SUSY contribution can not be excluded up
to now due to the overall uncertainties.


title: Dynamical triggering of starbursts

abstract:
  Galaxy interactions/mergers, gravitational instabilities and density waves,
such as bars, are frequently invoked to trigger starbursts. These mechanisms
have been explored through numerical simulations, with the help of various star
formation recipes. Gravitational instabilities are necessary to initiate star
formation, but the main trigger might be the gas flows, to provide sufficient
fuel in a short time-scale. Gas accretion is also acting on the dynamics, in
favoring bars/spirals, which will drive the gas inwards. Large amounts of
external gas accretion are required to explain the bar frequency, and this
accretion rate can be provided by the cosmic filaments, as supported by
cosmological simulations. Subsequent interactions can then trigger starbursts
by driving this accreted gas inwards.


title:
Lens binarity vs limb darkening in close-impact galactic microlensing
  events

abstract:
  Although point caustics harbour a larger potential for measuring the
brightness profile of stars during the course of a microlensing event than
(line-shaped) fold caustics, the effect of lens binarity significantly limits
the achievable accuracy. Therefore, corresponding close-impact events make a
less favourable case for limb-darkening measurements than those events that
involve fold-caustic passages, from which precision measurements can easily and
routinely be obtained. Examples involving later Bulge giants indicate that a ~
10 % misestimate on the limb-darkening coefficient can result with the
assumption of a single-lens model that looks acceptable, unless the precision
of the photometric measurements is pushed below the 1 %-level even for these
favourable targets. In contrast, measurement uncertainties on the proper motion
between lens and source are dominated by the assessment of the angular radius
of the source star and remain practically unaffected by lens binarity. Rather
than judging the goodness-of-fit by means of a chi^2 test only, run tests
provide useful additional information that can lead to the rejection of models
and the detection of lens binarity in close-impact microlensing events.


title:
Observational population studies of cataclysmic variables - The golden
  era of surveys

abstract:
  We review the properties of the currently known CV population from an
accountants point of view. In particular, it is examined to what extent
different selection mechanisms (variability, X-ray emission, colours,
spectroscopic properties) affect the observed CV orbital period distribution.
Large-scale surveys provide homogeneously selected CV samples, for which
observational biases can in principle be modelled. Such samples will eventually
provide the essential observational input for an improved understanding of CV
evolution, and we highlight the impact of several completed and on-going
surveys.


title: Quantum-Gravity phenomenology and high energy particle propagation

abstract:
  Quantum-gravity effects may introduce relevant consequences for the
propagation and interaction of high energy cosmic rays particles. Assuming the
space-time foamy structure results in an intrinsic uncertainty of energy and
momentum of particles, we show how low energy (under GZK) observations can
provide strong constraints on the role of the fluctuating space-time structure.


title: Nuclear Starbursts in Nearby Seyfert Galaxies

abstract:
  Active galaxies are often associated with starbursts, which are possible
sources of fuelling for the nuclear black holes. By means of optical (3500-7500
A) spectroscopic and narrow-band photometric data (H_alpha+[NII]6548,6583 and
[OIII]5007) it is possible to detect starburst features in active nuclei and to
study the correlation with Seyfert type and the surrounding environment. Here
we present evidences of young stellar populations (HI high order Balmer lines)
and extended H_alpha emission (indicative of HII regions) in 6 nearby Seyfert
galaxies (z < 0.02). These very preliminary results seem to suggest that the
nuclear starburst presence does not depend on the Seyfert type, favouring the
hypothesis of the AGN Unified Model. By estimating the present SFR (< 10^6
years) and recent SFR (< 10^9 years) we observe that these objects have
experienced most of star formation episodes in past epochs. This supports the
hypothesis of a starburst-AGN connection, favouring an evolutionary scenario in
which the AGN survives to the starburst.


title: Expansive components in H II regions

abstract:
  We study the presence of low intensity high velocity components, which we
have termed wing features in the integrated Halpha emission line profiles of
the HII region populations of the spiral barred galaxies NGC 1530, NGC 3359 and
NGC 6951. We find that more than a third of the HII region line profiles in
each galaxy show these components. The highest fraction is obtained in the
galaxy whose line profiles show the best S:N, which suggests that wing features
of this type may well exist in most, if not all, HII region line profiles.
Applying selection criteria to the wing features, we obtain a sample of HII
regions with clearly defined high velocity components in their profiles.
Deconvolution of a representative sample of the line profiles eliminates any
doubt that the wing features could possibly be due to instrumental effects. We
present an analysis of the high velocity low intensity features fitting them
with Gaussian functions; the emission measures, central velocities and velocity
dispersions for the red and blue features take similar values. We interpret the
features as signatures of expanding shells inside the HII regions. Up to a
shell radius of R(shell)~0.2R(reg), the stellar winds from the central ionizing
stars appear to satisfy the energy and momentum requirements for the formation
and driving the shell. Several examples of the most luminous HII regions show
that the shells appear to have larger radii; in these cases additional
mechanisms may well be needed to explain the kinetic energies and momenta of
the shells.


title:
A New Milky Way Companion: Unusual Globular Cluster or Extreme Dwarf
  Satellite?

abstract:
  We report the discovery of SDSSJ1049+5103, an overdensity of resolved blue
stars at (\alpha_{2000}, \delta_{2000}) = (162.343, 51.051). This object
appears to be an old, metal-poor stellar system at a distance of 45 +/- 10 kpc,
with a half-light radius of 23$\pm 10$ pc and an absolute magnitude of M_V =
-3.0^{+2.0}_{-0.7}. One star that is likely associated with this companion has
an SDSS spectrum confirming it as a blue horizontal branch star at 48 kpc. The
color-magnitude diagram of SDSSJ1049+5103 contains few, if any, horizontal or
red giant branch stars, similar to the anomalously faint globular cluster AM 4.
The size and luminosity of SDSSJ1049+5103 places it at the intersection of the
size-luminosity relationships followed by known globular clusters and by Milky
Way dwarf spheroidals. If SDSSJ1049+5103 is a globular cluster, then its
properties are consistent with the established trend that the largest radius
Galactic globular clusters are all in the outer halo. However, the five known
globular clusters with similarly faint absolute magnitudes all have half-mass
radii that are smaller than SDSSJ1049+5103 by a factor of $\gtrsim$ 5. If it is
a dwarf spheroidal, then it is the faintest yet known by two orders of
magnitude, and is the first example of the ultra-faint dwarfs predicted by some
theories. The uncertain nature of this new system underscores the sometimes
ambiguous distinction between globular clusters and dwarf spheroidals. A simple
friends-of-friends search for similar blue, small scalesize star clusters
detected all known globulars and dwarfs closer than 50 kpc in the SDSS area,
but yielded no other candidates as robust as SDSSJ1049+5103.


title: Preon stars: a new class of cosmic compact objects

abstract:
  In the context of the standard model of particle physics, there is a definite
upper limit to the density of stable compact stars. However, if a more
fundamental level of elementary particles exists, in the form of preons,
stability may be re-established beyond this limiting density. We show that a
degenerate gas of interacting fermionic preons does allow for stable compact
stars, with densities far beyond that in neutron stars and quark stars. In
keeping with tradition, we call these objects "preon stars", even though they
are small and light compared to white dwarfs and neutron stars. We briefly note
the potential importance of preon stars in astrophysics, e.g., as a candidate
for cold dark matter and sources of ultra-high energy cosmic rays, and a means
for observing them.


title:
Lithium in Very Metal-poor Dwarf Stars - Problems for Standard Big Bang
  Nucleosynthesis?

abstract:
  The standard model of primordial nucleosynthesis by the Big Bang as selected
by the WMAP-based estimate of the baryon density ($\Omega_bh^2$) predicts an
abundance of $^7$Li that is a factor of three greater than the generally
reported abundance for stars on the Spite plateau, and an abundance of $^6$Li
that is about a thousand times less than is found for some stars on the
plateau. This review discusses and examines these two discrepancies. They can
likely be resolved without major surgery on the standard model of the Big Bang.
In particular, stars on the Spite plateau may have depleted their surface
lithium abundance over their long lifetime from the WMAP-based predicted
abundances down to presently observed abundances, and synthesis of $^6$Li (and
$^7$Li) via $\alpha + \alpha$ fusion reactions may have occurred in the early
Galaxy. Yet, there remain fascinating ways in which to remove the two
discrepancies involving aspects of a new cosmology, particularly through the
introduction of exotic particles.


title:
Constrained Simulations of the Magnetic Field in the Local Universe and
  the Propagation of UHECRs

abstract:
  We use simulations of LSS formation to study the build-up of magnetic fields
(MFs) in the ICM. Our basic assumption is that cosmological MFs grow in a MHD
amplification process driven by structure formation out of a seed MF present at
high z. Our LCDM initial conditions for the density fluctuations have been
statistically constrained by the observed galaxies, based on the IRAS 1.2-Jy
all-sky redshift survey. As a result, prominent galaxy clusters in our
simulation coincide closely with their real counterparts. We find excellent
agreement between RMs of our simulated clusters and observational data. The
improved resolution compared to previous work also allows us to study the MF in
large-scale filaments, sheets and voids. By tracing the propagation of UHE
protons in the simulated MF we construct full-sky maps of expected deflection
angles of protons with arrival energies E=1e20eV and 4e19eV, respectively.
Strong deflections are only produced if UHE protons cross clusters, however
covering only a small area on the sky. Multiple crossings of sheets and
filaments over larger distances may give rise to noticeable deflections,
depending on the model adopted for the magnetic seed field. Based on our
results we argue that over a large fraction of the sky the deflections are
likely to remain smaller than the present experimental angular sensitivity.
Therefore, we conclude that forthcoming air shower experiments should be able
to locate sources of UHE protons and shed more light on the nature of
cosmological MFs.


title: The Alcock-Paczynski test in redshifted twenty one centimeter maps

abstract:
  We examine the possibility of constraining the cosmological mean mass and
dark energy densities by an application of the Alcock-Paczynski test on
redshifted 21-cm maps of the epoch of reionization. The 21-cm data will be
provided as a function of frequency and angular positions on the sky. The ratio
of the frequency to angular distance scales can be determined by inspecting the
anisotropy pattern of the correlation function of brightness temperature. We
assess the sensitivity of the distance ratio to the cosmological parameters and
present a technique for disentangling geometrical distortions from redshift
space distortions caused by peculiar motions.


title: The great disk of Milky-Way satellites and cosmological sub-structures

abstract:
  We show that the shape of the observed distribution of Milky Way (MW)
satellites is inconsistent with being drawn from a cosmological sub-structure
population with a confidence of 99.5 per cent. Most of the MW satellites
therefore cannot be related to dark-matter dominated satellites.


title: The \chi Factor: Determining the Strength of Activity in Low Mass Dwarfs

abstract:
  We describe a new, distance-independent method for calculating the magnetic
activity strength in low mass dwarfs, L_{H\alpha}/L_{bol}. Using a
well-observed sample of nearby stars and cool standards spanning spectral type
M0.5 to L0, we compute ``\chi'', the ratio between the continuum flux near
H-alpha and the bolometric flux, f_{\lambda6560}/f_{bol}. This ratio may be
multiplied by the measured equivalent width of the H-alpha emission line to
yield L_{H\alpha}/L_{bol}. We provide \chi values for all objects in our
sample, as well as fits to \chi as a function of color and average values by
spectral type. This method was used by West et al.(2004) to examine trends in
magnetic activity strength in low mass stars.


title: Production of photons in a bouncing universe

abstract:
  Using a new non-singular solution,it is shown that the production of photons
in dilaton electrodynamics in a cosmological setting is increased if the effect
of matter creation on the geometry is taken into account. This increment may be
related to the problem of the origin of magnetic fields in the universe.


title:
Ram Pressure Stripping in the Low Luminosity Virgo Cluster Elliptical
  Galaxy NGC 4476

abstract:
  We present a deep VLA search for HI emission from the low-luminosity Virgo
Cluster elliptical galaxy NGC 4476, which contains 1.1 x 10^8 M_sun of
molecular gas in an undisturbed disk in regular rotation. No HI was detected.
The rms noise in the final image corresponds to a 3 sigma column density
sensitivity of 1.2 x 10^20 cm^{-2} at the position of NGC 4476, averaged over
the 4 kpc beam. The total HI mass is less than 1.5 x 10^7 M_sun. If we compare
our HI upper limit to the H_2 content, we find that NGC 4476 is extremely
deficient in HI compared to other galaxies detected in these two species. The
H_2/HI mass ratio for NGC 4476 is > 7, whereas typical H_2/HI ratios for
elliptical galaxies detected in both HI and H_2 are <~2. Based on this extreme
HI deficiency and the intra-cluster medium (ICM) density at the projected
distance from M87 we argue that either NGC 4476 has undergone ram-pressure
stripping while traveling through the Virgo cluster core or its average
molecular gas density is larger and its interstellar UV field is smaller than
in typical spiral galaxies. NGC 4476 is located 12' in projection from M87,
which causes extreme continuum confusion problems. We also discuss in detail
the techniques used for continuum subtraction. The spectral dynamic range of
our final image is 50,000 to 1.


title:
SDSSJ140228.22+632133.3: A New Spectroscopically Selected Gravitational
  Lens

abstract:
  (abridged) We present Gemini integral-field unit (IFU) spectroscopy and
Hubble Space Telescope (HST) F435W- and F814W-band images of a new four-image
gravitational lens, SDSSJ140228.22+632133.3, obtained as part of an HST
Snapshot program designed to expand the sample of known gravitational lenses
amenable to detailed photometric, lensing, and dynamical studies. The lens is a
smooth elliptical galaxy at a redshift of z_l = 0.2046 +/- 0.0001 with a Sloan
r-band magnitude of 17.00 +/- 0.05 and a stellar velocity dispersion of 267 +/-
17 km s^-1, obtained from its SDSS spectrum. Multiple emission lines place the
quadruply-imaged source at a redshift of z_s = 0.4814 +/- 0.0001. The
best-fitting singular isothermal ellipsoid lens model gives an Einstein radius
b = 1.35" +/- 0.05" (or [4.9 +/- 0.2] h_65^-1 kpc), corresponding to a total
mass of (30.9 +/- 2.3) x 10^10 h_65^-1 M_sun within the critical curve. In
combination with HST photometry this gives a rest-frame B-band mass-to-light
ratio of (8.1 +/- 0.7) h_65 times solar within the same region. The lens model
predicts a luminosity-weighted stellar dispersion within the 3"-diameter SDSS
aperture of sigma_* ~= 270 km s^-1, in good agreement with the observed value.
Using the model to de-lens the four lensed images yields a source with a
smooth, monotonically-decreasing brightness distribution.


title: The Drag Induced Resonant Capture for Kuiper Belt Objects

abstract:
  It has been an interesting question that why there are one-third of Kuiper
Belt Objects (KBOs) trapped into the 3:2 resonance but, in contrast, only
several KBOs are claimed to be associated with the 2:1 resonance. In a model
proposed by Zhou et al. (2002), the stochastic outward migration of the Neptune
could reduce the number of particles in the 2:1 resonance and thus the objects
in the 3:2 resonance become more distinct. As a complementary study, we
investigate the effect of proto-stellar discs on the resonance capture. Our
results show that the gaseous drag of a proto-stellar disc can trap KBOs into
the 3:2 resonance rather easily. In addition, no objects are captured into the
2:1 resonance in our simulation.


title: A Spreading Layer Origin for Dwarf Nova Oscillations

abstract:
  Dwarf nova outbursts often show coherent ($Q\sim10^4-10^6$) sinusoidal
oscillations with the largest pulsed fraction in the extreme ultraviolet.
Called dwarf nova oscillations (DNOs), they have periods of $P\approx3-40 {\rm
s}$ and scale with luminosity as $P\propto L^{-\beta}$ with
$\beta\approx0.1-0.2$. We propose that DNOs may be produced by nonradial
oscillations in a thin hydrostatic layer of freshly accreted material, the
``spreading layer'' (SL), at the white dwarf (WD) equator. This would naturally
explain a number of key properties of DNOs, including their frequency range,
sinusoidal nature, sensitivity to accretion rate, and why they are only seen
during outburst. In support of this hypothesis we construct a simple model that
treats the SL as a cavity containing shallow surface waves, each with the same
radial structure, but split into three different modes denoted by their
azimuthal wavenumber, $m$. The $m=0$ latitudinally propagating mode best
matches the periods and scalings associated with most DNOs, and DNOs with
periods shorter than the WD Keplerian period are explained by the $m=-1$
prograde mode. We also predict a third set of oscillations, produced by the
$m=1$ retrograde mode, and show its expected dependence on accretion rate.


title: MHD tidal waves on a spinning magnetic compact star

abstract:
  In an X-ray binary system, the companion star feeds the compact neutron star
with plasma materials via accretions. The spinning neutron star is likely
covered with a thin "magnetized ocean" and may support {\it magnetohydrodynamic
(MHD) tidal waves}. While modulating the thermal properties of the ocean, MHD
tidal waves periodically shake the base of the stellar magnetosphere that traps
energetic particles, including radiating relativistic electrons. For a radio
pulsar, MHD tidal waves in the stellar surface layer may modulate radio
emission processes and leave indelible signatures on timescales different from
the spin period. Accretion activities are capable of exciting these waves but
may also obstruct or obscure their detections meanwhile. Under fortuitous
conditions, MHD tidal waves might be detectable and offer valuable means to
probe properties of the underlying neutron star. Similar situations may also
occur for a cataclysmic variable -- an accretion binary system that contains a
rotating magnetic white dwarf. This Letter presents the theory for MHD tidal
waves in the magnetized ocean of a rotating degenerate star and emphasizes
their potential diagnostics in X-ray and radio emissions.


title:
The r-process nucleosynthesis: a continued challenge for nuclear physics
  and astrophysics

abstract:
  The identification of the astrophysical site and the specific conditions in
which r-process nucleosynthesis takes place remain unsolved mysteries of
astrophysics. The present paper emphasizes some important future challenges
faced by nuclear physics in this problem, particularly in the determination of
the radiative neutron capture rates by exotic nuclei close to the neutron drip
line and the fission probabilities of heavy neutron-rich nuclei. These
quantities are particularly relevant to determine the composition of the matter
resulting from the decompression of initially cold neutron star matter. New
detailed r-process calculations are performed and the final composition of
ejected inner and outer neutron star crust material is estimated. We discuss
the impact of the many uncertainties in the astrophysics and nuclear physics on
the final composition of the ejected matter. The similarity between the
predicted and the solar abundance pattern for A > 140 nuclei as well as the
robustness of the prediction with varied input parameters makes this scenario
one of the most promising that deserves further exploration.


title: 3D-Kinematics of White Dwarfs from the SPY-Project

abstract:
  We present kinematics of a sample of 398 DA white dwarfs from the SPY project
(ESO SN Ia Progenitor surveY) and discuss kinematic criteria for a distinction
of thin disk, thick disk, and halo populations. This is the largest homogeneous
sample of white dwarfs for which 3D space motions have been determined. Radial
velocities and spectroscopic distances obtained by the SPY project are combined
with our measurements of proper motions to derive 3D space motions. Galactic
orbits and further kinematic parameters are computed. Our kinematic criteria
for assigning population membership are deduced from a sample of F and G stars
taken from the literature for which chemical criteria can be used to
distinguish between thin disk, thick disk and halo. Our kinematic population
classification scheme is based on the position in the U-V-velocity diagram, the
position in the J_z-eccentricity diagram and the Galactic orbit. We combine
this with age estimates and find seven halo and 23 thick disk white dwarfs.


title:
Strong Lensing Probabilities in a Cosmological Model with a Running
  Primordial Power Spectrum

abstract:
  The combination of the first-year Wilkinson Microwave Anisotropy Probe (WMAP)
data with other finer scale cosmic microwave background (CMB) experiments (CBI
and ACBAR) and two structure formation measurements (2dFGRS and Lyman $\alpha$
forest) suggest a $\Lambda$CDM cosmological model with a running spectral power
index of primordial density fluctuations. Motivated by this new result on the
index of primordial power spectrum, we present the first study on the predicted
lensing probabilities of image separation in a spatially flat $\Lambda$CDM
model with a running spectral index (RSI-$\Lambda$CDM model). It is shown that
the RSI-$\Lambda$CDM model suppress the predicted lensing probabilities on
small splitting angles of less than about 4$^{''}$ compared with that of
standard power-law $\Lambda$CDM (PL-$\Lambda$CDM) model.


title: XMM-Newton spectroscopy of an X-ray selected sample of RL AGNs

abstract:
  This paper presents the X-ray spectroscopy of an X-ray selected sample of 25
radio-loud (RL) AGNs extracted from the XBSS sample. The main goal is to study
the origin of the X-ray spectral differences usually observed between
radio-loud and radio-quiet (RQ) AGNs. To this end, a comparison sample of 53 RQ
AGNs has been also extracted from the same XBSS sample and studied together
with the sample of RL AGNs. We have focused the analysis on the distribution of
the X-ray spectral indices of the power-law component that models the large
majority of the spectra in both samples. We find that the mean X-ray energy
spectral index is very similar in the 2 samples and close to alpha_X~1.
However, the intrinsic distribution of the spectral indices is significantly
broader in the sample of RL AGNs. In order to investigate the origin of this
difference, we have divided the RL AGNs into blazars and ``non-blazars'', on
the basis of the available optical and radio information. We find strong
evidence that the broad distribution observed in the RL AGN sample is mainly
due to the presence of the blazars. Furthermore, within the blazar class we
have found a link between the X-ray spectral index and the value of the
radio-to-X-ray spectral index suggesting that the observed X-ray emission is
directly connected to the emission of the relativistic jet. This trend is not
observed among the ``non-blazars'' RL AGNs. This favours the hypothesis that,
in these latter sources, the X-ray emission is not significantly influenced by
the jet emission and it has probably an origin similar to the RQ AGNs. Overall,
the results presented here indicate that the observed distribution of the X-ray
spectral indices in a given sample of RL AGNs is strongly dependent on the
amount of relativistic beaming present in the selected sources.


title:
Subluminous O stars from the ESO Supernova Progenitor Survey -
  Observation versus Theory

abstract:
  The ESO Supernova Progenitor Survey (SPY) has identified 58 (mostly
helium-rich) subluminous O stars. We use the Balmer line strength to
distinguish sdO from He-sdO (no Balmer lines) and present the results of the
analyses of high resolution optical VLT-UVES spectra using an extensive grid of
NLTE atmosphere models covering a large range in Teff, log g and helium
abundances. The stellar atmospheric parameters are derived from line profile
fits using a chi**2 technique. The resulting distribution in the (Teff, log g)
diagram as well as the luminosity function are discussed in the context of
stellar evolution scenarios. By combining our results with those for the sdB
stars from SPY (Lisker et al. 2004) we discuss the implications for binary
population synthesis models of Han et al. (2003). Models with a low CEE
efficiency and a constant mass ratio distribution provide a reasonable
explanation of the observed properties of the SPY sample of sdB and sdO stars
indicating that the sdO stars form the hot and luminous extension of the sdB
sequence. However, for the He-sdO stars none of the considered evolution
scenarios are in agreement with the measured parameters of our programme stars.
We conclude that He-sdO stars are formed by a different process than the sdB
and sdO stars.


title: Looking for obscured QSOs in the X-ray emitting ERO population

abstract:
  We present XMM-Newton data centered on one of the MUNICS Near Infrared
Cluster Survey fields (S2F1) and we discuss the X-ray properties of the 6 X-ray
emitting EROs found. For one of them we have already obtained the redshift
using near-infrared spectroscopic data, while for the remaining 5 EROs the
analysis is based on photometric redshifts. We find evidence for the presence
of an X-ray obscured QSO in at least 5 out of the 6 X-ray emitting EROs. For
these 5 objects we derive intrinsic (2-10 keV) luminosities in excess of 10^44
erg/s and intrinsic column densities higher than 10^22 cm^-2. These values have
been obtained through a basic X-ray spectral analysis for the three brightest
sources and through the analysis of the hardness ratios for the remaining two.
All of these 5 X-ray emitting EROs appear extended in the optical/near-infrared
bands indicating that the host galaxy emission dominates at these wavelengths.
This suggests that the hosted AGNs are likely to be absorbed also in the
optical/near-infrared bands: i.e. they are likely X-ray obscured possible type
2 QSOs. For the remaining ERO the presence of an AGN is suggested both by its
high 0.5-2 keV luminosity (L(0.5-2 keV)~10^43 erg/s) and by its
X-ray-to-optical flux ratio. In this case the quality of the present data
prevents us from placing firm constraints on the AGN type hosted. Finally, the
near-IR spectrum obtained for one of the 6 EROs classifies the host galaxy as
an elliptical at z~1.7 with a stellar mass well in excess of 10^11 M_\odot.
This result corroborates the possible link between the QSO activity and the
formation of massive spheroids.


title: Chemical Evolution in the Carina Dwarf Spheroidal

abstract:
  We present metallicities for 487 red giants in the Carina dwarf spheroidal
(dSph) galaxy that were obtained from FLAMES low-resolution Ca triplet (CaT)
spectroscopy. We find a mean [Fe/H] of -1.91 dex with an intrinsic dispersion
of 0.25 dex, whereas the full spread in metallicities is at least one dex. The
analysis of the radial distribution of metallicities reveals that an excess of
metal poor stars resides in a region of larger axis distances. These results
can constrain evolutionary models and are discussed in the context of chemical
evolution in the Carina dSph.


title: Survey on solar X-ray flares and associated coherent radio emissions

abstract:
  The radio emission during 201 X-ray selected solar flares was surveyed from
100 MHz to 4 GHz with the Phoenix-2 spectrometer of ETH Zurich. The selection
includes all RHESSI flares larger than C5.0 jointly observed from launch until
June 30, 2003. Detailed association rates of radio emission during X-ray flares
are reported. In the decimeter wavelength range, type III bursts and the
genuinely decimetric emissions (pulsations, continua, and narrowband spikes)
were found equally frequently. Both occur predominantly in the peak phase of
hard X-ray (HXR) emission, but are less in tune with HXRs than the
high-frequency continuum exceeding 4 GHz, attributed to gyrosynchrotron
radiation. In 10% of the HXR flares, an intense radiation of the above genuine
decimetric types followed in the decay phase or later. Classic meter-wave type
III bursts are associated in 33% of all HXR flares, but only in 4% they are the
exclusive radio emission. Noise storms were the only radio emission in 5% of
the HXR flares, some of them with extended duration. Despite the spatial
association (same active region), the noise storm variations are found to be
only loosely correlated in time with the X-ray flux. In a surprising 17% of the
HXR flares, no coherent radio emission was found in the extremely broad band
surveyed. The association but loose correlation between HXR and coherent radio
emission is interpreted by multiple reconnection sites connected by common
field lines.


title: CALLISTO - A new concept for solar radio

abstract:
  A new radio spectrometer, CALLISTO, is presented. It is a dual-channel
frequency-agile receiver based on commercially available consumer electronics.
Its major characteristic is the low price for hardware and software, and the
short assembly time, both two or more orders of magnitude below existing
spectrometers. The instrument is sensitive at the physical limit and extremely
stable. The total bandwidth is 825 MHz, and the width of individual channels is
300 kHz. A total of 1000 measurements can be made per second. The spectrometer
is well suited for solar low-frequency radio observations pertinent to space
weather research. Five instruments of the type were constructed until now and
put into operation at several sites, including Bleien (Zurich) and NRAO (USA).
First results in the 45 - 870 MHz range are presented. Some of them were
recorded in a preliminary setup during the time of high solar activity in
October and November 2003.


title:
Fine structure of the chromospheric activity in Solar-type stars - The
  Halpha Line

abstract:
  A calibration of H-alpha as both a chromospheric diagnostic and an age
indicator is presented, complementing the works previously done on this subject
(Herbig 1985, Pasquini & Pallavicini 1991. The chromospheric diagnostic was
built with a statistically significant sample, covering nine years of
observations, and including 175 solar neighborhood stars. Regarding the age
indicator, the presence of stars for which very accurate ages are determined,
such as those belonging to clusters and kinematic groups, lends confidence to
our analysis. We also investigate the possibility that stars of the same age
might have gone through different tracks of chromospheric decay, identifying -
within the same age range - effects of metallicity and mass. These parameters,
however, as well as age, seem to be significant only for dwarf stars, losing
their meaning when we analyze stars in the subgiant branch. This result
suggests that, in these evolved stars, the emission mechanism cannot be
magnetohydrodynamical in nature, in agreement with recent models (Fawzy et al.
2002c, and references therein). The Sun is found to be a typical star in its
H-alpha chromospheric flux, for its age, mass and metallicity. As a byproduct
of this work, we developed an automatic method to determine temperatures from
the wings of H-alpha, which means the suppression of the error inherent to the
visual procedure used in the literature.


title: An update on the SCUBA-2 project

abstract:
  SCUBA-2, which replaces SCUBA (the Submillimeter Common User Bolometer Array)
on the James Clerk Maxwell Telescope (JCMT) in 2006, is a large-format
bolometer array for submillimeter astronomy. Unlike previous detectors which
have used discrete bolometers, SCUBA-2 has two dc-coupled, monolithic, filled
arrays with a total of ~10,000 bolometers. It will offer simultaneous imaging
of a 50 sq-arcmin field of view at wavelengths of 850 and 450 microns. SCUBA-2
is expected to have a huge impact on the study of galaxy formation and
evolution in the early Universe as well as star and planet formation in our own
Galaxy. Mapping the sky to the same S/N up to 1000 times faster than SCUBA, it
will also act as a pathfinder for the new submillimeter interferometers such as
ALMA. SCUBA-2's absorber-coupled pixels use superconducting transition edge
sensors operating at 120 mK for performance limited by the sky background
photon noise. The monolithic silicon detector arrays are deep-etched by the
Bosch process to isolate the pixels on silicon nitride membranes. Electrical
connections are made through indium bump bonds to a SQUID time-domain
multiplexer (MUX). We give an overview of the SCUBA-2 system and an update on
its status, and describe some of the technological innovations that make this
unique instrument possible.


title:
Metallicities of the beta Cephei stars from low-resolution ultraviolet
  spectra

abstract:
  We derive basic stellar parameters (angular diameters, effective
temperatures, metallicities) and interstellar reddening for all beta Cephei
stars observed during the IUE satellite mission, including those belonging to
three open clusters. The parameters are derived by means of an algorithmic
procedure of fitting theoretical flux distributions to the low-resolution IUE
spectra and ground-based spectrophotometric observations. Since the metallicity
has a special importance for pulsating B type stars, we focus our attention in
particular on this parameter.


title:
Constraints on a quintessence model from gravitational lensing
  statistics

abstract:
  Constraints on an exact quintessence scalar-field model with an exponential
potential are derived from gravitational lens statistics. An exponential
potential can account for data from both optical quasar surveys and radio
selected sources. Based on the Cosmic Lens All-Sky Survey (CLASS) sample,
lensing statistics provides, for the pressureless matter density parameter, an
estimate of Omega_{M0} = 0.31(-0.14)(+0.12).


title: Metallicity of mono- and multiperiodic beta Cephei stars

abstract:
  Analyzing IUE ultraviolet spectra of beta Cep pulsating stars we have noticed
that multiperiodic variables have a larger mean metal abundance in the
photosphere, [m/H], than monoperiodic ones. We apply statistical tests to
verify this dichotomy. We obtain that, with a large probability, the
multiperiodic beta Cep stars have greater values of [m/H]. This result is
consistent with the linear non-adiabatic theory of pulsation of early B-type
stars.


title: Nonlocal String Tachyon as a Model for Cosmological Dark Energy

abstract:
  There are many different phenomenological models describing the cosmological
dark energy and accelerating Universe by choosing adjustable functions. In this
paper we consider a specific model of scalar tachyon field which is derived
from the NSR string field theory and study its cosmological applications. We
find that in the effective field theory approximation the equation of state
parameter w<-1, i.e. one has a phantom Universe. It is shown that due to
nonlocal effects there is no quantum instability that the usual phantom models
suffer from. Moreover due to a flip effect of the potential the Universe does
not enter to a future singularity.


title:
Star Formation, Massive Stars, and Super Star Clusters in Nearby
  Galaxies with the SKA

abstract:
  The Square Kilometer Array (SKA) will enable studies of star formation in
nearby galaxies with a level of detail never before possible outside of the
Milky Way. Because the earliest stages of stellar evolution are often
inaccessible at optical and near-infrared wavelengths, high spatial resolution
radio observations are necessary to explore extragalactic star formation. The
SKA will have the sensitivity to detect individual ultracompact HII regions out
to the distance of nearly 50 Mpc, allowing us to study their spatial
distributions, morphologies, and population statistics in a wide range of
environments. Radio observations of Wolf-Rayet stars outside of the Milky Way
will also be possible for the first time, greatly expanding the range of
conditions in which their mass loss rates can be determined from free-free
emission. On a vastly larger scale, natal of super star clusters will be
accessible to the SKA out to redshifts of nearly z~0.1. The unprecedented
sensitivity of radio observations with the SKA will also place tight
constraints on the star formation rates as low as 1 M_sun/yr in galaxies out to
a redshift of z~1 by directly measuring the thermal radio flux density without
assumptions about a galaxy's magnetic field strength, cosmic ray production
rate, or extinction.


title:
Two viable quintessence models of the Universe: confrontation of
  theoretical predictions with observational data

abstract:
  We use some of the recently released observational data to test the viability
of two classes of minimally coupled scalar field models of quintessence with
exponential potentials for which exact solutions of the Einstein equations are
known. These models are very sturdy, depending on only one parameter - the
Hubble constant. To compare predictions of our models with observations we
concentrate on the following data: the power spectrum of the CMBR anisotropy as
measured by WMAP, the publicly available data on type Ia supernovae, and the
parameters of large scale structure determined by the 2-degree Field Galaxy
Redshift Survey (2dFGRS). We use the WMAP data on the age of the universe and
the Hubble constant to fix the free parameters in our models. We then show that
the predictions of our models are consistent with the observed positions and
relative heights of the first 3 peaks in the CMB power spectrum, with the
energy density of dark energy as deduced from observations of distant type Ia
supernovae, and with parameters of the large scale structure as determined by
2dFGRS, in particular with the average density of dark matter. Our models are
also consistent with the results of the Sloan Digital Sky Survey (SDSS).
Moreover, we investigate the evolution of matter density perturbations in our
quintessential models, solve exactly the evolution equation for the density
perturbations, and obtain an analytical expression for the growth index $f$. We
verify that the approximate relation f ~ Omega_M^(alpha) also holds in our
models.


title: Sulfur chemistry and isotopic ratios in the starburst galaxy NGC 253

abstract:
  Based on observations of the most abundant sulfur-bearing molecules (H2S, CS,
NS, SO, H2CS, OCS, and SO2) carried out with the IRAM 30m telescope and SEST,
we present the first analysis of the sulfur chemistry of an extragalactic
source, the nuclear region of the starburst galaxy NGC 253. This is the first
time that H2S and, tentatively, H2CS are detected towards the nucleus of a
starburst galaxy. Source averaged fractional abundances of these molecules are
a few 10^-9, except for CS and OCS which are more abundant (10^-8). Sulfur
isotopic ratios, 32S/34S~8+-2 and 34S/33S>9, are measured through observations
of 13CS, C34S, and C33S. A comparison with the observed relative abundances
towards different prototypical Galactic sources suggests that the chemical
composition of NGC 253 is similar to that found towards the molecular clouds
complexes like Sgr B2 in the nuclear region of the Milky Way. The large
overabundance of OCS compared to the predictions of time-dependent sulfur
chemistry models supports the idea that OCS is likely injected into the gas
phase from the grain mantles by low velocity shocks.


title:
The Nearest Star of spectral type O3: A Component of the Multiple System
  HD 150136

abstract:
  From radial velocities determined in high signal-to-noise digital spectra, we
report the discovery that the brightest component of the binary system HD
150136 is of spectral type O3. We also present the first double-lined orbital
solution for this binary. Our radial velocities confirm the previously
published spectroscopic orbital period of 2.6 days. He II absorptions appear
double at quadratures, but single lines of N V and N IV visible in our spectra
define a radial velocity orbit of higher semi-amplitude for the primary
component than do the He II lines. From our orbital analysis, we obtain minimum
masses for the binary components of 27 and 18$\modot$. The neutral He
absorptions apparently do not follow the orbital motion of any of the binary
components, thus they most probably arise in a third star in the system.


title: A comprehensive model for the Monoceros tidal stream

abstract:
  We have compiled an extensive dataset on potential parts of the Monoceros
tidal stream and performed an exhaustive survey of dwarf galaxy semi-analytic
orbits in order to constrain its orbital properties. The best-fit orbits are
subsequently realized as self-consistent N-body simulations in order to
reproduce the spatial and velocity distribution of satellite debris. We find
that all kinematic and geometric constraints can be fit by a single stream
allowing for multiple wraps. The orbital eccentricity and inclination of the
progenitor are strongly constrained to be e = 0.10 \pm 0.05 and i = 25 \pm 5
deg. Ten new estimates of proper motions from the Sloan Digital Sky Survey
(SDSS) clearly exclude all retrograde orbits. Particles lost by the satellite
populate two, nearly concentric rings naturally explaining the detection of
stream stars at both 6--8 kpc (Ibata et al. 2003, Newberg et al. 2003) and
12--18 kpc (the Tri/And stream; Rocha-Pinto et al. 2003) from the Sun. We have
attempted to predict the present location of the Monoceros stream progenitor
using different information: (i) the kinematical and spatial distribution of
detections and (ii) the different mean metallicity in the innner and the outer
rings. A current location at l ~ 245, b ~ -18., with a distance to the Sun
r_s~15 kpc, reproduces the available constraints. The mass of the progenitor
has been poorly determined due to the slow orbital decay. Similar fits have
been obtained for masses (3-9)10^8 M_sun. Additionally, we have analyzed to
possible common origin of the Canis Major dwarf and the Monoceros stream,
unfortunately, without a conclusive result.


title:
Close binary companions of the HAeBe stars LkHa 198, Elias 1, HK Ori and
  V380 Ori

abstract:
  We present diffraction-limited bispectrum speckle interferometry observations
of four well-known Herbig Ae/Be (HAeBe) stars, LkHa 198, Elias 1, HK Ori and
V380 Ori. For two of these, LkHa 198 and Elias 1, we present the first
unambiguous detection of close companions. The plane of the orbit of the new
LkHa 198 companion appears to be significantly inclined to the plane of the
circumprimary disk, as inferred from the orientation of the outflow. We show
that the Elias 1 companion may be a convective star, and suggest that it could
therefore be the true origin of the X-ray emission from this object. In the
cases of HK Ori and V380 Ori, we present new measurements of the relative
positions of already-known companions, indicating orbital motion. For HK Ori,
photometric measurements of the brightness of the individual components in four
bands allowed us to decompose the system spectral energy distribution (SED)
into the two separate component SEDs. The primary exhibits a strong infrared
excess which suggests the presence of circumstellar material, whereas the
companion can be modelled as a naked photosphere. The infrared excess of HK Ori
A was found to contribute around two thirds of the total emission from this
component, suggesting that accretion power contributes significantly to the
flux. Submillimetre constraints mean that the circumstellar disk cannot be
particularly massive, whilst the near-infrared data indicates a high accretion
rate. Either the disk lifetime is very short, or the disk must be seen in an
outburst phase.


title:
Observational evidence of spin-induced precession in active galactic
  nuclei

abstract:
  We show that it is possible to explain the physical origin of jet precession
in active galactic nuclei (AGNs) through the misalignment between the rotation
axes of the accretion disk and of the Kerr black hole. We apply this scenario
to quasars, Seyfert galaxies and also to the Galactic Center black hole Sgr A*,
for which signatures of either jet or disk precession have been found. The
formalism adopted is parameterized by the ratio of the precession period to the
black hole mass and can be used to put constraints to the physical properties
of the accretion disk as well as to the black hole spin in those systems.


title:
Quantification of discreteness effects in cosmological N-body
  simulations: I. Initial Conditions

abstract:
  The relation between the results of cosmological N-body simulations, and the
continuum theoretical models they simulate, is currently not understood in a
way which allows a quantification of N dependent effects. In this first of a
series of papers on this issue, we consider the quantification of such effects
in the initial conditions of such simulations. A general formalism developed in
[1] allows us to write down an exact expression for the power spectrum of the
point distributions generated by the standard algorithm for generating such
initial conditions. Expanded perturbatively in the amplitude of the input (i.e.
theoretical, continuum) power spectrum, we obtain at linear order the input
power spectrum, plus two terms which arise from discreteness and contribute at
large wavenumbers. For cosmological type power spectra, one obtains as
expected, the input spectrum for wavenumbers k smaller than that characteristic
of the discreteness. The comparison of real space correlation properties is
more subtle because the discreteness corrections are not as strongly localised
in real space. For cosmological type spectra the theoretical mass variance in
spheres and two point correlation function are well approximated {\it above} a
finite distance. For typical initial amplitudes this distance is a few times
the inter-particle distance, but it diverges as this amplitude (or,
equivalently, the initial red-shift of the cosmological simulation) goes to
zero, at fixed particle density. We discuss briefly the physical significance
of these discreteness terms in the initial conditions, in particular with
respect to the definition of the continuum limit of N-body simulations.


title: Metallicity measurements using atomic lines in M and K dwarf stars

abstract:
  We report the first survey of chemical abundances in M and K dwarf stars
using atomic absorption lines in high resolution spectra. We have measured Fe
and Ti abundances in 35 M and K dwarf stars using equivalent widths measured
from (lambda / Delta lambda) = 33,000 spectra. Our analysis takes advantage of
recent improvements in model atmospheres of low-temperature dwarf stars. The
stars have temperatures between 3300 and 4700 K, with most cooler than 4100 K.
They cover an iron abundance range of -2.44 < [Fe/H] < +0.16. Our measurements
show [Ti/Fe] decreasing with increasing [Fe/H], a trend similar to that
measured for warmer stars where abundance analysis techniques have been tested
more thoroughly. This study is a step toward the observational calibration of
procedures to estimate the metallicity of low-mass dwarf stars using
photometric and low-resolution spectral indices.


title:
Taking the pulse of the shortest orbital period binary system RX
  J0806.3+1527

abstract:
  RX J0806.3+1527 is thought to be a 321s orbital period (the shortest known)
double white dwarf binary system. According to the double degenerate binary
(DDB) scenario this source is expected to be one of the strongest gravitational
wave (GW) emitter candidates. In the last years RX J0806.3+1527 has been
studied in great details, through multiwavelength observational campaigns and
from the point of view of data analysis result interpretations. We present here
the timing results obtained thanks to a 3.5-year long optical monitoring
campaign carried out by the Very Large Telescope (VLT) and the Telescopio
Nazionale Galileo (TNG) which allowed us to detect and study the orbital period
derivative (spin-up at a rate of about 10^-3 s/yr) of the 321s modulation, to
detect the linear polarisation (at a level of about 2%), and to study the broad
band energy spectrum. The VLT/TNG observational strategy we used allowed us to
rely upon a P-Pdot coherent solution which we finally extended backward to the
1994 ROSAT observation of RX J0806.3+1527.


title: M31's Heavy Element Distribution and Outer Disk

abstract:
  Hubble Space Telescope imaging of 11 fields in M31 were reduced to
color-magnitude diagrams. The fields were chosen to sample all galactocentric
radii to 50 kpc. Assuming that the bulk of the sampled stellar populations are
older than a few Gyr, the colors of the red giants map to an abundance
distribution with errors of order 0.1 dex in abundance. The radially sampled
abundance distributions are all about the same width, but show a mild abundance
gradient that flattens outside ~20 kpc. The various distributions were weighted
and summed with the aid of new surface brightness profile fits to obtain an
abundance distribution representative of the entirety of M31. M31 is a system
near chemical maturity. This ``observed closed box'' is compared to analytical
closed box models. M31 suffers from a lack of metal-poor stars and metal-rich
stars relative to the simplest closed-box model in the same way as the solar
neighborhood.Comparing to several simple chemical evolution models, neither
complete mixing of gas at all times nor zero mixing, inhomogeneous models give
the most convincing match to the data. As noted elsewhere, the outer disk of
M31 is a factor of ten more metal-rich than the Milky Way halo, ten times more
metal-rich than the dwarf spheroidals cospatial with it, and more metal-rich
than most of the globular clusters at the same galactocentric radius.
Difficulties of interpretation are greatly eased if we posit that the M31 disk
dominates over the halo at all radii out to 50 kpc. In fact, scaling from
current density models of the Milky Way, one should not expect to see halo
stars dominating over disk stars until beyond our 50 kpc limit. A corollary
conclusion is that most published studies of the M31 "halo" are actually
studies of its disk.


title: Using close stars as probes of hot accretion flow in Sgr A*

abstract:
  The extremely hot and tenuous accretion flow in the immediate vicinity of Sgr
A* is believed to be invisible (too dim) in the X-ray band, except for short
X-ray flares. Here we point out that during pericenter passages, close
brightest stars irradiate the inner region of the accretion flow, providing a
plenty of optical/UV photons. These seed photons are Compton up-scattered by
the hot electrons of the accretion flow to higher frequencies, some into the
X-ray band, potentially making the innermost accretion flow much brighter in
X-rays than usual. We propose to use coordinated near infra-red and X-ray
observations of close star passages to put constraints onto Sgr A* accretion
theories. The absence of a noticeable change in the steady emission of Sgr A*
as observed by Chandra in the year 2002, when the star named S2 passed through
a pericenter of its orbit, already rules out the hotter of the ``standard''
Advection-Dominated Accretion Flows. The less dense accretion flows, in
particular the model of Yuan et al. (2003), passes the test and is constrained
to accretion rates no larger than $\sim 10^{-7}$ Solar masses per year.


title: Symmetry in the changing jets of SS433 and its true distance from us

abstract:
  We present the deepest yet radio image of the Galactic jet source, SS433,
which reveals over two full precession cycles (> 2 x 163 days) of the jet axis.
Systematic and identifiable deviations from the traditional kinematical model
for the jets are found: variations in jet speed, lasting for as long as tens of
days, are necessary to match the detailed structure of each jet. It is
remarkable that these variations are equal and opposite, matching the two jets
simultaneously. This explains certain features of the correlated redshift
residuals found in fits to the kinematic model of SS433 reported in the
literature. Asymmetries in the image caused by light travel time enabled us to
measure the jet speeds of particular points to be within a range from 0.24c to
0.28c, consistent with, yet determined independently from, the speeds derived
from the famous moving optical emission lines. Taken together with the angular
periodicity of the zigzag/corkscrew structure projected on the plane of the sky
(produced by the precession of the jet axis), these measurements determine
beyond all reasonable doubt the distance to SS433 to be 5.5 +/- 0.2 kpc,
significantly different from the distance most recently inferred using neutral
hydrogen measurements together with the current rotation model for the Galaxy.


title:
Jet velocity in SS433: its anti-correlation with precession-cone angle
  and dependence on orbital phase

abstract:
  We present a re-analysis of the optical spectroscopic data on SS433 from the
last quarter-century and demonstrate that these data alone contain systematic
and identifiable deviations from the traditional kinematic model for the jets:
variations in speed, which agree with our analysis of recent radio data; in
precession-cone angle and in phase. We present a simple technique for
separating out the jet speed from the angular properties of the jet axis,
assuming only that the jets are symmetric. With this technique, the archival
optical data reveal that the variations in jet speed and in precession-cone
angle are anti-correlated in the sense that when faster jet bolides are ejected
the cone opening angle is smaller. We also find speed oscillations as a
function of orbital phase.


title:
Integral field spectroscopy of the ultraluminous X-ray source Holmberg
  II X-1

abstract:
  We present optical integral field observations of the H II region containing
the ultraluminous X-ray source Holmberg II X-1. We confirm the existence of an
X-ray ionized nebula as the counterpart of the source due to the detection of
an extended He II (4686A) region (21 x 47 pc) at the Chandra ACIS-S position.
An extended blue objects with a size of 11 x 14 pc is coincident with the
X-ray/He II region, which could indicate either a young stellar complex or a
cluster. We have derived an X-ray to optical luminosity ratio of Lx/Lb>170, and
presumable it is Lx/Lb~300-400 using the recent HST ACS data. We find a complex
velocity dispersion at the position of the ULX. In addition, there is a radial
velocity variation in the X-ray ionized region found in the He II emission of
+-50 km/s on spatial scales of 2-3 arcsec. We believe that the putative black
hole not only ionizes the surrounding HII gas, but also perturbs it dynamically
(via jets or the accretion disk wind). The spatial analysis of the public
Chandra ACIS-S data reveals a point-like X-ray source and marginal indication
of an extended component (<<15 % of the total flux). The XMM-Newton EPIC-PN
spectrum of HoII X-1 is best fitted with an absorbed power-law in addition to
either a thermal thick plasma or a thermal thin plasma or a multi-colour disk
black body (MCD). In all cases, the thermal component shows relatively low
temperatures (kT~0.14-0.22 keV). Finally we discuss the optical/X-ray
properties of HoII X-1 with regards to the possible nature of the source.


title:
Discovery of Irradiation Induced Variations in the Light Curve of the
  Classical Nova Cygni 2001 No.2 (V2275 Cyg)

abstract:
  We present the CCD photometry, light curve and time series analysis of the
classical nova V2275 Cyg (N Cyg 2001 No.2). The source was observed for 14
nights in total using an R filter in 2002 and 2003 with the 1.5 m
Russian-Turkish joint telescope (RTT150) at the TUBITAK (The Scientific and
Technical Research Council of Turkey) National Observatory in Antalya Turkey,
as part of a large program on the CCD photometry of Cataclysmic Variables
(CVs). We report the detection of two distinct periodicities in the light curve
of the nova : a) P_1=0.31449(15) d -- 7.6 h, b) P_2=0.017079(17) d -- 24.6 min.
The first period is evident in both 2002 and 2003 whereas the second period is
only detected in the 2003 data set. We interpret the first period as the
orbital period of the system and attribute the orbital variations to aspect
changes of the secondary irradiated by the hot WD. We suggest that the nova was
a Super Soft X-ray source in 2002 and, perhaps, in 2003. The second period
could be a QPO originating from the oscillation of the ionization front (due to
a hot WD) below the inner Lagrange point as predicted by King (1989) or a beat
frequency in the system as a result of the magnetic nature of the WD if steady
accretion has already been re-established.


title: Is There a Deficit of Solar Neutrinos?

abstract:
  Measurements on the isotopic and elemental compositions of meteorites,
planets, lunar samples, the solar wind, and solar flares since 1960 suggest
that the standard solar model may be in error. A new solar model suggests that
the observed number of solar neutrinos represents at least 87% of the number
generated: There is little if any deficit of solar neutrinos.