title: An ultracompact X-ray binary in the globular cluster M15 (NGC7078)

abstract:
  We have used the Advanced Camera for Surveys on board the Hubble Space
Telescope to image the core of the globular cluster M15 in the far-ultraviolet
(FUV) waveband. Based on these observations, we identify the FUV counterpart of
the recently discovered low-mass X-ray binary M15 X-2. Our time-resolved FUV
photometry shows a modulation with 0.062+/-0.004 mag semi-amplitude and we
clearly detect a period of 22.5806+/-0.0002 min. We have carried out extensive
Monte Carlo simulations which show that the signal is consistent with being
coherent over the entire observational time range of more than 3000 cycles.
This strongly suggests that it represents the orbital period of the binary
system. M15 X-2 is FUV bright (approx. 17 mag) and is characterized by an
extremely blue spectral energy distribution (F_lambda ~ lambda^{-2.0}). We also
find evidence for an excess of flux between 1500 and 1600 \AA and probably
between 1600 and 2000 \AA, which might be due to CIV 1550 and HeII 1640
emission lines. We also show that M15 X-2's X-ray luminosity can be powered by
accretion at the rate expected for gravitational-wave-driven mass transfer at
this binary period. The observed FUV emission appears to be dominated by an
irradiated accretion disk around the neutron star primary, and the variability
can be explained by irradiation of the low-mass white dwarf donor if the
inclination of the system is approx. 34 degree. We conclude that all
observational characteristics of M15 X-2 are consistent with it being an
ultracompact X-ray binary, only the third confirmed such object in a globular
cluster.


title:
Vertical distribution of Galactic disk stars: III. The Galactic disk
  surface mass density from red clump giants

abstract:
  We used red clump stars to measure the surface mass density of the Galactic
disk in the solar neighbourhood. High resolution spectra of red clump stars
towards the NGP have been obtained with the ELODIE spectrograph at OHP for
Tycho-2 selected stars, and nearby Hipparcos counterparts were also observed.
We determined their distances, velocities, and metallicities to measure the
gravitational force law perpendicular to the Galactic plane. As in most
previous studies, we applied one-parameter models of the vertical gravitational
potential. We obtained a disk surface mass density within 1.1kpc of the
Galactic plane, Sigma_{1.1kpc}=64+/-5 Msun_pc^{-2}, with an excellent formal
accuracy, however we found that such one-parameter models can underestimate the
real uncertainties. Applying two-parameter models, we derived more realistic
estimates of the total surface mass density within 800pc from the Galactic
plane, Sigma_{0.8kpc}=57-66 Msun pc^{-2}, and within 1.1kpc,
Sigma{1.1kpc}=57-79 Msun pc^{-2}. This can be compared to literature estimates
of \sim40 Msun pc^{-2} in stars and to 13 Msun pc^{-2} in the less accurately
measured ISM contribution. We conclude that there is no evidence of large
amounts of dark matter in the disk and, furthermore, that the dark matter halo
is round or not vey much flattened.
  A by-product of this study is the determination of the half period of
oscillation by the Sun through the Galactic plane, 42+/-2Myr, which cannot be
related to the possible period of large terrestrial impact craters \sim
33-37Myr.


title: Radiation Pressure in Massive Star Formation

abstract:
  Stars with masses of >~ 20 solar masses have short Kelvin times that enable
them to reach the main sequence while still accreting from their natal clouds.
The resulting nuclear burning produces a huge luminosity and a correspondingly
large radiation pressure force on dust grains in the accreting gas. This effect
may limit the upper mass of stars that can form by accretion. Indeed,
simulations and analytic calculations to date have been unable to resolve the
mystery of how stars of 50 solar masses and up form. We present two new ideas
to solve the radiation pressure problem. First, we use three-dimensional
radiation hydrodynamic adaptive mesh refinement simulations to study the
collapse of massive cores. We find that in three dimensions a configuration in
which radiation holds up an infalling envelope is Rayleigh-Taylor unstable,
leading radiation driven bubbles to collapse and accretion to continue. We also
present Monte Carlo radiative transfer calculations showing that the cavities
created by protostellar winds provides a valve that allow radiation to escape
the accreting envelope, further reducing the ability of radiation pressure to
inhibit accretion.


title: The cluster relic source in A521

abstract:
  We present high sensitivity radio observations of the merging cluster A521,
at a mean redsfhit z=0.247. The observations were carried out with the GMRT at
610 MHz and cover a region of $\sim$1 square degree, with a sensitivity limit
of $1\sigma$ = 35 $\mu$Jy b$^{-1}$. The most relevant result of these
observations is the presence of a radio relic at the cluster periphery, at the
edge of a region where group infalling into the main cluster is taking place.
Thanks to the wealth of information available in the literature in the optical
and X-ray bands, a multi--band study of the relic and its surroundings was
performed. Our analysis is suggestive of a connection between this source and
the complex ongoing merger in the A521 region. The relic might be ``revived'
fossil radio plasma through adiabatic compression of the magnetic field or
shock re--acceleration due to the merger events. We also briefly discussed the
possibility that this source is the result of induced ram pressure stripping of
radio lobes associated with the nearby cluster radio galaxy J0454--1016a.
Allowing for the large uncertainties due to the small statistics, the number of
radio emitting early--type galaxies found in A521 is consistent with the
expectations from the standard radio luminosity function for local (z$\le$0.09)
cluster ellipticals.


title:
Broad-band photometric colors and effective temperature calibrations for
  late-type giants. I. Z=0.02

abstract:
  We present new synthetic broad-band photometric colors for late-type giants
based on synthetic spectra calculated with the PHOENIX model atmosphere code.
The grid covers effective temperatures T_eff=3000...5000K, gravities log
g=-0.5...+3.5, and metallicities [M/H]=+0.5...-4.0. We show that individual
broad-band photometric colors are strongly affected by model parameters such as
molecular opacities, gravity, microturbulent velocity, and stellar mass. Our
exploratory 3D modeling of a prototypical late-type giant shows that convection
has a noticeable effect on the photometric colors too, as it alters
significantly both the vertical and horizontal thermal structures in the outer
atmosphere. The differences between colors calculated with full 3D
hydrodynamical and 1D model atmospheres are significant (e.g., \Delta(V-K)~0.2
mag), translating into offsets in effective temperature of up to ~70K. For a
sample of 74 late-type giants in the Solar neighborhood, with interferometric
effective temperatures and broad-band photometry available in the literature,
we compare observed colors with a new PHOENIX grid of synthetic photometric
colors, as well as with photometric colors calculated with the MARCS and ATLAS
model atmosphere codes. (abridged)


title: Kink waves in solar spicules: observation and modelling

abstract:
  Height series of Doppler observation at the solar limb (covering 3800 - 8700
km distance above the photosphere) in $H_{\alpha}$ spectral line obtained by
big coronagraph of Abastumani Astrophysical Observatory \citep{khu} show the
periodic spatial distribution of Doppler velocities in spicules. We suggest
that the periodic spatial distribution is caused by propagating kink waves in
spicule. The wave length is found to be $\sim$ 3500 km. Numerical modelling of
kink wave propagation from the photosphere to observed heights gives the wave
length of kink waves at the photosphere to be $\sim$ 1000 km, which indicates
to the granular origin of the waves. The period of waves is estimated to be in
the range of 35-70 s.


title: Planets of young stars: the TLS radial velocity survey

abstract:
  We report on the search for planets orbiting 46 nearby young stars performed
at the State Observatory of Turingia (TLS) by means of a radial velocity
survey. The aim of this program is to test the theories of formation/evolution
of planetary systems. For 19(8) stars we can exclude planets with Msini > 1 MJ
(5 MJ) and P < 10 days; we find 1 short period binary and 5 stars with long
period RV-trend. One good young exo-planet candidate is presented.


title:
Resonant conversion of standing acoustic oscillations into Alfv{\'e}n
  waves in the $\beta ~ 1$ region of the solar atmosphere

abstract:
  We show that 5-minute acoustic oscillations may resonantly convert into
Alfv{\'e}n waves in the $\beta{\sim}1$ region of the solar atmosphere.
Considering the 5-minute oscillations as pumping standing acoustic waves
oscillating along unperturbed vertical magnetic field, we find on solving the
ideal MHD equations that amplitudes of Alfv{\'e}n waves with twice the period
and wavelength of acoustic waves exponentially grow in time when the sound and
Alfv{\'e}n speeds are equal, i.e. $c_s \approx v_A$. The region of the solar
atmosphere where this equality takes place we call a {\it swing layer}. The
amplified Alfv{\'e}n waves may easily pass through the chromosphere and
transition region carrying the energy of p-modes into the corona.


title:
ULTRACAM photometry of the eclipsing cataclysmic variables GY Cnc, IR
  Com and HT Cas

abstract:
  We present high-speed, three-colour photometry of the eclipsing cataclysmic
variables GY Cnc, IR Com and HT Cas. We find that the sharp eclipses in GY Cnc
and IR Com are due to eclipses of the white dwarf. There is some evidence for a
bright spot on the edge of the accretion disc in GY Cnc, but not in IR Com.
Eclipse mapping of HT Cas is presented which shows changes in the structure of
the quiescent accretion disc. Observations in 2002 show the accretion disc to
be invisible except for the presence of a bright spot at the disc edge. 2003
observations, however, clearly show a bright inner disc and the bright spot to
be much fainter than in 2002. Although no outburst was associated with either
set of quiescent observations, the system was ~0.6 mJy brighter in 2003, mainly
due to the enhanced emission from the inner disc. We propose that these changes
are due to variations in the mass transfer rate from the secondary star and
through the disc. The disc colours indicate that it is optically thin in both
its inner and outer regions. We estimate the white dwarf temperature of HT Cas
to be 15 000 +/- 1000 K in 2002 and 14 000 +/- 1000 K in 2003.


title: Constrained Simulations of Dark Matter Halos

abstract:
  The formation and structure of dark matter halos is studied by constrained
simulations. A series of experiments of the formation of a 10^12 Msun/h halo is
designed to study the dependence of the density profile on its merging history.
We find that the halo growth consist of several quiescent phases intermitted by
violent events, with the density well approximated by the NFW profile during
the former phases. We find that (1) the NFW scale radius R_s stays constant
during the quiescent phase and grows abruptly during the violent one. In
contrast, the virial radius grows linearly during the quiescent and abruptly
during the violent phases. (2) The central density stays unchanged during the
quiescent phase while dropping abruptly during the violent phase, and it does
not reflect the formation time of the halo. (3) The clear separation of the
evolution of an individual halo into quiescent and violent phases implies that
its entire evolution cannot be fitted by simple scaling relations.


title: Atomic hydrogen in the one-sided "compact double" radio galaxy 2050+364

abstract:
  European VLBI Network spectral imaging of the "compact double" radio source
2050+364 in the UHF band at 1049 MHz has resolved the HI absorbing region, and
has shown a faint continuum component to the North (N), in addition to the
well-known East-West double (E, W). Re-examination of VLBI continuum images at
multiple frequencies suggests that 2050+364 may well be a one-sided core-jet
source, which appears as a double over a limited frequency range. One of the
dominant features, W, would then be the innermost visible portion of the jet,
and could be at or adjacent to the canonical radio core. The other, E, is
probably related to shocks at a sudden bend of the jet, towards extended
steep-spectrum region N. A remarkably deep and narrow HI absorption line
component extends over the entire projected extent of 2050+364. It coincides in
velocity with the [OIII] optical doublet lines to within 10 km/s. This HI
absorption could arise in the atomic cores of NLR clouds, and the motion in the
NLR is then remarkably coherent both along the line-of-sight and across a
projected distance of > 300 pc on the plane of the sky. Broader, shallower HI
absorption at lower velocities covers only the plausible core area W. This
absorption could be due to gas which is either being entrained by the inner jet
or is flowing out from the accretion region; it could be related to the BLR.


title: Inflation models and observation

abstract:
  We consider small-field models which invoke the usual framework for the
effective field theory, and large-field models which go beyond that. Present
and future possibilities for discriminating between the models are assessed, on
the assumption that the primordial curvature perturbation is generated during
inflation. With PLANCK data, the theoretical and observational uncertainties on
the spectral index will be comparable, providing useful discrimination between
small-field models. Further discrimination between models may come later
through the tensor fraction, the running of the spectral index and
non-gaussianity. The prediction for the trispectrum in a generic multi-field
inflation model is given for the first time.


title: Supernova Remnant 1987A: Opening the Future by Reaching the Past

abstract:
  We report an up-turn in the soft X-ray light curve of supernova remnant (SNR)
1987A in late 2003 (~6200 days after the explosion), as observed with the
Chandra X-ray Observatory. Since early 2004, the rapid increase of the 0.5-2
keV band X-ray light curve can no longer be described by the exponential
density distribution model with which we successfully fitted the data between
1990 and 2003. Around day ~6200, we also find that the fractional contribution
to the observed soft X-ray flux from the decelerated shock begins to exceed
that of the fast shock and that the X-ray brightening becomes "global" rather
than "spotty". We interpret these results as evidence that the blast wave has
reached the main body of the dense circumstellar material all around the inner
ring. This interpretation is supported by other recent observations, including
a deceleration of the radial expansion of the X-ray remnant, a significant
up-turn in the mid-IR intensities, and the prevalence of the optical hot spots
around the entire inner ring, all of which occur at around day 6000. In
contrast to the soft X-ray light curve, the hard band (3-10 keV) X-ray light
curve increases at a much lower rate which is rather similar to the radio light
curve. The hard X-ray emission may thus originate from the reverse shock where
the radio emission is likely produced. Alternatively, the low increase rate of
the hard X-rays may simply be a result of the continuous softening of the
overall X-ray spectrum.


title: Generating the curvature perturbation at the end of inflation

abstract:
  The dominant contribution to the primordial curvature perturbation may be
generated at the end of inflation. Taking the end of inflation to be sudden,
formulas are presented for the spectrum, spectral tilt and non-gaussianity.
They are evaluated for a minimal extension of the original hybrid inflation
model.


title:
The Galactic magnetic field as spectrograph for ultra-high energy cosmic
  rays

abstract:
  We study the influence of the regular component of the Galactic magnetic
field (GMF) on the arrival directions of ultra-high energy cosmic rays
(UHECRs). We find that, if the angular resolution of current experiments has to
be fully exploited, deflections in the GMF cannot be neglected even for E=10^20
eV protons, especially for trajectories along the Galactic plane or crossing
the Galactic center region. On the other hand, the GMF could be used as a
spectrograph to discriminate among different source models and/or primaries of
UHECRs, if its structure would be known with sufficient precision. We compare
several GMF models introduced in the literature and discuss for the example of
the AGASA data set how the significance of small-scale clustering or
correlations with given astrophysical sources are affected by the GMF. We point
out that the non-uniform exposure to the extragalactic sky induced by the GMF
should be taken into account estimating the significance of potential
(auto-)correlation signals.


title:
Quantum correlations in inflationary spectra and violation of Bell
  inequalities

abstract:
  In spite of the macroscopic character of the fluctuation amplitudes, we show
that the standard inflationary distribution of primordial density fluctuations
still exhibits inherently quantum mechanical correlations (which cannot be
mimicked by any classical stochastic ensemble). To this end, we propose a
Gedanken experiment for which certain Bell inequalities are violated. We also
compute the effect of decoherence and show that the violation persists provided
that the decoherence lies below a certain non-vanishing threshold. Moreover,
there exists a higher threshold above which no violation of any Bell
inequalities can occur, so that the corresponding distributions can be
interpreted as stochastic ensembles of classical fluctuations.


title: Active Cores in Deep Fields

abstract:
  Deep field observations are an essential tool to probe the cosmological
evolution of galaxies. In this context, X-ray deep fields provide information
about some of the most energetic cosmological objects: active galactic nuclei
(AGN). Astronomers are interested in detecting sufficient numbers of AGN to
probe the accretion history at high redshift. This talk gives an overview of
the knowledge resulting from a highly complete soft X-ray selected sample
collected with ROSAT, XMM-Newton and Chandra deep fields. The principal outcome
based on X-ray luminosity functions and space density evolution studies is that
low-luminosity AGN evolve in a dramatically different way from high-luminosity
AGN: The most luminous quasars perform at significantly earlier cosmic times
and are most numerous in a unit volume at cosmological redshift z~2. In
contrast, low-luminosity AGN evolve later and their space density peaks at
z~0.7. This finding is also interpreted as an anti-hierarchical growth of
supermassive black holes in the Universe. Comparing this with star formation
rate history studies one concludes that supermassive black holes enter the
cosmic stage before the bulk of the first stars. Therefore, first solutions of
the so-called hen-egg problem are suggested. Finally, status developments and
expectations of ongoing and future extended observations such as the XMM-COSMOS
project are highlighted.


title:
The Supernova Legacy Survey: Measurement of Omega_M, Omega_Lambda and w
  from the First Year Data Set

abstract:
  We present distance measurements to 71 high redshift type Ia supernovae
discovered during the first year of the 5-year Supernova Legacy Survey (SNLS).
These events were detected and their multi-color light-curves measured using
the MegaPrime/MegaCam instrument at the Canada-France-Hawaii Telescope (CFHT),
by repeatedly imaging four one-square degree fields in four bands. Follow-up
spectroscopy was performed at the VLT, Gemini and Keck telescopes to confirm
the nature of the supernovae and to measure their redshift. With this data set,
we have built a Hubble diagram extending to z=1, with all distance measurements
involving at least two bands. Systematic uncertainties are evaluated making use
of the multi-band photometry obtained at CFHT. Cosmological fits to this first
year SNLS Hubble diagram give the following results : Omega_M = 0.263 +/-
0.042(stat) +/- 0.032(sys) for a flat LambdaCDM model; and w = -1.023 +/-
0.090(stat) +/- 0.054(sys) for a flat cosmology with constant equation of state
w when combined with the constraint from the recent Sloan Digital Sky Survey
measurement of baryon acoustic oscillations.


title: On the Origin of the Absorption Features in SS433

abstract:
  We present high-resolution optical spectroscopy of the X-ray binary system
SS433, obtained over a wide range of orbital phases. The spectra display
numerous weak absorption features, and include the clearest example seen to
date of those features, resembling a mid-A type supergiant spectrum, that have
previously been associated with the mass donor star. However, the new data
preclude the hypothesis that these features originate solely within the
photosphere of the putative mass donor, indicating that there may be more than
one region within the system producing an A supergiant-like spectrum, probably
an accretion disc wind. Indeed, whilst we cannot confirm the possibility that
the companion star is visible at certain phase combinations, it is possible
that all supergiant-like features observed thus far are produced solely in a
wind. We conclude that great care must be taken when interpreting the behaviour
of these weak features.


title:
Intergalactic Photon Spectra from the Far IR to the UV Lyman Limit for
  $0 < z < 6$ and the Optical Depth of the Universe to High Energy Gamma-Rays

abstract:
  We calculate the intergalactic photon density as a function of both energy
and redshift for 0 < z < 6 for photon energies from .003 eV to the Lyman limit
cutoff at 13.6 eV in a Lambda-CDM universe with $\Omega_{\Lambda} = 0.7$ and
$\Omega_{m} = 0.3$. Our galaxy evolution model gives results which are
consistent with Spitzer deep number counts and the spectral energy distribution
of the extragalactic background radiation. We use our photon density results to
extend previous work on the absorption of high energy gamma-rays in
intergalactic space owing to interactions with low energy photons and the 2.7 K
cosmic background radiation. We calculate the optical depth of the universe,
tau, for gamma-rays having energies from 4 GeV to 100 TeV emitted by sources at
redshifts from ~0 to 5. We also give an analytic fit with numerical
coefficients for approximating $\tau(E_{\gamma}, z)$. As an example of the
application of our results, we calculate the absorbed spectrum of the blazar
PKS 2155-304 at z = 0.117 and compare it with the spectrum observed by the
H.E.S.S. air Cherenkov gamma-ray telescope array.


title:
Stellar Rotation in Young Clusters. I. Evolution of Projected Rotational
  Velocity Distributions

abstract:
  Open clusters offer us the means to study stellar properties in samples with
well-defined ages and initial chemical composition. Here we present a survey of
projected rotational velocities for a large sample of mainly B-type stars in
young clusters to study the time evolution of the rotational properties of
massive stars. The survey is based upon moderate resolution spectra made with
the WIYN 3.5 m and CTIO 4 m telescopes and Hydra multi-object spectrographs,
and the target stars are members of 19 young open clusters with an age range of
approximately 6 to 73 Myr. We made fits of the observed lines He I 4026, 4387,
4471 and Mg II 4481 using model theoretical profiles to find projected
rotational velocities for a total of 496 OB stars. We find that there are fewer
slow rotators among the cluster B-type stars relative to nearby B stars in the
field. We present evidence consistent with the idea that the more massive B
stars (M > 9 solar masses) spin down during their main sequence phase. However,
we also find that the rotational velocity distribution appears to show an
increase in the numbers of rapid rotators among clusters with ages of 10 Myr
and higher. These rapid rotators appear to be distributed between the zero age
and terminal age main sequence locations in the Hertzsprung-Russell diagram,
and thus only a minority of them can be explained as the result of a spin up at
the terminal age main sequence due to core contraction. We suggest instead that
some of these rapid rotators may have been spun up through mass transfer in
close binary systems.


title:
The importance of muon information on primary mass discrimination of
  ultra-high energy cosmic rays

abstract:
  Several methods can be used to perform statistical inference of primary
composition of cosmic rays measured with water Cerenkov detectors as those in
use at the Pierre Auger Southern Observatory. In the present work we assess the
impact of additional information about the number of muons in the air shower,
on the problem of statistical primary mass discrimination. Several tools are
studied, including neural networks, principal component analysis and
traditional methods in current use in the field. For our case study we use
hypothetical plastic scintillators as muon counters, buried at the side and
outside the shade of the water Cerenkov tanks. The study is extended to protons
and Fe nuclei impinging on an array with two different spacings, 750 and 1500 m
and, therefore, suitable to the 1-10 EeV energy range. A prototype of such a
detector is under construction.


title:
The Magnetic Field in the Star-forming Region Cepheus A from Water Maser
  Polarization Observations

abstract:
  We present linear and circular polarization observations of the water masers
in 4 distinct regions spread over 1x2 arcseconds around the HW2 high-mass young
stellar object in the Cepheus A star-forming region. We find magnetic fields
between 100-500 mG in the central maser region, which has been argued to trace
a circumstellar disk. The masers further from HW2 have field strengths between
30-100 mG. In all cases the magnetic field pressure is found to be similar to
the dynamic pressure, indicating that the magnetic field is capable of
controlling the outflow dynamics around HW2. In addition to several water maser
complexes observed before, we also detect a new maser filament, ~1 arcsec (~690
AU) East of HW2, which we interpret as a shocked region between the HW2 outflow
and the surrounding medium. We detect a linear polarization gradient along the
filament as well as a reversal of the magnetic field direction. This is thought
to mark the transition between the magnetic field associated with the outflow
and that found in the surrounding molecular cloud. In addition to the magnetic
field we determine several other physical properties of the maser region,
including density and temperatures as well as the maser beaming angles.


title: Constraining Inverse Curvature Gravity with Supernovae

abstract:
  We show that the current accelerated expansion of the Universe can be
explained without resorting to dark energy. Models of generalized modified
gravity, with inverse powers of the curvature can have late time accelerating
attractors without conflicting with solar system experiments. We have solved
the Friedman equations for the full dynamical range of the evolution of the
Universe. This allows us to perform a detailed analysis of Supernovae data in
the context of such models that results in an excellent fit. Hence, inverse
curvature gravity models represent an example of phenomenologically viable
models in which the current acceleration of the Universe is driven by curvature
instead of dark energy. If we further include constraints on the current
expansion rate of the Universe from the Hubble Space Telescope and on the age
of the Universe from globular clusters, we obtain that the matter content of
the Universe is 0.07 <= omega_m <= 0.21 (95% Confidence). Hence the inverse
curvature gravity models considered can not explain the dynamics of the
Universe just with a baryonic matter component.


title:
Lightcurves of 20--100 kilometer Kuiper Belt Objects using the Hubble
  Space Telescope

abstract:
  We report high precision photometry of three small and one larger Kuiper Belt
Objects (KBOs) obtained with the Advanced Camera for Surveys onboard the Hubble
Space Telescope (ACS/HST). The three small bodies are the smallest KBOs for
which lightcurve measurements are available. 2003 BF91 has a diameter of 20
kilometers (assuming 10% albedo) and a 1.09 magnitude, 9.1-hour lightcurve that
is feasibly explained by the rotation of an elongated, coherent body that is
supported by material strength and best imagined as an icy outer Solar System
analog to asteroid (243) Ida. Two other small KBOs, 2003 BG91 and 2003 BH91
(diameters 31 and 18 km, with albedo 10%), exhibit an unremarkable lightcurve
and no detectable photometric variation, respectively. For the larger KBO 2000
FV53 (116 km diameter, assuming 10% albedo) we strongly detect a non-sinusoidal
periodic (7.5 hours) brightness variation with a very small amplitude (0.07
mag). This KBO may be nearly spherical, a result that might not be unusual in
the Kuiper Belt but would be remarkable among outer Solar System satellites of
similar size. We carry out a study of possible physical states and bulk
densities under the assumptions of both fluid equilibrium and finite, non-zero
internal friction. The densities for the these KBOs are likely to be in the
range 1--2 g/cm3, and a plausible solution for 2000 FV53 is a rubble pile of
this density that is held slightly out of the minimum-energy shape by internal
friction among constituent blocks that are relatively small. Our interpretation
of 2000 FV53 as a pulverized but essentially primordial object and 2003 BF91 as
a collisional fragment is consistent with models of collisional timescales in
the outer Solar System. We compile all published KBO lightcurve data and
compare our results to the larger population. [abridged]


title:
The Astrometric-Spectroscopic Binary System HIP 50796: An Overmassive
  Companion

abstract:
  We report spectroscopic observations of the star HIP 50796, previously
considered (but later rejected) as a candidate member of the TW Hya
association. Our measurements reveal it to be a single-lined binary with an
orbital period of 570 days and an eccentricity of e = 0.61. The astrometric
signature of this orbit was previously detected by the HIPPARCOS satellite in
the form of curvature in the proper motion components, although the period was
unknown at the time. By combining our radial velocity measurements with the
HIPPARCOS intermediate data (abscissae residuals) we are able to derive the
full three-dimensional orbit, and determine the dynamical mass of the unseen
companion as well as a revised trigonometric parallax that accounts for the
orbital motion. Given our primary mass estimate of 0.73 solar masses (mid-K
dwarf), the companion mass is determined to be 0.89 solar masses, or about 20%
larger than the primary. The likely explanation for the larger mass without any
apparent contribution to the light is that the companion is itself a closer
binary composed of M dwarfs. The near-infrared excess and X-ray emission
displayed by HIP 50796 support this. Our photometric modeling of the excess
leads to a lower limit to the mass ratio of the close binary of about q = 0.8,
and individual masses of 0.44-0.48 solar masses and 0.41-0.44 solar masses. The
new parallax (20.6 +/- 1.9 mas) is significantly smaller than the original
HIPPARCOS value, and more precise.


title:
An absolutely calibrated survey of polarized emission from the northern
  sky at 1.4 GHz

abstract:
  A new polarization survey of the northern sky at 1.41 GHz is presented. The
observations were carried out using the 25.6m telescope at the Dominion Radio
Astrophysical Observatory in Canada, with an angular resolution of 36 arcmin.
The data are corrected for ground radiation to obtain Stokes U and Q maps on a
well-established intensity scale tied to absolute determinations of zero
levels, containing emission structures of large angular extent, with an rms
noise of 12 mK. Survey observations were carried out by drift scanning the sky
between -29 degr and +90 degr declination. The fully sampled drift scans,
observed in steps of 0.25 degr to 2.5 degr in declination, result in a northern
sky coverage of 41.7% of full Nyquist sampling. The survey surpasses by a
factor of 200 the coverage, and by a factor of 5 the sensitivity, of the
Leiden/Dwingeloo polarization survey (Spoelstra 1972) that was until now the
most complete large-scale survey. The temperature scale is tied to the
Effelsberg scale. Absolute zero-temperature levels are taken from the
Leiden/Dwingeloo survey after rescaling those data by the factor of 0.94. The
paper describes the observations, data processing, and calibration steps. The
data are publicly available at http://www.mpifr-bonn.mpg.de/div/konti/26msurvey
or http://www.drao.nrc.ca/26msurvey.


title: HESS J1825-137: A pulsar wind nebula associated with PSR B1823-13?

abstract:
  HESS J1825-137 was detected with a significance of 8.1 $\sigma$ in the
Galactic Plane survey conducted with the H.E.S.S. instrument in 2004. Both HESS
J1825-137 and the X-ray pulsar wind nebula G18.0--0.7 (associated with the
Vela-like pulsar PSR B1823-13) are offset south of the pulsar, which may be the
result of the SNR expanding into an inhomogeneous medium. The TeV size ($\sim
35$ pc, for a distance of 4 kpc) is $\sim 6$ times larger than the X-ray size,
which may be the result of propagation effects as a result of the longer
lifetime of TeV emitting electrons, compared to the relatively short lifetime
of keV synchrotron emitting electrons. The TeV photon spectral index of $\sim
2.4$ can also be related to the extended PWN X-ray synchrotron photon index of
$\sim 2.3$, if this spectrum is dominated by synchrotron cooling. The
anomalously large size of the pulsar wind nebula can be explained if the pulsar
was born with a relatively large initial spindown power and braking index
$n\sim 2$, provided that the SNR expanded into the hot ISM with relatively low
density ($\sim 0.003$ cm$^{-3}$).


title:
Post-outburst radio observation of the region around McNeil's nebula
  (V1647 Ori)

abstract:
  We present post-outburst (~ 100 days after outburst) radio continuum
observation of the region (~ 30' x 30') around McNeil's nebula (V1647 Orionis).
The observations were carried out using the Giant Metrewave Radio Telescope
(GMRT), India, at 1272 MHz on 2004 Feb 14.5 UT. Although 8 sources have been
detected within a circular diameter of 25' centred on V1647 Ori, we did not
detect any radio continuum emission from McNeil's nebula. We assign a 5-sigma
upper limit of 0.15 mJy/beam for V1647 Ori where the beam size is 5.6" x 2.7".
Even at higher frequencies of 4.9 and 8.5 GHz (VLA archival data), no radio
emission has been detected from this region. Three scenarios namely, emission
from homogeneous HII region, ionised stellar wind and shock ionised gas, are
explored in the light of our GMRT upper-limit. For the case of homogeneous HII
region, the radius of the emitting region is constrained to be <~ 26 AU
corresponding to a temperature >~ 2,500 K, which is consistent with the
reported radio and H-alpha emission. In the ionised stellar wind picture, our
upper limit of radio emission translates to the ratio of mass loss rate and
terminal velocity, (M_dot/v_infinity) < 1.2-1.8 x 10^(-10) (M_sun/yr)/(km/s).
On the other hand, if the stellar wind shocks the dense neutral (molecular)
cloud, the radio upper limit implies that the fraction of the wind encountering
the dense obstacle is <50%. Based on a recent measurement of X-ray outburst and
later monitoring, the expected radio emission has been estimated. Using our
radio limit, the radius (<~ 36 AU) and electron density (>~ 7.2 x 10^7 cm^(-3)
of the radio emitting plasma have been constrained using a two phase medium in
pressure equilibrium for a volume filling factor of 0.9.


title:
On the vacuum fluctuations and the cosmological constant: Comment on the
  paper by T.Padmanabhan

abstract:
  The formula for the dark energy, derived by Padmanabhan in a recent Letter to
Editor (Class.Quantum Grav. September 2005, the formula given in its Abstract),
was actually derived 4 years earlier ourselves in astro-ph/0105245;
Mod.Phys.Lett. A18, 561, 2003. Among dozens of references in that Letter, no
quotation to our paper. Based on the same Zeldovich idea on vacuum
fluctuations, Padmanabhan derives it from scaling considerations, while we had
gone into more details and shown that the formula fits the observed value of
the cosmological constant if l=0 modes are relevant.


title:
Global oscillations of a fluid torus as a modulation mechanism for
  black-hole high-frequency QPOs

abstract:
  We study strong-gravity effects on modulation of radiation emerging from
accreting compact objects as a possible mechanism for flux modulation in QPOs.
We construct a toy model of an oscillating torus in the slender approximation
assuming thermal bremsstrahlung for the intrinsic emissivity of the medium and
we compute observed (predicted) radiation signal including contribution of
indirect (higher-order) images and caustics in the Schwarzschild spacetime. We
show that the simplest oscillation mode in an accretion flow, axisymmetric
up-and-down motion at the meridional epicyclic frequency, may be directly
observable when it occurs in the inner parts of accretion flow around black
holes. Together with the second oscillation mode, an in-and-out motion at the
radial epicyclic frequency, it may then be responsible for the high-frequency
modulations of the X-ray flux observed at two distinct frequencies (twin
HF-QPOs) in micro-quasars.


title:
Millisecond pulsar population in the Galactic center and high energy
  contributions

abstract:
  We propose that there possibly exists a population of millisecond pulsars in
the Galactic center region. Millisecond pulsars (MSPs) could emit GeV
gamma-rays through synchrotron-curvature radiation as predicted by outer gap
models. In the same time, the compact wind nebulae around millisecond pulsars
can emit X-rays though synchrotron radiation and TeV photons through inverse
Compton processes. Besides, millisecond pulsar winds provide good candidates
for the electron-positrons sources in the Galactic center. Therefore, we
suggest that the millisecond pulsar population could contribute to the weak
unidentified Chandra X-ray sources, the diffuse gamma-rays detected by EGRET,
electron-positron annihilation lines and TeV photons detected by HESS toward
the Galactic center.


title: The correlations and anticorrelations in QPO data

abstract:
  Double peak kHz QPO frequencies in neutron star sources varies in time by a
factor of hundreds Hz while in microquasar sources the frequencies are fixed
and located at the line \nu_2 = 1.5 \nu_1 in the frequency-frequency plot. The
crucial question in the theory of twin HFQPOs is whether or not those observed
in neutron-star systems are essentially different from those observed in black
holes. In black hole systems the twin HFQPOs are known to be in a 3:2 ratio for
each source. At first sight, this seems not to be the case for neutron stars.
For each individual neutron star, the upper and lower kHz QPO frequencies,
\nu_2 and \nu_1, are linearly correlated, \nu_2=A \nu_1 + B, with the slope A <
1.5, i.e., the frequencies definitely are not in a 1.5 ratio. In this
contribution we show that when considered jointly on a frequency-frequency
plot, the data for the twin kHz QPO frequencies in several (as opposed to one)
neutron stars uniquely pick out a certain preferred frequency ratio that is
equal to 1.5 for the six sources examined so far.


title:
Systematic motions in the Galactic plane found in the Hipparcos
  Catalogue using Herschel's Method

abstract:
  Two motions in the galactic plane have been detected and characterized, based
on the determination of a common systematic component in Hipparcos catalogue
proper motions. The procedure is based only on positions, proper motions and
parallaxes, plus a special algorithm which is able to reveal systematic trends.
Our results come from two stellar samples. Sample 1 has 4566 stars and defines
a motion of apex (l,b)=(177.8,3.7)+/-(1.5,1.0) and space velocity V=27+/-1
km/s. Sample 2 has 4083 stars and defines a motion of apex
(l,b)=(5.4,-0.6)+/-(1.9,1.1) and space velocity V=32+/-2 km/s. Both groups are
distributed all over the sky and cover a large variety of spectral types, which
means that they do not belong to a specific stellar population. Herschel's
method is used to define the initial samples of stars and later to compute the
common space velocity. The intermediate process is based on the use of a
special algorithm to determine systematic components in the proper motions. As
an important contribution, this paper sets out a new way to study the
kinematics of the solar neighborhood, in the search for streams, associations,
clusters and any other space motion shared by a large number of stars, without
being restricted by the availability of radial velocities.


title: Evolutionary status of late-type contact binaries

abstract:
  A new scenario for evolution of contact binaries is presented and discussed.
Arguments are given that W UMa-type systems are formed from detached binaries
which lose angular momentum via magnetized wind. This takes typically several
Gyr. Such an age is sufficient for the initially more massive component to
deplete hydrogen in its core and to fill the Roche lobe. As a result, mass
transfer occurs with a reversal of the mass ratio. After a fast mass exchange
the present primaries of W UMa-type binaries land close to ZAMS whereas the
secondaries develop small helium cores, which makes them considerably
over-sized relative to ZAMS stars of the same mass. As a result, both
components can fulfill the mass-radius relation for contact systems while being
in thermal equilibrium. This solves the "Kuiper paradox". Further mass transfer
in a contact phase proceeds on a nuclear time scale of the secondary. Hydrogen
rich matter is transferred to the primary in the first part of this phase. This
keeps the primary close to ZAMS. When the mass of the secondary decreases below
the mass of the original hydrogen-burning core, helium-rich matter is
transferred to the primary shifting it towards TAMS. This prediction agrees
with observations of the position of the components of contact binaries on the
mass-radium diagram. The ultimate fate of the binary is coalescence of both
components.


title: Spectroscopic Redshifts for Seven Lens Galaxies

abstract:
  We report VLT observations of 11 lensed quasars, designed to measure the
redshifts of their lens galaxies. We successfully determined the redshifts for
seven systems, five of which were previously unknown. The securely measured
redshifts for the lensing galaxies are: HE0047-1756 z=0.408; PMNJ0134-0931
z=0.766; HE0230-2130 z=0.522; HE0435-1223 z=0.455; SDSS0924+021 z=0.393;
LBQS1009-025 z=0.871; and WFIJ2033-472 z=0.658. For four additional systems
(BRI0952-0115, Q1017-207, Q1355-2257 and PMNJ1632-003) we estimate tentative
redshifts based on some features in their spectra.


title: X-ray Emission from the nearby PSR B1133+16

abstract:
  We detected a nearby (d=360 pc), old (5 Myr) pulsar B1133+16 with Chandra.
The observed pulsar's flux is $(0.8\pm 0.2)\times 10^{-14}$ ergs cm$^{-2}$
s$^{-1}$ in the 0.5-8 keV band. Because of the small number of counts detected,
the spectrum can be described by various models. A power-law fit of the
spectrum gives a photon index $\Gamma = 2.5$ and an isotropic luminosity of
$1.4\times 10^{29}$ ergs s$^{-1}$ in the 0.5-8 keV band, which is about
$1.6\times 10^{-3}$ of the spin-down power $\dot{E}$. The spectrum can also be
fitted by a blackbody model with a temperature of $\approx 2.8$ MK and a
projected emitting area of $\sim 500$ m$^2$, possibly a hot polar cap. The
X-ray properties of PSR B1133+16 are similar to those of other old pulsars
observed in X-rays, particularly the drifting pulsar B0943+10.


title:
Riemannian geometrical constraints on magnetic vortex filaments in
  plasmas

abstract:
  Two theorems on the Riemannian geometrical constraints on vortex magnetic
filaments acting as dynamos in (MHD) flows are presented. The use of
Gauss-Mainard-Codazzi equations allows us to investigate in detail the
influence of curvature and torsion of vortex filaments in the MHD dynamos. This
application follows closely previous applications to Heisenberg spin equation
to the investigations in magnetohydrostatics given by Schief (Plasma Physics J.
10, 7, 2677 (2003)). The Lorentz force on vortex filaments are computed and the
ratio between the forces along different directions are obtained in terms of
the ratio between the corresponding magnetic fields which equals also the ratio
between the Frenet torsion and vortex line curvature. A similar relation
between Lorentz forces, magnetic fields and twist, which is proportional to
total torsion integral has been obtained by Ricca (Fluid Dyn. Res. 36,319
(2005)) in the case of inflexional desiquilibrium of magnetic flux-tubes. This
is due to the fact that the magnetic vortex lines are a limit case of the
magnetic flux-tubes when the lenght of the tube is much greater than the radius
of the tube. Magnetic helicity equation of the filament allows us again to
determine the magnetic fields ratio from Frenet curvature and torsion of the
vortex lines.


title: MAGPIS: A Multi-Array Galactic Plane Imaging Survey

abstract:
  We present the Multi-Array Galactic Plane Imaging Survey (MAGPIS), which maps
portions of the first Galactic quadrant with an angular resolution, sensitivity
and dynamic range that surpasses existing radio images of the Milky Way by more
than an order of magnitude. The source detection threshold at 20 cm is in the
range 1--2 mJy over the 85% of the survey region (5 deg < l < 32 deg, |b| < 0.8
deg) not covered by bright extended emission. We catalog over 3000 discrete
sources (diameters mostly <30 arcsec) and present an atlas of ~400 diffuse
emission regions. New and archival data at 90 cm for the whole survey area are
also presented. Comparison of our catalogs and images with the MSX mid-infrared
data allow us to provide preliminary discrimination between thermal and
non-thermal sources. We identify 49 high-probability supernova remnant
candidates, increasing by a factor of seven the number of known remnants with
diameters smaller than 5 arcmin in the survey region; several are pulsar wind
nebula candidates and/or very small diameter remnants (D<45 arcsec). We report
the tentative identification of several hundred H II regions based on a
comparison with the mid-IR data; they range in size from unresolved
ultra-compact sources to large complexes of diffuse emission on scales of half
a degree. In several of the latter regions, cospatial nonthermal emission
illustrates the interplay between stellar death and birth. We comment briefly
on plans for followup observations and our extension of the survey; when
complemented by data from ongoing X-ray and mid-IR observations, we expect
MAGPIS to provide the most complete census yet obtained of the birth and death
of massive stars in the Milky Way. Catalogs and images are available on the
MAGPIS web site (http://third.ucllnl.org/gps).


title: The Evolution of the First Core in Rotating Molecular Core

abstract:
  We present the evolution path of the first core in rotating molecular cloud
core and the evolution during the second collapse phase using axisymmetric
numerical calculations. The structure and evolution of the rotating first core
is characterized by the angular momentum $J_{\rm core}$ and mass $M_{\rm
core}$, both of which increase with time by accretion from the infalling
envelope. We find the evolution path of it can be considered as a sequence of
equilibrium solutions with a constant $J_{\rm core}/M_{\rm core}^2$. Such
evolution paths are in good agreement with the results of three-dimensional
numerical simulations. The evolution paths is completely different from
spherical case. Except for extremely small rotation rate of $J_{\rm
core}/M_{\rm core}^2 < 0.015 G/(\sqrt{2} c_{\rm iso})$, the first core does not
increase in the central density beyond a certain maximum value and can not
begins the second collapse direct and grows in mass by accretion. Such a first
core has a very long time-scale and seems to suffer from a non-axisymmetric
evolution. In the usual case, we expect that the time-scale of a rotating first
core becomes several thousand years and several percent of the prestellar cores
contain a first core at least. Such a rotating first core has a small average
luminosity of $L_{\rm core} = 0.003-0.03$($\dot{M}_{\rm core}/\dot{M}_{\rm
ref}$) L$_{\odot}$.


title: IC 225: a dwarf elliptical galaxy with a peculiar blue core

abstract:
  We present the discovery of a peculiar blue core in the elliptical galaxy IC
225 by using images and spectrum from the Sloan Digital Sky Survey (SDSS). The
outer parts of the surface brightness profiles of u-, g-, r-, i- and z-band
SDSS images for IC 225 are well fitted with an exponential function. The
fitting results show that IC 225 follows the same relations between the
magnitude, scale length and central surface brightness for dwarf elliptical
galaxies. Its absolute blue magnitude (M_B) is -17.14 mag, all of which suggest
that IC 225 is a typical dwarf elliptical galaxy. The g-r color profile
indicates a very blue core with a radius of 2 arcseconds, which is also clearly
seen in the RGB image made of g-, r- and i-band SDSS images. The SDSS optical
spectrum exhibits strong and very narrow nebular emission lines. The metal
abundances derived by the standard methods, which are 12+log(O/H) = 8.98,
log(N/O) = -0.77 and 12+log(S+/H+) = 6.76, turn out to be significantly higher
than that predicted by the well-known luminosity-metallicity relation. After
carefully inspecting the central region of IC 225, we find that there are two
distinct nuclei, separated by 1.4 arcseconds, the off-nucleated one is even
bluer than the nucleus of IC 225. The asymmetric line profiles of higher-order
Balmer lines indicate that the emission lines are bluer shifted relative to the
absorption lines, suggesting that the line emission arises from the off-center
core, whose nature is a metal-rich Hii region. To the best of our knowledge, it
is the first high-metallicity Hii region detected in a dwarf elliptical galaxy.


title:
Discovery of an Optically-Faint Quasar at z=5.70 and Implications for
  the Faint End of the Quasar Luminosity Function

abstract:
  We present observations of an optically-faint quasar, RD J114816.2+525339,
discovered from deep multi-color observations of the field around the z = 6.42
quasar SDSS J1148+5251. The two quasars have a projected separation of 109
arcsec and both are outliers in r-z versus z-J color-color space. Keck
spectroscopy reveals RD J114816.2+525339 to be a broad-absorption line quasar
at z = 5.70. With z_AB = 23.0, RD J114816.2+525339 is 3.3 mag fainter than SDSS
J1148+5251, making it the faintest quasar known at z>5.5. This object was
identified in a survey of ~2.5 square degrees. The implied surface density of
quasars at these redshifts and luminosities is broadly consistent with previous
extrapolations of the faint end of the quasar luminosity function and supports
the idea that active galaxies provide only a minor component of the reionizing
ultraviolet flux at these redshifts.


title: The theory of spectral evolution of the GRB prompt emission

abstract:
  We develop the theory of jitter radiation from GRB shocks containing
small-scale magnetic fields and propagating at an angle with respect to the
line of sight. We demonstrate that the spectra vary considerably: the
low-energy photon index, $\alpha$, ranges from 0 to -1 as the apparent viewing
angle goes from 0 to $\pi/2$. Thus, we interpret the hard-to-soft evolution and
the correlation of $\alpha$ with the photon flux observed in GRBs as a combined
effect of temporal variation of the viewing angle and relativistic aberration
of an individual thin, instantaneously illuminated shell. The model predicts
that about a quarter of time-resolved spectra should have hard spectra,
violating the synchrotron $\alpha=-2/3$ line of death. The model also naturally
explains why the peak of the distribution of $\alpha$ is at $\alpha\approx-1$.
The presence of a low-energy break in the jitter spectrum at oblique angles
also explains the appearance of a soft X-ray component in some GRBs and a
relatively small number of them. We emphasize that our theory is based solely
on the first principles and contains no {\it ad hoc} (phenomenological)
assumptions.


title: An Unbiased Survey for Molecular Clouds in the Southern Galactic Warp

abstract:
  We have made an unbiased survey for molecular clouds in the Galactic Warp.
This survey, covering an area of 56 square degrees at l = 252 deg to 266 deg
and b = -5 deg to -1 deg, has revealed 70 molecular clouds, while only 6 clouds
were previously known in the region. The number of molecular clouds is, then,
an order of magnitude greater than previously known in this sector at R > 14.5
kpc. The mass of the clouds is in a range from 7.8x10(2) Mo to 8.4x10(4) Mo,
significantly less than the most massive giant molecular clouds in the inner
disk, ~10(6) Mo, while the cloud mass spectrum characterized by a power law is
basically similar to other parts of the Galaxy. The X factor, N(H2)/Wco(12CO),
derived from the molecular clouds in the Warp is estimated to be 3.5(+/-1.8)
times larger than that in the inner disk. The total molecular mass in the Warp
is estimated as 7.3x10(5) Mo, and total mass in the far-outer Galaxy (R > 14.5
kpc) can be estimated as 2x10(7) Mo. The spatial correlation between the CO and
HI distribution appears fairly good, and the mass of the molecular gas is about
1% of that of the atomic gas in the far-outer Galaxy. This ratio is similar to
that in the interarm but is ten times smaller than those of the spiral arms.
Only 6 of the 70 Warp clouds show signs of star formation at the IRAS
sensitivity and star formation efficiency for high-mass stars in the Warp is
found to be smaller than those in other molecular clouds in the Galaxy.


title: Multi-spot ignition in type Ia supernova models

abstract:
  We present a systematic survey of the capabilities of type Ia supernova
explosion models starting from a number of flame seeds distributed around the
center of the white dwarf star. To this end we greatly improved the resolution
of the numerical simulations in the initial stages. This novel numerical
approach facilitates a detailed study of multi-spot ignition scenarios with up
to hundreds of ignition sparks. Two-dimensional simulations are shown to be
inappropriate to study the effects of initial flame configurations. Based on a
set of three-dimensional models, we conclude that multi-spot ignition scenarios
may improve type Ia supernova models towards better agreement with
observations. The achievable effect reaches a maximum at a limited number of
flame ignition kernels as shown by the numerical models and corroborated by a
simple dimensional analysis.


title:
GMOS IFU observations of the stellar and gaseous kinematics in the
  centre of NGC 1068

abstract:
  We present a datacube covering the central 10 arcsec of the archetypal active
galaxy NGC 1068 over a wavelength range 4200 to 5400 Angstrom. obtained during
the commissioning of the integral field unit (IFU) of the Gemini Multiobject
Spectrograph (GMOS) installed on the Gemini-North telescope. The datacube shows
a complex emission line morphology in the [OIII] doublet and Hbeta line. To
describe this structure phenomenologically we construct an atlas of velocity
components derived from multiple Gaussian component fits to the emission lines.
The atlas contains many features which cannot be readily associated with
distinct physical structures. While some components are likely to be associated
with the expected biconical outflow, others are suggestive of high velocity
flows or disk-like structures. As a first step towards interpretation, we seek
to identify the stellar disk using kinematical maps derived from the Mgb
absorption line feature at 5170 Angstrom and make associations between this and
gaseous components in the atlas of emission line components.


title:
A very deep Chandra observation of the Perseus cluster: shocks, ripples
  and conduction

abstract:
  We present the first results from a very deep Chandra X-ray observation of
the core of the Perseus cluster of galaxies. A pressure map reveals a clear
thick band of high pressure around the inner radio bubbles. The gas in the band
must be expanding outward and the sharp front to it is identified as a shock
front, yet we see no temperature jump across it; indeed there is more soft
emission behind the shock than in front of it. We conclude that in this inner
region either thermal conduction operates efficiently or the co-existing
relativistic plasma seen as the radio mini-halo is mediating the shock. If
common, isothermal shocks in cluster cores mean that we cannot diagnose the
expansion speed of radio bubbles from temperature measurements alone. They can
at times expand more rapidly than currently assumed without producing
significant regions of hot gas. Bubbles may also be significantly more
energetic. The pressure ripples found in earlier images are identified as
isothermal sound waves. A simple estimate based on their amplitude confirms
that they can be an effective distributed heat source able to balance radiative
cooling. We see multiphase gas with about 10^9 Msun at a temperature of about
0.5 keV. Much, but not all, of this cooler gas is spatially associated with the
optical filamentary nebula around the central galaxy, NGC 1275. A residual
cooling flow of about 50 Msun/yr may be taking place. A channel is found in the
pressure map along the path of the bubbles, with indications found of outer
bubbles. The channel connects in the S with a curious cold front.


title:
Some further comments on the paper "biparametric scale adaptive filter
  design" for the detection of compact sources as proposed by M. Lopez-Caniego
  et. al 2005, MNRAS 359, 993

abstract:
  In this note we re-propose the arguments presented in Vio (2005) examining
the superiority of the 'bi-parametric scale adaptive filter' (BSAF) when
dealing with source detection as claimed by (Lopez-Caniego 2005a) and confirmed
in Lopez-Caniego (2005b). We suggest here that the dispute can be easily solved
if these authors provide the community with a detailed derivation of a basic
equation.


title: GCIRS34W: An irregular variable in the Galactic Centre

abstract:
  We report the results of time-resolved photometric and spectroscopic
near-infrared observations of the Ofpe/WN9 star and LBV candidate GCIRS34W in
the Galactic Centre star cluster. Diffraction limited resolution photometric
observations obtained in H and K bands show a strong, non-periodic variability
on time scales from months to years in both bands accompanied by variations of
the stellar colour. Three K band spectra obtained in 1996, 2003 and 2004 with
integral field spectrometers are identical within their accuracies and exclude
significant spectroscopic variability. The most probable explanation of the
stellar photometric variability is obscuration by circumstellar material
ejected by the star. The approximated position of GCIRS34W in a HR diagram is
located between O supergiants and LBVs, suggesting that this star is a
transitional object between these two phases of stellar evolution.


title:
Formation of Giant Planets by Concurrent Accretion of Solids and Gas
  inside an Anti-Cyclonic Vortex

abstract:
  We study the formation of a giant gas planet by the core--accretion
gas--capture process, with numerical simulations, under the assumption that the
planetary core forms in the center of an anti-cyclonic vortex. The presence of
the vortex concentrates particles of centimeter to meter size from the
surrounding disk, and speeds up the core formation process. Assuming that a
planet of Jupiter mass is forming at 5 AU from the star, the vortex enhancement
results in considerably shorter formation times than are found in standard
core--accretion gas--capture simulations. Also, formation of a gas giant is
possible in a disk with mass comparable to that of the minimum mass solar
nebula.


title:
The Magnificent Seven: Nearby Isolated Neutron Stars with strong
  Magnetic Fields

abstract:
  Although the true origin of the broad absorption lines in X-ray spectra of
thermal isolated neutron stars is not clear yet, our current knowledge about
the "magnificent seven" strongly suggests that they are highly magnetized
($10^{13} - 10^{14}$ G), slowly rotating cooling neutron stars. Further timing
studies would be very useful to obtain more independent estimates of the
magnetic field strength (as they currently only exist from RX J0720.4-3125).


title: The clumpiness of Luminous Blue Variable winds

abstract:
  We present the first systematic spectropolarimetric study of Luminous Blue
Variables (LBVs), and find that at least half those objects studied display
evidence for intrinsic polarization -- a signature of significant inhomogeneity
at the base of the wind. Furthermore, multi-epoch observations reveal that the
polarization is variable in both strength and position angle. This evidence
points away from a simple axi-symmetric wind structure \`{a} la the B[e]
supergiants, and instead suggests a wind consisting of localised density
enhancements, or `clumps'. We show with an analytical model that, in order to
produce the observed variability, the clumps must be large, produced at or
below the photosphere, and ejected on timescales of days. More details of LBV
wind-clumping will be determined through further analysis of the model and a
polarimetric monitoring campaign.


title: Monte Carlo simulations of radio emission from cosmic ray air showers

abstract:
  As a basis for the interpretation of data gathered by LOPES and other
experiments, we have carried out Monte Carlo simulations of geosynchrotron
radio emission from cosmic ray air showers. The simulations, having been
verified carefully with analytical calculations, reveal a wealth of information
on the characteristics of the radio signal and their dependence on specific air
shower parameters. In this article, we review the spatial characteristics of
the radio emission, its predicted frequency spectrum and its dependence on
important air shower parameters such as the shower zenith angle, the primary
particle energy and the depth of the shower maximum, which can in turn be
related to the nature of the primary particle.


title: Discovery of the Millisecond X-Ray Pulsar HETE J1900.1-2455

abstract:
  We report the discovery of millisecond pulsations from the low-mass X-ray
binary HETE J1900.1-2455 which was discovered by the detection of a type I
X-ray burst by the High Energy Transient Explorer 2 (HETE-2). The neutron star
emits coherent pulsations at 377.3 Hz and is in an 83.3 minute circular orbit
with a companion with a mass greater than 0.016 solar masses and likely less
than 0.07 solar masses. The companion star's Roche lobe could be filled by a
brown dwarf with no need for heating or non-standard evolution. During one
interval with an unusually high X-ray flux, the source produced quasiperiodic
oscillations with a single peak at 883 Hz and on subsequent days, the
pulsations were suppressed. We consider the distribution of spin versus orbital
period in neutron star low-mass X-ray binaries.


title: A seismological analysis of Delta Scuti stars in the Pleiades cluster

abstract:
  A comparison between the oscillation frequencies of six multi-periodic Delta
Scuti stars of the Pleiades cluster and the eigenfrequencies of rotating
stellar models that match the corresponding stellar parameters has been carried
out. The assumption that all the stars considered have some common parameters,
such as metallicity, distance or age, is imposed as a constraint. As a result,
we have a best fit solution associated with a cluster metallicity of [Fe/H] ~
0.067, an age between 70x10^6 and 100x10^6 yr and a distance modulus of
mv-Mv=5.60-5.70 mag. All the stars were found to oscillate mainly in
non-radial, low degree, low order p modes. Estimates of mass and rotation rates
for each star are also obtained


title: Quantum electrodynamical shocks and solitons in astrophysical plasmas

abstract:
  The nonlinear propagation of low-frequency circularly polarized waves in a
magnetized dusty plasma is analyzed. It is found that wave steepening and shock
formation can take place due to the presence of nonlinear quantum vacuum
effects, thus giving rise to ultra-intense electromagnetic shocks. Moreover, it
is shown that solitary wave structures are admitted even under moderate
astrophysical conditions. The results may have applications to astrophysical
plasmas, as well as next generation laser interactions with laboratory plasmas
containing dust clusters.


title: Amorphous alumina in the extended atmosphere of Alpha Orionis

abstract:
  In this paper we study the extended atmosphere of the late-type supergiant
Alpha Orionis. Infrared spectroscopy of red supergiants reveals strong
molecular bands, some of which do not originate in the photosphere but in a
cooler layer of molecular material above it. Lately, these layers have been
spatially resolved by near and mid-IR interferometry. In this paper, we try to
reconcile the IR interferometric and ISO-SWS spectroscopic results on Alpha
Orionis with a thorough modelling of the photosphere, molecular layer(s) and
dust shell. From the ISO and near-IR interferometric observations, we find that
Alpha Orionis has only a very low density water layer close above the
photosphere. However, mid-IR interferometric observations and a narrow-slit
N-band spectrum suggest much larger extra-photospheric opacity close to the
photosphere at those wavelengths, even when taking into account the detached
dust shell. We argue that this cannot be due to the water layer, and that
another source of mid-IR opacity must be present. We show that this opacity
source is probably neither molecular nor chromospheric. Rather, we present
amorphous alumina (Al2O3) as the best candidate and discuss this hypothesis in
the framework of dust-condensation scenarios.


title: Planet formation and migration

abstract:
  We review the observations of extrasolar planets, ongoing developments in
theories of planet formation, orbital migration, and the evolution of
multiplanet systems.


title:
A marked correlation function analysis of halo formation times in the
  Millennium Simulation

abstract:
  We study the environmental dependence of the formation epoch of dark matter
haloes in the Millennium Simulation: a ten billion particle N-body simulation
of standard LambdaCDM cosmology. A sensitive test of this dependence - the
marked correlation function - reveals highly significant evidence that haloes
of a given mass form earlier in denser regions. We define a marked
cross-correlation function, which helps quantify how this effect depends upon
the choice of the halo population used to define the environment. The mean halo
formation redshift as a function of the local overdensity in dark matter is
also well determined, and we see an especially clear dependence for
galaxy-sized haloes. This contradicts one of the basic predictions of the
excursion set model of structure formation, even though we see that this theory
predicts other features of the distribution of halo formation epochs rather
well. It also invalidates an assumption usually employed in the popular halo,
or HOD, models of galaxy clustering, namely that the distribution of halo
properties is a function of halo mass but not of halo environment.


title: The in-flight spectroscopic performance of the Swift XRT CCD camera

abstract:
  The Swift X-ray Telescope (XRT) focal plane camera is a front-illuminated MOS
CCD, providing a spectral response kernel of 144 eV FWHM at 6.5 keV. We
describe the CCD calibration program based on celestial and on-board
calibration sources, relevant in-flight experiences, and developments in the
CCD response model. We illustrate how the revised response model describes the
calibration sources well. Loss of temperature control motivated a laboratory
program to re-optimize the CCD substrate voltage, we describe the small changes
in the CCD response that would result from use of a substrate voltage of 6V.


title: Light Dark Matter

abstract:
  The SPI spectrometer aboard of the INTEGRAL satellite has released a map of
the e+e- annihilation emission line of unprecedented quality, showing that most
of the photons arise from a region coinciding with the stellar bulge of the
Milky Way. The impressive intensity (10^-3 photon/cm^2/s) and morphology (round
and wide) of the emission is begging an explanation. Different classes of
astrophysical objects could inject positrons in the interstellar medium of the
bulge, but the only acceptable ones should inject them at energies low enough
to avoid excessive bremsstrahlung emission in the soft gamma ray regime. Among
the ~ MeV injectors, none seems generous enough to sustain the high level of
annihilation observed. Even the most profuse candidate, namely the beta+
radioactivity of 56 Co nuclei created and expelled in the interstellar medium
by explosive nucleosynthesis of type Ia supernovae, falls short explaining the
phenomenon due to the small fraction of positrons leaking out from the ejecta
(3 %), together with the low SNIa rate in the bulge (0.03 per century).
  It is therefore worth exploring alternative solutions, as for instance, the
idea that the source of the positrons is the annihilation of light dark matter
(LDM) particles of the kind recently proposed, totally independently, by Boehm
and Fayet. Assuming that LDM is the culprit, crucial constraints on the
characteristics (mass and annihilation cross-section) of the associated
particle may be discussed, combining direct gamma ray observations and models
of the early Universe. In particular, the mass of the LDM particles should be
significantly less than 100 MeV, so that the e+ and e- resulting from their
annihilations do not radiate exceedingly through bremsstrahlung in the
interstellar gas of the galactic bulge.


title: Properties of SS433 and ultraluminous X-ray sources in external galaxies

abstract:
  We suggest that the ultraluminous X-ray sources located in external galaxies
(ULXs) are supercritical accretion disks like that in SS433, observed close to
the disk axis. We estimate parameters of the SS433 funnel, where the
relativistic jets are formed. Emergent X-ray spectrum in the proposed model of
the multicolor funnel (MCF) is calculated. The spectrum can be compared with
those of ULXs. We predict a complex absorption-line spectrum with broad and
shallow K$\alpha$/Kc blends of the most abundant heavy elements and particular
temporal variability. Another critical idea comes from observations of nebulae
around the ULXs. We present results of 3D-spectroscopy of nebulae of two ULXs
located in Holmberg II and NGC6946. In both cases the nebula is found to be
powered by the central black hole. The nebulae are compared with SS433 nebula
(W50).


title: Darker Side of the Universe

abstract:
  Observations suggest that nearly seventy per cent of the energy density in
the universe is unclustered and exerts negative pressure. Theoretical
understanding of this component (`dark energy'), which is driving an
accelerated expansion of the universe, is {\it the} problem in cosmology today.
I discuss this issue with special emphasis on the cosmological constant as the
possible choice for the dark energy. Several curious features of a universe
with a cosmological constant are described and some possible approaches to
understand the nature of the cosmological constant are discussed.


title:
Modelling galaxy spectra in presence of interstellar dust. I. The model
  of ISM and the library of dusty SSPs

abstract:
  In this paper, the first of a series of two devoted to modelling the spectra
of galaxies of different morphological type in presence of dust, we present our
description of the dust both in the diffuse ISM and the molecular clouds. Our
model for the dust takes into account three components, i.e. graphite,
silicates and polycyclic aromatic hydrocarbons. We consider and adapt to our
aims two prescriptions for the size distribution of the dust grains and two
models for the emission of the dusty ISM. We cross-check the emission and
extinction models of the ISM by calculating the extinction curves and the
emission for the typical environments of the Milky Way and the Large and Small
Magellanic Clouds and by comparing the results with the observational data. The
final model we have adopted is an hybrid one which stems from combining the
analysis of Guhathakurta et al (1989) for the emission of graphite and
silicates and Puget et al. (1985) for the PAH emission, and using the
distribution law of Weingartner et al. (2001a) and the ionization model for
PAHs of Weingartner et al. (2001b). We apply the model to calculate the SED of
SSPs of different age and chemical composition, which may be severely affected
by dust in young, massive stars while they are still embedded in their parental
MCs. We use the "Ray Tracing" method to solve the problem of radiative transfer
and to calculate libraries of SSP SEDs. Particular care is paid to model the
contribution from PAHs, introducing different abundances of C in the population
of very small carbonaceous grains (VSGs) and different ionization states in
PAHs. The SEDs of young SSPs are then compared with observational data of star
forming regions of four local galaxies successfully reproducing their SEDs from
the UV-optical regions to the mid and far infrared.


title: 3D kinematics of white dwarfs from the SPY project II

abstract:
  We present the kinematics of a sample of 398 DA white dwarfs from the SPY
project (ESO SN Ia Progenitor surveY) and discuss kinematic criteria for
distinguishing thin-disk, thick-disk, and halo populations. This is the largest
homogeneous sample of white dwarfs for which 3D space motions have been
determined. Since the percentage of old stars among white dwarfs is higher than
among main-sequence stars, they are presumably valuable tools in studies of old
populations, such as the halo and the thick disk. Radial velocities and
spectroscopic distances were combined with our measurements of proper motions
to derive 3D space motions. Galactic orbits were computed. Our kinematic
criteria for assigning population membership were deduced from a sample of F
and G stars, for which chemical criteria can be used to distinguish between a
thin-disk, a thick-disk and a halo star. Our kinematic population
classification scheme is based on the position in the U-V-velocity diagram, the
position in the Jz-eccentricity diagram, and the Galactic orbit. We combined
this with age information and found seven halo and 27 thick-disk white dwarfs
in this brightness limited sample. Correspondingly 2% of the white dwarfs
belong to the halo and 7% to the thick disk. The mass contribution of the
thick-disk white dwarfs is found to be substantial, but is insufficient to
account for the missing dark matter. (abbreviated)


title: Diffractive Interstellar Scintillation of the Quasar J1819+3845 at 21cm

abstract:
  We report the discovery of fast, frequency-dependent intensity variations
from the scintillating intra-day variable quasar J1819+3845 at a wavelength of
21cm which resemble diffractive interstellar scintillations observed in
pulsars. The timescale (down to 20 min) and the bandwidth (frequency
decorrelation bandwidth of 160 MHz) of the observed variations jointly imply
that the component of the source exhibiting this scintillation must possess a
brightness temperature well in excess of the inverse Compton limit. A specific
model in which both the source and scintillation pattern are isotropic implies
a brightness temperature 0.5 x 10^13 z_{pc} K, where previous estimates place
the distance to the scattering medium in the range z_{pc}=4-12pc, yielding a
minimum brightness temperature >20 times the inverse Compton limit. An
independent estimate of the screen distance using the 21cm scintillation
properties alone indicates a minimum screen distance of z approx 40pc and a
brightness temperature above 2 x 10^14 K. There is no evidence for anisotropy
in the scattering medium or source from the scintillation characteristics, but
these estimates may be reduced by a factor comparable to the axial ratio if the
source is indeed elongated.


title: The chemical evolution of Barium and Europium in the Milky Way

abstract:
  We compute the evolution of the abundances of barium and europium in the
Milky Way and we compare our results with the observed abundances from the
recent UVES Large Program "First Stars". We use a chemical evolution model
which already reproduces the majority of observational constraints. We confirm
that barium is a neutron capture element mainly produced in the low mass AGB
stars during the thermal-pulsing phase by the 13C neutron source, in a slow
neutron capture process. However, in order to reproduce the [Ba/Fe] vs. [Fe/H]
as well as the Ba solar abundance, we suggest that Ba should be also produced
as an r-process element by massive stars in the range 10-30 solar masses. On
the other hand, europium should be only an r-process element produced in the
same range of masses (10-30 solar masses), at variance with previous
suggestions indicating a smaller mass range for the Eu producers. As it is well
known, there is a large spread in the [Ba/Fe] and [Eu/Fe] ratios at low
metallicities, although smaller in the newest data. With our model we estimate
for both elements (Ba and Eu) the ranges for the r-process yields from massive
stars which better reproduce the trend of the data. We find that with the same
yields which are able to explain the observed trends, the large spread in the
[Ba/Fe] and [Eu/Fe] ratios cannot be explained even in the context of an
inhomogeneous models for the chemical evolution of our Galaxy. We therefore
derive the amount by which the yields should be modified to fully account for
the observed spread. We then discuss several possibilities to explain the size
of the spread. We finally suggest that the production ratio of [Ba/Eu] could be
almost constant in the massive stars.


title: Host galaxies of 2MASS-selected QSOs at redshift over 0.3

abstract:
  We have obtained optical imaging with the Canada France Hawaii Telescope
(CFHT) of 21 2MASS-selected QSOs of redshift greater than 0.3. This paper
complements the sample of lower redshift 2MASS QSOs previously published. The
QSOs have higher overall and nuclear luminosity, bluer colours, and higher
ratio of nuclear to host flux than the lower redshift sample. From these and
other properties, we argue that the sample is consistent with the emergence of
the AGN from dusty starbursts following major tidal interactions between
galaxies.


title: Dynamical Cusp Regeneration

abstract:
  After being destroyed by a binary supermassive black hole, a stellar density
cusp can regrow at the center of a galaxy via energy exchange between stars
moving in the gravitational field of the single, coalesced hole. We illustrate
this process via high-accuracy N-body simulations. Regeneration requires
roughly one relaxation time and the new cusp extends to a distance of roughly
one-fifth the black hole's influence radius, with density rho ~ r^{-7/4}; the
mass in the cusp is of order 10% the mass of the black hole. Growth of the cusp
is preceded by a stage in which the stellar velocity dispersion evolves toward
isotropy and away from the tangentially-anisotropic state induced by the
binary. We show that density profiles similar to those observed at the center
of the Milky Way and M32 can regenerate themselves in several Gyr following
infall of a second black hole; the presence of density cusps at the centers of
these galaxies can therefore not be used to infer that no merger has occurred.
We argue that Bahcall-Wolf cusps are ubiquitous in stellar spheroids fainter
than M_V ~ -18.5 that contain supermassive black holes, but the cusps have not
been detected outside of the Local Group since their angular sizes are less
than 0.1". We show that the presence of a cusp implies a lower limit of
\~10^{-4} per year on the rate of stellar tidal disruptions, and discuss the
consequences of the cusps for gravitational lensing and the distribution of
dark matter on sub-parsec scales.


title:
Kinematic evidence for different Planetary Nebulae Populations in the
  elliptical galaxy NGC 4697

abstract:
  We have analysed the magnitudes, kinematics and positions of a complete
sample of 320 PNs in the elliptical galaxy NGC 4697. We show (i) that the PNs
in NGC 4697 do not constitute a single population that is a fair tracer of the
distribution of all stars. The radial velocity distributions, mean velocities,
and dispersions of bright and faint subsamples differ with high statistical
confidence. (ii) Using the combined data for PNs brighter than 26.2, we have
identified a subpopulation of PNs which is azimuthally unmixed and
kinematically peculiar, and which thus neither traces the distribution of all
stars nor can it be in dynamical equilibrium with the galaxy potential. (iii)
The planetary nebula luminosity functions (PNLF) of two kinematic subsamples in
NGC 4697 differ with 99.7% confidence, ruling out a universal PNLF. We estimate
that the inferred secondary PN population introduces an uncertainty in the
bright cutoff magnitude of ~ 0.15 mag for this galaxy. -- We argue that this
secondary PN distribution may be associated with a younger, >~ 1 Gyr old
stellar population, perhaps formed in tidal structures that have now fallen
back onto the galaxy, as has previously been suggested for the X-ray point
sources in this galaxy, or coming from a more recent merger/accretion with a
red galaxy. The use of PNs for extragalactic distance determinations is not
necessarily compromised, but their use as dynamical tracers of dark halos will
require deep observations and careful analysis of large PN samples.


title: The Bright End of the Luminosity Function of Red Sequence Galaxies

abstract:
  We study the bright end of the luminosity distribution of galaxies in fields
with Luminous Red Galaxies (LRG) from the Sloan Digital Sky Survey (SDSS).
Using 2099 square degree of SDSS imaging data, we search for luminous (> L*)
early-type galaxies within 1.0 Mpc/h of a volume-limited sample of 12,608
spectroscopic LRG in the redshift range 0.12 < z < 0.38. Most of these objects
lie in rich environments, with the LRG being the brightest object within 1.0
Mpc/h. The luminosity gap, M12, between the first and second-rank galaxies
within 1.0 Mpc/h is large (~0.8 mag), substantially larger than can be
explained with an exponentially decaying luminosity function of galaxies. The
brightest member is less luminous (by 0.1 to 0.2 mag), and shows a larger gap
in LRG selected groups than in cluster-like environments. The large luminosity
gap shows little evolution with redshift to z = 0.4, ruling out the scenario
that these LRG selected brightest cluster or group galaxies grow by recent
cannibalism of cluster members.


title: Spitzer Discovery of Very Low Luminosity Objects

abstract:
  The Spitzer Space Telescope allows for the first time to search
systematically for very low luminosity (= 0.1 L_sun) objects (VeLLOs)
associated with dense molecular cores. They may be the first candidate Class 0
sources with sub-stellar masses. We describe such a source in the dense
molecular core L1148. VeLLO natal cores show properties that are unusual for
star-forming cores. The low luminosity and in some cases the lack of prominent
outflow could be the result of the small gas supply near the VeLLO.


title: Calibrating models of ultralow-mass stars

abstract:
  Evolutionary and atmospheric models have become available for young
ultralow-mass objects. These models are being used to determine fundamental
parameters from observational properties. TiO bands are used to determine
effective temperatures in ultralow-mass objects, and together with Na- and
K-lines to derive gravities at the substellar boundary. Unfortunately, model
calibrations in (young) ultralow-mass objects are rare. As a first step towards
a calibration of synthetic spectral features, I show molecular bands of TiO,
which is a main opacity source in late M-dwarfs. The TiO $\epsilon$-band at
8450\AA is systematically too weak. This implies that temperatures determined
from that band are underestimated, and I discuss implications for determining
fundamental parameters from high resolution spectra.


title: Speckle Statistics in Adaptively Corrected Images

abstract:
  (abridged) Imaging observations are generally affected by a fluctuating
background of speckles, a particular problem when detecting faint stellar
companions at small angular separations. Knowing the distribution of the
speckle intensities at a given location in the image plane is important for
understanding the noise limits of companion detection. The speckle noise limit
in a long-exposure image is characterized by the intensity variance and the
speckle lifetime. In this paper we address the former quantity through the
distribution function of speckle intensity. Previous theoretical work has
predicted a form for this distribution function at a single location in the
image plane. We developed a fast readout mode to take short exposures of
stellar images corrected by adaptive optics at the ground-based UCO/Lick
Observatory, with integration times of 5 ms and a time between successive
frames of 14.5 ms ($\lambda=2.2$ $\mu$m). These observations temporally
oversample and spatially Nyquist sample the observed speckle patterns. We show,
for various locations in the image plane, the observed distribution of speckle
intensities is consistent with the predicted form. Additionally, we demonstrate
a method by which $I_c$ and $I_s$ can be mapped over the image plane. As the
quantity $I_c$ is proportional to the PSF of the telescope free of random
atmospheric aberrations, this method can be used for PSF calibration and
reconstruction.


title: The 1<z<5 Infrared Luminosity Function of Type I Quasars

abstract:
  We determine the rest-frame 8 micron luminosity function of type I quasars
over the redshift range 1<z<5. Our sample consists of 292 24 micron sources
brighter than 1 mJy selected from 7.17 square degrees of the Spitzer Space
Telescope MIPS survey of the NOAO Deep Wide-Field Survey Bootes field. The AGN
and Galaxy Evolution Survey (AGES) has measured redshifts for 270 of the R<21.7
sources and we estimate that the contamination of the remaining 22 sources by
stars and galaxies is low. We are able to select quasars missed by ultra-violet
excess quasar surveys, including reddened type I quasars and 2.2<z<3.0 quasars
with optical colors similar to main sequence stars. We find reddened type I
quasars comprise 20% of the type I quasar population. Nonetheless, the shape,
normalization, and evolution of the rest-frame 8 micron luminosity function is
comparable to that of quasars selected from optical surveys. The 8 micron
luminosity function of type I quasars is well approximated by a power-law with
index -2.75(+/-0.14). We directly measure the peak of the quasar space density
to be at z=2.6(+/-0.3).


title: Chromospherically Active Stars in the Galactic Bulge

abstract:
  We present the results from the discovery and study of ~3000
chromospherically active giant and subgiant stars toward the Galactic bulge. We
find that these stars are predominantly RS CVn binaries with rotation periods
between 10 and 100 days. We discover that the average rotational period of
these stars decreases with their distance from the Galactic plane. We find that
the primary stars in the RS CVn systems are predominantly first-ascent giants.
Our research also suggests that, if these stars have spot cycles like the sun,
then the cycle period must be longer than 10 years on average. We confirm that
the amplitude of the spot-induced modulations observed in the light curves of
these objects is generally larger at minimum light than at maximum.
Furthermore, we confirm that the amplitudes of the modulations due to stellar
spots generally increases as the observed change in average brightness
increases. We find no evidence for a relationship between a CA star's
brightness and its rotational period. However, the average period does increase
with colour for stars with periods >~30 days.


title: Do red giants have short mode lifetimes?

abstract:
  We show evidence that the red giant star ksi Hya has an oscillation mode
lifetime, tau, of about 2 days significantly shorter than predicted by theory
(tau = 17 days, Houdek & Gough 2002). If this is a general trend of red giants
it would limit the prospects of asteroseismology on these stars because of poor
coherence of the oscillations.


title:
CaII K observations of QSOs in the line-of-sight to the Magellanic
  Bridge

abstract:
  We describe medium-resolution spectroscopic observations taken with the ESO
Multi-Mode Instrument in the CaII K line (3933.661 Angstroms) towards 7 QSOs
located in the line-of-sight to the Magellanic Bridge. At a spectral resolution
R = 6,000, five of the sightlines have a signal-to-noise ratio of 20 or higher.
Definite Ca absorption due to Bridge material is detected towards 3 objects,
with probable detection towards two other sightlines. Gas-phase CaII K Bridge
and Milky Way abundances or lower limits for the all sightlines are estimated
by the use of Parkes 21-cm HI emission line data. These data only have a
spatial resolution of 14 arcminutes compared with the optical observations
which have milli-arcsecond resolution. With this caveat, for the three objects
with sound CaII K detections, we find that the ionic abundance of CaII K
relative to HI, A=log(N(CaK)/N(HI)) for low-velocity Galactic gas ranges from
-8.3 to -8.8 dex, with HI column densities varying from 3-6x10^20 cm^-2. For
Magellanic Bridge gas, the values of A are 0.5 dex higher, ranging from -7.8 to
-8.2 dex, with N(HI)=1-5x10^20 cm^-2. Higher values of A correspond to lower
values of N(HI), although numbers are small. For the sightline towards
B0251--675, the Bridge gas has two different velocities, and in only one of
these is CaII K tentatively detected, perhaps indicating gas of a different
origin or present-day characteristics (such as dust content), although this
conclusion is uncertain and there is the possibility that one of the components
could be related to the Magellanic Stream. Higher signal-to-noise CaII K data
and higher resolution HI data are required to determine whether A changes with
N(HI) over the Bridge and if the implied difference in the metalicity of the
two Bridge components towards B0251-675 is real.


title: A ~ 7.5 Earth-Mass Planet Orbiting the Nearby Star, GJ 876

abstract:
  High precision, high cadence radial velocity monitoring over the past 8 years
at the W. M. Keck Observatory reveals evidence for a third planet orbiting the
nearby (4.69 pc) dM4 star GJ 876. The residuals of three-body Newtonian fits,
which include GJ 876 and Jupiter mass companions b and c, show significant
power at a periodicity of 1.9379 days. Self-consistently fitting the radial
velocity data with a model that includes an additional body with this period
significantly improves the quality of the fit. These four-body (three-planet)
Newtonian fits find that the minimum mass of companion ``d'' is m sin i = 5.89
+- 0.54 Earth masses and that its orbital period is 1.93776 (+- 7x10^-5) days.
Assuming coplanar orbits, an inclination of the GJ 876 planetary system to the
plane of the sky of ~ 50 degrees gives the best fit. This inclination yields a
mass for companion d of m = 7.53 +- 0.70 Earth masses, making it by far the
lowest mass companion yet found around a main sequence star other than our Sun.
Precise photometric observations at Fairborn Observatory confirm low-level
brightness variability in GJ 876 and provide the first explicit determination
of the star's 96.7-day rotation period. Even higher precision short-term
photometric measurements obtained at Las Campanas imply that planet d does not
transit GJ 876.


title: New lambda6cm observations of the Cygnus Loop

abstract:
  Radio continuum and polarization observations of the entire Cygnus Loop at
6cm wavelength were made with the Urumqi 25m telescope. The 6cm map is analysed
together with recently published maps from the Effelsberg 100m telescope at
21cm and 11cm. The integrated flux density of the Cygnus Loop at 6cm is
90+/-9Jy, which implies a spectral index of -0.40+/-0.06 being consistent with
that of Uyaniker et al. (2004) in the wavelength range up to 11cm. This rules
out any global spectral steepening up to 6cm. However, small spectral index
variations in some regions of the source are possible, but there are no
indications for any spectral curvature. The linear polarization data at 6cm
show percentage polarizations up to 35% in some areas of the Cygnus Loop,
exceeding those observed at 11cm. The Rotation Measure is around -21rad/m^2 in
the southern area, which agrees with previous observations. However, the
distribution of Rotation Measures is rather complex in the northern part of the
Cygnus Loop, where the 21cm emission is totally depolarized. Rotation Measures
based on 11cm and 6cm data are significantly larger than in the southern part.
The difference in the polarization characteristic between the northern and
southern part supports previous ideas that the Cygnus Loop consists of two
supernova remnants.


title:
Very Large Telescope three micron spectra of dust-enshrouded red giants
  in the Large Magellanic Cloud

abstract:
  We present ESO/VLT spectra in the 2.9--4.1 micron range for a large sample of
infrared stars in the Large Magellanic Cloud (LMC), selected on the basis of
MSX and 2MASS colours to be extremely dust-enshrouded AGB star candidates. Out
of 30 targets, 28 are positively identified as carbon stars, significantly
adding to the known population of optically invisible carbon stars in the LMC.
We also present spectra for six IR-bright stars in or near three clusters in
the LMC, identifying four of them as carbon stars and two as oxygen-rich
supergiants. We analyse the molecular bands of C2H2 at 3.1 and 3.8 micron, HCN
at 3.57 micron, and sharp absorption features in the 3.70--3.78 micron region
that we attribute to C2H2. There is evidence for a generally high abundance of
C2H2 in LMC carbon stars, suggestive of high carbon-to-oxygen abundance ratios
at the low metallicity in the LMC. The low initial metallicity is also likely
to have resulted in less abundant HCN and CS. The sample of IR carbon stars
exhibits a range in C2H2:HCN abundance ratio. We do not find strong
correlations between the properties of the molecular atmosphere and
circumstellar dust envelope, but the observed differences in the strengths and
shapes of the absorption bands can be explained by differences in excitation
temperature. High mass-loss rates and strong pulsation would then be seen to be
associated with a large scale height of the molecular atmosphere.


title:
Multi-periodic photospheric pulsations and connected wind structures in
  HD64760

abstract:
  We report on the results of an extended optical spectroscopic monitoring
campaign on the early-type B supergiant HD64760 (B0.5Ib) designed to probe the
deep-seated origin of spatial wind structure. This new study is based on
high-resolution echelle spectra obtained with the FEROS instrument at ESO La
Silla. 279 spectra were collected over 10 consecutive nights in 2003. From the
period analysis of the line-profile variability of the photospheric lines we
identify three closely spaced periods around 4.810 hrs and a splitting of
+/-3%. The velocity - phase diagrams of the line-profile variations for the
distinct periods reveal characteristic prograde non-radial pulsation patterns
of high order corresponding to pulsation modes with l and m in the range 6-10.
The three pulsation modes have periods clearly shorter than the characteristic
pulsation time scale and show small horizontal velocity fields and hence are
identified as p-modes. The beating of the three pulsation modes leads to a
retrograde beat pattern with two regions of constructive interference
diametrically opposite on the stellar surface and a beat period of 162.8hrs
(6.8days). This beat pattern is directly observed in the spectroscopic time
series of the photospheric lines. The wind-sensitive lines display features of
enhanced emission, which appear to follow the maxima of the photospheric beat
pattern.


title: Caught in the act: The Onset of massive star formation

abstract:
  Combining mid-infrared data from the SPITZER Space Telescope with cold gas
and dust emission observations from the Plateau de Bure Interferometer, we
characterize the Infrared Dark Cloud IRDC18223-3 at high spatial resolution.
The millimeter continuum data reveal a massive `184Msun gas core with a
projected size of ~28000AU that has no associated protostellar mid-infrared
counterpart. However, the detection of 4.5mum emission at the edge of the core
indicates early outflow activity, which is supported by broad CO and CS
spectral line-wing emission. Moreover, systematically increasing N2H+(1-0)
line-width toward the mm core center can be interpreted as additional evidence
for early star formation. Furthermore, the N2H+(1-0) line emission reveals a
less massive secondary core which could be in an evolutionary stage prior to
any star formation activity.


title:
The Initial Mass Function in disc galaxies and in galaxy clusters: the
  chemo-photometric picture

abstract:
  The observed brightness of the Tully-Fisher relation suggests a low stellar
M/L ratio and a "bottom-light" IMF in disc galaxies, but the corresponding
efficiency of chemical enrichment tends to exceed the observational estimates.
Either suitable tuning of the IMF slope and mass limits or metal outflows from
disc galaxies must then be invoked.
  A standard Solar Neighbourhood IMF cannot explain the high metallicity of the
hot intra-cluster medium: a different IMF must be at work in clusters of
galaxies. Alternatively, if the IMF is universal and chemical enrichment is
everywhere as efficient as observed in clusters, substantial loss of metals
must occur from the Solar Neighbourhood and from disc galaxies in general; a
"non-standard" scenario challenging our understanding of disc galaxy formation.