title: Variation of the IMF

abstract:
  (abridged) The {stellar IMF} has been found to be essentially invariant.
While some apparent differences are seen, the uncertainties inherent to this
game do not allow a firm conclusion to be made that the IMF varies
systematically with conditions. The IMF integrated over entire galaxies,
however, is another matter. Chemical and photometric properties of various
galaxies do hint at {galaxial IMFs} being steeper than the stellar IMF, as is
also deduced from direct star-count analysis in the MW. These results are
sensitive to the modelling of stellar populations and to corrections for
stellar evolution, and are thus also uncertain. However, by realising that
galaxies are made from dissolving star clusters, star clusters being viewed as
{the fundamental building blocks of galaxies}, the result is found that
galaxial IMFs must be significantly steeper than the stellar IMF, because the
former results from a folding of the latter with the star-cluster mass
function. Furthermore, this notion leads to the important insight that galaxial
IMFs must vary with galaxy mass, and that the galaxial IMF is a strongly
varying function of the star-formation history for galaxies that have assembled
only a small mass in stars. Cosmological implications of this are discussed.


title: Theoretical Models of Superbursts on Accreting Neutron Stars

abstract:
  We carry out a general-relativistic global linear stability analysis of the
amassed carbon fuel on the surface of an accreting neutron star to determine
the conditions under which superbursts occur. We reproduce the general
observational characteristics of superbursts, including burst fluences,
recurrence times, and the absence of superbursts on stars with accretion rates
below 10% of the Eddington limit. By comparing our results with observations,
we are able to set constraints on neutron star parameters such as the stellar
radius and neutrino cooling mechanism in the core. Specifically, we find that
accreting neutron stars with ordered crusts and highly efficient neutrino
emission in their cores (due to direct URCA or pionic reactions, for example)
produce extremely energetic (> 10^44 ergs) superbursts which are inconsistent
with observations, in agreement with previous investigations. Also, because of
pycnonuclear burning of carbon, they do not have superbursts in the range of
accretion rates at which superbursts are actually observed unless the crust is
very impure. Stars with less efficient neutrino emission (due to modified URCA
reactions, for example) produce bursts that agree better with observations.
Stars with highly inefficient neutrino emission in their cores produce bursts
that agree best with observations. All systems that accrete primarily hydrogen
and in which superbursts are observed show evidence of H- and He-burning
delayed mixed bursts. We speculate that delayed mixed bursts provide sufficient
amounts of carbon fuel for superbursts and are thus a prerequisite for having
superbursts. We compare our global stability analysis to approximate one-zone
criteria used by other authors and identify a particular set of approximations
that give accurate results for most choices of parameters. (abstract truncated)


title: The low-luminosity galaxy population in the NGC 5044 Group

abstract:
  We present multicolour imaging for 33 dwarf and intermediate-luminosity
galaxies in the field of the NGC 5044 Group, complemented with mid-resolution
spectroscopy for a subsample of 13 objects. With these data, a revised
membership and morphological classification is made for the galaxies in the
sample. We were able to confirm all but one of the "definite members" included
in the spectroscopic subsample, which were originally classified based on
morphological criteria; however, an important fraction of background galaxies
is probably present among "likely" and "possible" members.
  The presence of a nucleus could be detected in just five out of the nine
galaxies originally classified as dE,N, thus confirming the intrisic difficulty
of photographic-plate morphological classification for this kind of object. Our
deep surface photometry provided clear evidences for disc structure in at least
three galaxies previously catalogued as dE or dS0. Their transition-type
properties are also evident from the colour-magnitude diagram, where they lie
near the late-type galaxies locus, suggesting an evolutionary connection
between a parent disc-galaxy population and at least part of present-day dEs.
Six new dSph candidates were also found, most of them at small projected
distances from NGC 5044, the central galaxy of the Group.
  The NGC 5044 Group appears clearly defined in redshift space, with a mean
heliocentric radial velocity, <v_r>=2461 +/- 84 km/s (z=0.0082), and a moderate
dispersion, \sigma_{v_r}=431 km/s. Our data show no luminosity segregation for
early-type galaxies: both dwarf and bright E/S0 systems show very similar
velocity distributions (\sigma_{v_r} ~ 290 km/s), in contrast to late-type
galaxies that seem to display a broader distribution (\sigma_{v_r} ~ 680 km/s).


title:
The Evolution of Supernovae in Circumstellar Wind-Blown Bubbles I.
  Introduction and One-Dimensional Calculations

abstract:
  Mass loss from massive stars ($\ga 8 \msun$) can result in the formation of
circumstellar wind blown cavities surrounding the star, bordered by a thin,
dense, cold shell. When the star explodes as a core-collapse supernova (SN),
the resulting shock wave will interact with this modified medium around the
star, rather than the interstellar medium. In this work we first explore the
nature of the circumstellar medium around massive stars in various evolutionary
stages. This is followed by a study of the evolution of SNe within these
wind-blown bubbles. The evolution depends primarily on a single parameter
$\Lambda$, the ratio of the mass of the dense shell to that of the ejected
material. We investigate the evolution for different values of this parameter.
We also plot approximate X-ray surface brightness plots from the simulations.
Our results show that in many cases the SN remnant spends a significant amount
of time within the bubble. The low density within the bubble can delay the
onset of the Sedov stage, and may end up reducing the amount of time spent in
the Sedov stage. The complicated density profile within the bubble makes it
difficult to infer the mass-loss properties of the pre-SN star by studying the
evolution of the resulting supernova remnant.


title:
A model for selective line-driven acceleration of ions in the solar
  winds of OB-type stars occurring via the nonlinear process of stimulated
  Rayleigh scattering

abstract:
  A conceptually novel model - one in which stimulated (i.e. induced) resonance
Rayleigh scattering causes ions of select species to become accelerated to very
high terminal velocities in the solar winds of OB-type stars - is proposed to
explain the general appearance of so-called P Cygni profiles that often
dominate the vacuum ultraviolet (VUV) spectra of such stars. The high rate of
stimulated scattering enables ions of the resonant species in the solar wind to
become accelerated to terminal velocities as high as 1000 km/sec. Since
stimulated scattering processes are characterized by pump power thresholds, the
model readily explains why only select species are accelerated to very high
velocities in a given star's solar wind, and also why a dramatic P Cygni
profile for a given ion species can often discontinuously be present or absent
when spectra of stars varying only slightly in spectral type are compared.


title: HST/ACS Coronagraphic Imaging of the AU Microscopii Debris Disk

abstract:
  We present {\it Hubble Space Telescope} Advanced Camera for Surveys
multicolor coronagraphic images of the recently discovered edge-on debris disk
around the nearby ($\sim10$ pc) M dwarf AU Microscopii. The disk is seen
between $r = $0\farcs 75 -- 15'' (7.5 -- 150 AU) from the star. It has a thin
midplane with a projected full-width-at-half-maximum (FWHM) thickness of 2.5 --
3.5 AU within $r < 50$ AU of the star that increases to 6.5 -- 9 AU at $r \sim
75$ AU. The disk's radial brightness profile is generally flat for $r < 15$ AU,
then decreases gradually ($I \propto r^{-1.8}$) out to $r \approx 43$ AU,
beyond which it falls rapidly ($I \propto r^{-4.7}$). Within 50 AU the midplane
is straight and aligned with the star, and beyond that it deviates by
$\sim3^{\circ}$, resulting in a bowed appearance that was also seen in
ground-based images. Three-dimensional modelling of the disk shows that the
inner region ($r < 50$ AU) is inclined to the line-of-sight by $<1^{\circ}$ and
the outer disk by $\sim3^{\circ}$. The inclination of the outer disk and
moderate forward scattering ($g \approx 0.4$) can explain the apparent bow. The
intrinsic, deprojected FWHM thickness is 1.5 -- 10 AU, increasing with radius.
The models indicate that the disk is clear of dust within $\sim12$ AU of the
star, in general agreement with the previous prediction of 17 AU based on the
infrared spectral energy distribution. The disk is blue, being 60% brighter at
$B$ than $I$ relative to the star. One possible explanation for this is that
there is a surplus of very small grains compared to other imaged debris disks
that have more neutral or red colors. This may be due to the low radiation
pressure exerted by the late-type star. Observations at two epochs show that an
extended source seen along the midplane is a background galaxy.


title:
Measurement of Galaxy Cluster Sizes, Radial Profiles, and Luminosity
  Functions from SDSS Photometric Data

abstract:
  Imaging data from the Sloan Digital Sky Survey is used to measure the
empirical size-richness relation for a large sample of galaxy clusters. Using
population subtraction methods, we determine the radius at which the cluster
galaxy number density is 200/Omega_m times the mean galaxy density, without
assuming a model for the radial distribution of galaxies in clusters. If these
galaxies are unbiased on Mpc scales, this galaxy-density-based R_200 reflects
the characteristic radii of clusters. We measure the scaling of this
characteristic radius with richness over an order of magnitude in cluster
richness, from rich clusters to poor groups. We use this information to examine
the radial profiles of galaxies in clusters as a function of cluster richness,
finding that the concentration of the galaxy distribution decreases with
richness and is systematically lower than the concentrations measured for dark
matter profiles in N-body simulations. Using these scaled radii, we investigate
the behavior of the cluster luminosity function, and find that it is well
matched by a Schechter function for galaxies brighter than M_r = -18 only after
the central galaxy has been removed. We find that the luminosity function
varies with richness and with distance from the cluster center, underscoring
the importance of using an aperture that scales with cluster mass to compare
physically equivalent regions of these different systems. We note that the
lowest richness systems in our catalog have properties consistent with those
expected of the earliest-forming halos; our cluster-finding algorithm, in
addition to reliably finding clusters, may be efficient at finding fossil
groups.


title: Characterisation of extrasolar planetary transit candidates

abstract:
  The detection of transits is an efficient technique to uncover faint
companions around stars. The full characterisation of the companions (M-type
stars, brown dwarfs or exoplanets) requires high-resolution spectroscopy to
measure properly masses and radii. With the advent of massive variability
surveys over wide fields, the large number of possible candidates makes such a
full characterisation impractical for all of them. We explore here a fast
technique to pre-select the most promising candidates using either near-IR
photometry or low resolution spectroscopy. We develop a new method based on the
well-calibrated surface brightness relation along with the correlation between
mass and luminosity for main sequence stars, so that not only giant stars can
be excluded but also accurate effective temperatures and radii can be measured.
The main source of uncertainty arises from the unknown dispersion of extinction
at a given distance. We apply this technique to our observations of a sample of
34 stars extracted from the 62 low-depth transits identified by OGLE during
their survey of some 10e5 stars stars in the Carina fields of the Galactic
disc. We infer that at least 78% of the companions of the stars which are well
characterised in this sample are not exoplanets. Stars OGLE-TR-105, OGLE-TR-109
and OGLE-TR-111 are the likeliest to host exoplanets and deserve
high-resolution follow-up studies. OGLE-TR-111 was very recently confirmed as
an exoplanet with M_planet = 0.53 +- 0.1 M_Jup (Pont et al. 2004), confirming
the efficiency of our method in pre-selecting reliable planetary transit
candidates.


title:
Offsets between H-alpha and CO arms of a spiral galaxy NGC 4254: A New
  Method for Determining the Pattern Speed of Spiral Galaxies

abstract:
  We examined offsets between HII regions and molecular clouds belonging to
spiral arms of a late type spiral galaxy NGC 4254 (M99). We used a high
resolution CO(1-0) image obtained by Nobeyama Millimeter Array (NMA) and an
H-alpha image. We derived angular offsets (theta) in the galactic disk, and
found that these offsets show a linear dependence on the angular rotation
velocity of gas (Omega_G). This linear relation can be expressed by an
equation: theta =(Omega_G - Omega_P) * t_{H-alpha}, where Omega_P and
t_{H-alpha} are constant. Here, Omega_P corresponds to the pattern speed of
spiral arms and t_{H-alpha} is interpreted as the timescale between the peak
compression of the molecular gas in spiral arms and the peak of massive star
formation. We may thus determine Omega_P and t_{H-alpha} simultaneously by
fitting a line to our theta - Omega_G plot, if we assumed they are constant.
  From our plot, we obtained t_{H-alpha} =4.8 (+/- 1.2) Myr and Omega_P = 26
(+10/-6) km/s/kpc, which are consistent with previous studies. We suggest that
this theta - Omega_G plot can be a new tool to determine the pattern speed and
the typical timescale needed for star formations.


title: Determining the Actual Local Density of Dark Matter Particles

abstract:
  Even if dark matter particles are unambiguously discovered in experiments,
there is no clear reason to expect that the dark matter problem has been
solved. It is very easy to provide examples of dark matter scenarios (e.g. in
supersymmetric models) where nearly identical detector signals correspond to
extremely different relic densities. Therefore, the density of the particles
discovered must be determined before their cosmological relevance is
established. In this talk, I will present a general method to estimate the
local density of dark matter particles using both dark matter and hadron
collider experimental data when it becomes available. These results were
obtained in collaboration with Gordon Kane at the University of Michigan.


title: The steady-state structure of accretion discs in central magnetic fields

abstract:
  We develop a new analytic solution for the steady-state structure of a thin
accretion disc under the influence of a magnetic field that is anchored to the
central star. The solution takes a form similar to that of Shakura and Sunyaev
and tends to their solution as the magnetic moment of the star tends to zero.
As well as the Kramer's law case, we obtain a solution for a general opacity.
The effects of varying the mass transfer rate, spin period and magnetic field
of the star as well as the opacity model applied to the disc are explored for a
range of objects. The solution depends on the position of the magnetic
truncation radius. We propose a new approach for the identification of the
truncation radius and present an analytic expression for its position.


title: The Halo Lithium Plateau: Outstanding Issues

abstract:
  We examine outstanding issues in the analysis and interpretation of the halo
Li plateau. We show that the majority of very Li-poor halo Li-plateau stars (5
out of 8) have high projected rotation velocities vsini between 4.7 and 10.4 km
s^-1. Such stars have very different evolutionary histories to Li-normal
plateau stars, and hence cannot be included in studies of Li depletion by
normal halo dwarfs. Uncertainties in the effective temperature scale for
metal-poor stars continue to challenge the analysis of Li.


title: Star and cluster formation in extreme environments

abstract:
  Current empirical evidence on the star-formation processes in the extreme,
high-pressure environments induced by galaxy encounters (mostly based on
high-resolution Hubble Space Telescope observations) strongly suggests that
star CLUSTER formation is an important and perhaps even the dominant mode of
star formation in such starburst events. The sizes, luminosities, and mass
estimates of the young massive star clusters (YMCs) are entirely consistent
with what is expected for young Milky Way-type globular clusters (GCs). Recent
evidence lends support to the scenario that GCs, which were once thought to be
the oldest building blocks of galaxies, are still forming today. Here, I
present a novel empirical approach to assess the shape of the
initial-to-current YMC mass functions, and hence their possible survival
chances for a Hubble time.


title:
A Genetic Algorithm-Based Exploration of Three Filament Models: A Case
  for the Magnetic Support of the G11.11-0.12 Infrared-Dark Cloud

abstract:
  The G11.11-0.12 infrared-dark cloud has a filamentary appearance, both in
extinction against the diffuse infrared emission of the Galactic plane and in
emission at 850 microns. We use a novel computational technique based on an
advanced genetic algorithm to explore thoroughly 3 different models of
self-gravitating, pressure truncated filaments and to constrain their
parameters. Specifically, the models tested are the non-magnetic Ostriker
(1964) model, a generalized version of the magnetic Stodolkiewicz (1963) model,
and the magnetic Fiege & Pudritz (2000) model. Previous results showed that
G11.11-0.12 has a much steeper r^{-4} radial density profile than other
filaments, where the density varies approximately as r^{-2}, and that this
steep density profile is consistent with the Ostriker (1964) model. We present
a more complete analysis that shows that the radial structure of G11.11-0.12 is
consistent with regimes of each of these models. All of the magnetic models
that agree with the data are threaded by a dominant poloidal magnetic field,
and most have dynamically significant fields. Thus, G11.11-0.12 is an excellent
candidate for radial support by a magnetic field that is predominantly
poloidal. We predict the polarization patterns expected for both magnetic
models and show that the two magnetic models produce different polarization
patterns that should be distingished by observations.


title:
The impact of non-LTE effects and granulation inhomogeneities on the
  derived iron and oxygen abundances in metal-poor halo stars

abstract:
  This paper presents the results of a detailed theoretical investigation of
the impact of non-LTE effects and of granulation inhomogeneities on the derived
iron and oxygen abundances in the metal-poor halo subgiant HD140283. Our
analysis is based on both the `classical' one-dimensional (1D) stellar
atmosphere models and on the new generation of three-dimensional (3D)
hydrodynamical models. We find that the non-LTE effects on the iron abundance
derived from Fe {\sc i} lines are very important, amounting to ${\sim}0.9$ dex
and to ${\sim}0.6$ dex in the 3D and 1D cases, respectively. On the other hand,
we find that non-LTE and 3D effects have to be taken into account for a
reliable determination of the iron abundance from weak Fe {\sc ii} lines,
because the significant overexcitation of their upper levels in the granular
regions tend to produce emission features. As a result such Fe {\sc ii} lines
are weaker than in LTE and the abundance correction amounts to ${\sim}0.4$ dex
for the 3D case. We derive also the oxygen-to-iron abundance ratio in the
metal-poor star HD140283 by using the O {\sc i} triplet at 7772--5 \AA and the
forbidden [O {\sc i}] line at 6300 \AA. Interestingly, when both non-LTE and 3D
effects are taken into account there still remains significant discrepancies in
the iron abundances derived from Fe {\sc i} and Fe {\sc ii} lines, as well as
in the oxygen abundances inferred from the O {\sc i} and [O {\sc i}] lines. We
conclude that the metalicity of this type of metal-poor stars could be
significantly larger than previously thought, which may have far-reaching
implications in stellar astrophysics.


title: Type Ia SN1999cw: photometric and spectroscopic study

abstract:
  The preliminary analysis of the optical data of SN1999cw show that this
object has the photometric and spectroscopic behavior of a Type Ia supernova
similar to SN1991T, reaching an apparent magnitude at maximum B(max)=14.30 and
a Delta m_{15}(B)=0.94.


title: Shock-Heated Gas in the Large Scale Structure of the Universe

abstract:
  Cosmological shock waves play a major role in heating baryonic gas in the
large scale structure of the universe. In this contribution we study the
shock-heated gas in connection with shocks themselves. The distributions of
shock speed and temperature of shock-hated gas both should reflect the depth of
gravitational potential of associated nonlinear structures, so their
morphology. From their distributions we find, in addition to hot gas in and
around clusters/groups and warm-hot intergalactic medium (WHIM) with
T=10^5-10^7 K mostly in filaments, there is a significant amount of low
temperature WHIM with T < 10^5 K distributed mostly as sheet-like structures.
Not only the WHIM with T=10^5-10^7 K but also the WHIM with T < 10^5 K make up
a significant fraction of gas mass, implying the low temperature WHIM could be
important in resolving the missing baryon problem. The shock-heated gas in
filaments and sheets are manifested best through emissions and absorptions in
soft X-ray and far UV. We confirm that the WHIM with T=10^5-10^7 K makes
significant contributions to the soft X-ray background, absorptions of highly
ionized species such as OVII and OVIII in AGN spectra, and line emissions from
OVII and OVIII ions, as pointed by previous studies. However, the WHIM with T <
10^5 K is the major contributor to absorptions of lower ionized species such as
OV and OVI, because these photo-ionized ions are most abundant in sheets of low
density and temperature. (abridged)


title:
CP noninvariance and an effective cosmological constant: the energy
  density in a pseudoscalar field which arises from a cosmological,
  spontaneously-broken chiral symmetry

abstract:
  We present and discuss the properties and the main results of a cosmological
model with a spontaneously-broken chiral symmetry. The model contains and
relates dynamically, two spin-zero fields. The scalar field can provide the
dynamical basis for inflation in the early universe. The pseudoscalar,
Goldstone field can provide an early, small residual vacuum energy density, the
absolute value of which we estimate to be similar to the present, empirically
small vacuum energy density. The small energy scale for this effective
cosmological constant is estimated separately, by relating it dynamically to
the empirical, small scale of neutrino mass. CP invariance is broken
spontaneously. This provides a natural basis for the early generation of an
antineutrino-neutrino asymmetry, whose magnitude we estimate, and find to be
significant.


title: A model for the challenging "bi-drifting" phenomenon in PSR J0815+09

abstract:
  A new drifting pulsar, PSR J0815+09, was discovered in the Arecibo drift-scan
searches. An intriguing feature of this source is that within the four pulse
components in the integrated pulse profile, the sub-pulse drifting direction in
the two leading components is opposite from that in the two trailing
components. In view that the leading theoretical model for pulsar sub-pulse
drifting can only interpret one-direction sub-pulse drifting, the observed
"bi-drifting" phenomenon from PSR J0815+09 poses a great challenge to the
pulsar theory. The inner annular gap (IAG), a new type of inner particle
accelerator, was recently proposed to explain both $\gamma$-ray and radio
emission from pulsars. Here we show that the coexistence of the IAG and the
conventional inner core gap (ICG) offers a natural interpretation to the
bi-drifting phenomenon. In particular, the peculiar drifting behavior in PSR
J0815+09 can be reproduced within the inverse Compton scattering (ICS) model
for pulsar radio emission.


title: SS 433: a WR X-ray binary or a WR-type phenomenon ?

abstract:
  We present mid-infrared spectra of the microquasar SS 433 obtained with the
Infrared Space Observatory (spectroscopic mode of ISOPHOT) and compare them to
the spectra of four Wolf-Rayet stars. The mid-infrared spectrum of SS 433 shows
mainly HI and HeI emission lines and is very similar to the spectrum of WR 147,
a WN8(h)+B0.5V binary with a colliding wind. The 2-12 micron continuum emission
corresponds to optically thin and partially optically thick free-free emission
from which we calculate a mass loss rate of 1.4-2.2x10^{-4} M_sun/yr if the
wind is homogeneous and a third of these values if it is clumped, which is
consistent with a strong WN stellar wind. We propose that this strong wind
outflows from a geometrically thick envelope of material surrounding the
compact object like a stellar atmosphere, imitating the Wolf-Rayet phenomenon.


title:
A fundamental plane of black hole activity: pushing forward the
  unification scheme

abstract:
  We examine the disc--jet connection in stellar mass and supermassive black
holes by investigating the properties of their compact emission in the hard
X-ray and radio bands. We compile a sample of ~100 active galactic nuclei with
measured mass, 5 GHz core emission, and 2-10 keV luminosity, together with 8
galactic black holes with a total of about 50 simultaneous observations in the
radio and X-ray bands. Using this sample, we study the correlations between the
radio (L_R) and the X-ray (L_X) luminosity and the black hole mass (M). We find
that the radio luminosity is correlated with both M and L_X, at a highly
significant level. We show how this result can be used to extend the standard
unification by orientation scheme to encompass unification by mass and
accretion rate.


title: The evolutionary phase of B[e] supergiants and unclassified B[e] stars

abstract:
  We present two classes of stars with yet unknown evolutionary phase: the B[e]
supergiants and the so-called unclassified B[e] stars. While the B[e]
supergiants are luminous post-main sequence stars with high mass progenitors,
not much is known of the unclassified stars. We discuss how it might be
possible to determine their evolutionary phases in the area of new large
telescopes.


title: High-Resolution Spectroscopy of the Transiting Planet Host Star TrES-1

abstract:
  We report on a spectroscopic determination of the stellar parameters and
chemical abundances for the parent star of the transiting planet TrES-1. Based
on a detailed analysis of iron lines in our Keck and HET spectra we derive
$T_\mathrm{eff} = 5250\pm 75$ K, $\log g = 4.6\pm 0.2$, and [Fe/H] $= 0.00\pm
0.09$. By measuring the \ion{Ca}{2} activity indicator and by putting useful
upper limits on the Li abundance we constrain the age of TrES-1 to be $2.5\pm
1.5$ Gyr. By comparing theoretical stellar evolution models with the
observational parameters we obtain $M_\star = 0.89\pm 0.05$ $M_\odot$, and
$R_\star = 0.83\pm 0.05$ $R_\odot$. Our improved estimates of the stellar
parameters are utilized in a new analysis of the transit photometry of TrES-1
to derive a mass $M_p = 0.76\pm 0.05$ $M_\mathrm{J}$, a radius $R_p =
1.04^{+0.08}_{-0.05}$ $R_\mathrm{J}$, and an inclination $i =
89^\circ.5^{+0.5}_{-1.3}$. The improved planetary mass and radius estimates
provide the grounds for new crucial tests of theoretical models of evolution
and evaporation of irradiated extrasolar giant planets.


title: The internal dynamical equilibrium of HII regions: a statistical study

abstract:
  We present an analysis of the integrated Halpha emission line profiles for
the HII region population of the spiral galaxies NGC 1530, NGC 6951 and NGC
3359. We show that 70% of the line profiles show two or three Gaussian
components. The relations between the Halpha luminosity and non-thermal line
width for the HII regions of the three galaxies are studied and compared with
the relation found taken all the HII regions of the three galaxies as a single
distribution. A clearer envelope in non-thermal line width is found when only
those HII regions with non-thermal line width bigger than 13kms are considered.
The linear fit for the envelope is logL=36.8+2.0*log(sigma). The masses of the
HII regions on the envelope using the virial theorem and the mass estimates
from the Halpha luminosity are comparable, which offers evidence that the HII
regions on the envelope are virialized systems, while the remaining regions,
the majority, are not in virial equilibrium.


title:
From Clark Lake to Chandra: Closing in on the Low End of the
  Relativistic Electron Spectra in Extragalactic Sources

abstract:
  The limited angular resolutions and sensitivities historically available
below 300 MHz have made it difficult to define the low end of the electron
energy distribution, N(gamma). We extrapolate down from the well observed
segments of radio spectra with almost complete ignorance of what N(gamma) is
actually doing. We do not know if there is a low energy cutoff or if there are
other deviations from extrapolated power laws. The result is that we really do
not have a good estimate of the total energy density and pressure of the
relativistic plasmas we study. The situation is even worse for Inverse Compton
(IC) X-ray emission, several flavors of which rely on electrons of Lorentz
factors, gamma, of 1000, 300, or in some cases of order 50. If our assumed
extrapolations are wrong, some IC emission models may have to be abandoned. We
present several examples and demonstrate that the Long Wave Array (LWA) should
have sufficient sensitivity and resolution to obtain meaningful constraints on
N(gamma) at low energies.


title: Simple route to non-Gaussianity in inflation

abstract:
  We present a simple way to calculate non-Gaussianity in inflation using fully
non-linear equations on long wavelengths with stochastic sources to take into
account the short-wavelength quantum fluctuations. Our formalism includes both
scalar metric and matter perturbations, combining them into variables which are
invariant under changes of time slicing in the long-wavelength limit. We
illustrate this method with a perturbative calculation in the single-field
slow-roll case. We also introduce a convenient choice of variables to
graphically present the full momentum dependence of the three-point correlator.


title: The Earth's Gamma-ray Albedo as observed by EGRET

abstract:
  The Earth's high energy gamma-ray emission is caused by cosmic ray
interactions with the atmosphere. The EGRET detector on-board the CGRO
satellite is only the second experiment (after SAS-2) to provide a suitable
dataset for the comprehensive study of this emission. Approximately 60% of the
EGRET dataset consist of gamma photons from the Earth. This conference
contribution presents the first results from the first analysis project to
tackle this large dataset. Ultimate purpose is to develop an analytical model
of the Earth's emission for use in the GLAST project. The results obtained so
far confirm the earlier results from SAS-2 and extend them in terms of
statistical precision and angular resolution.


title:
Masses, Parallax, and Relativistic Timing of the PSR J1713+0747 Binary
  System

abstract:
  We report on 12 years of observations of PSR J1713+0747, a pulsar in a 68-day
orbit with a white dwarf. Pulse times of arrival were measured with
uncertainties as small as 200 ns. The timing data yielded measurements of the
relativistic Shapiro delay, perturbations of pulsar orbital elements due to
secular and annual motion of the Earth, and the pulsar's parallax, as well as
pulse spin-down, astrometric, and Keplerian measurements. The observations
constrain the masses of the pulsar and secondary star to be m1=1.3+-0.2 solar
masses and m2=0.28+-0.03 solar masses, respectively (68% confidence). Combining
the theoretical orbital period-core mass relation with the observational
constraints yields a somewhat higher pulsar mass, m1=1.53-0.06+0.08 solar
masses. The parallax is 0.89+-0.08 mas, corresponding to a distance of 1.1+-0.1
kpc; the precision of the parallax measurement is limited by uncertainties in
the electron content of the solar wind. The transverse velocity is unusually
small, 33+-3 km/s. We find significant timing noise on time scales of several
years, but no more than expected by extrapolating timing noise statistics from
the slow pulsar population. With the orientation of the binary orbit fully
measured, we are able to improve on previous tests of equivalence principle
violations.


title: Distances and Metallicities for 17 Local Group Galaxies

abstract:
  We have obtained Johnson V and Gunn i photometry for a large number of Local
Group galaxies using the Isaac Newton Telescope Wide Field Camera (INT WFC).
The majority of these galaxies are members of the M31 subgroup and the
observations are deep enough to study the top few magnitudes of the red giant
branch in each system. We previously measured the location of the tip of the
red giant branch (TRGB) for Andromeda I, Andromeda II and M33 to within
systematic uncertainties of typically < 0.05 mags (McConnachie et al. 2004). As
the TRGB acts as a standard candle in old, metal poor stellar populations, we
were able to derive distances to each of these galaxies. Here we derive TRGB
distances to the giant spiral galaxy M31 and 13 additional dwarf galaxies -
NGC205, NGC185, NGC147, Pegasus, WLM, LGS3, Cetus, Aquarius, AndIII, AndV,
AndVI, AndVII and the newly discovered dwarf spheroidal AndIX. The observations
for each of the dwarf galaxies were intentionally taken in photometric
conditions. In addition to the distances, we also self-consistently derive the
median metallicity of each system from the colour of their red giant branches.
This allows us to take into account the small metallicity variation of the
absolute I magnitude of the TRGB. The homogeneous nature of our data and the
identical analysis applied to each of the 17 Local Group galaxies ensures that
these estimates form a reliable set of distance and metallicity determinations
that are ideal for comparative studies of Local Group galaxy properties.


title: Radiation Processes in GRBs. Prompt Emission

abstract:
  A substantial fraction of prompt GRB spectra have soft spectral indexes
exceeding the maximum allowed by the synchrotron model alpha_{max}=-2/3. Some
spectra also exhibit very sharp break at E_p, inconsistent with the smooth
synchrotron spectra. These facts pose a serious problem for the ``optically
thin synchrotron'' interpretation of the prompt emission. We review various
models suggested in order to resolve this puzzle.


title:
Bipolar Symbiotic Planetary Nebulae in the Thermal-IR: M2-9, Mz3, and
  He2-104

abstract:
  We present thermal-IR images of three extreme bipolar objects, M2-9, Mz3, and
He2-104. They are bipolar planetary nebulae with bright central stars and are
thought to be powered by symbiotic binary systems. The mid-IR images spatially
resolve the SEDs of the central engines from the surrounding nebulae. A warm
dust component of several hundred degrees can account for the core emission,
while a cooler component of about 100 K produces the more extended emission
from the bipolar lobes. In every case, the dust mass for the unresolved core
region is orders of magnitude less than that in the extended lobes, raising
doubts that the hypothetical disks in the core could have been responsible for
pinching the waists of the nebulae. We find total masses of roughly 0.5-1 Msun
in the nebulae of M2-9 and Mz3, requiring that this material was donated by
intermediate-mass progenitor stars. The mass of He2-104's nebula is much lower,
and any extended emission is too faint to detect in our images. Extended dust
around both M2-9 and Mz3 resembles the distribution of ionized gas. Our images
of Mz3 have the highest signal-to-noise in the extended polar lobes, and we
show that the fairly uniform color temperature derived from our images can
explain the 110 K dust component that dominates the far-IR SED. In the case of
Mz3, most of the mass traced by dust is concentrated at high latitudes.


title: Quiescent observations of the WZ Sge type dwarf nova PQ Andromedae

abstract:
  We have obtained time series optical spectra of the cataclysmic variable PQ
And in quiescence. The spectra show a white dwarf continuum with narrow Balmer
emission superimposed over strong Balmer absorption. The emission lines have
blue and red components whose strength changes with time. An analysis of the
H$\alpha$ emission line implies a short orbital period below the period gap.
Given its lack of accretion disk features, its large and infrequent outbursts,
and an orbital period below the period gap, PQ And is probably a low accretion
rate object similar to WZ Sge. In addition, white dwarf model fits imply that
PQ And is an excellent ZZ Cet candidate.


title: Mg II Absorption Systems in SDSS QSO Spectra

abstract:
  We present the results of a MgII absorption-line survey using QSO spectra
from the SDSS EDR. Over 1,300 doublets with rest equivalent widths greater than
0.3\AA and redshifts $0.366 \le z \le 2.269$ were identified and measured. We
find that the $\lambda2796$ rest equivalent width ($W_0^{\lambda2796}$)
distribution is described very well by an exponential function $\partial
N/\partial W_0^{\lambda2796} = \frac{N^*}{W^*} e^{-\frac{W_0}{W^*}}$, with
$N^*=1.187\pm0.052$ and $W^*=0.702\pm0.017$\AA. Previously reported power law
fits drastically over-predict the number of strong lines. Extrapolating our
exponential fit under-predicts the number of $W_0 \le 0.3$\AA systems,
indicating a transition in $dN/dW_0$ near $W_0 \simeq 0.3$\AA. A combination of
two exponentials reproduces the observed distribution well, suggesting that
MgII absorbers are the superposition of at least two physically distinct
populations of absorbing clouds. We also derive a new redshift parameterization
for the number density of $W_0^{\lambda2796} \ge 0.3$\AA lines:
$N^*=1.001\pm0.132(1+z)^{0.226\pm0.170}$ and $W^*=0.443\pm0.032(1+z)^{0.634\pm
0.097}$\AA. We find that the distribution steepens with decreasing redshift,
with $W^*$ decreasing from $0.80\pm0.04$\AA at $z=1.6$ to $0.59\pm0.02$\AA at
$z=0.7$. The incidence of moderately strong MgII $\lambda2796$ lines does not
show evidence for evolution with redshift. However, lines stronger than
$\approx 2$\AA show a decrease relative to the no-evolution prediction with
decreasing redshift for $z \lesssim 1$. The evolution is stronger for
increasingly stronger lines. Since $W_0$ in saturated absorption lines is an
indicator of the velocity spread of the absorbing clouds, we interpret this as
an evolution in the kinematic properties of galaxies from moderate to low z.


title: Herbig Ae/Be Stars in nearby OB associations

abstract:
  We have carried out a study of the early type stars in nearby OB associations
spanning an age range of $\sim$ 3 to 16 Myr, with the aim of determining the
fraction of stars which belong to the Herbig Ae/Be class. We studied the B, A,
and F stars in the nearby ($\le 500$ pc) OB associations Upper Scorpius,
Perseus OB2, Lacerta OB1, and Orion OB1, with membership determined from
Hipparcos data. We obtained spectra for 440 Hipparcos stars in these
associations, from which we determined accurate spectral types, visual
extinctions, effective temperatures, luminosities and masses, using Hipparcos
photometry. Using colors corrected for reddening, we find that the Herbig Ae/Be
stars and the Classical Be stars (CBe) occupy clearly different regions in the
JHK diagram. Thus, we use the location on the JHK diagram, as well as the
presence of emission lines and of strong 12 microns flux relative to the visual
to identify the Herbig Ae/Be stars in the associations. We find that the Herbig
Ae/Be stars constitute a small fraction of the early type stellar population
even in the younger associations. Comparing the data from associations with
different ages and assuming that the near-infrared excess in the Herbig Ae/Be
stars arises from optically thick dusty inner disks, we determined the
evolution of the inner disk frequency with age. We find that the inner disk
frequency in the age range 3 - 10 Myr in intermediate mass stars is lower than
that in the low mass stars (< 1msun). This indicates that the time-scales for
disk evolution are much shorter in the intermediate mass stars, which could be
a consequence of more efficient mechanisms of inner disk dispersal (viscous
evolution, dust growth and settling toward the midplane).


title: Phase Variation in the Pulse Profile of SMC X-1

abstract:
  We present the results of timing and spectral analysis of X-ray high state
observations of the high-mass X-ray pulsar SMC X-1 with Chandra, XMM-Newton,
and ROSAT, taken between 1991 and 2001. The source has L_X ~ 3-5 x 10^38
ergs/s, and the spectra can be modeled as a power law plus blackbody with kT_BB
\~ 0.18 keV and reprocessed emission radius R_BB ~ 2 x 10^8 cm, assuming a
distance of 60 kpc to the source. Energy-resolved pulse profiles show several
distinct forms, more than half of which include a second pulse in the soft
profile, previously documented only in hard energies. We also detect
significant variation in the phase shift between hard and soft pulses, as has
recently been reported in Her X-1. We suggest an explanation for the observed
characteristics of the soft pulses in terms of precession of the accretion
disk.


title:
3-D Photoionization Structure and Distances of Planetary Nebulae II.
  Menzel 1

abstract:
  We present the results of a spatio-kinematic study of the planetary nebula
Menzel 1 using spectro-photometric mapping and a 3-D photoionization code. We
create several 2-D emission line images from our long-slit spectra, and use
these to derive the line fluxes for 15 lines, the Halpha/Hbeta extinction map,
and the [SII] line ratio density map of the nebula. We use our photoionization
code constrained by these data to derive the three-dimensional nebular
structure and ionizing star parameters of Menzel 1 by simultaneously fitting
the integrated line intensities, the density map, and the observed morphologies
in several lines, as well as the velocity structure. Using theoretical
evolutionary tracks of intermediate and low mass stars, we derive a mass for
the central star of 0.63+-0.05 Msolar. We also derive a distance of 1050+_150
pc to Menzel 1.


title: A Lyman Continuum Explorer - LyContEx

abstract:
  GALEX has identified large numbers of extra galactic objects that are too
faint to be observed by FUSE. These star forming systems are potential sources
of Lyman continuum (Lyc) radiation and may contribute to the metagalactic
background radiation that ionizes most of the baryons in the universe. By
measuring the level of Lyc radiation leaking from these galaxies we can
quantify the contribution of stars, relative to quasars, to the ionizing
background at low redshift (0.025 <~ z <~ 0.4) and provide insight into the
reionization processes at high redshift. A meter class instrument with a
moderate spectral dispersion, wide-field, multi-object spectrograph can detect
Lyc leak from a statistically significant number of these galaxies, if the
average escape fraction f_{esc} <~ 1%. Such an instrument will have enormous
discovery potential because of the large number of extra-galactic objects that
exist within its grasp. LyContEx will be scientifically productive, synergistic
with existing surveys, and can be developed into a far ultraviolet mission in
the near future.


title: The Temperature Structure of the Warm-Hot Intergalactic Medium

abstract:
  We study the temperature structure of the intergalactic medium (IGM) using a
large cosmological N-body/SPH simulation. We employ a two-temperature model for
the thermal evolution of the ionized gas, in which the relaxation process
between electrons and ions is explicitly included. In the diffuse, hot IGM, the
relaxation time is comparable to the age of the Universe and hence the electron
temperature in post-shock regions remains significantly smaller than the ion
temperature. We show that, at the present epoch, a large fraction of the
warm/hot intergalactic medium (WHIM) has a well-developed two temperature
structure, with typical temperature differences of order a factor of a few.
Consequently, the fraction of metals in various ionization states such as OVI,
OVII, and OVIII, as well as their line emissivities, can differ locally by more
than an order of magnitude from those computed with a single temperature model.
It is thus necessary to follow the evolution of the electron temperature
explicitly to determine absorption and emission by the WHIM. Although
equipartition is nearly achieved in the denser intracluster medium (ICM), we
find an appreciable systematic deviation between the gas-mass weighted electron
temperature and the mean temperature even at half the virial radii of clusters.
There is thus a reservoir of warm (Te < 1keV) gas in and around massive
clusters. Our results imply that relaxation processes need to be considered in
describing and interpreting observational data from existing X-ray telescopes
as well as from future missions designed to detect the WHIM, such as the
Diffuse Intergalactic Oxygen Surveyor and the Missing Baryon Explorer.


title:
The Rossiter-McLaughlin effect and analytic radial velocity curves for
  transiting extrasolar planetary systems

abstract:
  A transiting extrasolar planet sequentially blocks off the light coming from
the different parts of the disk of the host star in a time dependent manner.
Due to the spin of the star, this produces an asymmetric distortion in the line
profiles of the stellar spectrum, leading to an apparent anomaly of the radial
velocity curves, known as the Rossiter - McLaughlin effect. Here, we derive
approximate but accurate analytic formulae for the anomaly of radial velocity
curves taking account of the stellar limb darkening. The formulae are
particularly useful in extracting information of the projected angle between
the planetary orbit axis and the stellar spin axis, \lambda, and the projected
stellar spin velocity, V sin I_s. We create mock samples for the radial curves
for the transiting extrasolar system HD209458, and demonstrate that constraints
on the spin parameters (V sin I_s, \lambda) may be significantly improved by
combining our analytic template formulae and the precision velocity curves from
high-resolution spectroscopic observations with 8-10 m class telescopes. Thus
future observational exploration of transiting systems using the Rossiter -
McLaughlin effect is one of the most important probes to better understanding
of the origin of extrasolar planetary systems, especially the origin of their
angular momentum.


title: Satellite number density profiles of primary galaxies in the 2dFGRS

abstract:
  We analyse the projected radial distribution of satellites around bright
primary galaxies in the 2dFGRS. We have considered several primary-satellite
subsamples to search for dependences of the satellite number density profile,
\rho(r_p), on properties of satellites and primaries. We find significant
differences of the behaviour of \rho(r_p) depending on primary characteristics.
In star-forming primaries, the satellite number density profile is consistent
with power laws within projected distance 20<r_p<500 kpc. On the other hand,
passively star forming primaries show flat profiles for 20<r_p<70 kpc, well
fitted by generalized King models with a large core radius parameter (r_c ~ 68
kpc). In the external regions of the haloes (r_p>100 kpc), the density profiles
of all primaries is well described by power laws, although we notice that for
red, early spectral type primaries, the outer slope obtained is steeper than
that corresponding to blue, late spectral type ones. We have tested our results
by control samples of galaxies identical to the samples of satellites in
apparent magnitude and projected distance to the primary, but with a large
relative velocity. This sample of unphysical primary-galaxy pairs shows a flat
radial density beyond r_p=20 kpc indicating that our results are not biased
toward a decrease of the true number of objects due to catalogue selection
effects. Our results can be understood in terms of dynamical friction and tidal
stripping on satellites in the primary haloes. These processes can effectively
transfer energy to the dark matter, flattening the central steep profiles of
the satellite distribution in evolved systems.


title: Limiting the dimming of distant type Ia supernovae

abstract:
  Distant supernovae have been observed to be fainter than what is expected in
a matter dominated universe. The most likely explanation is that the universe
is dominated by an energy component with negative pressure -- dark energy.
However, there are several astrophysical processes that could, in principle,
affect the measurements and in order to be able to take advantage of the
growing supernova statistics, the control of systematic effects is crucial. We
discuss two of these; extinction due to intergalactic grey dust and dimming due
to photon-axion oscillations and show how their effect on supernova
observations can be constrained using observed quasar colours and spectra. For
a wide range of intergalactic dust models, we are able to rule out any dimming
larger than 0.2 magnitudes for a type Ia supernova at z=1. The corresponding
limit for intergalactic Milky Way type dust is 0.03 mag. For the more
speculative model of photons mixing with axions, we find that the effect is
independent of photon energy for certain combinations of parameter values and a
dimming as large as 0.6 magnitudes cannot be ruled out. These effects can have
profound implications for the possibility of constraining dark energy
properties using supernova observations.


title: Radio-loud and Radio-quiet X-ray Binaries: LSI+61303 in Context

abstract:
  The three basic ingredients - a spinning compact object, an accretion disc
and a collimated relativistic jet - make microquasars a galactic scaled-down
version of the radio-loud AGN. That explains the large interest attributed to
this new class of objects, which up to now consists of less than 20 members.
Microquasars belong to the much larger class of X-ray binary systems, where
there exists a compact object together with its X-ray emitting accretion disc,
but the relativistic jet is missing. When does an X-ray binary system evolve
into a microquasar? Ideal for studying such kind of a transition is the
periodic microquasar LS I +61303 formed by a compact object accreting from the
equatorial wind of a Be star and with more than one event of super-critical
accretion and ejection along the eccentric orbit. For ejections at periastron
passage the relativistic electrons suffer severe inverse Compton losses by
upscattering the UV photons of the Be star at high energy: At periastron
passage Gamma-ray emission has been observed, whereas radio outbursts have
never been observed in 20 years of radio flux monitoring. For ejections
displaced from periastron passage the losses are less severe and radio
outbursts are observed. The radio emission mapped on scales from a few AU to
hundreds of AU shows a double-sided relativistic (beta=0.6c) S-shaped jet,
similar to the well-known precessing jet of SS 433.


title: Constraining Van der Waals quintessence by observations

abstract:
  We discuss an alternative approach to quintessence modifying the usual
equation of state of the cosmological fluid in order to see if going further
than the approximation of perfect fluid allows to better reproduce the
available data. We consider a cosmological model comprising only two fluids,
namely baryons (modelled as dust) and dark matter with a Van der Waals equation
of state. First, the general features of the model are presented and then the
evolution of the energy density, the Hubble parameter and the scale factor are
determined showing that it is possible to obtain accelerated expansion choosing
suitably the model parameters. We use the estimated age of the universe and the
data on the dimensionless coordinate distances to Type Ia supernovae and
distant radio galaxies to see whether Van der Waals quintessence is viable to
explain dark energy and to constrain its parameters.


title: The gamma-ray emitting microquasar LSI+61303

abstract:
  LS I +61 303 is one of the most studied X-ray binary systems because of its
two peculiarities: On the one hand being the probable counterpart of the
variable gamma ray source 2CG 135+01 (Gregory and Taylor 1978; Tavani et al.
1998) and on the other hand being a periodic radio source (Taylor and Gregory
1982). The recent discovery of a radio emitting jet extending ca. 200 AU at
both sides of a central core (Massi et al. 2004) in all evidence has shown the
occurrence of accretion/ejection processes in this system. However, the radio
outbursts do not occur at periastron passage, where the accretion is at its
maximum, but several days later. In addition, when the gamma-ray emission of
2CG 135+01 is examined along the orbital phase of LS I +61 303 one sees that
this emission seems to peak at periastron passage (Massi 2004). Here in detail
we analyse the trend of the gamma-ray data versus orbital phase and discuss the
delay between peaks at gamma-rays and in the radio band within the framework of
a two-peak accretion/ejection model proposed by Taylor et al. (1992) and
further developed by Marti' and Paredes (1995).


title:
Relations Between Timing Features and Colors in Accreting Millisecond
  Pulsars

abstract:
  We have studied the aperiodic X-ray timing and color behavior of the
accreting millisecond pulsars SAX J1808.4-3658, XTE J1751-305, XTE J0929-314,
and XTE J1814-338 using large data sets obtained with the Rossi X-ray Timing
Explorer. We find that the accreting millisecond pulsars have very similar
timing properties to the atoll sources and the low luminosity bursters. Based
on the correlation of timing and color behavior SAX J1808.4-3658 can be
classified as an atoll source, and XTE J0929-314 and XTE J1814-338 are
consistent with being atoll sources, but the color behavior of XTE J1751-305 is
different. Unlike in other atoll sources the hard color in the extreme island
state of XTE J1751-305 is strongly correlated with soft color and intensity,
and is not anti-correlated with any of the characteristic frequencies. We found
previously, that the frequencies of the variability components of atoll sources
follow a universal scheme of correlations. The frequency correlations of the
accreting millisecond pulsars are similar, but in the case of SAX J1808.4-3658
and XTE J0929-314 shifted compared to those of the other atoll sources in a way
that is most easily described as a shift in upper and lower kilohertz QPO
frequency by a factor close to 1.5. Although, we note that the shift in lower
kilohertz QPO frequency is based on only one observation for SAX J1808.4-3658.
XTE J1751-305 and XTE J1814-338, as well as the low luminosity bursters show no
or maybe small shifts.


title: Spectroscopic confirmation of high-redshift supernovae with the ESO VLT

abstract:
  We present VLT FORS1 and FORS2 spectra of 39 candidate high-redshift
supernovae that were discovered as part of a cosmological study using Type Ia
supernovae (SNe Ia) over a wide range of redshifts. From the spectra alone, 20
candidates are spectrally classified as SNe Ia with redshifts ranging from
z=0.212 to z=1.181. Of the remaining 19 candidates, 1 might be a Type II
supernova and 11 exhibit broad supernova-like spectral features and/or have
supernova-like light curves. The candidates were discovered in 8 separate
ground-based searches. In those searches in which SNe Ia at z ~ 0.5 were
targeted, over 80% of the observed candidates were spectrally classified as SNe
Ia. In those searches in which SNe Ia with z > 1 were targeted, 4 candidates
with z > 1 were spectrally classified as SNe Ia and later followed with ground
and space based observatories. We present the spectra of all candidates,
including those that could not be spectrally classified as supernova.


title:
Do Magnetic Fields Prevent Hydrogen from Accreting onto Cool Metal-line
  White Dwarf Stars?

abstract:
  It is generally assumed that metals detected in the spectra of a few cool
white dwarfs cannot be of primordial origin and must be accreted from the
interstellar medium. However, the observed abundances of hydrogen, which should
also be accreted from the interstellar medium, are lower than expected from
metal accretion. Magnetic fields are thought to be the reason for this
discrepancy. We have therefore obtained circular polarization spectra of the
helium-rich white dwarfs GD40 and L745-46A, which both show strong metal lines
as well as hydrogen. Whereas L745-46A might have a magnetic field of about
-6900 G, which is about two times the field strength of 3000G necessary to
repell hydrogen at the Alfen radius, only an upper limit for the field strength
of GD40 of 4000G (with 99% confidence) can be set which is far off the minimum
field strength of 144000G to repell hydrogen.


title: Phantom Dark Energy, Cosmic Doomsday, and the Coincidence Problem

abstract:
  Phantom dark energy models, with w < -1, are characterized by a future
singularity and therefore a finite lifetime for the universe. Because the
future singularity is triggered by the onset of dark-energy domination, the
universe spends a significant fraction of its total lifetime in a state for
which the dark energy and matter densities are roughly comparable. We
calculate, as a function of w, the fraction of the total lifetime of the
universe for which the dark energy and matter densities differ by less than the
ratio r_0 in either direction. For r_0 = 10, this fraction varies from 1/3 to
1/8 as w varies from -1.5 to -1.1; the fraction is smaller for smaller values
of r_0. This result indicates that the coincidence problem is significantly
ameliorated in phantom-dominated cosmologies with a future singularity.


title: Discovery of magnetic fields in CPNs

abstract:
  For the first time we have directly detected magnetic fields in central stars
of planetary nebulae by means of spectro-polarimetry with FORS1 at the VLT. In
all four objects of our sample we found kilogauss magnetic fields, in NGC 1360
and LSS1362 with very high significance, while in Abell36 and EGB5 the
existence of a magnetic field is probable but with less certainty. This
discovery supports the hypothesis that the non-spherical symmetry of most
planetary nebulae is caused by magnetic fields in AGB stars. Our high discovery
rate demands mechanisms to prevent full conservation of magnetic flux during
the transition to white dwarfs.


title:
The effects of stellar dynamics on the evolution of young dense stellar
  systems

abstract:
  In the present paper we report on first results of a project in Brussels
where we study the effects of stellar dynamics on the evolution of young dense
stellar systems using the 3 decades expertise in massive star evolution and our
population (number and spectral) synthesis code. We highlight an
unconventionally formed object scenario (UFO-scenario) for Wolf Rayet binaries
and study the effects of a luminous blue variable-type instability wind mass
loss formalism on the formation of intermediate mass black holes.


title: Controlled Antihydrogen Propulsion for NASA's Future in Very Deep Space

abstract:
  To world-wide notice, in 2002 the ATHENA collaboration at CERN (in Geneva,
Switzerland) announced the creation of order 100,000 low energy antihydrogen
atoms. Thus, the concept of using condensed antihydrogen as a low-weight,
powerful fuel (i.e., it produces a thousand times more energy per unit weight
of fuel than fission/fusion) for very deep space missions (the Oort cloud and
beyond) had reached the realm of conceivability. We briefly discuss the history
of antimatter research and focus on the technologies that must be developed to
allow a future use of controlled, condensed antihydrogen for propulsion
purposes. We emphasize that a dedicated antiproton source (the main barrier to
copious antihydrogen production) must be built in the US, perhaps as a joint
NASA/DOE/NIH project. This is because the only practical sources in the world
are at CERN and the proposed facility at GSI in Germany. We outline the scope
and magnitude of such a dedicated national facility and identify critical
project milestones. We estimate that, starting with the present level of
knowledge and multi-agency support, the goal of using antihydrogen for
propulsion purposes may be accomplished in ~50 years.


title:
uvbyCaHbeta CCD Photometry of Clusters. V. The Metal-Deficient Open
  Cluster NGC 2243

abstract:
  CCD photometry on the intermediate-band uvbyCaHbeta system is presented for
the metal-deficient open cluster, NGC 2243. Restricting the data to probable
single members of the cluster using the CMD and the photometric indices alone
generates a sample of 100 stars at the cluster turnoff. The average E(b-y) =
0.039 (0.003 s.e.m.) or E(B-V) = 0.055 (0.004 s.e.m.), where the errors refer
to internal errors alone. With this reddening, [Fe/H] is derived from both m_1
and hk, using b-y and Hbeta as the temperature index. The agreement among the
four approaches is excellent, leading to a final weighted average of [Fe/H] =
-0.57 (0.03 s.e.m.) for the cluster, on a scale where the Hyades has [Fe/H] =
+0.12. Using a combination of photometric and spectroscopic data, 27 probable
cluster members are identified and used to delineate the red giant branch and a
well-defined clump at V = 13.70, while eliminating the so-called second clump
at V = 14.1. Interpolation between isochrones of appropriate [Fe/H] leads to an
apparent modulus of (m-M) = 13.15 +/- 0.1 and an age of 3.8 +/- 0.2 Gyr. A
differential CMD comparison with Berkeley 29, a cluster with a galactocentric
distance almost twice that of NGC 2243, constrains Berkeley 29 to be at least
as young and as metal-rich as NGC 2243.


title: The Starburst IMF -- An Impossible Measurement?

abstract:
  The starburst IMF is probably as much of theoretical interest and practical
relevance as it is a subject of observational controversy. In this conference
paper we review the most common methods (star counts, dynamical masses, and
line ratios) to derive or constrain the IMF, and discuss potential problems and
shortcomings that often lead to claims of anomalous IMF slopes and mass
cut-offs.


title: The mass composition of cosmic rays above 10^17 eV

abstract:
  Our knowledge of the mass composition of cosmic rays is deficient at all
energies above 10^17. Here systematic differences between different
measurements are discussed and, in particular, it is argued that there is no
compelling evidence to support the common assumption that vast majority of the
cosmic rays of the highest energies are protons. Our knowledge of the mass
needs to be improved if we are to resolve uncertainties about the energy
spectrum. Improvement is also needed for proper interpretation of data on the
arrival direction distribution of cosmic ray.


title: Deuterated Thioformaldehyde in the Barnard 1 Cloud

abstract:
  We present observations of the singly and doubly deuterated species of
thioformaldehyde, HDCS and D$_2$CS, towards the dark cloud Barnard 1. This is
the first detection of D$_2$CS in Space and in dense and cold prestellar
regions. Column densities obtained using rotational diagrams and a Large
Velocity Gradient model show an extremely high D-enhancement in
thioformaldehyde in Barnard 1. Although the column density of H$_2$CS is
smaller than that of H$_2$CO, both species show similar D-enhancements in their
singly and doubly deuterated species. A chemical model -including multiply
deuterated species- has been used in order to interpret the observations.
  Predicted rotational frequencies from laboratory data for HDCS and D$_2$CS
are significantly in error when compared to the observed frequencies in Space.
Consequently, we have derived new rotational constants for these two species
and for H$_2$CS and H$_2$C$^{34}$S using the observed frequencies in Barnard 1.
The new rotational constants allow to predict the rotational transitions of
these species with the accuracy needed for the narrow line emerging from dark
clouds. Rotational constants for HDCS and D$_2$CS have been obtained from the
observed transitions in the laboratory and in Space.


title: Weighing stellar - mass black holes with Gaia

abstract:
  Stellar-mass black holes have been detected by radial-velocity observations
in star/black hole binaries. These allow only the determination of the mass
function. Tracking the astrometric orbits of the visible components of the
star/black hole binaries would allow the full determination of the black hole
masses, which would be of great astrophysical interest. We investigate the
possibilities to do this with Gaia. A very promising object seems to be Cyg
X-1. The donor star is an O9.7Iab supergiant having a mass of 25 M_Sun, and the
mass of the black hole is estimated to be at least 13 M_Sun masses. The period
of 5.6 days implies a semi-major axis of 1.01 micropc of the binary orbit. At
the distance of Cyg X-1 (2.5kpc) this translates into a semi-major axis of
about 28 microarcsec for the visible component, which can be detected by Gaia.
We discuss further candidates.


title:
How to reconcile the C and s-process abundances in the metal-poor star
  V453 Oph ?

abstract:
  In this poster we present a detailed chemical analysis of the RV Tauri star
of low intrinsic metallicity, V453 Oph ([Fe/H]=-2.2), which shows a mild but
clear s-process surface overabundance. This result is strengthened by a
relative analysis to the RV Tauri star DS Aqr of similar metal deficiency
([Fe/H]=-1.6), but without such s-process enrichment. A remarkable result is
that the s-process enrichment of V453 Oph is not accompanied by a measurable C
enhancement. To explain the surface abundances observed in V453 Oph, two
nucleosynthesis models are considered. The first model assumes the partial
mixing of protons during the radiative interpulse phase while the second
scenario is based on the possible production of s-process elements within the
flash-driven convective pulse only. Both models can give a satisfactory
explanation for the s-process enrichment of V453 Oph, but not the simultaneous
low C-abundance observed.


title:
Did most present-day spirals form during the last 8 Gyrs? A formation
  history with violent episodes revealed by panchromatic observations

abstract:
  (abridged) Studies of distant galaxies have shown that ellipticals and large
spirals were already in place 8 Gyr ago, leading to a very modest recent star
formation in intermediate mass galaxies. This is challenged by a recent
analysis (Heavens et al. 2004) of the fossil record of the stellar populations
of ~10^5 nearby galaxies, which show that intermediate mass galaxies have
formed or assembled the bulk of their stars 4 to 8 Gyr ago. Here we present
direct observational evidence supporting the Heavens et al's findings from a
long term, multi-wavelength study of 195 z>0.4 intermediate mass galaxies,
mostly selected from the CFRS survey. We show that a recent and efficient star
formation is revealed at IR wavelengths since ~15% of intermediate mass
galaxies at z>0.4 are indeed luminous IR galaxies (LIRGs), a phenomenon far
more common than in the local Universe. The star formation in LIRGs is
sufficient in itself to produce 38% of the total stellar mass of intermediate
mass galaxies and then to account for most of the reported stellar mass
formation since z=1. The high occurrence of LIRGs is easily understood only if
they correspond to episodic peaks of star formation, during which galaxies are
reddened through short IREs (infrared episodes). We examine how galaxy IREs can
be related to the emergence at high redshift, of the abundant population of
galaxies with small size, blue core and many irregularities. We show that
recent merging and gas infall naturally explain both morphological changes and
episodic star formation history in a hierarchical galaxy formation frame. We
propose a simple scenario in which 75+-25% of intermediate mass spirals have
experienced recently their last major merger event, leading to a drastic
reshaping of their bulges and disks during the last 8 Gyrs.


title:
High resolution infrared spectra of NGC 6342 and NGC 6528: two
  moderately reddened Bulge Globular Clusters

abstract:
  Using the NIRSPEC spectrograph at Keck II, we have obtained infrared echelle
spectra covering the range 1.5-1.8 micron for the moderately reddened bulge
globular clusters NGC 6342 and NGC 6528, finding [Fe/H]= -0.60 and -0.17 dex,
respectively. We measure an average alpha-enhancement of approx +0.33 dex in
both clusters, consistent with previous measurements on other metal rich bulge
clusters, and favoring the scenario of a rapid bulge formation and chemical
enrichment. We also measure very low 12C/13C isotopic ratios (approx 5 in NGC
6342 and approx 8 in NGC 6528), suggesting that extra-mixing mechanisms due to
cool bottom processing are at work during evolution along the Red Giant Branch.


title: The radio-ultraviolet spectral energy distribution of the jet in 3C273

abstract:
  We present deep VLA and HST observations of the large-scale jet in 3C 273
matched to 0.3" resolution. The observed spectra show a significant flattening
in the infrared-ultraviolet wavelength range. The jet's emission cannot
therefore be assumed to arise from a single electron population and requires
the presence of an additional emission component. The observed smooth
variations of the spectral indices along the jet imply that the physical
conditions vary correspondingly smoothly. We determine the maximum particle
energy for the optical jet using synchrotron spectral fits. The slow decline of
the maximum energy along the jet implies particle reacceleration acting along
the entire jet. In addition to the already established global anti-correlation
between maximum particle energy and surface brightness, we find a weak positive
correlation between small-scale variations in maximum particle energy and
surface brightness. The origin of these conflicting global and local
correlations is unclear, but they provide tight constraints for reacceleration
models.


title:
The CIDA Variability Survey of Orion OB1. I: the low-mass population of
  Ori OB 1a and 1b

abstract:
  We present results of a large scale, multi-epoch optical survey of the Ori
OB1 association, carried out with the QuEST camera at the Venezuela National
Astronomical Observatory. We identify for the first time the widely spread
low-mass, young population in the Orion OB1a and OB1b sub-associations.
Candidate members were picked up by their variability in the V-band and
position in color-magnitude diagrams. We obtained spectra to confirm
membership. In a region spanning ~ 68 deg^2 we found 197 new young stars; of
these, 56 are located in the Ori OB1a subassociation and 142 in Ori OB1b.
Comparison with the spatial extent of molecular gas and extinction maps
indicates that the subassociation Ori 1b is concentrated within a ring-like
structure of radius ~2 deg (~15 pc at 440 pc), centered roughly on the star
epsilon Ori in the Orion belt. The ring is apparent in 13CO and corresponds to
a region with an extinction Av>=1. The stars exhibiting strong Ha emission, an
indicator of active accretion, are found along this ring, while the center is
populated with weak Ha emitting stars. In contrast, Ori OB1a is located in a
region devoid of gas and dust. We identify a grouping of stars within a ~3
deg^2 area located in 1a, roughly clustered around the B2 star 25 Ori. The
Herbig Ae/Be star V346 Ori is also associated with this grouping, which could
be an older analog of sigma Ori. Using using several sets of evolutionary
tracks we find an age of 7 - 10 Myr for Ori 1a and of ~4 - 6 Myr for Ori OB1b,
consistent with previous estimates from OB stars. Indicators such as the
equivalent width of Ha and near-IR excesses show that while a substantial
fraction of accreting disks remain at ages ~5 Myr, inner disks are essentially
dissipated by 10 Myr.


title: Disk evolution in the Ori OB1 association

abstract:
  We analyze multi-band photometry of a subsample of low mass stars in the
associations Ori OB1a and 1b discovered during the CIDA Orion Variability
Survey, which have ages of 7 - 10 Myr and 3 - 5 Myr, respectively. We obtained
UBVRcIc photometry at Mt. Hopkins for 6 Classical T Tauri stars (CTTS) and 26
Weak T Tauri stars (WTTS) in Ori OB1a, and for 21 CTTS and 2 WTTS in Ori OB1b.
We also obtained L band photometry for 14 CTTS at Mt. Hopkins, and 10um and
18um photometry with OSCIR at Gemini for 6 CTTS; of these, all 6 were detected
at 10um while only one was detected at 18um. We estimate mass accretion rates
from the excess luminosity at U, and find that they are consistent with
determinations for a number of other associations, with or without high mass
star formation. The observed decrease of mass accretion rate with age is
qualitatively consistent with predictions of viscous evolution of accretion
disks. We find an overall decrease of disk emission from Taurus to Ori OB1b to
Ori OB1a. This decrease implies that significant grain growth and settling
towards the midplane has taken place in the inner disks of Ori OB1. We compare
the SED of the star detected at both 10um and 18um with disk models for similar
stellar and accretion parameters. We find that the low <= 18 um fluxes of this
Ori OB1b star cannot be due to the smaller disk radius expected from viscous
evolution in the presence of the FUV radiation fields from the OB stars in the
association. Instead, we find that the disk of this star is essentially a flat
disk, with little if any flaring, indicating a a significant degree of dust
settling towards the midplane, as expected from dust evolution in
protoplanetary disks.


title: Mid-Infrared Selection of Active Galaxies

abstract:
  Mid-infrared photometry provides a robust technique for identifying active
galaxies. While the ultraviolet to mid-infrared continuum of normal galaxies is
dominated by the composite stellar black body curve and peaks at approximately
1.6 microns, the ultraviolet to mid-infrared continuum of active galaxies is
dominated by a power law. Consequently, with sufficient wavelength baseline,
one can easily distinguish AGN from stellar populations. Mirroring the tendency
of AGN to be bluer than galaxies in the ultraviolet, where galaxies (and stars)
sample the blue, rising portion of stellar spectra, AGN tend to be redder than
galaxies in the mid-infrared, where galaxies sample the red, falling portion of
the stellar spectra. We report on Spitzer Space Telescope mid-infrared colors,
derived from the IRAC Shallow Survey, of nearly 10,000 spectroscopically
identified sources from the AGN and Galaxy Evolution Survey. Based on this
spectroscopic sample, we find that simple mid-infrared color criteria provide
remarkably robust separation of active galaxies from normal galaxies and
Galactic stars, with over 80% completeness and less than 20% contamination.
Considering only broad-lined AGN, these mid-infrared color criteria identify
over 90% of spectroscopically identified quasars and Seyfert 1s. Applying these
color criteria to the full imaging data set, we discuss the implied surface
density of AGN and find evidence for a large population of optically obscured
active galaxies.


title:
Exploring Properties of Dark and Visible Mass Distribution on Different
  Scales in the Universe

abstract:
  In this short note we discuss recent observation of linear correlation on
log-log scale between distribution of dark and visible mass in gravitationally
bound systems. The coefficient of such correlation appears to be essentially
the same for various systems of dramatically different scales such as spiral
galaxies of different luminosities and galaxy clusters. We briefly touch
possible interpretations of this observation and implications for the mass of
dark matter particle.


title:
Deep-Ocean Crusts as Telescopes: Using Live Radioisotopes to Probe
  Supernova Nucleosynthesis

abstract:
  Live 60Fe has recently been detected in a deep-ocean ferromanganese crust,
isolated in layers dating from about 3 Myr ago. Since 60Fe has a mean life of
2.2 Myr, a near-Earth supernova is the only likely source for such a signal,
and we explore here the consequences of a supernova origin. We combine the 60Fe
data with several supernova nucleosynthesis models to calculate the supernova
distance as a function of progenitor mass, finding an allowed range of 15-120
pc. We also predict the signals expected for several other radioisotopes, which
are independent of the supernova distance. Species likely to be present near or
above background levels are 10Be, 26Al, 53Mn, 182Hf and 244Pu. Of these, 182Hf
and 244Pu are nearly background-free, presenting the best opportunities to
provide strong confirmation of the supernova origin of the 60Fe signal, and to
demonstrate that at least some supernovae are the source for the r-process. The
accuracies of our predictions are hampered by large uncertainties in the
predicted 60Fe yields for supernovae of different masses, so the new crust data
motivate a redoubled theoretical attack on this problem.


title: From the Earliest Seeds to Today's Supermassive Black Holes

abstract:
  I review scenarios for the assembly of supermassive black holes (MBHs) at the
center of galaxies that trace their hierarchical build-up far up in the dark
matter halo "merger tree". Monte Carlo realizations of the merger hierarchy in
a LCDM cosmology, coupled to semi-analytical recipes, are a powerful tool to
follow the merger history of halos and the dynamics and growth of the MBHs they
host. X-ray photons from miniquasars powered by intermediate-mass "seed" holes
may permeate the universe more uniformly than EUV radiation, make the
low-density diffuse intergalactic medium warm and weakly ionized prior to the
epoch of reionization breakthrough, and set an entropy floor. The spin
distribution of MBHs is determined by gas accretion, and is predicted to be
heavily skewed towards fast-rotating Kerr holes, to be already in place at
early epochs, and not to change significantly below redshift 5. Decaying MBH
binaries may shape the innermost central regions of galaxies and should be
detected in significant numbers by LISA.


title: The Cosmic Evolution of Hard X-ray Selected Active Galactic Nuclei

abstract:
  We use highly spectroscopically complete deep and wide-area Chandra surveys
to determine the cosmic evolution of hard X-ray-selected AGNs. We determine
hard X-ray luminosity functions (HXLFs) for all spectral types and for
broad-line AGNs (BLAGNs) alone. At z<1.2, both are well described by pure
luminosity evolution. Thus, all AGNs drop in luminosity by almost an order of
magnitude over this redshift range. We show that this observed drop is due to
AGN downsizing. We directly compare our BLAGN HXLFs with the optical QSO LFs
and find that the optical QSO LFs do not probe faint enough to see the downturn
in the BLAGN HXLFs. We rule out galaxy dilution as a partial explanation for
the observation that BLAGNs dominate the number densities at the higher X-ray
luminosities, while optically-narrow AGNs (FWHM<2000 km/s) dominate at the
lower X-ray luminosities by measuring the nuclear UV/optical properties of the
Chandra sources using the HST ACS GOODS-North data. The UV/optical nuclei of
the optically-narrow AGNs are much weaker than expected if they were similar to
the BLAGNs. We therefore postulate the need for a luminosity dependent unified
model. Alternatively, the BLAGNs and the optically-narrow AGNs could be
intrinsically different source populations. We cover both interpretations by
constructing composite spectral energy distributions--including long-wavelength
data from the MIR to the submillimeter--by spectral type and by X-ray
luminosity. We use these to infer the bolometric corrections (from hard X-ray
luminosities to bolometric luminosities) needed to map the accretion history.
We determine the accreted supermassive black hole mass density for all spectral
types and for BLAGNs alone using the observed evolution of the hard X-ray
energy density production rate and our inferred bolometric corrections.


title: Is the interstellar gas of starburst galaxies well mixed?

abstract:
  The extent to which the ISM in galaxies is well mixed is not yet settled.
Measured metal abundances in the diffuse neutral gas of star--forming gas--rich
dwarf galaxies are deficient with respect to that of the ionized gas. The
reasons, if real, are not clear and need to be based on firm grounds. Far-UV
spectroscopy of giant HII regions such as NGC604 in the spiral galaxy M33 using
FUSE allows us to investigate possible systematic errors in the metallicity
derivation. We still find underabundances of nitrogen, oxygen, argon, and iron
in the neutral phase by a factor of~6. This could either be explained by the
presence of less chemically evolved gas pockets in the sightlines or by dense
clouds out of which HIIregions form. Those could be more metallic than the
diffuse medium.


title: Praesepe and the seven white dwarfs

abstract:
  We report the discovery, from our preliminary survey of the Praesepe open
cluster, of two new spectroscopically confirmed white dwarf candidate members.
We derive the effective temperatures and surface gravities of WD0837+218 and
WD0837+185 (LB5959) to be 17845 +555 -565K and log g = 8.48 +0.07 -0.08 and
14170 +1380 -1590K and log g =8.46 +0.15 -0.16 respectively. Using theoretical
evolutionary tracks we estimate the masses and cooling ages of these white
dwarfs to be 0.92+/-0.05Msun and 280 +40 -30Myrs and 0.90+/-0.10Msun and 500
+170 -100Myrs respectively. Adopting reasonable values for the cluster age we
infer the progenitors of WD0837+218 and WD0837+185 had masses of 2.6 < M <
Mcrit Msun and 2.4 < M < 3.5Msun respectively, where Mcrit is the maximum mass
of a white dwarf progenitor. We briefly discuss these findings in the context
of the observed deficit of white dwarfs in open clusters and the initial
mass-final-mass relationship.


title: Helical motion and the origin of QPO in blazar-type sources

abstract:
  Recent observations and analysis of blazar sources provide strong evidence
for (i) the presence of significant periodicities in their lightcurves and (ii)
the occurrence of helical trajectories in their radio jets. In scenarios, where
the periodicity is caused by differential Doppler boosting effects along a
helical jet path, both of these facts may be naturally tied together. Here we
discuss four possible driving mechanisms for the occurrence of helical
trajectories: orbital motion in a binary system, Newtonian-driven jet
precession, internal jet rotation and motion along a global helical magnetic
field. We point out that for non-ballistic helical motion the observed period
may appear strongly shortened due to classical travel time effects. Finally,
the possible relevance of the above mentioned driving mechanisms is discussed
for Mkn~501, OJ 287 and AO 0235+16.


title: The gravitational wave signature of young and dense star clusters

abstract:
  Young star clusters are often born with such high stellar densities that
stellar collisions play an important role in their further evolution. In such
environments the same star may participate in several tens to hundreds of
collisions ultimately leading to the collapse of the star to a black hole of
intermediate mass. At later time the black hole may acquire a companion star by
tidal capture or by dynamical --3-body-- capture. When this companion star
evolves it will fill its Roche-lobe and transfer mass to its accompanying black
hole. This then leads to a bright phase of X-ray emission but the binary may
also be visible as a source of gravitational wave radiation in the LISA band.
If the star captured by the intermediate mass black hole is relatively low mass
($\aplt 2$ \msun) the binary will be visible as a bright source in
gravitational waves and X-rays for the entire lifetime of the binary. The
majority of compact binaries which formed from the population of primordial
binaries in young and dense star clusters do not lead to detectable
gravitational wave sources.


title: Quantitative Stellar Spectral Classification. III. Spectral Resolution

abstract:
  The method developed by Stock and Stock (1999) to derive absolute magnitudes
and intrinsic colors is applied to simulated low-resolution spectra. The
simulation is made by convolving real spectra with a Gaussian function,
$\sigma$ (the full width at half maximum) related to the final spectral
resolution. The accuracy with which the stellar parameters are determined
indicates that the method may be applied to typical objective-prism spectra. We
show that changes in the spectral resolution do not significantly affect the
stellar parameters obtained with this method for early-type stars, whereas for
later-type stars an improved approach is necessary.


title:
Differential rotation of the active G5V star Kappa1 Ceti: Photometry
  from the MOST satellite

abstract:
  About 30.5 days of nearly uninterrupted broadband photometry of the
solar-type star Kappa1 Ceti, obtained with the MOST (Microvariability &
Oscillations of STars) satellite, shows evidence for two large starspots with
different rotation periods of 8.9 and approximately 9.3 days
(DeltaOmega/Omega~4%). Ground based measurements in 2002 and 2003 of Ca II H &
K emission reveal variations in chromospheric activity with a period of about
9.3 days. The data were obtained during the MOST commissioning phase. When the
data are combined with historical observations, they indicate that the 9.3-day
spot has been stable in its period for over 30 years. The photometry, with a
sampling rate of approximately once per minute, was also used to search for
acoustic (p-mode) oscillations in the star. We detect no clear evidence for
p-modes in the Kappa1 Ceti photometry, with a noise level around 7-9 mu_mag at
frequencies in the range 0.5-4 mHz (3-sigma detection limit of 21 - 27 mu_mag).
There were no flares or planetary transits during the 30.5 days of MOST
monitoring with light amplitudes greater than 2 mmag (durations greater than
200 minutes) and 3 mmag (2-200 min durations). While this rules out any
close-in planets of >=0.5 Jupiter diameters with an orbital inclination close
to 90 deg, the scatter in differential radial velocities permit a close giant
planet in a more highly inclined orbit.


title: Magnetic Fields in Molecular Cloud Cores

abstract:
  Observations of magnetic field strengths imply that molecular cloud fragments
are individually close to being in a magnetically critical state, even though
both magnetic field and column density measurements range over two orders of
magnitude. The turbulent pressure also approximately balances the
self-gravitational pressure. These results together mean that the
one-dimensional velocity dispersion $\sigv$ is proportional to the mean \Alf
speed of a cloud $\va$. Global models of MHD turbulence in a molecular cloud
show that this correlation is naturally satisfied for a range of different
driving strengths of the turbulence. For example, an increase of turbulent
driving causes a cloud expansion which also increases $\va$. Clouds are in a
time averaged balance but exhibit large oscillatory motions, particularly in
their outer rarefied regions. We also discuss models of gravitational
fragmentation in a sheet-like region in which turbulence has already
dissipated, including the effects of magnetic fields and ion-neutral friction.
Clouds with near-critical mass-to-flux ratios lead to subsonic infall within
cores, consistent with some recent observations of motions in starless cores.
Conversely, significantly supercritical clouds are expected to produce extended
supersonic infall.


title:
Palomar/Las Campanas Imaging Atlas of Blue Compact Dwarf Galaxies: II.
  Surface Photometry and the Properties of the Underlying Stellar Population

abstract:
  We present the results from an analysis of surface photometry of B, R, and
Halpha images of a total of 114 nearby galaxies drawn from the Palomar/Las
Campanas Imaging Atlas of Blue Compact Dwarf galaxies. Surface brightness and
color profiles for the complete sample have been obtained. We determine the
exponential and Sersic profiles that best fit the surface brightness
distribution of the underlying stellar population detected in these galaxies.
We also compute the (B-R) color and total absolute magnitude of the underlying
stellar population and compared them to the integrated properties of the
galaxies in the sample. Our analysis shows that the (B-R) color of the
underlying population is systematically redder than the integrated color,
except in those galaxies where the integrated colors are strongly contaminated
by line and nebular-continuum emission. We also find that galaxies with
relatively red underlying stellar populations (typically (B-R)>~1mag) show
structural properties compatible with those of dwarf elliptical galaxies (i.e.
a smooth light distribution, fainter extrapolated central surface brightness
and larger scale lengths than BCD galaxies with blue underlying stellar
populations). At least ~15% of the galaxies in the sample are compatible with
being dwarf elliptical (dE) galaxies experiencing a burst of star formation.
For the remaining BCD galaxies in the sample we do not find any correlation
between the recent star formation activity and their structural differences
with respect to other types of dwarf galaxies.


title: Accreting Neutron Stars and Black Holes: A Decade of Discoveries

abstract:
  This is a review of recent observational and theoretical developments related
to accreting neutron stars and black holes in binary systems.


title: Interaction of young stellar object jets with their accretion disk

abstract:
  I reexamine recent observations of velocity profiles across jets blown by
young stellar objects, and argue that the observations do not support the
interpretation of jets rotating around their symmetry axes. Instead, I propose
that the interaction of the jets with a twisted-tilted (wrapped) accretion disk
can form the observed asymmetry in the jets' line of sight velocity profiles.
The proposed scenario is based on two plausible assumptions. (1) There is an
inclination between the jet and the outer parts of the disk; the jet is
perpendicular to the inner part of the disk; Namely, there is a twisted-tilted
(wrapped) disk. (2) The disk-jet interaction slows down the jet as the jet
entrains mass from the disk, with larger decelaration of jet segments closer to
the tilted disk. The proposed scenario can account for the basic properties of
the observed velocity profiles, while having the advantage that there is no
need to refer to any magnetic jet launching model, and there is no need to
invoke jet rotation with a huge amount of angular momentum.


title:
A method for determining radio continuum spectra, and its application to
  large surveys

abstract:
  A new tool to extract cross-identifications and radio continuum spectra from
radio catalogues contained in the VIZIER database of the CDS is presented. The
code can handle radio surveys at different frequencies with different
resolutions. It has been applied to 22 survey catalogues at 11 different
frequencies containing a total of 3.5 million sources, which resulted in over
700000 independent radio cross-identifications and ~67000 independent radio
spectra with more than two frequency points. A validation of the code has been
performed using independent radio cross-correlations from the literature. The
mean error of the determined spectral index is +-0.3. The code produces an
output of variable format that can easily be adapted to the purpose of the
user.


title:
Phase-dependent changes in the wind lines in the HMXRB's SMC X-1 and
  4U1700-37

abstract:
  The High Mass X-ray Binaries (HMXRB's) SMC X-1 and 4U1700-37 have been
observed with FUSE to study the effect of the X-ray source on the stellar wind
of the primary. In both systems phase dependent changes in the wind lines have
been observed, indicating the creation of a X-ray ionization zone in the
stellar wind. The high X-ray luminosity of SMC X-1 ionizes much of the wind and
leaves a Stromgren zone. This disrupts the resonance-line acceleration of the
wind in portions of the orbit, quencing the wind and disrupting the mass flow.
A similar but less dramatic effect was found for the first time in 4U1700-37.
This so-called Hatchett-McCray (HM) effect had been predicted for 4U1700-37,
but was not previously detected.


title: FUSE Observations of eta Carinae

abstract:
  Eta Carinae was observed by FUSE through the LWRS (30 arcsec x30 arcsec) and
HIRS (1.25 arcsec x 20 arcsec) apertures in March and April 2004. There are
significant differences between the two spectra. About half of the LWRS flux
appears to be due to two B-type stars near the edge of the LWRS aperture, 14
arcsec from eta Carinae. The HIRS spectrum (LiF1 channel) therefore reveals the
intrinsic FUV spectrum of eta Carinae without this stellar contamination. The
HIRS spectrum contains strong interstellar H2 having high rotational excitation
(up to J=8). Most of the atomic species with prominent ISM features (C II, Fe
II, Ar I, P II, etc) also have strong blue-shifted absorption to v= ~ -580 km/s
that is associated with expanding debris from the 1840 eruption.


title: Cosmological influence of super-Hubble perturbations

abstract:
  The existence of cosmological perturbations of wavelength larger than the
Hubble radius is a generic prediction of the inflationary paradigm. We provide
the derivation beyond perturbation theory of a conserved quantity which
generalizes the linear comoving curvature perturbation. As a by-product, we
show that super-Hubble-radius (super-Hubble) perturbations have no physical
influence on local observables e.g., the local expansion rate) if cosmological
perturbations are of the adiabatic type.


title: ANTARES Status & Milestones : News from Deep-Sea

abstract:
  The ANTARES project aims to build a deep-sea Cherenkov Telescope for High
Energy Neutrino Astronomy located in the Mediterranean Sea. The experiment,
currently in the construction phase, has recently achieved an important
milestone : the operation of a prototype line and of a line with monitoring
instruments. These deployments allowed a thorough understanding of
environmental parameters.


title: Supernovae type Ia data favour coupled phantom energy

abstract:
  We estimate the constraints that the recent high-redshift sample of
supernovae type Ia put on a phenomenological interaction between dark energy
and dark matter. The interaction can be interpreted as arising from the time
variation of the mass of dark matter particles. We find that the coupling
correlates with the equation of state: roughly speaking, a negative coupling
(in our sign convention) implies phantom energy ($w_{\phi}<-1$) while a
positive coupling implies ``ordinary'' dark energy. The constraints from the
current supernovae Ia Hubble diagram favour a negative coupling and an equation
of state $w_{\phi}<-1$. A zero or positive coupling is in fact unlikely at 99%
c.l. (assuming constant equation of state); at the same time non-phantom values
($w_{\phi}>-1$) are unlikely at 95%. We show also that the usual bounds on the
energy density weaken considerably when the coupling is introduced: values as
large as $\Omega_{m0}=0.7$ become acceptable for as concerns SNIa. We find that
the rate of change of the mass $\dot{m}/m$ of the dark matter particles is
constrained to be $\delta_{0}$ in a Hubble time, with $-10<\delta_{0}<-1$ to
95% c.l.. We show that a large positive coupling might in principle avoid the
future singularity known as ``big rip'' (occurring for $w_{\phi}<-1$) but the
parameter region for this to occur is almost excluded by the data. We also
forecast the constraints that can be obtained from future experiments, focusing
on supernovae and baryon oscillations in the power spectra of deep redshift
surveys. We show that the method of baryon oscillations holds the best
potential to contrain the coupling.


title:
Beam mismatch effects in Cosmic Microwave Background polarization
  measurements

abstract:
  Measurement of cosmic microwave background polarization is today a major goal
of observational cosmology. The level of the signal to measure, however, makes
it very sensitive to various systematic effects. In the case of Planck, which
measures polarization by combining data from various detectors, the beam
asymmetry can induce a temperature leakage or a polarization mode mixing. In
this paper, we investigate this effect using realistic simulated beams and
propose a first-order method to correct the polarization power spectra for the
induced systematic effect.


title: A Far-Ultraviolet View of Starburst Galaxies

abstract:
  Recent observational and theoretical results on starburst galaxies related to
the wavelength regime below 1200 A are discussed. The review covers stars,
dust, as well as hot and cold gas. This wavelength region follows trends
similar to those seen at longer wavelengths, with several notable exceptions.
Even the youngest stellar populations show a turn-over in their spectral energy
distributions, and line-blanketing is much more pronounced. Furthermore, the O
VI line allows one to probe gas at higher temperatures than possible with lines
at longer wavelengths. Molecular hydrogen lines (if detected) provide a glimpse
of the cold phase. I cover the crucial wavelength regime below 912 A and the
implications of recent attempts to detect the escaping ionizing radiation.


title: Curvature Perturbations from Broken Symmetries

abstract:
  We present a new general mechanism to generate curvature perturbations after
the end of the slow-roll phase of inflation. Our model is based on the simple
assumption that the potential driving inflation is characterized by an
underlying global symmetry which is slightly broken.