title: Efficient radiative transfer in dust grain mixtures

abstract:
  The influence of a dust grain mixture consisting of spherical dust grains
with different radii and/or chemical composition on the resulting temperature
structure and spectral energy distribution of a circumstellar shell is
investigated. The comparison with the results based on an approximation of dust
grain parameters representing the mean optical properties of the corresponding
dust grain mixture reveal that (1) the temperature dispersion of a real dust
grain mixture decreases substantially with increasing optical depth, converging
towards the temperature distribution resulting from the approximation of mean
dust grain parameters, and (2) the resulting spectral energy distributions do
not differ by more than 10% if >= 2^5 grain sizes are considered which
justifies the mean parameter approximation and the many results obtained under
its assumption so far. Nevertheless, the dust grain temperature dispersion at
the inner boundary of a dust shell may amount to >>100K and has therefore to be
considered in the correct simulation of, e.g., chemical networks.
  In order to study the additional influence of geometrical effects, a
two-dimensional configuration -- the HH30 circumstellar disk -- was considered,
using model parameters from Cotera et al. (2001) and Wood et al. (2002). A
drastic inversion of the large to small grain temperature distribution was
found within the inner approx. 1AU of the disk.


title: Accelerating Flat Universe and Analytic Study of the m-z Relation

abstract:
  An accelerating flat universe with a variable cosmological term is obtained
in the Robertson-Walker metric. The variable cosmological term is defined by
the correction terms of the metric tensor field. Simple solutions of the scale
factor and the cosmological term are shown. In this model of the universe, the
magnitude-redshift relation is analytically studied to see if the model
reproduces the tendency of the present observational data. The equation of
state parameter $\gamma$ is touched.


title: WZ Sge-Type Star V592 Herculis

abstract:
  We observed the entire course of the 1998 outburst of V592 Her, which was
originally reported as a nova in 1968. We have been able to construct a full
light curve of the outburst, which is characterized by a rapid initial decline
(0.98 mag/d), which smoothly developed into a plateau phase with a slower
linear decline. We detected superhumps characteristic to SU UMa-type dwarf
novae ~7 d after the optical maximum. The overall behavior of the light curve
and the development of superhumps were characteristic to a WZ Sge-type dwarf
nova. Combined with the past literature, we have been able to uniquely
determine the superhump period to be 0.05648(2) d. From this period, together
with a modern interpretation of the absolute magnitude of the outburst light
curve, we conclude that the overall picture of V592 Her is not inconsistent
with a lower main-sequence secondary star in contrast to a previous claim that
V592 Her contains a brown dwarf.


title:
Spectroscopy of New High Proper Motion Stars in the Northern Sky. I. New
  Nearby Stars, New High Velocity Stars, and an Enhanced Classification Scheme
  for M Dwarfs

abstract:
  We define an enhanced spectral classification scheme for M dwarf stars, and
use it to derive spectral classification of 104 northern stars with proper
motions larger than 0.5"/yr which we discovered in a survey of high proper
motion stars at low galactic latitudes. The final tally is as follows: 54 M
dwarfs, 25 sdK and sdM subdwarfs, 14 esdK and esdM extreme subdwarfs, and 11 DA
and DC white dwarfs. Among the most interesting cases, we find one star to be
the coolest subdwarf ever reported (LSR2036+5059, with spectral type sdM7.5), a
new M9.0 dwarf only about 6pc distant (LSR1835+3259), and a new M6.5 dwarf only
7pc from the Sun (LSR2124+4003). Spectroscopic distances suggests that 27 of
the M dwarfs, 3 of the white dwarfs, and one of the subdwarfs (LSR2036+5059)
are within 25pc of the Sun, making them excellent candidates for inclusion in
the solar neighborhood census. Estimated sky-projected velocities suggest that
most of our subdwarfs and extreme subdwarfs have halo kinematics. We find that
several white dwarfs and non metal-poor M dwarfs also have kinematics
consistent with the halo, and we briefly discuss their possible origin.


title: Analysing Multi-Color Observations of Young Star Clusters in Mergers

abstract:
  We present a new evolutionary synthesis (ES) tool specifically developed for
the analysis of multi-color data of young star clusters (YSCs) in interacting
galaxies. Our ESO/ST-ECF ASTROVIRTEL project provides an unprecedented database
of UV--optical--NIR observations from the HST/WFPC2, HST/NICMOS and VLT data
archives. Comparison of these data with ES models for clusters of various
metallicities which include gaseous emission as well as various degrees of dust
extinction, allows one to independently determine metallicities, ages and
extinction for individual clusters. These, in turn, are the basis to derive the
mass functions of the YSC systems and to predict the future evolution of their
luminosity functions and color distributions. Comparing YSC systems of various
ages will, we anticipate, allow us to ``see cluster disruption processes at
work''.


title: Search For Oxygen in Cool DQ White Dwarf Atmospheres

abstract:
  We report new infrared spectroscopic observations of cool DQ white dwarfs by
using Coolspec on the 2.7m Harlan-Smith Telescope. DQs have helium-rich
atmospheres with traces of molecular carbon thought to be the result of
convective dredge-up from their C/O interiors. Recent model calculations
predict that oxygen should also be present in DQ atmospheres in detectable
amounts. Our synthetic spectra calculations for He-rich white dwarfs with
traces of C and O indicate that CO should be easily detected in the cool DQ
atmospheres if present in the expected amounts. Determination of the oxygen
abundance in the atmosphere will reveal the C/O ratio at the core/envelope
boundary, constraining the important and uncertain ^{12}C(alpha,gamma)^{16}O
reaction rate.


title:
The Mean Electromotive Force for MHD Turbulence: the Case of a Weak Mean
  Magnetic Field and Slow Rotation

abstract:
  The mean electromotive force in the framework of mean--field
magnetohydrodynamics is found with a particular attention to the effect of a
mean rotation of the fluid on the mean electromotive force. Anisotropy of the
turbulence due to gradients of its intensity or its helicity are admitted. The
mean magnetic field is considered to be weak enough to exclude quenching
effects. Magnetic fluctuations with a zero mean magnetic field are taken into
account. The Omega x J -effect works in the same way with velocity fluctuations
and magnetic fluctuations. A contribution to the electromotive force connected
with the symmetric parts of the gradient tensor of the mean magnetic field was
found in the case of rotation, resulting from velocity or magnetic
fluctuations. The implications of the results for the mean electromotive force
for mean--field dynamo models are discussed with special emphasis to dynamos
working without alpha-effect.


title:
A very young star forming region detected by the ISOPHOT Serendipity
  Survey

abstract:
  We present a multi-wavelength study of the star forming region ISOSS J
20298+3559, which was identified by a cross-correlation of cold compact sources
from the 170 micron ISOPHOT Serendipity Survey (ISOSS) database coinciding with
objects detected by the MSX, 2MASS and IRAS infrared surveys. ISOSS J
20298+3559 is associated with a massive dark cloud complex (M ~ 760
M$_{\odot}$) and located in the Cygnus X giant molecular cloud. We derive a
distance of 1800 pc on the basis of optical extinction data. The low average
dust temperature (T ~ 16 K) and large mass (M ~ 120 M$_{\odot}$) of the dense
inner part of the cloud, which has not been dispersed, indicates a recent begin
of star formation. The youth of the region is supported by the early
evolutionary stage of several pre- and protostellar objects discovered across
the regio n: I) Two candidate Class 0 objects with masses of 8 and 3.5
M$_{\odot}$, II) a gravitationally bound, cold (T ~ 12 K) and dense (n(H$_{2}$)
\~ 2 x 10$^{5}$ cm$^{-3}$) cloud core with a mass of 50 M$_{\odot}$ and III) a
Herbig B2 star with a mass of 6.5 M$_{\odot}$ and a bolometric luminosity of
2200 L$_{\odot}$, showing evidence for ongoing accretion and a stellar age of
less than 40000 years. The dereddened SED of the Herbig star is well reproduced
by an accretion disc + star model. The externally heated cold cloud core is a
good candidate for a massive pre-protostellar object. The star formation
efficiency in the central cloud region is about 14 %.


title: Identification of Cool White Dwarfs in the NOAO Deep Wide-Field Survey

abstract:
  We report our search for the cool white dwarfs belonging to the Galactic disk
by extending the NOAO Deep Wide-Field Survey. Narrow-band DDO51 photometry of
the Deep Wide-Field Survey's northern field was obtained using the 4m-Mayall
Telescope and the MOSAIC imager to separate cool white dwarfs from other
stellar types of similar T_eff. Follow-up spectroscopy of four white dwarf
candidates from our photometric search resulted in the discovery of two new
cool white dwarfs as companions to M dwarfs.


title: Adaptive optics imaging of the MBM 12 association

abstract:
  We report adaptive optics (AO) observations of the young and nearby
association MBM 12 obtained with the Canada-France-Hawaii Telescope. Our main
observational result is the discovery of six new binary systems, LkHa 264, E
0255+2018, RX J0255.4+2005, S18, MBM 12-10, RX J0255.3+1915, and the
confirmation of HD 17332, already known as a binary. We also detected a
possible quadruple system. It is composed of the close binary LkHa 263 AB
(separation of 0.41 ''), of LkH\alpha 262 located 15.25 '' from LkHa 263 A, and
of LkHa 263 C, located 4.1 '' from LkH\alpha 263 A. A preliminary study of the
binary fraction suggests a binary excess in the MBM 12 association as compared
to the field and IC 348. Because of the high binarity rate, previous
estimations of spectral types and measurements of IR excesses for several
candidate members of MBM 12 have to be revised. LkH\alpha 263 C is a nebulous
object that we interpret as a disk oriented almost perfectly edge-on and seen
in scattered light. This object has already been reported by Jayawardhana et
al. (2002). Scattered light models allow us to estimate some of the structural
parameters (i.e. inclination, diameter and to a lesser extent dust mass) of the
circumstellar disk. We find an inclination of 89^o and a outer radius for the
disk, 165 AU if the distance to MBM 12 is 275 pc. With the present data set, we
do not attempt to re-assess the distance to MBM 12. We estimate however that
the distance to the candidate member RX J0255.3+1915 is d > 175 pc.


title: The dark matter halo of the gravitational lens galaxy 0047-2808

abstract:
  The location of the images in a multiple-image gravitational lens system are
strongly dependent on the orientation angle of the mass distribution. As such,
we can use the location of the images and the photometric properties of the
visible matter to constrain the properties of the dark halo. We apply this to
the optical Einstein Ring system 0047-2808 and find that the dark halo is
almost spherical and is aligned in the same direction as the stars to within a
few degrees.


title:
1WGAJ1216.9+3743: Chandra Finds an Extremely Steep Ultraluminous X-ray
  Source

abstract:
  We report the discovery of a new ultraluminous X-ray source (ULX) in the
nearby galaxy NGC 4244 from Chandra archival data. The source,
1WGAJ1216.9+3743, is one of the least luminous and softest ULXs discovered so
far. Its X-ray spectrum is the best available for a representative of the soft
ULXs, a class of sources recently discovered by Chandra and XMM-Newton.
1WGAJ1216.9+3742 appears point-like in the Chandra image and has a complex
spectral shape: a multicolor disk model, suitable for brighter ULXs, is
inadequate for this source. 1WGAJ1216.9+3743 spectrum is heavily absorbed (NH ~
(1-4)E21 cm^-2),and very soft. The best-fit power-law model gives a photon
index ~ 5 and implies a luminosity L(0.5-10 keV) ~ 1E39 erg/s. A comparison
with previous detections shows that, despite the variability displayed by the
source during the Chandra observation, 1WGAJ1216.9+3743 count rate, spectral
shape and absorption are practically unchange over a 9-year period. We
performed also deep optical imaging of the field containing the X-ray source,
and found a possible R ~ 23.7 counterpart.


title:
White Dwarfs in Globular Clusters - Progenitors, Successors and the Real
  Thing

abstract:
  I will start by discussing the evolutionary status of the white dwarf
*progenitors*, the hot UV bright stars. Observations of UIT-selected UV bright
stars in globular clusters suggest that a high percentage of them manage to
evolve from the horizontal branch to the white dwarf region without passing
through the thermally pulsing AGB phase, thereby avoiding the planetary nebula
stage.
  The white dwarf successors are stars experiencing a very late helium core
flash while already on the helium white dwarf cooling curve. While they have
been around theoretically for quite some time strong candidates could be
verified only quite recently.
  And, last not least, the *white dwarfs* themselves offer new opportunities to
derive distances and ages of globular clusters, which I will discuss. For a
discussion of white dwarfs in binaries see the reviews by Adrienne Cool and
Frank Verbunt in this volume.


title: Clustering Evolution Between z=1 And Today

abstract:
  We present results of an investigation of clustering evolution of field
galaxies between a redshift of z\~1 and the present epoch. The current analysis
relies on a sample of ~14000 galaxies in two fields of the COMBO-17 survey. The
redshift distribution extends to z~1.1. The amplitude of the three-dimensional
correlation function can be estimated by means of the projected correlation
function w(r_p). The validity of the deprojection was tested on the Las
Campanas Redshift Survey (LCRS). In a flat cosmology with non-zero cosmological
constant for bright galaxies (M_B<-18) the clustering growth is proportional to
(1+z)^{-2}. However, the measured clustering evolution clearly depends on
Hubble type. While locally the clustering strength of early type galaxies is
equal to that of the bright galaxies, at high redshifts they are much stronger
clustered, and thus the clustering has to evolve much more slowly.


title: Cooling of Neutron Stars: Two Types of Triplet Neutron Pairing

abstract:
  We consider cooling of neutron stars (NSs) with superfluid cores composed of
neutrons, protons, and electrons (assuming singlet-state pairing of protons,
and triplet-state pairing of neutrons). We mainly focus on (nonstandard)
triplet-state pairing of neutrons with the $|m_J| = 2$ projection of the total
angular momentum of Cooper pairs onto quantization axis. The specific feature
of this pairing is that it leads to a power-law (nonexponential) reduction of
the emissivity of the main neutrino processes by neutron superfluidity. For a
wide range of neutron critical temperatures $T_{cn}$, the cooling of NSs with
the $|m_J| = 2$ superfluidity is either the same as the cooling with the $m_J =
0$ superfluidity, considered in the majority of papers, or much faster. The
cooling of NSs with density dependent critical temperatures $T_{cn}(\rho)$ and
$T_{cp}(\rho)$ can be imitated by the cooling of the NSs with some effective
critical temperatures $T_{cn}$ and $T_{cp}$ constant over NS cores. The
hypothesis of strong neutron superfluidity with $|m_J| = 2$ is inconsistent
with current observations of thermal emission from NSs, but the hypothesis of
weak neutron superfluidity of any type does not contradict to observations.


title:
QU Car: a very high luminosity nova-like binary with a carbon-enriched
  companion

abstract:
  QU Car is listed in cataclysmic variable star catalogues as a nova-like
variable. This little-studied, yet bright interacting binary is re-appraised
here in the light of new high-quality ultraviolet (UV) interstellar line data
obtained with STIS on board the Hubble Space Telescope. The detection of a
component of interstellar absorption at a mean LSR velocity of $-$14 km
s$^{-1}$ indicates that the distance to QU Car may be $\sim$2 kpc or more -- a
considerable increase on the previous lower-limiting distance of 500 pc. If so,
the bolometric luminosity of QU Car could exceed $10^{37}$ ergs s$^{-1}$. This
would place this binary in the luminosity domain occupied by known
compact-binary supersoft X-ray sources. Even at a 500 pc, QU Car appears to be
the most luminous nova-like variable known.
  New intermediate dispersion optical spectroscopy of QU Car spanning
3800--7000 \AA is presented. These data yield the discovery that C{\sc iv}
$\lambda\lambda$5801,12 is present as an unusually prominent emission line in
an otherwise low-contrast line spectrum. Using measurements of this and other
lines in a recombination line analysis, it is shown that the C/He abundance as
proxied by the n(C$^{4+}$)/n(He$^{2+}$) ratio may be as high as 0.06 (an order
of magnitude higher than the solar ratio). Furthermore, the C/O abundance ratio
is estimated to be greater than 1. These findings suggest that the companion in
QU Car is a carbon star. If so, it would be the first example of a carbon star
in such a binary. An early-type R star best matches the required abundance
pattern and could escape detection at optical wavelengths provided the distance
to QU Car is $\sim$2 kpc or more.


title:
Gravitational lensing by spherically symmetric lenses with angular
  momentum

abstract:
  Following Sereno (2002a), we discuss the bending of light rays by spherically
symmetric lenses with angular momentum. For several astrophysical systems, such
as white dwarfs and galaxies, gravitomagnetism induces a correction on the
deflection angle as large as 0.1%.


title: Search for ultraluminous X-ray sources in nearby galaxies

abstract:
  Little is presently known about the nature of ultraluminous X-ray sources
(ULX). Different hypotheses have been proposed to explain their properties:
intermediate-mass BHs, Kerr BHs, young SNR, or background AGN. Some of the
current problems and open questions in this research field are here reviewed.


title: The Milky Way and the evolution of disk galaxies

abstract:
  We present a phenomenological approach to the study of disk galaxy evolution,
based on i) a detailed modelling of the Milky Way (used as a prototype disk
galaxy) and ii) an extension of the model to other disks through some simple
scaling relations, obtained in the framework of Cold Dark matter models. The
main conclusion is that, on average, massive disks have formed the bulk of
their stars earlier than their lower mass counterparts. It is not yet clear why
the ``star formation hierarchy'' has been apparently opposite to the ``dark
matter assembly'' hierarchy.


title:
The RAPTOR Experiment: A System for Monitoring the Optical Sky in Real
  Time

abstract:
  The Rapid Telescopes for Optical Response (RAPTOR) experiment is a spatially
distributed system of autonomous robotic telescopes that is designed to monitor
the sky for optical transients. The core of the system is composed of two
telescope arrays, separated by 38 kilometers, that stereoscopically view the
same 1500 square-degree field with a wide-field imaging array and a central 4
square-degree field with a more sensitive narrow-field "fovea" imager. Coupled
to each telescope array is a real-time data analysis pipeline that is designed
to identify interesting transients on timescales of seconds and, when a
celestial transient is identified, to command the rapidly slewing robotic
mounts to point the narrow-field ``fovea'' imagers at the transient. The two
narrow-field telescopes then image the transient with higher spatial resolution
and at a faster cadence to gather light curve information. Each "fovea" camera
also images the transient through a different filter to provide color
information. This stereoscopic monitoring array is supplemented by a rapidly
slewing telescope with a low resolution spectrograph for follow-up observations
of transients and a sky patrol telescope that nightly monitors about 10,000
square-degrees for variations, with timescales of a day or longer, to a depth
about 100 times fainter. In addition to searching for fast transients, we will
use the data stream from RAPTOR as a real-time sentinel for recognizing
important variations in known sources. Altogether, the RAPTOR project aims to
construct a new type of system for discovery in optical astronomy--one that
explores the time domain by "mining the sky in real time".


title: Solar Wind Acceleration in Coronal Holes

abstract:
  This paper reviews the current state of our understanding of high-speed solar
wind acceleration in coronal holes. Observations by SOHO, coupled with
interplanetary particle measurements going back several decades, have put
strong constraints on possible explanations for how the protons, electrons, and
minor ions receive their extreme kinetic properties. The asymptotic plasma
conditions of the wind depend on energy and momentum deposition both at the
coronal base (where, e.g., the mass flux is determined) and in the extended
acceleration region between 2 and 10 solar radii (where the plasma becomes
collisionless and individual particle species begin to exhibit non-Maxwellian
velocity distributions with different moments). The dissipation of
magnetohydrodynamic fluctuations (i.e., waves, turbulence, and shocks) is
believed to dominate the heating in the extended corona, and spectroscopic
observations from the UVCS instrument on SOHO have helped to narrow the field
of possibilities for the precise modes, generation mechanisms, and damping
channels. We will survey recent theoretical and observational results that have
contributed to new insights, and we will also show how next-generation
instruments can be designed to identify and characterize the dominant physical
processes to an unprecedented degree.


title: An exoplanet in orbit around tau^1 Gruis

abstract:
  We report the detection of a new candidate exoplanet around the metal-rich
star tau^1 Gruis. With M sin $i$ = 1.23+/-0.18 M_JUP, a period of 1326+/-300 d
and an orbit with an eccentricity of 0.14+/-0.14 it adds to the growing
population of long period exoplanets with near-circular orbits. This population
now comprises more than 20% of known exoplanets.
  When the companion to tau^1 Gruis is plotted together with all exoplanets
found by the Anglo-Australian Planet Search and other radial velocity searches
we find evidence for a peak in the number of short-period exoplanets, followed
by a minimum of planets between around 7 and 50 days and then an apparent rise
in the number of planets per unit radius that seems to set in by a hundred
days, indicating more planets farther from the host star. This is very
different from the gaussian-like period distribution found for stellar
companions. This lends support to the idea that once a clearing in the inner
protoplanetary disk develops, it halts the inward migration of planets. In
particular, the smooth distribution of exoplanets arising from planetary
migration through a disk is altered by an accumulation of exoplanets at the
point where the disk has been cleared out.


title:
Stellar Radioactivities and diffuse gamma-ray line emission in the Milky
  Way

abstract:
  After a short historical introduction to the field of gamma-ray line
astronomy with radioactivities, I present an overview of recent results
concerning the massive star yields of those radioactivities. I comment on the
implications of those results (concerning long-lived radioactivities, like
Al-26 and Fe-60) for gamma-ray line astronomy, in the light of past (COMPTEL
and GRIS) and forthcoming (INTEGRAL) observations


title:
A New Mass Degeneracy in Gravitational Lenses: Is there a crisis between
  a large $H_0$ and the time delay by a large lens halo?

abstract:
  Isothermal models and other simple smooth models of dark matter halos of
gravitational lenses often predict a dimensionless time delay $H_0\Delta t$
much too small to be comfortable with the observed time delays $\Delta t$ and
the widely accepted $H_0$ value ($\sim 70$ km/s/Mpc). This conflict or crisis
of the CDM has been highlighted by several recent papers of Kochanek, who
claims that the standard value of $H_0$ favors a strangely small halo as
compact as the stellar light distribution with an overall nearly Keplerian
rotation curve. In an earlier paper (Paper I, astro-ph/0209191) we argue that
this is not necessarily the case, at least in a perfectly symmetrical Einstein
cross system. Here we introduce a {\it new mass degeneracy} of lens systems to
give a counter example to Kochanek's claims. We fit the time delay and image
positions in the quadruple image system PG1115+080. Equally good fits are found
between lens models with flat vs. Keplerian rotation curves. Time delays in
both types of models can be fit with the standard value of $H_0$. We
demonstrate that it may still be problematic to constrain the size of lens dark
halos even if the data image positions are accurately given and the cosmology
is precisely specified.


title:
Perturbations to Stellar Structure in 2D: Stellar Rotation and Heating
  in X-ray Binaries

abstract:
  We have developed a numerical code with which we study the effects of 2D
perturbations on stellar structure. We present new numerical and analytical
results on the heating of a main-sequence star in a binary system by its
companion.


title:
Photometric Redshifts for an Optical/Near-Infrared Catalogue in the
  Chandra Deep Field South

abstract:
  Photometric redshifts have proven a powerful tool in identifying galaxies
over a large range of lookback times. We have been generalising this technique
to incorporate the selection of candidate high redshift QSOs. We have applied
this to a large optical/near-infrared imaging survey in 6 wavebands aiming to
push farther in redshift (and fainter in luminosity) than previous studies. We
believe that study of these very faint and distant objects provides valuable
insights into galaxy formation and evolution.
  Here we present work in progress and preliminary results for a catalogue of
objects detected as part of the Las Campanas Infrared Survey. This is a
stepping stone to the type of survey data that will become available in the
next few years from projects such as UKIDSS and VISTA.


title: On biases in the predictions of stellar population synthesis models

abstract:
  Sampling fluctuations in stellar populations give rise to dispersions in
observables when a small number of sources contribute effectively to the
observables. This is the case for a variety of linear functions of the spectral
energy distribution (SED) in small stellar systems, such as galactic and
extragalactic HII regions, dwarf galaxies or stellar clusters. In this paper we
show that sampling fluctuations also introduce systematic biases and
multi-modality in non-linear functions of the SED, such as luminosity ratios,
magnitudes and colours. In some cases, the distribution functions of rational
and logarithmic quantities are bimodal, hence complicating considerably the
interpretation of these quantities in terms of age or evolutionary stages.
These biases can be only assessed by Monte Carlo simulations. We find that
biases are usually negligible when the effective number of stars, Neff, which
contribute to a given observable is larger than 10. Bimodal distributions may
appear when Neff is between 10 and 0.1. Predictions from any model of stellar
population synthesis become extremely unreliable for small Neff values,
providing an operational limit to the applicability of such models for the
interpretation of integrated properties of stellar systems. In terms of stellar
masses, assuming a Salpeter Initial Mass Function in the range 0.08 -- 120 Mo,
Neff=10 corresponds to about 10**5 Mo (although the exact value depends on the
age and the observable). This bias may account, at least in part, for claimed
variations in the properties of the stellar initial mass function in small
systems, and arises from the discrete nature of small stellar populations.


title: Probing the Neutron-Capture Nucleosynthesis History of Galactic Matter

abstract:
  The heavy elements formed by neutron capture processes have an interesting
history from which we can extract useful clues to and constraints upon both the
characteristics of the processes themselves and the star formation and
nucleosynthesis history of Galactic matter. Of particular interest in this
regard are the heavy element compositions of extremely metal-deficient stars.
At metallicities [Fe/H] <= -2.5, the elements in the mass region past barium (A
>= 130-140 have been found (in non carbon-rich stars) to be pure r-process
products. The identification of an environment provided by massive stars and
associated Type II supernovae as an r-process site seems compelling. Increasing
levels of heavy s-process (e.g., barium) enrichment with increasing
metallicity, evident in the abundances of more metal-rich halo stars and disk
stars, reflect the delayed contributions from the low- and intermediate-mass (M
\~ 1-3 Msol) stars that provide the site for the main s-process nucleosynthesis
component during the AGB phase of their evolution. New abundance data in the
mass region 60 <~ A <~ 130 is providing insight into the identity of possible
alternative r-process sites. We review recent observational studies of heavy
element abundances both in low metallicity halo stars and in disk stars,
discuss the observed trends in light of nucleosynthesis theory, and explore
some implications of these results for Galactic chemical evolution,
nucleosynthesis, and nucleocosmochronology.


title:
Electromotive Force and Large-Scale Magnetic Dynamo in a Turbulent Flow
  with a Mean Shear

abstract:
  An effect of sheared large-scale motions on a mean electromotive force in a
nonrotating turbulent flow of a conducting fluid is studied. It is demonstrated
that in a homogeneous divergence-free turbulent flow the alpha-effect does not
exist, however a mean magnetic field can be generated even in a nonrotating
turbulence with an imposed mean velocity shear due to a new ''shear-current"
effect. A contribution to the electromotive force related with the symmetric
parts of the gradient tensor of the mean magnetic field (the kappa-effect) is
found in a nonrotating turbulent flows with a mean shear. The kappa-effect and
turbulent magnetic diffusion reduce the growth rate of the mean magnetic field.
It is shown that a mean magnetic field can be generated when the exponent of
the energy spectrum of the background turbulence (without the mean velocity
shear) is less than 2. The ''shear-current" effect was studied using two
different methods: the Orszag third-order closure procedure and the stochastic
calculus. Astrophysical applications of the obtained results are discussed.


title: A 1" Telescope: The Optimal Approach to Bright-Star Planetary Transits

abstract:
  Planetary transits of bright stars, V < 10, offer the best opportunity for
detailed studies of extra-solar planets, such as are already being carried out
for HD209458b. Since these stars are rare, they should be searched over the
entire sky. In the limits of zero read-out time, zero sky noise, and perfect
optics, the sensitivity of an all-sky survey is independent of telescope
aperture: for fixed detector size and focal ratio, the greater light-gathering
power of larger telescopes is exactly cancelled by their reduced field of view.
Finite read-out times strongly favor smaller telescopes because exposures are
longer so a smaller fraction of time is wasted on readout. However, if the
aperture is too small, the sky noise in one pixel exceeds the stellar flux and
the field of view becomes so large that optical distortions become
unmanageable. We find that the optimal aperture is about 1". A one-year survey
using such a 1" telescope could detect essentially all hot-jupiter transits of
V < 10 stars observable from a given site.


title: Large scattering events and the formation of planetary systems

abstract:
  In the nucleated instability picture of gas giant formation, the final stage
is the rapid accretion of a massive gas envelope by a solid core, bringing
about a tenfold or more increase in mass. This tends to trigger the scattering
of any nearby bodies, including other would-be giant planet cores; it has been
shown in past work that the typical outcome is an outer planetary system very
similar to our own. Here, we show that the gravitational scattering
accompanying the formation of gas giant planets can also produce, in some
cases, outer planets with semimajor axes much larger than those in the Solar
System, and eccentricities which remain high for tens of millions of years.
Rings, gaps and asymmetries detected in a number of circumstellar dust disks,
which hint at the presence of embedded planets at stellocentric distances far
beyond where planet formation is expected to occur, may be connected to such a
scenario.


title: Gravitation of the Casimir Effect and the Cosmological Non-Constant

abstract:
  Whereas the total energy in zero-point fluctuations of the particle physics
vacuum gives rise to the cosmological constant problem, differences in the
vacuum give rise to real physical phenomena, such as the Casimir effect. Hence
we consider the zero-point energy bound between two parallel conducting plates
-- proxy for a solid slice of cosmological constant -- as a convenient
laboratory in which to investigate the gravitation and inertia of vacuum
energy. We calculate the Casimir effect in a weak gravitational field,
obtaining corrections to the vacuum stress-energy and attractive force on the
plates due to the curvature of spacetime. These results suggest that if the
cosmological constant is due to zero-point energy then it is susceptible to
fluctuations induced by gravitational sources.


title: A 20 Thousand Solar Mass Black Hole in the Stellar Cluster G1

abstract:
  We present the detection of a 2.0(+1.4,-0.8)x10^4 solar mass black hole (BH)
in the stellar cluster G1 (Mayall II), based on data taken with the Space
Telescope Imaging Spectrograph onboard the Hubble Space Telescope. G1 is one of
the most massive stellar clusters in M31. The central velocity dispersion (25
kms) and the measured BH mass of G1 places it on a linear extrapolation of the
correlation between BH mass and bulge velocity dispersion established for
nearby galaxies. The detection of a BH in this low-mass stellar system suggests
that (1) the most likely candidates for seed massive BHs come from stellar
clusters, (2) there is a direct link between massive stellar clusters and
normal galaxies, and (3) the formation process of both bulges and massive
clusters is similar due to their concordance in the M_BH/sigma relation.
Globular clusters in our Galaxy should be searched for central BHs.


title:
Hubble Space Telescope Evidence for an Intermediate-Mass Black Hole in
  the Globular Cluster M15: I. STIS Spectroscopy and WFPC2 Photometry

abstract:
  In this series of two papers we describe a project with STIS on HST to
measure the line-of-sight velocities of stars in the central few arcsec of the
dense globular cluster M15. This first paper focuses on the observations and
reduction of the data. We `scanned' the central region of M15 spectroscopically
by consecutively placing an 0.1 arcsec slit at 18 adjacent positions. Careful
and complicated data reduction and analysis were required. The spectral pixel
size exceeds the velocity dispersion of M15, which puts the project at the
limit of what is feasible with STIS. We applied corrections for the following
effects: drifts in the STIS wavelength scale during an HST orbit; the orbital
velocity component of HST along the line-of-sight to the cluster, and its
variations during the HST orbit; and the apparent wavelength shift that is
perceived for a star that is not centered in the slit. To make these
corrections we present a detailed study of the HST/STIS point-spread function
and line-spread function. We also present a catalog with positions and U, B and
V magnitudes of 31,983 stars in M15, created from existing HST/WFPC2 data. We
extract 19,200 one-dimensional spectra from the STIS data, each for a different
position in M15, and each with a velocity scale accurate to better than 2.5
km/s. We develop an algorithm that co-adds the spectra for individual apertures
and use it to extract spectra of individual stars with minimum blending and
maximum S/N. In Paper II we use these spectra to extract the line-of-sight
velocities of individual stars. The velocities constrain the central structure,
dynamics and mass distribution of the cluster, and provide evidence for the
existence of an intermediate-mass black hole in the center of the
cluster.[ABRIDGED]


title:
Hubble Space Telescope Evidence for an Intermediate-Mass Black Hole in
  the Globular Cluster M15: II. Kinematical Analysis and Dynamical Modeling

abstract:
  We analyze HST/STIS spectra (see Paper I) of the central region of the dense
globular cluster M15. We infer the velocities of 64 individual stars,
two-thirds of which have their velocity measured for the first time. This
triples the number of stars with measured velocities in the central 1 arcsec of
M15 and doubles the number in the central 2 arcsec. Combined with existing
ground-based data we obtain the radial profiles of the projected kinematical
quantities. The RMS velocity sigma_RMS rises to 14 km/s in the central few
arcsec, somewhat higher than the values of 10-12 km/s inferred previously from
ground-based data. To interpret the results we construct dynamical models based
on the Jeans equation, which imply that M15 must have a central concentration
of non-luminous material. If this is due to a single black hole, then its mass
is M_BH = (3.9 +/- 2.2) x 10^3 solar masses. This is consistent with the
relation between M_BH and sigma_RMS that has been established for galaxies.
Also, the existence of intermediate-mass black holes in globular clusters is
consistent with several scenarios for globular cluster evolution proposed in
the literature. Therefore, these results may have important implications for
our understanding of the evolution of globular clusters, the growth of black
holes, the connection between globular cluster and galaxy formation, and the
nature of the recently discovered `ultra-luminous' X-ray sources in nearby
galaxies. Instead of a single black hole, M15 could have a central
concentration of dark remnants (e.g., neutron stars) due to mass segregation.
However, the best-fitting Fokker-Planck models that have previously been
constructed for M15 do not predict a central mass concentration that is
sufficient to explain the observed kinematics.[ABRIDGED]


title:
Highly Resolved X-ray Spectra with Chandra: Dynamics of Neutral and
  Ionized Matter

abstract:
  The High Energy Transmission Grating Spectrometer (HETGS) onboard the Chandra
X-ray Observatory has so far produced a large number of high resolution X-ray
spectra with unprecedented spectroscopic details. Spectra from outflows in
galactic and extragalactic X-ray sources indicate plasmas with a wide range of
properties. Optically thick fluorescent matter and warm photoionized regions
play as much a role as very hot regions where collisional ionization and
scattering dominate the emission. Through the measurements of blue- and
redshifts the complex dynamics of these plasmas is revealed. Quite intriguing
in this respect is the case of X-ray absorption of neutral matter. In many
cases spectral features are found to be of high complexity though the detection
of edges from intermediate Z elements as well as absorption lines from
monatomic species to molecular compounds. With the application of line
diagnostic tools and more accurate atomic data bases we are now able to model
the properties of these plasmas as well as measure line shifts and shapes to
constrain their spatial distribution and dynamics. In various examples, i.e.
plasmas from accretion disks, winds, stationary clouds as well as the ISM, the
power of highly resolved X-ray spectra is demonstrated and the scientific
capability of XEUS in this context is explored.


title:
Tidally-Triggered Star Formation in Close Pairs of Galaxies 2:
  Constraints on Burst Strengths and Ages

abstract:
  Galaxy-galaxy interactions rearrange the baryons in galaxies and trigger
substantial star formation; the aggregate effects of these interactions on the
evolutionary histories of galaxies in the Universe are poorly understood. We
combine B and R-band photometry and optical spectroscopy to estimate the
strengths and timescales of bursts of triggered star formation in the centers
of 190 galaxies in pairs and compact groups. Based on an analysis of the
measured colors and EW(H-alpha), we characterize the pre-existing and triggered
populations separately. The best-fitting burst scenarios assume stronger
reddening corrections for line emission than for the continuum and continuous
star formation lasting for \gtrsim a hundred Myr. The most realistic scenarios
require an initial mass function that is deficient in the highest-mass stars.
The color of the pre-existing stellar population is the most significant source
of uncertainty. Triggered star formation contributes substantially (probably >=
50%) to the R-band flux in the central regions of several galaxies; tidal tails
do not necessarily accompany this star formation. Many of the galaxies in our
sample have bluer centers than outskirts, suggesting that pre- or non-merger
interactions may lead to evolution along the Hubble sequence. These objects
would appear blue and compact at higher redshifts; the older, redder outskirts
of the disks would be difficult to detect. Our data indicate that galaxies with
larger separations on the sky contain weaker, and probably older, bursts of
star formation on average. However, confirmation of these trends requires
further constraints on the colors of the older stellar populations and on the
reddening for individual galaxies.


title:
Adaptive Optics Observations of Vega: Eight Detected Sources and Upper
  Limits to Planetary-Mass Companions

abstract:
  From adaptive optics observations with the Palomar 5-meter telescope we place
upper limits on the masses of any planetary companions located between ~30-230
AU away from Vega, where our data are sensitive to depths ranging from H=12.5
mag to H=19.0 mag fainter than Vega itself. Our observations cover a
plus-shaped area with two 25"x57" elements, excluding 7"x7" centered on the
star. We have identified 2 double and 4 single point sources. These projected
companions are 14.9-18.9 mag fainter than Vega, and if physically associated
would have masses ranging from 4 to 35 Mjup and orbital radii 170-260 AU.
Recent simulations of dusty rings around Vega predict the presence of a
perturbing body with mass <2-3 Mjup and orbital radius ~40-100 AU, though more
massive (~10 Mjup) planets cannot be excluded. None of the detected objects are
this predicted planet. Based on a color-magnitude, spectroscopic, and proper
motion analysis, all objects are consistent with being background sources.
Given the glare of Vega, a 2 Mjup object near the expected orbital radii would
not have been visible at the 5-sigma level in our data, though any >10 Mjup
brown dwarf could have been seen at separation >80 AU.


title:
Hydrodynamic Models of Line-Driven Accretion Disk Winds III: Local
  Ionization Equilibrium

abstract:
  We present time-dependent numerical hydrodynamic models of line-driven
accretion disk winds in cataclysmic variable systems and calculate wind
mass-loss rates and terminal velocities. The models are 2.5-dimensional,
include an energy balance condition with radiative heating and cooling
processes, and includes local ionization equilibrium introducing time
dependence and spatial dependence on the line radiation force parameters. The
radiation field is assumed to originate in an optically thick accretion disk.
Wind ion populations are calculated under the asumption that local ionization
equilibrium is determined by photoionization and radiative recombination,
similar to a photoionized nebula. We find a steady wind flowing from the
accretion disk. Radiative heating tends to maintain the temperature in the
higher density wind regions near the disk surface, rather than cooling
adiabatically. For a disk luminosity Ldisk = Lsun, white dwarf mass Mwd = 0.6
Msun, and white dwarf radii Rwd = 0.01 Rsun, we obtain a wind mass-loss rate of
dMwind/dt =4E-12 Msun/yr, and a terminal velocity of ~ 3000 km/s. These results
confirm the general velocity and density tructures found in our earlier
constant ionization equilibrium adiabatic CV wind models. Further we establish
here 2.5D numerical models that can be extended to QSO/AGN winds where the
local ionization equilibrium will play a crucial role in the overall dynamics.


title:
Discrimination of Quark Stars from Neutron Stars in Quadrupole
  Oscillations

abstract:
  The frequencies and damping times due to gravitational radiation are
calculated for self-bound quark star models. The results are compared with
those for neutron star models. They are markedly contrasted in less
relativistic cases. The distinction derived here from a simple model of quark
stars may be relevant to the future theoretical and observational studies,
since the oscillation properties essentially depend on the mass and radius of
an equilibrium star.


title: Galactic Recycling: The HI Ring Around NGC 1533

abstract:
  We report the discovery of a new HI ring around the S0 galaxy NGC 1533. The
ring orbits at a radius of 35 kpc, well outside the optical extent of the
galaxy. We have conducted N-body/SPH numerical simulations to show this HI ring
could be the merger remnant of a tidally destroyed galaxy. We find no optical
component associated with the HI ring. However, observations hint at H-alpha
emission associated with the SE part of the ring only. The H-alpha is in the
form of a few very small isolated emission line regions. The large HI velocity
dispersions (up to 30 km/s) and velocity gradients (up to 50 km/s/kpc) in this
region indicate the H-alpha emission could be due to star formation triggered
by clouds colliding within the ring.


title: Superhumps of CC Cancri Revisited

abstract:
  We observed the 2001 November superoutburst of CC Cnc. This observation makes
the first detailed coverage of a superoutburst of this object. The
best-determined mean superhump period is 0.075518 +/- 0.000018 d, which is 2.7%
longer than the reported orbital period. This fractional superhump excess is a
quite typical value for a normal SU UMa-type dwarf nova, excluding the
previously raised possibility that CC Cnc may have an anomalously large
fractional superhump excess. During the superoutburst plateau, the object
showed a decrease of the superhump period at dot(P)/P = -10.2(1.3) x 10^(-5),
which is one of the largest negative period derivative known in all SU UMa-type
dwarf novae.


title:
The 2-D structure of dusty disks around Herbig Ae/Be stars, I. Models
  with grey opacities

abstract:
  In this paper the two-dimensional structure of protoplanetary disks around
Herbig Ae/Be stars is studied. This is done by constructing a self-consistent
model based on 2-D radiative transfer coupled to the equation of vertical
hydrostatics. As a simplifying assumption a grey opacity is used. It is found
that the disk can adopt four different structures, dependent on the surface
density distribution Sigma(R) as a function of radius, i.e. on radial- and
vertical optical depth of the disk. For the case of high to intermediate
vertical optical depth, the temperature and density structures are in agreement
with the simple ``disk with inner hole'' model of Dullemond, Dominik & Natta
(2001, henceforth DDN01). At large radii the disk adopts a flaring shape as
expected, and near the dust destruction radius (located at about 0.5 AU for
most Herbig Ae stars) the disk is superheated and puffs up. The region directly
behind this ``puffed-up inner dust wall'' is shadowed, as predicted by DDN01.
For the case of intermediate to low vertical optical depth, but still high
radial optical depth, the 2-D models show that the shadow can cover the entire
disk. The disk is then no longer flaring. When the disk is optically thin even
in radial direction, it becomes unshadowed again because the inner rim can no
longer block the stellar light. Finally, for disks that flare at intermediate
radii, but become too optically thin at large radii, the outer parts once again
become shadowed. But this time the shadowing is caused by the flaring part of
the disk instead of the inner rim. Observational consequences of these four
geometries are discussed.


title:
Origin of Correlations between Central Black Holes Masses and Galactic
  Bulge Velocity Dispersions

abstract:
  We argue that the observed correlations between central black holes masses
M_{BH} and galactic bulge velocity dispersions \sigma_e in the form
M_{BH}\propto\sigma_e^4 may witness on the pregalactic origin of massive black
holes. Primordial black holes would be the centers for growing protogalaxies
which experienced multiple mergers with ordinary galaxies. This process is
accompanied by the merging of black holes in the galactic nuclei.


title: Detection of Solar-like Oscillations in the G7 Giant Star xi Hya

abstract:
  We report the firm discovery of solar-like oscillations in a giant star. We
monitored the star xi Hya (G7III) continuously during one month with the
CORALIE spectrograph attached to the 1.2m Swiss Euler telescope. The 433
high-precision radial-velocity measurements clearly reveal multiple oscillation
frequencies in the range 50 - 130 uHz, corresponding to periods between 2.0 and
5.5 hours. The amplitudes of the strongest modes are slightly smaller than 2
m/s. Current model calculations are compatible with the detected modes.


title:
Effects of a Soft X-ray Background on Structure Formation at High
  Redshift

abstract:
  We use three dimensional hydrodynamic simulations to investigate the effects
of a soft X-ray background, that could have been produced by an early
generation of mini-quasars, on the subsequent cooling and collapse of high
redshift pregalactic clouds. The simulations use an Eulerian adaptive mesh
refinement technique with initial conditions drawn from a flat Lambda-dominated
cold dark matter model cosmology to follow the nonequilibrium chemistry of nine
chemical species in the presence of both a soft ultraviolet Lyman-Werner H_2
photodissociating flux and a soft X-ray background extending to 7.2 keV.
Although we vary the normalization of the X-ray background by two orders of
magnitude, the positive feedback effect of the X-rays on cooling and collapse
of the pregalactic cloud expected due to the increased electron fraction is
quite mild, only weakly affecting the mass threshold for collapse and the
fraction of gas within the cloud that is able to cool. Inside most of the cloud
we find that H_2 is in photodissociation equilibrium with the soft UV flux. The
net buildup of the electron density needed to enhance H_2 formation occurs too
slowly compared to the H_2 photodissociation and dynamical timescales within
the cloud to overcome the negative impact of the soft UV photodissociating flux
on cloud collapse. However, we find that even in the most extreme cases the
first objects to form do rely on molecular hydrogen as coolant and stress that
our results do not justify the neglect of these objects in models of galaxy
formation.


title: Optical counterparts to four X-ray sources in the Small Magellanic Cloud

abstract:
  We report on the spectroscopic and photometric analysis of possible optical
counterparts to four X-ray sources in the Small Magellanic Cloud: AX
J0049.4-7323, AX J0057.4-7325, RX J0058.2-7321 and RX J0101.1-7206. In the case
of the last two, we suggest that the presence of strong Halpha emission from
previously proposed optical candidates is definite confirmation that these are
Be stars. Similarly, we detected strong Halpha emission from the optical source
identified with RX J0049.7-7323 within the error circle for AX J0049.4-7323 and
we conclude that these are one and the same object. We were unable to detect
any Halpha emission from any of the candidates for AX J0057.4-7325 and the
associated photometric analysis was also inconclusive.


title:
Metal abundances and kinematics of quasar absorbers - II. Absorption
  systems toward Q0347-3819 and APM BR J0307-4945

abstract:
  Detailed Monte Carlo Inversion analysis of the spectral lines from three
Lyman limit systems (LLS) [N(HI) > 10^{17} cm^-2] and nine lower N(HI) systems
[2 10^{14} < N(HI) < 2 10^{16} cm^-2] observed in the VLT/UVES spectra of
Q0347-3819 (in the range 2.21 <= z <= 3.14) and of APM BR J0307-4945 (at z =
4.21 and 4.81) is presented. Combined with the results from a previous work,
the analyzed LLSs show that they are a heterogeneous population originating in
different environments. A functional dependence of the line-of-sight velocity
dispersion sigma_v on the absorber size L is confirmed: the majority of the
analyzed systems follow the scaling relation sigma_v ~ (N_H L)^{0.3} (with N_H
being the total gas column density). This means that most absorbers may be
related to virialized systems like galaxies or their halos. Previously noted
enhancement of the metal content in small size systems is also confirmed:
metallicities of Z ~ (1/3-1/2)Z_solar are found in systems with L < 0.4 kpc,
whereas we observe much lower metal abundances in systems with larger linear
sizes. For the first time in LLSs, a pronounced [alpha-element/iron-peak]
enrichment is revealed: the absorber at z = 2.21 shows [O/Fe] = 0.65+/-0.11,
[Si/Fe] = 0.51+/-0.11, and [Mg/Fe] = 0.38+/-0.11. Several absorption systems
exhibit characteristics which are very similar to that observed in
high-velocity clouds in the Milky Way and may be considered as high-redshift
counterparts of Galactic HVCs.


title:
Energy, momentum and angular momentum radiation from chiral cosmic
  string loops

abstract:
  We derived expressions for energy, momentum and angular momentum losses due
to gravitational and electromagnetic radiation from the closed superconducting
chiral cosmic strings of arbitrary form. The expressions for corresponding
radiation rates into the unit solid angle have the form of four-dimensional
integrals. In the special case of piece-wise linear strings these formulas are
reduced to sums over the kinks. We calculate numerically the total radiation
rates for three examples of string loops in dependence of current along the
string.


title: Inflationary models inducing non-Gaussian metric fluctuations

abstract:
  We construct explicit models of multi-field inflation in which the primordial
metric fluctuations do not necessarily obey Gaussian statistics. These models
are realizations of mechanisms in which non-Gaussianity is first generated by a
light scalar field and then transferred into curvature fluctuations. The
probability distribution functions of the metric perturbation at the end of
inflation are computed. This provides a guideline for designing strategies to
search for non-Gaussian signals in future CMB and large scale structure
surveys.


title:
Helium variation due to self-pollution among Globular Cluster stars:
  consequences on the horizontal branch morphology

abstract:
  It is becoming clear that `self--pollution' by the ejecta of massive
asymptotic giant branch stars has an important role in the early chemical
evolution of globular cluster stars, producing CNO abundance spreads which are
observed also at the surface of unevolved stars. Considering that the ejecta
which are CNO processed must also be helium enriched, we have modelled stellar
evolution of globular cluster stars by taking into account this possible helium
enhancement with respect to the primordial value. We show that the differences
between the main evolutionary phases (main sequence, turn--off and red giants)
are small enough that it would be very difficult to detect them
observationally. However, the difference in the evolving mass may play a role
in the morphology of the horizontal branch, and in particular in the formation
of blue tails, in those globular clusters which show strong CNO abundance
variations, such as M13 and NGC 6752.


title:
XMM-Newton Measurements of the Elemental Abundances in the Intracluster
  Medium

abstract:
  Based on XMM-Newton observations of a sample of galaxy clusters, we have
measured the elemental abundances (mainly O, Si, S, and Fe) and their spatial
distributions in the intracluster medium (ICM). In the outer region of the ICM,
observations of the O:Si:S:Fe ratio are consistent with the solar value,
suggesting that the metals in the ICM were produced by a mix of supernovae
(SNe) Ia and II. On the other hand, around the cD galaxy, the O/Fe ratios are
about half of the solar value because of a central excess of the Fe abundance.
An increase of the relative contribution from SNe Ia in the cD galaxy to the
metal production towards the center is the most likely explanation.


title: The WSO, a world-class observatory for the ultraviolet

abstract:
  The World Space Observatory is an unconventional space project proceeding via
distributed studies. The present design, verified for feasibilty, consists of a
1.7-meter telescope operating at the second Largangian point of the Earth-Sun
system. The focal plane instruments consist of three UV spectrometers covering
the spectral band from Lyman alpha to the atmospheric cutoff with R~55,000 and
offering long-slit capability over the same band with R~1,000. In addition, a
number of UV and optical imagers view adjacent fields to that sampled by the
spectrometers. Their performance compares well with that of HST/ACS and the
spectral capabilities of WSO rival those of HST/COS.


title: Self-similar spherical shock solution with sustained energy injection

abstract:
  We present the generalization of the Sedov-Taylor self-similar strong
spherical shock solution for the case of a central energy source varying in
time, $E=A t^k$, where $A$ and $k$ are constants. The known Sedov-Taylor
solution corresponds to a particular adiabatic case of $k=0$ or \emph{instant
shock} with an instant energy source of the shock, $E=A$. The self-similar
hydrodynamic flow in the nonadiabatic $k\neq0$ case exists only under the
appropriate local entropy (energy) input which must be supported by some
radiative mechanism from the central engine. The specific case of $k=1$
corresponds to a permanent energy injection into the shock, or injection shock
with a central source of constant luminosity, $L=A$, $E=A t$. The generalized
self-similar shock solution may be applied to astrophysical objects in which
the duration of central source activity is longer than the shock expansion
time, e.g. the early phase of SN explosions, strong wind from stars and young
pulsars, non-steady spherical outflow from black holes and collapsing dense
stellar clusters with numerous neutron star collisions.


title: The Mass of Quasar Broad Emission Line Regions

abstract:
  We show that the mass of ionized gas in the Broad Line Regions (BLRs) of
luminous QSOs is at least several hundred Msun, and probably of order 10^3-10^4
M_sun. BLR mass estimates in several existing textbooks suggest lower values,
but pertain to much less luminous Seyfert galaxies or include only a small
fraction of the ionized/emitting volume of the BLR. The previous estimates also
fail to include the large amounts of BLR gas that emit at low efficiency (in a
given line), but that must be present based on reverberation and other studies.
Very highly ionized gas, as well as partially ionized and neutral gas lying
behind the ionization zones, are likely additional sources of mass within the
BLR. The high masses found here imply that the chemical enrichment of the BLR
cannot be controlled by mass ejection from one or a few stars. A significant
stellar population in the host galaxies must be contributing. Simple scaling
arguments based on normal galactic chemical enrichment and solar or higher BLR
metallicities show that the minimum mass of the enriching stellar population is
of order 10 times the BLR mass, or greater than 10^4-10^5 M_sun. More realistic
models of the chemical and dynamical evolution in galactic nuclei suggest that
much larger, bulge-size stellar populations are involved.


title: Cooling flow bulk motion corrections to the Sunyaev Zel'dovich effect

abstract:
  We study the influence of converging cooling flow bulk motions on the
Sunyaev-Zel'dovich (SZ) effect. To that purpose we derive a modified Kompaneets
equation which takes into account the contribution of the accelerated electron
media of the cooling flow inside the cluster frame. The additional term is
different from the usual kinematic SZ-effect, which depends linearly on the
velocity, whereas the contribution described here is quadratic in the
macroscopic electron fluid velocity, as measured in the cluster frame. For
clusters with a large cooling flow mass deposition rate and/or a small central
electron density, it turns out that this effect becomes relevant.


title: Cosmic Numbers: A Physical Classification for Cosmological Models

abstract:
  We introduce the notion of the cosmic numbers of a cosmological model, and
discuss how they can be used to naturally classify models according to their
ability to solve some of the problems of the standard cosmological model.


title:
The Joint astrophysical Plasmadynamic EXperiment (J-PEX): A
  high-resolution rocket spectrometer

abstract:
  We report on the successful sounding rocket flight of the high resolution
(R=3000-4000) J-PEX EUV spectrometer. J-PEX is a novel normal incidence
instrument, which combines the focusing and dispersive elements of the
spectrometer into a single optical element, a multilayer-coated grating. The
high spectral resolution achieved has had to be matched by unprecedented high
spatial resolution in the imaging microchannel plate detector used to record
the data. We illustrate the performance of the complete instrument through an
analysis of the 220-245A spectrum of the white dwarf G191-B2B obtained with a
300 second exposure. The high resolution allows us to detect a low-density
ionized helium component along the line of sight to the star and individual
absorption lines from heavier elements in the photosphere.


title: On Radiation Drag and Neutrons in GRBs

abstract:
  As it was recently shown by Derishev etal (1999), initial GRB ejecta are
likely to contain comparable number of protons and neutrons. During
acceleration process, and/or later, due to interaction with external medium,
such ejecta are likely to be split into spatially distinct shells of neutron
and proton-electron plasmas. This leads to dynamical effects which can affect
the afterglow light curves. In this paper we study these effects including, for
the first time, radiation drag imposed on the neutron rich ejecta. In the
presence of efficient radiation drag and for typical ejecta Lorentz factor
(below 400), this is the neutron shell which moves faster and, after conversion
to proton-electron plasma, powers the afterglow. After certain amount of
deceleration, this shell is hit by the second one. Such collision will lead to
reflaring, as observed in some afterglow light curves.


title: The puzzlingly small CaII triplet absorption in elliptical galaxies

abstract:
  We measure the central values (within Re/8) of the CaII triplet line indices
CaT* and CaT and the Paschen index PaT at 8600 AA for a 93%-complete sample of
75 nearby early-type galaxies with BT<12 and Vgal<2490 km/s. We find that the
values of CaT* are constant to within 5% over the range of central velocity
dispersions 100<sigma<340 km/s, while the PaT (and CaT) values are mildly
anti-correlated with sigma. Using simple and composite stellar population
models, we show that: a) The measured CaT* and CaT are lower than expected from
simple stellar population models (SSPs) with Salpeter initial mass functions
(IMFs) and with metallicities and ages derived from optical Lick (Fe, Mg and
Hbeta) indices. Uncertainties in the calibration, the fitting functions and the
SSP modeling taken separately cannot explain the discrepancy. On the average,
the observed PaT values are within the range allowed by the models and the
large uncertainties in the fitting functions. b) The steepening of the IMF at
low masses required to lower the CaT* and CaT indices to the observed values is
incompatible with the measured FeH index at 9916 AA and the dynamical
mass-to-light ratios of ellipticals. c) Composite stellar populations with a
low-metallicity component reduce the disagreement, but rather artificial
metallicity distributions are needed. Another explanation may be that calcium
is indeed underabundant in ellipticals.


title:
The ASCA X-Ray Spectrum of Arp 102B and Evaluation of Simple Models for
  Its Associated, Metastable Fe II Absorber

abstract:
  We have observed the broad-line radio galaxy Arp 102B with ASCA in order to
determine the absorbing column density towards its X-ray source and measure its
X-ray spectrum. The ultimate goal was to constrain the properties of the medium
responsible for the metastable Fe II absorption lines observed in its UV
spectrum. The 0.5-10 keV X-ray spectrum is described by a simple power-law
model of photon index 1.58+/-0.04 modified by photoelectric absorption with an
column density of (2.8+/-0.3)x10^{21} cm^{-2}. An Fe K-alpha line is not
detected with an upper limit to its equivalent width of 200 eV (assuming FWHM =
60,000 km/s. Using the above column density the observed S.E.D. as constraints,
we explore simple photoionization models for the absorber for a wide range of
densities and ionization parameters in an effort to reproduce the strengths of
the UV absorption lines. We find that densities of at least 1x10^{11} cm^{-3}
are needed. However, a single ionization parameter cannot explain all of the
observed lines. An ionization parameter between 10^{-2.5} and 10^{-3.5} is
needed for the Mg and Fe lines and the soft X-ray absorption, but lines from
Si, C, Al, and H require different density-ionization parameter combinations.
According to the models, such an absorbing medium must be located very close to
the source of ionizing radiation (within 5,000 gravitational radii) and must be
very compact. As such, the properties of this absorbing medium differ from
those of more luminous quasars, but are reminiscent of the absorber in the
Seyfert galaxy NGC 4151. We suggest that the absorber is in the form of thin
sheets or filaments embedded in a wind wind that overlays the accretion disk of
Arp 102B. This picture is consistent with all of the available constraints on
the central engine of this object.


title:
Did Zhao & Qin Solve the Apparant Conflict Beween Gravitational Lens
  Time Delays, Dark Matter and the Hubble Constant?

abstract:
  The solution proposed by Zhao & Qin to the apparent conflict between
gravitational lens time delays, local estimates of the Hubble constant and
current expectations for the structure of CDM halos is discussed. Two essential
points emerge. First, the degeneracy is exactly the same as the local surface
density degeneracy previously discussed in the literature. Second, the proposed
mass distribution is inconsistent with CDM halo models. The Hubble constant is
raised by making the dark matter far less centrally concentrated than predicted
for CDM halos, much like the changes suggested for reconciling CDM halos with
the rotation curves of dwarf and LSB galaxies. Thus, while galaxies still have
dark matter, the Zhao & Qin solution to the time delay problem requires
fundamental changes in the CDM paradigm for halo structure.


title:
Toward An Empirical Theory of Pulsar Emission VIII: Subbeam Circulation
  and the Polarization-Modal Structure of Conal Beams

abstract:
  The average polarization properties of conal single and double profiles
directly reflect the polarization-modal structure of the emission beams which
produce them. These average properties require that the circulating subbeam
systems which produce conal beams entail paired PPM and SPM emission elements
which are offset from each other in both magnetic azimuth and magnetic
colatitude.
  A clear delineation of the modal polarization topology of the conal beam
promises to address fundamental questions about the nature and origin of this
modal emission--and the modal parity at the outer beam edges is a fact of
considerable significance. The different angular dependences of the modal
``beamlets'' suggests that the polarization modes are generated via propagation
effects. This argument may prove much stronger if the modal emission is
fundamentally only partially polarized. Several theories now promise
quantitative comparison with the observations.


title:
FUSE Observations of the Post-AGB Star ZNG 1 in the Globular Cluster M5
  (NGC 5904)

abstract:
  We have observed the hot post-AGB star ZNG 1 in the globular cluster M5 with
the Far Ultraviolet Spectroscopic Explorer (FUSE). From the resulting spectrum,
we derive an effective temperature T_eff ~ 45,000 K, a rotational velocity
v_rot ~ 100 km/s, carbon and nitrogen abundances approximately ten times solar,
a wind with terminal velocity near 1000 km/s, and evidence for an expanding
shell of material around the star. The carbon and nitrogen enhancements suggest
dredge-up of nuclear-processed material on the AGB. The high rotational
velocity may reflect a previous merger with a binary companion.


title:
Photometry and Spectroscopy of the Optical Companion to the Pulsar PSR
  J1740-5340 in the Globular Cluster NGC 6397

abstract:
  We present photometric and spectroscopic observations of the optical
companion to the millisecond radio pulsar PSR J1740-5340 in the globular
cluster NGC 6397. An analysis of the photometric variability in the B, V, and
I-bands indicates an inclination of the system of 43.9+-2.1 degrees if the
optical companion fills its Roche lobe (a semi-detached configuration). The
spectroscopic data show a radial velocity variation with a semi-amplitude of
K=137.2 +- 2.4 km/sec, and a system velocity gamma=17.6 +- 1.5 km/sec,
consistent with cluster membership. We use these results to derive a mass of
the optical companion of M1=0.296 +- 0.034 Msol and M2=1.53 +- 0.19 Msol for
the pulsar. There is evidence for secular change of the amplitude of the
optical light curve of the variable measured over seven years. The change does
not have interpretation and its presence complicates reliable determination of
the absolute parameters of the binary.


title: Primordial Stellar Populations

abstract:
  We review the expected properties of the first stellar generations in the
Universe. In particular, we consider and discuss the diagnostics, based on the
emission from associated HII regions, that permit one to discern bona fide
primeval stellar generations from the ones formed after pollution by supernova
explosions has occurred. We argue that a proper characterization of truly
primeval stellar generations has to be based on spectra that show
simultaneously (a) the presence of high intensities and equivalent widths of
Hydrogen and Helium emission lines, such as Ly-alpha and HeII 1640A, and (b)
the absence of collisionally excited metal lines, mostly from the first heavy
elements to be synthetized in large quantities, i.e. C and O. These atomic
species are expected to produce emission lines, such as CIII] 1909A, OIII]
1666A, [OIII] 5007A, etc., with intensities above 10% the intensity of H-beta
already for metallicities as low as 0.001Z_sun. The expected performance of the
NASA/ESA/CSA NGST for the study and the characterization of primordial sources
is also discussed.


title: A search for cool subdwarfs: Stellar parameters for 134 candidates

abstract:
  The results of a search for cool subdwarfs are presented. Kinematic (U, V,
and W) and stellar parameters (Teff, log g, [Fe/H], and V_t) are derived for
134 candidate subdwarfs based on high resolution spectra. The observed stars
span 4200K < Teff < 6400K and -2.70 < [Fe/H] < 0.25 including only 8 giants
(log g < 4.0). Of the sample, 100 stars have MgH bands present in their
spectra. The targets were selected by their large reduced proper-motion, the
offset from the solar metallicity main sequence, or culled from the literature.
We confirm the claims made by Ryan (1989) regarding the NLTT catalog being a
rich source of subdwarfs and verify the success of the reduced proper-motion
constraint in identifying metal-poor stars.


title:
Chandra X-ray Imaging Spectroscopy of the Young Supernova Remnant
  Kesteven 75

abstract:
  We present a spatially resolved spectroscopic analysis of the young Galactic
supernova remnant Kes 75 (SNR G29.7-0.3) using the Chandra X-ray Observatory.
Kes 75 is one of an increasing number of examples of a shell-type remnant with
a central pulsar powering an extended radio/X-ray core. We are able to pinpoint
the location of the recently discovered pulsar, PSR J1846-0258, and confirm
that X-rays from the remnant's core component are consistent with non-thermal
power-law emission from both the pulsar and its surrounding wind nebula. We
find that the spectrum of the pulsar is significantly harder than that of the
wind nebula. Fainter, diffuse emission is detected from throughout the volume
delineated by the radio shell with a surface brightness distribution strikingly
similar to the radio emission. The presence of strong lines attributable to
ionized Mg, Si, and S indicate that at least some of this emission is thermal
in nature. However, when we characterize the emission using a model of an
underionized plasma with non-solar elemental abundances, we find we require an
additional diffuse high-energy component. We show that a significant fraction
of this emission is an X-ray scattering halo from the pulsar and its wind
nebula, although a nonthermal contribution from electrons accelerated in the
shock cannot be excluded.


title:
The Color-Magnitude Relation in Coma: Clues to the Age and Metallicity
  of Cluster Populations

abstract:
  We have observed three fields of the Coma cluster of galaxies with a narrow
band (modified Stromgren) filter system. Observed galaxies include 31 in the
vicinity of NGC 4889, 48 near NGC 4874, and 60 near NGC 4839 complete to
M_5500=-18 in all three subclusters. Spectrophotometric classification finds
all three subclusters of Coma to be dominated by red, E type (ellipticals/S0's)
galaxies with a mean blue fraction, f_B, of 0.10. The blue fraction increases
to fainter luminosities, possible remnants of dwarf starburst population or the
effects of dynamical friction removing bright, blue galaxies from the cluster
population by mergers. We find the color-magnitude (CM) relation to be well
defined and linear over the range of M_5500=-13 to -22. After calibration to
multi-metallicity models, bright ellipticals are found to have luminosity
weighted mean [Fe/H] values between -0.5 and +0.5, whereas low luminosity
ellipticals have [Fe/H] values ranging from -2 to solar. The lack of CM
relation in our continuum color suggests that a systematic age effect cancels
the metallicity effects in this bandpass. This is confirmed with our age index
which finds a weak correlation between luminosity and mean stellar age in
ellipticals such that the stellar populations of bright ellipticals are 2 to 3
Gyrs younger than low luminosity ellipticals.


title:
Unbiased cut selection for optimal upper limits in neutrino detectors:
  the model rejection potential technique

abstract:
  We present a method for optimising experimental cuts in order to place the
strongest constraints (upper limits) on theoretical signal models.
  The method relies only on signal and background expectations derived from
Monte-Carlo simulations, so no bias is introduced by looking at actual data,
for instance by setting a limit based on expected signal above the ``last
remaining data event.'' After discussing the concept of the ``average upper
limit,'' based on the expectation from an ensemble of repeated experiments with
no true signal, we show how the best model rejection potential is achieved by
optimising the cuts to minimise the ratio of this ``average upper limit'' to
the expected signal from the model. As an example, we use this technique to
determine the limit sensitivity of kilometre scale neutrino detectors to
extra-terrestrial neutrino fluxes from a variety of models, e.g. active
galaxies and gamma-ray bursts. We suggest that these model rejection potential
optimised limits be used as a standard method of comparing the sensitivity of
proposed neutrino detectors.


title: Photometric Study of KR Aurigae during the High State in 2001

abstract:
  We photometrically observed the VY Scl-type cataclysmic variable KR Aurigae
after its final rise from the fading episode in 2000-2001. Time-resolved
observation revealed that the light curve is dominated by persistent short-term
variation with time-scales of minutes to tens of minutes. On some nights,
quasi-periodic variations with periods of 10--15 min were observed. No coherent
variation was detected. The power spectral density of the variation has a power
law component (f^(-1.63)). The temporal properties of the short-term variations
in KR Aur present additional support for the possibility that flickering in CVs
may be better understood as a result of self-organized critical state as in
black-hole candidates. The light curve lacks "superhump"-type signals, which
are relatively frequently seen in VY Scl-type systems and which are suggested
to arise from tidal instability of the accretion disk induced by changing
mass-transfer rates. The present observation suggests a borderline of superhump
excitation in VY Scl-type stars between mass ratios q=0.43 (MV Lyr) and q=0.60
(KR Aur).


title: Direct Lens Imaging of Galactic Bulge Microlensing Events

abstract:
  Recently, from the Hubble Space Telescope (HST) images of one of the Large
Magellanic Cloud (LMC) events taken 6.3 years after the original lensing
measurement, Alcock et al. were able to directly image the lens. Although the
first resolved lens was identified for an LMC event, much more numerous lenses
are expected to be resolved for Galactic bulge events. In this paper, we
estimate the fraction of Galactic bulge events whose lenses can be directly
imaged under the assumption that all bulge events are caused by normal stars.
For this determination, we compute the distribution of lens proper motions of
the currently detected Galactic bulge events based on standard models of the
geometrical and kinematical distributions of lenses and their mass function. We
then apply realistic criteria for lens resolution, and the result is presented
as a function of the time elapsed after an original lensing measurement,
$\Delta t$. If followup observations are performed by using an instrument with
a resolving power of \theta_{PSF}=0.1'', which corresponds to that of HST
equipped with the new Advanced Camera for Surveys, we estimate that lenses can
be resolved for ~ 3% and 22% of disk-bulge events and for ~0.3% and 6% of bulge
self-lensing events after $\Delta t=10$ and 20 years, respectively. The
fraction increases substantially with the increase of the resolving power. If
the instrument has a resolution of \theta_{PSF}=0.05'', which can be achieved
by the {\it Next Generation Space Telescope}, we estimate that lenses can be
resolved for $\sim 22%$ and 45% of disk-bulge events and for ~6% and 23% of
bulge self-lensing events after \Delta t=10 and 20 years, respectively.


title: Hydrodynamic description of neutrino gas

abstract:
  The system of neutrino-antineutrino $(\nu\bar{\nu})$ - plasma is considered
taking into account their weak Fermi interaction. New fluid instabilities
driven by strong neutrino flux in a plasma are found. The nonlinear stationary
as well as nonstationary waves in the neutrino gas are discussed. It is shown
that a bunch of neutrinos, drifting with a constant velocity across a
homogeneous plasma, can also induce emission of lower energy neutrinos due to
scattering, i.e. the decay of a heavy neutrino $\nu_{H}$ into a heavy and a
light neutrino $\nu_L$ ($\nu_H\to\nu_H\nu_L$) in a plasma. Furthermore we find
that the neutrino production in stars does not lead in general to energy losses
from the neutron stars.

categories: astro-ph hep-th physics.gen-ph physics.plasm-ph


title:
The potential-energy tensors for subsystems. IV. Homeoidally striated
  density profiles with a central cusp

abstract:
  A general theory of homeoidally striated density profiles where no divergence
occurs, is adapted to cuspy density profiles, with a suitable choice of the
scaling density and the scaling radius. A general formulation of some physical
parameters, such as angular-momentum vector, rotational-energy tensor (both
calculated in connection with a special class of rotational velocity fields),
inertia tensor, and self potential-energy tensor, is performed. Other
potential-energy tensors involving two density profiles where the boundaries
are similar and similarly placed, are also expressed. Explicit results are
attained for three special cases of physical interest which fit to a good
extent the results of high-resolution simulations for dark matter haloes, and a
class of density profiles, which closely approximate the de Vaucouleurs
$r^{1/4}$ law for elliptical galaxies. The virial theorem in tensor form for
two-component systems is written for each subsystem, and applied to giant
elliptical galaxies. The predicted velocity dispersion along the line of sight,
in the limiting case where a principal axis points towards the observer, is
found to be consistent with observations except for (intrinsic) $E7$
configurations where the major axis points towards the observer. If dark matter
haloes host an amount of undetected baryons about twice as massive as the
stellar subsystem, and undetected baryons trace non baryonic matter therein,
two main consequences arise, namely (i) velocity dispersions along the line of
sight are lower than in absence of undetected baryons, and (ii) dark matter
haloes are dynamically ``hotter'' than stellar ellipsoids, the transition
occurring when the amount of undetected baryons is about one and a half times
that of the stellar subsystem.


title:
Cluster of galaxies around seven radio-loud QSOs at 1<z<1.6: K-band
  images

abstract:
  We have conducted a NIR study of the environments of seven radio-loud quasars
at redshifts 1<z<1.6. In present paper we describe deep $K$ band images
obtained for the fields of ~6X6 arcmin around the quasars with 3$\sigma$
limiting magnitudes of K~20.5. These fields were previously studied using deep
B and R band images (Sanchez & Gonzalez-Serrano 1999). Using together optical
and NIR data, it has been found a significant excess of galaxies which
optical-NIR colours, luminosity, spatial scale, and number of galaxies are
compatible with clusters at the redshift of the quasar.
  We have selected a sample of cluster candidates analyzing the R-K vs. K
diagram. A ~25% of the candidates present red optical-NIR colours and an
ultraviolet excess. This population has been also found in clusters around
quasars at the same redshifts (Tanaka et al. 2000; Haines et al. 2001). These
galaxies seem to follow a mixed evolution: a main passive evolution plus late
starformation processes. The quasars do not inhabit the core of the clusters,
being found in the outer regions. This result agrees with the hypothesis that
the origin/feeding mechanism of the nuclear activity were merging processes.
The quasars inhabit the region were a collision is most probably to produce a
merger.


title:
The influence of magnetic fields on the Sunyaev Zel'dovich effect in
  clusters of galaxies

abstract:
  We study the influence of intracluster large scale magnetic fields on the
thermal Sunyaev-Zel'dovich (SZ) effect. In a macroscopic approach we complete
the hydrostatic equilibrium equation with the magnetic field pressure
component. Comparing the resulting mass distribution with a standard one, we
derive a new electron density profile. For a spherically symmetric cluster
model, this new profile can be written as the product of a standard ($\beta$-)
profile and a radius dependent function, close to unity, which takes into
account the magnetic field strength. For non-cooling flow clusters we find that
the observed magnetic field values can reduce the SZ signal by $\sim 10%$ with
respect to the value estimated from X-ray observations and the $\beta$-model.
If a cluster harbours a cooling flow, magnetic fields tend to weaken the
cooling flow influence on the SZ-effect.


title: Testing a quintessence model with CMBR peaks location

abstract:
  We show that a model of quintessence with exponential potential, which allows
to obtain general exact solutions, can generate locations of CMBR peaks which
are fully compatible with present observational data


title: Solar-like oscillations in semiregular variables

abstract:
  Power spectra of the light curves of semiregular variables, based on visual
magnitude estimates spanning many decades, show clear evidence for stochastic
excitation. This supports the suggestion by Christensen-Dalsgaard et al. (2001)
that oscillations in these stars are solar-like, i.e., stochastically excited
by convection, with mode lifetimes ranging from years to decades.


title: Oscillations in alpha Cen A observed with UCLES at the AAT

abstract:
  We report Doppler measurements of alpha Cen A from time-series spectroscopy
made with UCLES at the 3.9-m AAT. Wavelength calibration using an iodine
absorption cell produced high-precision velocity measurements, whose power
spectrum shows the clear signature of solar-like oscillations, confirming the
detection reported by Bouchy and Carrier (2001).


title:
A search for TeV gamma-ray emission from SNRs, pulsars and unidentified
  GeV sources in the Galactic plane in the longitude range between -2 deg and
  85 deg

abstract:
  Using the HEGRA system of imaging atmospheric Cherenkov telescopes, one
quarter of the Galactic plane (-2 deg < l < 85 deg) was surveyed for TeV
gamma-ray emission from point sources and moderately extended sources (diameter
<= 0.8 deg). The region covered includes 86 known pulsars (PSR), 63 known
supernova remnants (SNR) and nine GeV sources, representing a significant
fraction of the known populations. No evidence for emission of TeV gamma
radiation was detected, and upper limits range from 0.15 Crab units up to
several Crab units, depending on the observation time and zenith angles
covered. The ensemble sums over selected SNR and pulsar subsamples and over the
GeV-sources yield no indication for emission from these potential sources. The
upper limit for the SNR population is at the level of 6.7% of the Crab flux and
for the pulsar ensemble at the level of 3.6% of the Crab flux.


title: A 60 pc counter-rotating core in NGC 4621

abstract:
  We present adaptive optics assisted OASIS integral field spectrography of the
S0 galaxy NGC 4621. Two-dimensional stellar kinematical maps (mean velocity and
dispersion) reveal the presence of a 60 pc diameter counter-rotating core
(CRC), the smallest observed to date. The OASIS data also suggests that the
kinematic center of the CRC is slightly offset from the center of the outer
isophotes. This seems to be confirmed by archival HST/STIS data. We also
present the HST/WFPC2 V-I colour map, which exhibits a central elongated red
structure, also slightly off-centered in the same direction as the kinematic
centre. We then construct an axisymmetric model of NGC 4621: the two-integral
distribution function is derived using the Multi-Gaussian Expansion and the
Hunter & Qian (1993) formalisms. Although the stellar velocities are reasonably
fitted, including the region of the counter-rotating core, significant
discrepancies between the model and the observations demonstrate the need for a
more general model (e.g. a three-integral model).


title:
Star Cluster Systems in Interacting and Starburst Galaxies: A
  Multicolour Approach

abstract:
  The large majority of extragalactic star cluster studies done to date have
essentially used two or three-passband aperture photometry, combined with
theoretical stellar population synthesis models, to obtain age estimates. The
accuracy to which this can be done depends on the number of observations
through different (broad-band) filters available as well as, crucially, on the
actual wavelength range covered. I show, based on the examples of the nearby
starburst galaxies NGC 3310 and M82, that the addition of, in particular,
near-infrared passbands to a set of optical filters greatly enhances our
ability to disentangle age, metallicity and extinction parameters for star
clusters with ages younger than a few Gyr. In addition, for the
intermediate-age star cluster system in the fossil starburst region of M82 we
find (i) a well-defined burst of cluster formation at slightly older ages than
derived from previous estimates based on optical fluxes alone, and (ii) that by
considering ONLY the clusters originating in this burst of cluster formation,
we uncover the first conclusive observational evidence for an unambiguous
turn-over in the luminosity function of a coeval star cluster system with an
age as young as ~1 Gyr.


title:
Correlations between X-ray and radio spectral properties of accreting
  black holes

abstract:
  We study correlations betwen X-ray spectral index, strength of Compton
reflection, and X-ray and radio fluxes in accreting black holes (Seyferts and
black-hole binaries). We critically evaluate the evidence for the correlation
of the X-ray spectral index with the strength of Compton reflection and
consider in detail statistical and systematic effects that can affect it. We
study patterns of spectral variability (in particular, pivoting of a power law
spectrum) corresponding to the X-ray index-flux correlation. We also consider
implications of the form of observed X-ray spectra and their variability for
interpretation of the correlation between the radio and X-ray fluxes. Finally,
we discuss accretion geometries that can account for the correlations and their
overall theoretical interpretations.


title: Interactions of High and Low-Mass Planets with Protoplanetary Disks

abstract:
  We present three-dimensional numerical simulations of the interaction of a
circular-orbit planet with a protoplanetary disk. We calculate the flow
pattern, the accretion rate, and torques on the planet. We consider planet
masses ranging from 1 Earth mass to 1 Jupiter mass.


title:
The ruff of equatorial emission around the SS433 jets: its spectral
  index and origin

abstract:
  We present unique radio observations of SS433, using MERLIN, the VLBA, and
the VLA, which allow us to, for the first time, properly image and derive a
meaningful spectral index for the `ruff' of equatorial emission which surrounds
SS433's jet. We interpret this smooth ruff as a wind-like outflow from the
binary.


title: Water emission in NGC1333-IRAS4: The physical structure of the envelope

abstract:
  We report ISO-LWS far infrared observations of CO, water and oxygen lines
towards the protobinary system IRAS4 in the NGC1333 cloud. We detected several
water, OH, CO rotational lines, and two [OI] and [CII] fine structure lines.
Given the relatively poor spectral and spatial resolution of these
observations, assessing the origin of the observed emission is not
straightforward. In this paper, we focus on the water line emission and explore
the hypothesis that it originates in the envelopes that surround the two
protostars, IRAS4 A and B, thanks to an accurate model. The model reproduces
quite well the observed water line fluxes, predicting a density profile, mass
accretion rate, central mass, and water abundance profile in agreement with
previous works. We hence conclude that the emission from the envelopes is a
viable explanation for the observed water emission, although we cannot totally
rule out the alternative that the observed water emission originates in the
outflow.


title: Revised orbital parameters for planets

abstract:
  Orbital parameters of planets are fitted directly to an appropriate set of
observations. It is shown how to use the rigorous Deming method combined with a
numerical integration of gravitation equations. In all, 65 parameters of the
nine planets (masses and initial positions and velocities at J2000) are listed.
The complete set of their standard errors, and the associated
variance-covariance matrix are presented. Derived parameters as the Solar
gravitational quantity G.Mo, and the Astronomical distance AU are re-evaluated.
It is demonstrated that a direct fit using time units overcomes the very high
correlation between the gravitational constant G and the Solar mass Mo. Much
more accurate values for these quantities are obtained.


title:
Evolution characteristics of central black hole of magnetized accretion
  disc

abstract:
  Evolution characteristics of a Kerr black hole (BH) are investigated by
considering coexistence of disc accretion with the Blandford-Znajek process
(the BZ process). (i) The rate of extracting energy from the rotating BH in the
BZ process and that in MC process are expressed by a unified formula, which is
derived by using an improved equivalent cicuit. (ii) The mapping relation
between the angular coordinate on the BH horizon and the radial coordinate on
the disc is given in the context of general relativity and conservation of
magnetic flux. (iii) The power and torque in the BZ process are compared with
those in MC process in detail. (iv)Evolution characteristics of the BH and
energy extracting efficiency are discussed by using the characteristics
functions of BH evolution in the corresponding parameter space. (v) Power
dissipation on the BH horizon and BH entropy increase are discussed by
considering the coexistence of the above energy mechanisms.


title: Post-outburst radio spectral evolution of Cygnus X-3

abstract:
  Multifrequency VLA and OVRO observations of the radio outburst of Cygnus X-3
in September 2001 are presented, illustrating the evolution of the spectrum of
the source over a period of six days. An estimate of the magnetic field in the
emitting region is made from the spectral turnover and possible explanations
for the spectral evolution are suggested.


title:
Revealing New Physical Structures in the Supernova Remnant N63A through
  Chandra Imaging Spectroscopy

abstract:
  We present Chandra X-ray observations of the supernova remnant (SNR) N63A in
the Large Magellanic Cloud (LMC). N63A, one of the brightest LMC remnants, is
embedded in an H II region and probably associated with an OB association. The
optical remnant consists of three lobes of emission contained within the
approximately three times larger X-ray remnant. Our Chandra data reveal a
number of new physical structures in N63A. The most striking of these are the
several ``crescent''-shaped structures located beyond the main shell that
resemble similar features seen in the Vela SNR. In Vela, these have been
interpreted as arising from high speed clumps of supernova ejecta interacting
with the ambient medium. Another distinct feature of the remnant is a roughly
triangular ``hole'' in the X-ray emission near the location of the optical
lobes and the brightest radio emission. X-ray spectral analysis shows that this
deficit of emission is a result of absorption by an intervening dense cloud
with a mass of ~450 M_sun that is currently being engulfed by the remnant's
blast wave. We also find that the rim of the remnant, as well as the
crescent-shaped features, have considerably softer X-ray spectra than the
interior. Limits on hard X-ray emission rule out a young, energetic pulsar in
N63A, but the presence of an older or less active one, powering a wind nebula
with a luminosity less than ~4e10^34 erg/s, is allowed.


title: Globular Cluster Populations: Signatures and Implications

abstract:
  The formation of populous secondary star cluster systems is a widespread
phenomenon in mergers of gas-rich galaxies. Many, if not most, of those
clusters are massive and compact enough to be young globular clusters (GCs). GC
systems in most E/S0 galaxies feature bimodal color distributions with a fairly
universal blue peak similar to the blue peak of halo GCs in the Milky Way (MW)
and M31, and a variable red peak. Due to the well-known age -- metallicity
degeneracy of optical broad-band colors, the metallicities and ages, and,
hence, the origin of the red peak GCs are not yet known. We use evolutionary
synthesis models for GC {\bf systems} of various metallicities to study the
time evolution of their luminosity functions (LFs) in various bands U,..., K
and of their color distributions. By comparison with the universal blue peak GC
population we investigate for which combinations of age and metallicity a
second GC population can or cannot be identified in typical observations of GC
color distributions and we discuss implications for the GC LF as a distance
indicator.


title: Spectral ageing: a new age perspective

abstract:
  We present an up-to-date critique of the physical basis for the spectral
ageing method. We find that the number of cases where this method may be
meaningfully applied to deduce the ages of classical double radio sources is
small indeed. This critique is much more than merely a re-expression of
anxieties about the calibration of spectral ageing (which have been articulated
by others in the past).