title:
Aperture Synthesis CO(J=1-0) Observations and Near-Infrared Photometry
  of the Non-Barred Seyfert Galaxy NGC 5033

abstract:
  Aperture synthesis observations of CO(J=1-0) emission and near-infrared
broad-band photometry of the non-barred Seyfert galaxy NGC 5033 (D = 18.7 Mpc)
were performed. Our 3".9 x 3".6 resolution CO observations reveal a perturbed
distribution and the kinematics of molecular gas in the center of NGC 5033; we
find the characteristic gaseous features that are widely observed in barred
spiral galaxies, such as two bright CO peaks near the center (separated by ~
3'' or 270 pc from the nucleus), two offset ridges of CO emission emanating
from the CO peaks, and a CO ring (with a radius of ~ 14'' or 1.3 kpc).
Double-peaked velocity profiles are also evident near the two CO peaks,
implying that these CO peaks are orbit crowding zones in a barred/oval
potential. Although NIR data only give an upper limit of the possible bar
lengths, due to a large inclination of the NGC 5033 disk (i = 68 deg), our CO
data clearly suggests the presence of a small (the semi-major axis of about
12'' - 15'' or 1.1 - 1.4 kpc) nuclear bar (or oval structure) in the center of
the ``non-barred'' galaxy NGC 5033. Our results demonstrate that
high-resolution CO imaging-spectroscopy is useful to search for nuclear bars,
even in highly inclined systems where isophoto fitting techniques are not
applicable. We find that the gas mass-to-dynamical mass ratio, M_gas/M_dyn, is
small (< 1%) within a radius of 2'' or 180 pc, in contrast to starburst nuclei.
This implies that the starburst does not cohabitate in the type-1.5 Seyfert
nucleus of N GC 5033.


title: Observations of the High-redshift Galaxy B2 0902+343 at 92cm

abstract:
  We present 92cm observations of the high-redshift galaxy B2 0902+343 (z=3.40)
with the Westerbork Synthesis Radio Telescope (WSRT). Twenty-one cm HI is
detected in absorption, at a depth of 15.9 mJy (=~6\sigma) and rest frame
velocity width 120 km/s. We also report a null detection of OH emission or
absorption at the 1665/1667 MHz rest-frame transitions. Based on our spectral
sensitivity, we derive an upper limit on OH maser luminosity of
log(L/Lsun)<5.2. In addition, we consider the possibility of absorption, and
estimate a maximum column depth N(OH) of 1x10^15 cm^-2, corresponding to at
most 2x10^5-9x10^6 Msun of OH in the galaxy. The implications of these results
are discussed in the context of current efforts to extend the OH megamaser
luminosity function and galactic merger rate to high redshift.


title: Stellar Population Models

abstract:
  This review deals with stellar population models computed by means of the
evolutionary synthesis technique that was pioneered by Beatrice Tinsley roughly
three decades ago. The focus is on the simplest models, the so called Simple
Stellar Populations, that describe instantaneous generations of single stars
with the same chemical composition and age. The development of these models
until very recent results is discussed, pinpointing the model uncertainties
that have been solved and those that still demand a cautionary use of the
models. The fundamental step of calibrating the models with galactic globular
clusters, for which ages and element abundances are known independently, is
illustrated by means of key examples.


title: Propagation model for cosmic ray species in the Galaxy

abstract:
  In a recent paper (Moskalenko et al., 2002), it has been shown that the flux
of secondary cosmic ray (CR) antiprotons appears to be contradictory to
measurements of secondary to primary nuclei ratios in cosmic rays when
calculated in the same Galactic propagation model. The contradiction appears as
a value of the diffusion coefficient necessary to match the secondary ratios
antiproton/proton and B/C. In particlular, it was shown that the reacceleration
models designed to match secondary to primary nuclei ratios produce too few
antiprotons. It is, however, clear that some reacceleration is unavoidable in
the turbulent interstellar medium. Here we discuss an idea of how to improve
reacceleration model by allowing for the damping of interstellar turbulences on
the small scale by cosmic rays, mostly protons. This would lead to increase in
the mean free path lenghts at low energies, the well-known phenomena
empirically discovered in the Leaky Box models, thus producing less secondary
nuclei. Antiprotons will remain almost non-affected due to their high energy
threshold of production cross section.


title: The Broadband Afterglow of GRB980703

abstract:
  We present radio observations of the afterglow of the bright gamma-ray burst
GRB980703 made between one day and one year after the burst. These data are
combined with published late-time radio measurements and existing optical,
near-infrared (NIR) and X-ray observations to create a comprehensive broadband
dataset for modeling the physical parameters of the outflow. While a
wind-stratified medium cannot be ruled out statistically, it requires a high
fraction of the shock energy in the electrons, and so is not favored on
theoretical grounds. Instead, the data are consistent with a fireball model in
which the ejecta are collimated and expanding into a constant density medium.
The radio data cannot be fit with an isotropic shock but instead require a jet
break at ~ 3.5 days, not seen at optical wavelengths due to the presence of a a
bright host galaxy. The addition of the full radio dataset constrains the
self-absorption frequency, giving an estimate of the circumburst density of n ~
30 cm^-3, a value which differs substantially from previous estimates. This
result is consistent with the growing number of GRB afterglows for which
broadband modeling yields n ~= 0.1-100 cm^-3, with a typical value ~ 10 cm^-3.


title:
The Origin of the Heavy Elements: Recent Progress in the Understanding
  of the r-Process

abstract:
  There has been significant progress in the understanding of the r-process
over the last ten years. The conditions required for this process have been
examined in terms of the parameters for adiabatic expansion from high
temperature and density. There have been many developments regarding
core-collapse supernova and neutron star merger models of the r-process.
Meteoritic data and observations of metal-poor stars have demonstrated the
diversity of r-process sources. Stellar observations have also found some
regularity in r-process abundance patterns and large dispersions in r-process
abundances at low metallicities. This review summarizes the recent results from
parametric studies, astrophysical models, and observational studies of the
r-process. The interplay between nuclear physics and astrophysics is
emphasized. Some suggestions for future theoretical, experimental, and
observational studies of the r-process are given.


title: The post-outburst photometric behaviour of V838 Mon

abstract:
  The unusual eruptive variable discovered in Monoceros in 2002 January
underwent dramatic photometric and spectroscopic changes in the months prior to
its 2002 June-August conjunction with the Sun. Optical and infrared (IR)
photometry obtained at the South African Astronomical Observatory (SAAO)
between 2002 January and June (JD 2452280-440) is presented here in an analysis
of the star's post-outburst behaviour. The light curve indicated 3 eruptions
took place in 2002 January, February and March. SAAO echelle spectra obtained
in the week prior to the March maximum indicated the ejection of a new shell of
material. JHKL photometry obtained during 2002 April showed the development of
an IR excess due to the formation of a dust shell. The shell appears to be
largely responsible for the rapid fade in the optical flux during 2002
April-May (Delta V > 6 mag within 3 weeks). Blueing of the optical colours
during the decline is likely due either to the revealing of an emission line
region surrounding V838 Mon, or the unveiling of the progenitor or a
spatially-close early-type star.


title: Did Egret Detect Distant Supernova Remnants?

abstract:
  It might be thought that supernova remnants (SNRs) more distant than a few
kiloparsec from Earth could not have been detected by the EGRET experiment.
This work analyzes the observational status of this statement in the light of
new CO studies of SNRs.


title: Supernova Explosions from Accretion Disk Winds

abstract:
  Winds blown from accretion disks formed inside massive rotating stars may
result in stellar explosions observable as Type Ibc and Type II supernovae. A
key feature of the winds is their ability to produce the radioactive Nickel-56
necessary to power a supernova light curve. The wind strength depends on
accretion disk cooling by neutrino emission and photo-disintegration of bound
nuclei. These cooling processes depend on the angular momentum of the stellar
progenitor via the virial temperature at the Kepler radius where the disk
forms. The production of an observable supernova counterpart to a Gamma-Ray
Burst (GRB) may therefore depend on the angular momentum of the stellar
progenitor. Stars with low angular momentum may produce a GRB without making an
observable supernova. Stars with large angular momentum may make extremely
bright and energetic supernovae like SN 1998bw. Stars with an intermediate
range of angular momentum may simultaneously produce a supernova and a GRB.


title: A Search for Eclipsing Binaries in Galactic Globular Clusters

abstract:
  We report on the discovery and analysis of short-period (0.1 days $< P <$ 5
days), photometrically varying binary stars around and below the main-sequence
turnoff of the globular clusters (GCs) NGC 3201, M10, & M12. These eclipsing
binaries (EBs) may be used to determine directly the distances to GCs and
constrain the Population II stellar main-sequence masses. During our search for
binaries, we discovered the signature of differential reddening across the
cluster fields which was especially strong for NGC 3201 and M10. We correct for
this differential reddening by calculating average $E_{V-I}$ values for stars
in small subregions of the field with respect to a fiducial region, which
significantly improves the appearance of the GC color-magnitude diagrams
(CMDs). The reddening zero point to be added to the differential value is
determined by isochrone fitting. The results of our differential dereddening
are presented in the form of high-resolution extinction maps. Our search for
EBs returned 14 variable stars (11 EBs) in the field of NGC 3201, 3 variables
(1 EB) in M10, and 2 EBs in M12. Of these variables, only one EB in NGC 3201 (a
blue straggler W Ursa Majoris contact system) is a definite GC-member, based on
spectroscopic observations. Another W UMa contact EB in M12 is most likely a
member of M12, based on its location in the color-magnitude diagram (CMD) and
its empirically calculated absolute magnitude. We present the phased
lightcurves for all variables, estimate their distances and GC membership, and
show their locations in the GC fields and CMDs, as well as the spectra of the
NGC 3201 EBs. Finally, we discuss the implications of our results and outline
future work.


title: Sub-mm and near-IR observations of galaxies selected at 170 microns

abstract:
  We present results from JCMT sub-mm observations of sources selected from the
{\sl ISO} FIRBACK (Far-IR BACKground) survey, along with UKIRT near-IR imaging
of a sub-sample. This gives valuable insight into the brightest $\sim$10% of
galaxies which contribute to the Cosmic Infrared Background (CIB). We estimate
the photometric redshifts and luminosities of these sources by fitting their
Spectral Energy Distributions (SEDs). The data appear to show a bimodal galaxy
distribution, with normal star-forming galaxies at $z\simeq0$, and a much more
luminous population at $z\sim0.4$--0.9. These are similar to the ultraluminous
infrared galaxies which are found to evolve rapidly with redshift in other
surveys. The detectability threshold of FIRBACK biases the sample away from
much higher redshift ($z\stackrel{>}{_{\sim}}1.5$) objects. Nevertheless, the
handful of $z\sim0.5$ sources which we identify are likely to be the low-$z$
counterparts of the typically higher-$z$ sources found in blank field sub-mm
observations. This sub-sample, being much more nearby than the average SCUBA
galaxies, has the virtue of being relatively easy to study in the optical.
Hence their detailed investigation could help elucidate the nature of the
sub-mm bright galaxies.


title: SN 2002cx: The Most Peculiar Known Type Ia Supernova

abstract:
  We present photometric and spectroscopic observations of supernova (SN)
2002cx, which reveal it to be unique among all observed type Ia supernovae (SNe
Ia). SN 2002cx exhibits a SN 1991T-like premaximum spectrum, a SN 1991bg-like
luminosity, and expansion velocities roughly half those of normal SNe Ia.
Photometrically, SN 2002cx has a broad peak in the $R$ band and a plateau phase
in the $I$ band, and slow late-time decline. The $(B - V)$ color evolution is
nearly normal, but the $(V - R)$ and $(V - I)$ colors are very red. Early-time
spectra of SN 2002cx evolve very quickly and are dominated by lines from
Fe-group elements; features from intermediate-mass elements (Ca, S, Si) are
weak or absent. Mysterious emission lines are observed around 7000 \AA\ at
about 3 weeks after maximum brightness. The nebular spectrum of SN 2002cx is
also unique, consisting of narrow iron and cobalt lines. The observations of SN
2002cx are inconsistent with the observed spectral/photometric sequence, and
provide a major challenge to our understanding of SNe Ia. No existing
theoretical model can successfully explain all observed aspects of SN 2002cx.


title: Detection of crystalline silicates around the T Tauri star Hen 3-600A

abstract:
  We have carried out mid-infrared N-band spectroscopic observations of the T
Tauri star Hen 3-600A in the TW Hydra association with the COMICS on the 8.2m
Subaru Telescope and found structured features in its spectrum. These
structured features are well explained by a combination of crystalline
forsterite, crystalline enstatite, silica and glassy olivine grains.
  Among intermediate-mass young stellar objects (YSOs), crystalline silicates
have already been detected, but no firm detection has been reported so far for
low-mass YSOs such as T Tauri stars. This is the first clear detection of
crystalline silicates in low-mass YSOs and shows that the crystallization event
occurs even in the protoplanetary disk of low-mass YSOs in the T Tauri phase.
The physical processes leading to the inferred dust composition in the
Hen3-600A system may be analogous to those occured in the early epoch of the
Solar system.


title: Rationale for the use of color information on Eddington

abstract:
  For the Eddington mission, the intrinsic stellar variability can be a major
source of noise in the detection of extrasolar planets by the transit method.
We derive that most detections of terrestrial planets (1-2 R_Earth) will occur
around G or K stars with 15-16th magnitude. When these stars are 7-12 times
more variable than the Sun on a 10 hour timescale, we demonstrate that the
detection can be performed with a higher S/N provided composite lightcurves
obtained with the combination of two colors are used instead of white ones. The
level of 10 hour variability for K stars is quite uncertain. We make two
"guess-estimates" of it and find that it could be several times larger than the
solar value. If these estimates were relevant, the color information would not
provide a significant advantage. Although we do not demonstrate a need for
colors, we point out the risk of an unpleasant surprise regarding the 10 hour
stellar variability. Indeed, there is presently no qualified proxy for this
variability. Besides, if Eddington were designed to provide this information at
the cost of added complexity but not sensitivity, white photometry by channel
summation would still be as efficient. Considering the risk that 10 hour
variability is higher than estimated, the Precaution Imperative points to a
study of practical implementations of photometry in different colors before
taking irreversible decisions about the Eddington instrument.


title:
The brightness temperature problem in extreme IDV quasars: a model for
  PKS 0405-385

abstract:
  I re-examine the brightness temperature problem in PKS 0405-385 which is an
extreme intra-day variable radio quasar with an inferred brightness temperature
of $\sim 5 \times 10^{14}$ K at 5 GHz, well above the Compton catastrophe limit
of $\sim 10^{11}$ K reached when the synchrotron photon energy density exceeds
the energy density of the magnetic field. If one takes into account the
uncertainty in the distance to the ionized clouds responsible for interstellar
scintillation causing rapid intra-day variability in PKS 0405-385 it is
possible that the brightness temperature could be as low as $\sim 10^{13}$ K at
5 GHz, or even lower. The radio spectrum can be fitted by optically thin
emission from mono-energetic electrons, or an electron spectrum with a
low-energy cut-off such that the critical frequency of the lowest energy
electrons is above the radio frequencies of interest. If one observes optically
thin emission along a long narrow emission region, the average energy density
in the emission region can be many orders of magnitude lower than calculated
from the observed intensity if one assumed a spherical emission region. I
discuss the physical conditions in the emission region and find that the
Compton catastrophe can then be avoided using a reasonable Doppler factor. I
also show that MeV to 100 GeV gamma-ray emission at observable flux levels
should be expected from extreme intra-day variable sources such as PKS
0405-385.


title:
Understanding Helical Magnetic Dynamo Spectra with a Nonlinear
  Four-Scale Theory

abstract:
  Recent MHD dynamo simulations for magnetic Prandtl number $>1$ demonstrate
that when MHD turbulence is forced with sufficient kinetic helicity, the
saturated magnetic energy spectrum evolves from having a single peak below the
forcing scale to become doubly peaked with one peak at the system (=largest)
scale and one at the forcing scale. The system scale field growth is well
modeled by a recent nonlinear two-scale nonlinear helical dynamo theory in
which the system and forcing scales carry magnetic helicity of opposite sign.
But a two-scale theory cannot model the shift of the small-scale peak toward
the forcing scale. Here I develop a four-scale helical dynamo theory which
shows that the small-scale helical magnetic energy first saturates at very
small scales, but then successively saturates at larger values at larger
scales, eventually becoming dominated by the forcing scale. The transfer of the
small scale peak to the forcing scale is completed by the end of the kinematic
growth regime of the large scale field, and does not depend on magnetic
Reynolds number $R_M$ for large $R_M$. The four-scale and two-scale theories
subsequently evolve almost identically, and both show significant field growth
on the system and forcing scales that is independent of $R_M$. In the present
approach, the helical and nonhelical parts of the spectrum are largely
decoupled. Implications for fractionally helical turbulence are discussed.


title:
How relevant is the torus activity/geometry for the TeV gamma-rays
  emitted in the jet of M87 ?

abstract:
  Motivated by unification schemes of active galactic nuclei, we review
evidence for the existence of a small-scale dust torus in M87, a Fanaroff-Riley
Class I radio galaxy. Since there is no direct evidence of any thermal emission
from its torus we consider indirect evidence, such as BLR activity and ageing
arguments to model the cold dust structure of M87. In the context of the jet --
accretion disk -- torus symbiosis we discuss the interactions of GeV and TeV
gamma-rays produced in the jet of M87 with the infrared radiation fields
external to the jet, produced by a less active torus. A thin and cold torus
with less defined outer boundaries could still posses problems to some of the
TeV emission from the jet.


title: A catalog of reference stars for long baseline stellar interferometry

abstract:
  The calibration process of long baseline stellar interferometers requires the
use of reference stars with accurately determined angular diameters. We present
a catalog of 374 carefully chosen stars among the all-sky network of infrared
sources provided by Cohen et al. 1999. The catalog benefits from a very good
sky coverage and a median formal error on the angular diameters of only 1.2%.
Besides, its groups together in a homogeneous handy set stellar coordinates,
uniform and limb-darkened angular diameters, photometric measurements, and
other parameters relevant to optical interferometry. In this paper, we describe
the selection criteria applied to qualify stars as reference sources. Then, we
discuss the catalog's statistical properties such as the sky coverage or the
distributions of magnitudes and angular diameters. We study the number of
available reference stars as a function of the baseline and the precision
needed on the visibility measurements. Finally, we compare the angular
diameters predicted in Cohen et al. 1999 with existing determinations in the
literature, and find a very good agreement.


title:
10 um wavefront spatial filtering: first results with chalcogenide
  fibers

abstract:
  Wavefront cleaning by single-mode fibers has proved to be efficient in
optical-infrared interferometry to improve calibration quality. For instance,
the FLUOR instrument has demonstrated the capability of fluoride glass
single-mode fibers in this respect in the K and L bands. New interferometric
instruments developped for the mid-infrared require the same capability for the
8-12 um range. We have initiated a program to develop single-mode fibers in the
prospect of the VLTI mid-infrared instrument MIDI and of the ESA/DARWIN and
NASA/TPF missions that require excellent wavefront quality. In order to
characterize the performances of chalcogenide fibers we are developping, we
have set up an experiment to measure the far-field pattern radiated at 10 um.
In this paper, we report the first and promising results obtained with this new
component.


title: Radio / X-ray correlation in the low/hard state of GX 339--4

abstract:
  We present the results of a long-term study of the black hole candidate GX
339-4 using simultaneous radio (from the Australia Telescope Compact Array) and
X-ray (from the Rossi X-ray Timing Explorer and BeppoSAX) observations
performed between 1997 and 2000. We find strong evidence for a correlation
between these two emission regimes that extends over more than three decades in
X-ray flux, down to the quiescence level of GX 339-4. This is the strongest
evidence to date for such strong coupling between radio and X-ray emission. We
discuss these results in light of a jet model that can explain the radio/X-ray
correlation. This could indicate that a significant fraction of the X-ray flux
that is observed in the low-hard state of black hole candidates may be due to
optically thin synchrotron emission from the compact jet.


title:
Observations of H1426+428 with HEGRA -- Observations in 2002 and
  reanalysis of 1999&2000 data

abstract:
  The HEGRA system of imaging air Cherenkov telescopes has been used to observe
the BL Lac object H1426+428 ($z=0.129$) for 217.5 hours in 2002. In this data
set alone, the source is detected at a confidence level of $5.3~\sigma$,
confirming this object as a TeV source. The overall flux level during the
observations in 2002 is found to be a factor of $\approx 2.5$ lower than during
the previous observations by HEGRA in 1999&2000. A new spectral analysis has
been carried out, improving the signal-to-noise ratio at the expense of a
slightly increased systematic uncertainty and reducing the relative energy
resolution to $\Delta E/E\le 12 %$ over a wide range of energies. The new
method has also been applied to the previously published data set taken in 1999
and 2000, confirming the earlier claim of a flattening of the energy spectrum
between 1 and 5 TeV. The data set taken in 2002 shows again a signal at
energies above 1 TeV. We combine the energy spectra as determined by the CAT
and VERITAS groups with our reanalyzed result of the 1999&2000 data set and
apply a correction to account for effects of absorption of high energy photons
on extragalactic background light in the optical to mid infrared band. The
shape of the inferred source spectrum is mostly sensitive to the
characteristics of the extragalactic background light between wavelengths of 1
and 15~$\mu$m


title: Neutrino energy loss rate in a stellar plasma

abstract:
  We review the purely leptonic neutrino emission processes, contributing to
the energy loss rate of the stellar plasma. We perform a complete analysis up
to the first order in the electromagnetic coupling constant. In particular the
radiative electromagnetic corrections, at order $\alpha$, to the process $e^+
e^- -> \nu \bar{\nu}$ at finite density and temperature have been computed.
This process gives one of the main contributions to the cooling of stellar
interior in the late stages of star evolution. As a result of the analysis we
find that the corrections affect the energy loss rate, computed at tree level,
by a factor $(-4 \div 1) %$ in the temperature and density region where the
pair annihilation is the most efficient cooling mechanism.


title: The mass profile of galaxy clusters out to ~2 r200

abstract:
  We analyze the internal dynamics of 43 non-interacting clusters which are
selected from the 2dF Galaxy Redshift Survey 100k public release. We join
together the 43 clusters into an ensemble cluster by appropriately scaling
their galaxy velocities and clustercentric distances. We solve the Jeans
equation for the hydrostatic equilibrium for the member galaxies within the
virial radius of the ensemble cluster, assuming isotropic orbits. We constrain
the cluster mass profile within the virial radius by exploring parameterized
models for the cluster mass-density profile. We find that both cuspy profiles
and profiles with a core are acceptable. In particular, the concentration
parameter of the best fit NFW model is as predicted from numerical simulations
in a LambdaCDM cosmology. Density profiles with very large core-radii are ruled
out. Beyond the virial radius, dynamical equilibrium cannot be taken for
granted, and the Jeans equation may not be applicable. In order to extend our
dynamical analysis out to ~2 virial radii, we rely upon the method which uses
the amplitude of caustics in the space of galaxy clustercentric distances and
velocities. We find very good agreement between the mass profile determined
with the caustic method and the extrapolation to ~2 virial radii of the
best-fit mass profile determined by the Jeans analysis in the virialized inner
region. We determine the mass-to-number density profile, and find it is fully
consistent with a constant within the virial radius. The mass-to-number density
profile is however inconsistent with a constant when the full radial range from
0 to ~2 virial radii is considered, unless the sample used to determine the
number density profile is restricted to the early-type galaxies.


title: Stability of matter in the accelerating spacetime

abstract:
  In the paper the Planck, Yukawa and Bohr forces were defined and calculated.
It was shown that the Planck force mediates the universe acceleration. The
Yukawa and Bohr forces describe the gradients of attractive strong and Coulomb
forces. It was shown that smallest, of the present day, value of Planck force
in comparison to values of the Yukawa and Bohr force guarantees the stability
of matter at T (age of universe), 10^17 s. In this paper the new particle with
mass m_(Bohr)=3.7 keV/c^2 is postulated. The range of the Coulomb force at the
atomic level is described by the formula r_(atomic)=hbar/(m_Bohr)c=0.1nm The
relation of the Planck, Yukawa, Bohr to the Schwiger force (for vacuum creation
of electron-pozyton pairs)is also outlined.


title: The TOOT Survey: status and early results

abstract:
  The TexOx-1000 (TOOT) radio source redshift survey is designed to find and
study typical radio-loud active galaxies to high redshift. They are typical in
the same sense that L* galaxies are typical of galaxies in the optical.
Previous surveys have only included the most luminous, rare objects at and
beyond the peak of activity at z~2, but in going a factor of 100 fainter than
the 3C survey, and in assembling a large sample, TOOT probes for the first time
the objects that dominate the radio luminosity density of the universe at high
redshift. Here we describe the current status of the TOOT survey and draw
preliminary conclusions about the redshift distribution of the radio sources.
So far, ~520 of the 1000 radio sources have redshifts, with ~440 of those in
well-defined, complete, sub-regions of the survey. For these we find a median
redshift of z=1, but the measured redshift distribution has a deficit of
objects with z~2, when compared to predictions based on extrapolating
luminosity functions constrained by higher-flux-density samples. These are the
more luminous objects that usually show emission lines, and which should not be
missed in the survey unless they are heavily reddened. The deficit may be real,
but it would not be too surprising to find a population of faint, reddened
radio sources at z~2-3 among the TOOT sources yet to have accurate redshifts.


title: The emission line sequence of H II galaxies

abstract:
  We consider 400 H II galaxies in which the oxygen abundances were obtained by
electron temperature based methods. We split the sample in three metallicity
bins. In each bin, a narrow sequence is found not only in pure emission line
ratio diagrams but also in terms of Hbeta equivalent width, indicating the
existence of an evolutionary sequence. Our diagrams show unambiguously the
existence of an evolution on a timescale of a few Myr. We compare the observed
sequences with photoionization models of appropriate metallicity. In order to
understand the evolution of H II galaxies one needs to consider the evolution
of the gas as well as that of the stars. The observations require EW(Hbeta) to
decrease more rapidly than predicted by the passive evolution of a starburst. A
photoionized adiabatic expanding bubble with a covering factor decreasing with
time reproduces most diagrams. However, the question of the heating of H II
galaxies and the origin of the nebular He II 4686 emission are not settled. We
find evidence for self-enrichment in nitrogen on a time scale of several Myr.


title: BeppoSAX observations of two unclassified LMXBs: X1543-624 and X1556-605

abstract:
  Observations of two unclassified Low Mass X-ray Binaries, X1543-624 and
X1556-605, are presented. In the 2-10 keV band the first of the two sources is
a factor two stronger than the other. Both sources do not show X-ray bursts,
dips or eclipses in their X-ray light curves. We find that both spectra are
described by a two-component model consisting of emission from a cool accretion
disk plus a Comptonized blackbody with kTbb ~ 1.5 keV in a low opacity plasma.
The spectrum of X1543-624 hardens from the first to the second observation,
when the source slowly moves from right to left in the colour-colour diagram.
The spectrum of X1556-605 can also be described by a model consisting of a
blackbody plus an unsaturated Comptonization with electron energy kTe ~ 4 keV.
In the first observation, X1543-624 shows evidence of a Fe K emission line at
6.4 keV. Moreover in both observations, the source spectrum exhibits an
emission feature around 0.7 keV, which is interpreted as due to the
superposition of the K edge absorption features of O and Ne elements with
uncommon relative abundances with respect to the solar one (O/O(sun) ~0.3,
Ne/Ne(sun) ~ 2.5). In the spectrum of X1556-605 no emission lines are observed.
We discuss these results and their implications on the source classification
and the accretion geometry on the compact object.


title:
Catalogue of cataclysmic binaries, low-mass X-ray binaries and related
  objects (Seventh edition)

abstract:
  The catalogue lists coordinates, apparent magnitudes, orbital parameters, and
stellar parameters of the components and other characteristc properties of 472
cataclysmic binaries, 71 low-mass X-ray binaries and 113 related objects with
known or suspected orbital periods together with a comprehensive selection of
the relevant recent literature. In addition the catalogue contains a list of
references to published finding charts for 635 of the 656 objects, and a
cross-reference list of alias object designations. Literature published before
1 January 2003 has, as far as possible, been taken into account. All data can
be accessed via the dedicated catalogue webpage at
http://www.mpa-garching.mpg.de/RKcat/ (MPA) and
http://physics.open.ac.uk/RKcat/ (OU). We will update the information given on
the catalogue webpage regularly, initially every six months.


title:
Testing the circumstellar disk hypothesis: A search for H2 outflow
  signatures from massive YSOs with linearly distributed methanol masers

abstract:
  The results of a survey searching for outflows using near-infrared imaging is
presented. Targets were chosen from a compiled list of massive young stellar
objects (YSOs) associated with methanol masers in linear distributions.
Presently, it is a widely held belief that these methanol masers are found in
(and delineate) circumstellar accretion disks around massive stars. If this
scenario is correct, one way to test the disk hypothesis is to search for
outflows perpendicular to the methanol maser distributions. The main objective
of the survey was to obtain wide-field near-infrared images of the sites of
linearly distributed methanol masers using a narrow-band 2.12 micron filter.
This filter is centered on the H2 v=1-0 S(1) line; a shock diagnostic that has
been shown to successfully trace CO outflows from young stellar objects.
Twenty-eight sources in total were imaged of which eighteen sources display H2
emission. Of these, only TWO sources showed emission found to be dominantly
perpendicular to the methanol maser distribution. Surprisingly, the H2 emission
in these fields is not distributed randomly, but instead the majority of
sources are found to have H2 emission dominantly PARALLEL to their distribution
of methanol masers. These results seriously question the hypothesis that
methanol masers exist in circumstellar disks. The possibility that linearly
distributed methanol masers are instead directly associated with outflows is
discussed.


title:
Potential of the Surface Brightness Fluctuation method to measure
  distances to dwarf ellipticals in nearby clusters

abstract:
  The potential of the Surface Brightness Fluctuation (SBF) method to determine
distances to dwarf ellipticals in nearby clusters is investigated. We find that
for the Fornax cluster, the SBF method yields reliable results down to very
faint magnitudes, in our case down to M_V ~- 11 mag when observing for about 1
hour at good seeing with an 8m-class telescope in the I-filter. Comparison
between real and simulated data for the Centaurus Cluster shows that our
simulations do not overestimate the achievable S/N of the SBF method.


title: Plasma physics in clusters of galaxies

abstract:
  Clusters of galaxies are the largest self-gravitating structures in the
universe. Each cluster is filled with a large-scale plasma atmosphere, in which
primordial matter is mixed with matter that has been processed inside stars.
This is a wonderful plasma physics laboratory. Our diagnostics are the data we
obtain from X-ray and radio telescopes. The thermal plasma is a strong X-ray
source; from this we determine its density and temperature. Radio data reveal a
relativistic component in the plasma, and first measurements of the
intracluster magnetic field have now been made. Energization of the particles
and the field must be related to the cosmological evolution of the cluster. The
situation is made even richer by the few galaxies in each cluster which host
radio jets. In these galaxies, electrodynamics near a massive black hole in the
core of the galaxy lead to a collimated plasma beam which propagates from the
nucleus out to supergalactic scales. These jets interact with the cluster
plasma to form the structures known as radio galaxies. The interaction disturbs
and energizes the cluster plasma. This complicates the story but also helps us
understand both the radio jets and the cluster plasma.


title: Cosmology, inflation, and the physics of nothing

abstract:
  These four lectures cover four topics in modern cosmology: the cosmological
constant, the cosmic microwave background, inflation, and cosmology as a probe
of physics at the Planck scale. The underlying theme is that cosmology gives us
a unique window on the ``physics of nothing,'' or the quantum-mechanical
properties of the vacuum. The theory of inflation postulates that vacuum
energy, or something very much like it, was the dominant force shaping the
evolution of the very early universe. Recent astrophysical observations
indicate that vacuum energy, or something very much like it, is also the
dominant component of the universe today. Therefore cosmology gives us a way to
study an important piece of particle physics inaccessible to accelerators. The
lectures are oriented toward graduate students with only a passing familiarity
with general relativity and knowledge of basic quantum field theory.


title: Image Simulation with Shapelets

abstract:
  We present a method to simulate deep sky images, including realistic galaxy
morphologies and telescope characteristics. To achieve a wide diversity of
simulated galaxy morphologies, we first use the shapelets formalism to
parametrize the shapes of all objects in the Hubble Deep Fields. We measure
this distribution of real galaxy morphologies in shapelet parameter space, then
resample it to generate a new population of objects. These simulated galaxies
can contain spiral arms, bars, discs, arbitrary radial profiles and even dust
lanes or knots. To create a final image, we also model observational effects,
including noise, pixellisation, astrometric distortions and a Point-Spread
Function. We demonstrate that they are realistic by showing that simulated and
real data have consistent distributions of morphology diagnostics: including
galaxy size, ellipticity, concentration and asymmetry statistics. Sample images
are made available on the world wide web. These simulations are useful to
develop and calibrate precision image analysis techniques for photometry,
astrometry, and shape measurement. They can also be used to assess the
sensitivity of future telescopes and surveys for applications such as supernova
searches, microlensing, proper motions, and weak gravitational lensing.


title: Propagation of secondary antiprotons and cosmic rays in the Galaxy

abstract:
  Recent measurements of the cosmic ray (CR) antiproton flux have been shown to
challenge existing CR propagation models. It was shown that the reacceleration
models designed to match secondary to primary nuclei ratios (e.g., B/C) produce
too few antiprotons. In the present paper we discuss one possibility to
overcome these difficulties. Using the measured antiproton flux AND B/C ratio
to fix the diffusion coefficient, we show that the spectra of primary nuclei as
measured in the heliosphere may contain a fresh local "unprocessed" component
at low energies perhaps associated with the Local Bubble, thus decreasing the
measured secondary to primary nuclei ratio. The independent evidence for SN
activity in the solar vicinity in the last few Myr supports this idea. The
model reproduces antiprotons, B/C ratio, and elemental abundances up to Ni
(Z<=28). Calculated isotopic distributions of Be and B are in perfect agreement
with CR data. The abundances of three "radioactive clock" isotopes in CR, 10Be,
26Al, 36Cl, are all consistent and indicate a halo size z_h~4 kpc based on the
most accurate data taken by the ACE spacecraft.


title: Spectroscopic analysis of newborn massive stars in SMC N81

abstract:
  We present the first results of a spectroscopic study of young massive stars
in the SMC High Excitation Blob N81. These stars have Mv values which are ~ 2
mag smaller than those of nor mal dwarf stars. Their UV STIS spectra reveal
features typical of O stars, but surprisingly weak wind components. The
preliminary modelling of these spectr a with the code CMFGEN (Hillier & Miller
1998) indicates a mass loss rate of the order 10e-9 Mdot/yr. If confirmed, such
a weak wind may indicate either a breakdown of the wind-momentum luminosity
relation at low luminosity, or a steeper slope of this relation at low
metallicity.


title:
Dust in Hot Gas: Far Infrared Emission from Three Local Elliptical
  Galaxies

abstract:
  We present far-IR ISO observations of three early-type galaxies in the Virgo
cluster. The data were recorded using the ISOPHOT instrument in both the P32
oversampled maps and the P39/37 sparse maps. The maps reach the limiting
sensitivity of the ISOPHOT instrument at 60, 90, and 180$\mu$m. Two of the most
prominent elliptical galaxies in Virgo -- NGC 4472 and NGC 4649 -- clearly show
no emission at far-IR wavelengths at a level of few tens of mJy, but NGC 4636
is detected at all three wavelengths. We have computed the far-IR emission from
dust for NGC4472 and NGC4636 under the assumption that dusty outflows from
evolving red giant stars are continuously supplying dust to the interstellar
medium and that the grains, once diffused into the interstellar medium, are
sputtered away by collisions with ions. While the calculated fluxes are
consistent with the observed upper limits for NGC4472, the dust emission
detected in NGC4636 support the hypothesis that additional dust has been
accreted in a very recent ($\lta$ few $10^8$ yrs) merger with a dusty, gas-rich
galaxy.


title: Micro-second Timing of PSR B1821-24 with Chandra/HRC-S

abstract:
  We perform absolute timing of PSR B1821-24 in M28, using a 50 ksec
observation with Chandra/HRC-S. We have obtained the highest signal-to-noise
X-ray pulsed lightcurve of this source to date, detecting two X-ray pulses, as
well as significant non-pulsed emission -- a persistent X-ray flux which
comprises 15+/-3% of the total X-ray flux of the pulsar. The Gaussian width of
the sharp X-ray peak is 34+/-3 micro-sec in time, implying a size of the X-ray
beam as it crosses the line of sight of 4.0+/-0.4 deg. We find evidence for a
significant trailing component in both X-ray peaks of the pulse profile.
Including three RXTE/PCA observations in our analysis, and tying the phases
together using a radio ephemeris obtained at Nancay, we find the absolute
phases in the X-ray wander with respect to this radio ephemeris by up to 60
micro-sec, likely due to the variable dispersion measure, which changes the
pulse arrival time in the radio band but not the X-ray band. The present
analysis makes clear that study of pulsar timing noise properties in
millisecond pulsars such as PSR B1821-24 -- hitherto only studied at radio
wavelengths, where variable dispersion measure requires a significant
correction -- can be studied at X-ray wavelengths, where the effect of variable
dispersion measure is negligible. We also examine the known uncertainties in
the absolute Chandra/HRC-S timing accuracy, which amount to +/-12 microsec. We
limit the amount of linear drift in the relative timing accuracy of HRC-S to
<3e-10 s s-1.


title:
Quantitative Spectroscopy of O Stars at Low Metallicity. O Dwarfs in NGC
  346

abstract:
  We present the results of a detailed UV and optical spectral analysis of the
properties of 6 dwarf O-type stars in the SMC H II region NGC 346. Stellar
parameters, chemical abundances, and wind parameters have been determined using
NLTE line blanketed models calculated with the photospheric code, Tlusty, and
with the wind code, CMFGEN. The results, in particular iron abundances,
obtained with the two NLTE codes compare very favorably, demonstrating that
basic photospheric parameters of O dwarfs can be reliably determined using NLTE
static model atmospheres. The two NLTE codes require a microturbulent velocity
to match the observed spectra. Our results hint at a decrease of the
microturbulent velocity from early O stars to late O stars. Similarly to
several recent studies of galactic, LMC and SMC stars, we derive effective
temperatures lower than predicted from the widely-used relation between
spectral type and Teff, resulting in lower stellar luminosities and lower
ionizing fluxes. From evolutionary tracks in the HR diagram, we find an age of
3 10^6 years for NGC 346. A majority of the stars in our sample reveal
CNO-cycle processed material at their surface during the MS stage, indicating
thus fast stellar rotation and/or very efficient mixing processes. We obtain an
overall metallicity, Z = 0.2 Zsun, in good agreement with other recent analyses
of SMC stars. The derived mass loss rate of the three most luminous stars
agrees with recent theoretical predictions. However, the three other stars of
our sample reveal very weak wind signatures. We obtain mass loss rates that are
significantly lower than 10^{-8} Msun/yr, which is below the predictions of
radiative line-driven wind theory by an order of magnitude or more. (abridged
version)


title: Relativistic Flows at the Hotspots of Radio Galaxies and Quasars?

abstract:
  We review the broad band properties of X-ray detected hotspots in radio
galaxies and quasars. We show that their collective properties can be unified
in a framework involving frequency dependent relativistic beaming and varying
orientations to the observer's line of sight. The simplest dynamic model
consistent with this picture is a slowing-down relativistic flow downstream
from the hotspot shock, suggesting that the jet flow remains relativistic to
the hotspot distances.


title: [Fe IV] emission in ionized nebulae

abstract:
  This paper presents an analysis of [Fe IV] emission based on new
identifications and previous measurements of [Fe IV] lines in 30 Doradus, IC
4846, M42, SMC N88A, and SBS 0335-052. The Fe abundances obtained by adding the
abundances of the relevant Fe ions (mainly Fe^{++} and Fe^{3+}) are found to be
lower, by factors in the range 2.6-5.9, than the Fe abundances implied by [Fe
III] emission and an ionization correction factor derived from ionization
models. The most likely explanation of this discrepancy is that either the
collision strengths for [Fe IV] or the Fe ionization fractions predicted by
models are unreliable. The available data neither allow one to distinguish
between these two possibilities nor to exclude another possible explanation:
that the discrepancy implies the presence of a gradient in the Fe abundance
within the ionized gas. Further measurements of [Fe IV] lines and checks on the
Fe^{3+} atomic data and ionization models are needed to reach a definitive
conclusion. The discrepancy introduces an uncertainty in the determination of
Fe abundances in ionized nebulae. This uncertainty has implications for our
understanding of both the evolution of dust in ionized nebulae and the chemical
history of low metallicity galaxies.


title: Galaxy Threshing and Ultra-Compact Dwarfs in the Fornax Cluster

abstract:
  We have discovered a new type of galaxy in the Fornax Cluster:
``ultra-compact'' dwarfs (UCDs). The UCDs are unresolved in ground-based
imaging and have spectra typical of old stellar systems. Although the UCDs
resemble overgrown globular clusters, based on VLT UVES echelle spectroscopy,
they appear to be dynamically distinct systems with higher internal velocity
dispersions and M/L ratios for a given luminosity than Milky Way or M31
globulars. Our preferred explanation for their origin is that they are the
remnant nuclei of dwarf elliptical galaxies which have been tidally stripped,
or ``threshed'' by repeated encounters with the central cluster galaxy,
NGC1399. If correct, then tidal stripping of nucleated dwarfs to form UCDs may,
over a Hubble time, be an important source of the plentiful globular cluster
population in the halo of NGC1399, and, by implication, other cD galaxies. In
this picture, the dwarf elliptical halo contents, up to 99% of the original
dwarf luminosity, contribute a significant fraction of the populations of
intergalactic stars, globulars, and gas in galaxy clusters.


title:
Resonance Occupation in the Kuiper Belt: Case Examples of the 5:2 and
  Trojan Resonances

abstract:
  As part of our ongoing Deep Ecliptic Survey (DES) of the Kuiper belt, we
report on the occupation of the 1:1 (Trojan), 4:3, 3:2, 7:4, 2:1, and 5:2
Neptunian mean-motion resonances (MMRs). The occupation of the 1:1 and 5:2 MMRs
is not easily understood within the standard model of resonance sweeping by a
migratory Neptune over an initially dynamically cold belt. Our dynamically hot,
5:2 resonant objects can librate with modest amplitudes of 90 deg within the
resonance for at least 1 Gyr. Their trajectories cannot be explained by close
encounters with Neptune alone, given the latter's current orbit. The hot orbits
of such 5:2 resonant KBOs, unlike hot orbits of previously known resonant KBOs,
may imply that these objects were pre-heated to large inclination and large
eccentricity prior to resonance capture by a migratory Neptune. Our first
discovered Neptunian Trojan, 2001QR322, may not owe its existence to Neptune's
migration at all. The trajectory of 2001QR322 is remarkably stable; the object
can undergo tadpole-type libration about Neptune's leading Lagrange (L4) point
for at least 1 Gyr with a libration amplitude of 24 deg. Trojan capture
probably occurred while Neptune accreted the bulk of its mass. For an assumed
albedo of 12--4%, our Trojan is 130--230 km in diameter. Model-dependent
estimates place the total number of Neptune Trojans resembling 2001QR322 at
20--60. Their existence might rule out violent orbital histories for Neptune.


title: Cluster--Galaxy Interactions in Coma

abstract:
  The galaxies NGC 4911 and 4921 in the Coma cluster provide spectacular
examples of luminous, grand design spirals passing through the hot intracluster
medium of a rich cluster of galaxies. Chandra ACIS-I imaging of their
environment, coupled with CFHT, HST/WFPC2, and VLA radio imaging, reveal the
interactions between the hot X-ray gas and the ISM of the spirals, highlighting
the linkage between galaxy and cluster evolution generated by such
interactions.


title:
Abundance Analysis of HE2148-1247, A Star With Extremely Enhanced
  Neutron Capture Elements

abstract:
  Abundances for 27 elements in the very metal poor dwarf star HE2148-1247 are
presented, including many of the neutron capture elements. We establish that
HE2148-1247 is a very highly s-process enhanced star with anomalously high Eu
as well, Eu/H about half Solar, demonstrating the large addition of heavy
nuclei at [Fe/H] = -2.3 dex. Ba and La are enhanced by a somewhat larger factor
and reach the solar abundance, while Pb significantly exceeds it. Ba/Eu is ten
times the solar r-process ratio but much less than that of the s-process,
indicating a substantial r-process addition as well. C and N are also very
highly enhanced. We have found that HE2148-1247 is a radial velocity variable.
The C, N and the s-process element enhancements thus presumably were produced
through mass transfer from a former AGB binary companion. The large enhancement
of heavy r-nuclides also requires an additional source as this is far above any
inventory in the ISM at such low [Fe/H]. We further hypothesize that accretion
onto the white dwarf from the envelope of the star caused accretion induced
collapse of the white dwarf, forming a neutron star, which then produced heavy
r-nuclides and again contaminated its companion. (abridged)


title: Stellar Sources for Heavy r-Process Nuclei

abstract:
  (Abridged) The stellar sites and the complete mechanism of r-process
nucleosynthesis are still unresolved issues. From consideration of the observed
abundances in metal-poor stars, it is proposed that the production of the heavy
r-process nuclei (with mass numbers A>130) is not related to the production of
the Fe group elements or of the elements with lower atomic numbers: Na, Mg, Al,
Si, Ca, Sc, and Ti. This requires that the production of the heavy r-nuclei not
occur in supernovae with extended shell structure, but be associated with
either bare neutron stars or SNe II in the range of 8-10 solar masses. From the
observations of stars with [Fe/H]=-3 but with high abundances of r-elements, it
is clear that these r-process enrichments cannot represent the composition of
the interstellar medium from which the stars were formed, but must represent
very local contamination from binary companions. Further evidence for very high
enrichments of s-process elements in metal-poor stars also requires binary
systems for explanation. We propose that the accretion-induced collapse (AIC)
of a white dwarf into a neutron star in a binary system may be associated with
the production of the heavy r-nuclei and may provide occasional coupling of
high r-process and high s-process enrichments in the envelopes of low-mass
stars with low [Fe/H]. If we assume that the bulk of the heavy r-nuclei are
produced in AIC events, then these events would have produced about 1.6 billion
neutron stars in the Galaxy.


title: Generation of Compressible Modes in MHD Turbulence

abstract:
  Astrophysical turbulence is magnetohydrodynamic (MHD) in its nature. We
discuss fundamental properties of MHD turbulence. In particular, we discuss the
generation of compressible MHD waves by Alfvenic turbulence and show that this
process is inefficient. This allows us to study the evolution of different
types of MHD perturbations separately.
  We describe how to separate MHD fluctuations into 3 distinct families -
Alfven, slow, and fast modes. We find that the degree of suppression of slow
and fast modes production by Alfvenic turbulence depends on the strength of the
mean field. We show that Alfven modes in compressible regime exhibit scalings
and anisotropy similar to those in incompressible regime. Slow modes passively
mimic Alfven modes. However, fast modes exhibit isotropy and a scaling similar
to that of acoustic turbulence both in high- and low-beta plasmas. We show that
our findings entail important consequences for theories of star formation,
cosmic ray propagation, dynamics of dust, and gamma ray bursts. We anticipate
many more applications of the new insight to MHD turbulence and expect more
revisions of the existing paradigms of astrophysical processes as the field
matures.


title:
The Surface Brightness and Colour-Magnitude Relations for Fornax Cluster
  Galaxies

abstract:
  We present BVI photometry of 190 galaxies in the central region of the Fornax
Cluster observed with the Michigan Curtis Schmidt Telescope. The cluster
members exhibit a strong surface brightness-magnitude relation in our data:
both giant and dwarf ellipticals decrease in surface brightness as luminosity
decreases. However the surface brightness-magnitude relation is no longer a
reliable method for determining cluster membership at surface brightnesses
fainter than 22 mag/sq.arcsec. The newly discovered ultra-compact dwarf
galaxies (UCDs) lie well off the normal surface brightness-magnitude relation.
We present the colour-magnitude relation for a sample of 113 cluster galaxies
as a function of morphological type. The UCDs also lie off the locus of this
relation. Their mean V-I colours are redder than dwarf galaxies of similar
luminosity, but similar to those of globular clusters associated with NGC 1399.
The location of the UCDs on both surface brightness and colour-magnitude plots
supports the hypothesis that they are the remnants of tidally stripped
nucleated dwarf elliptical galaxies.


title:
Determining the Lensing Fraction of SDSS Quasars: Methods and Results
  from the EDR

abstract:
  We present an algorithm for selecting gravitational lens candidates from
amongst Sloan Digital Sky Survey (SDSS) quasars. In median Early Data Release
(EDR) conditions, the algorithm allows for the recovery of pairs of equal flux
point sources down to separations of $\sim 0{\farcs}7$ or with flux ratios up
to $\sim$ 10:1 at a separation of $1\farcs5$. The algorithm also recovers a
wide variety of plausible quad geometries. We also present a method for
determining the selection function of this algorithm through the use of
simulated SDSS images and introduce a method for calibrating our simulated
images through truth-testing with real SDSS data. Finally, we apply our
algorithm and selection function to SDSS quasars from the EDR to get an upper
bound on the lensing fraction. We find 13 candidates among 5120 z $>$ 0.6 SDSS
quasars, implying an observed lensing fraction of not more than 4 $\times
10^{-3}$. There is one likely lens system in our final sample, implying an
observed lensing fraction of not less than $3 \times 10^{-5}$ (95% confidence
levels).


title:
The Deepest and Widest VLBI Survey yet: VLBA+GBT 1.4 GHz observations in
  Bootes

abstract:
  We present preliminary results from the deepest VLBI observations yet
conducted. VLBA+GBT 1.4 GHz observations of a region within NOAO-N, reach an
r.m.s. noise level of 9 microJy per beam. Three sources are clearly detected (>
7 sigma) within the inner 2 arcmins of the GBT primary beam, including two
sub-mJy sources and the ``in-beam'' calibrator. In addition, by tapering the
data, we map out a much larger area of sky, reaching well beyond the half-power
point of the GBT primary beam. An additional 6 sources are detected in the
extended field. We comment briefly on the scientific motivation for even deeper
and wider VLBI surveys, and note that the summed response of sources in the
field will permit self-calibration techniques to be employed in any region of
the radio sky, including so-called ``blank'' fields.


title:
Towards a self-consistent relativistic model of the exterior
  gravitational field of rapidly rotating neutron stars

abstract:
  We present a self-consistent, relativistic model of rapidly rotating neutron
stars describing their exterior gravitational field. This is achieved by
matching the new solution of Einstein's field equations found by Manko et al.
(2000) and the numerical results for the interior of neutron stars with
different equations of state calculated by Cook et al. (1994). This matching
process gives constraints for the choice of the five parameters of the vacuum
solution. Then we investigate some properties of the gravitational field of
rapidly rotating neutron stars with these fixed parameters.


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

abstract:
  We present kinematics of a sample of 107 DA white dwarfs from the SPY project
and discuss kinematic criteria for a distinction of thin disk, thick disk, and
halo populations. This is the first homogeneous sample of white dwarfs for
which 3D space motions have been determined. Studies of white dwarf kinematics
can help determine the fraction of the total mass of our Galaxy contained in
the form of thick disk and halo white dwarfs. Radial velocities and
spectroscopic distances obtained by the SPY project are combined with our
measurements of proper motions to derive 3D space motions. Galactic orbits and
further kinematic parameters are computed. Candidates for thick disk and halo
members are selected in a first step from the classical U-V-velocity diagram.
Our final assignment of population membership is based on orbits and position
in the angular-momentum-eccentricity diagram. We find four halo and twelve
thick disk white dwarfs.


title:
A deep Chandra observation of the cluster environment of the z=1.786
  radio galaxy 3C294

abstract:
  We report the results from a 200 ks Chandra observation of the z=1.786 radio
galaxy 3C294 and its cluster environment, increasing by tenfold our earlier
observation. The diffuse emission, extending about 100 kpc around the nucleus,
has a roughly hourglass shape in the N-S direction with surprisingly sharp
edges to the N and S. The spectrum of the diffuse emission is well fitted by
either a thermal model of temperature 3.5 keV and abundance <0.9 solar
(2-sigma), or a power-law with photon index 2.3. If the emission is due to hot
gas then the sharp edges mean that it is probably not in hydrostatic
equilibrium. Much of the emission is plausibly due to inverse Compton
scattering of the Cosmic Microwave Background (CMB) by nonthermal electrons
produced earlier by the radio source. The required relativistic electrons would
be of much lower energy and older than those responsible for the present radio
lobes. This could account for the lack of detailed spatial correspondence
between the X-rays and the radio emission, the axis of which is at a position
angle of about 45 deg. Hot gas would still be required to confine the
relativistic plasma; the situation could parallel that of the radio bubbles
seen as holes in nearby clusters, except that in 3C294 the bubbles are bright
in X-rays owing to the extreme power in the source and the sixty fold increase
in the energy density of the CMB. The X-ray spectrum of the radio nucleus is
hard, showing a reflection spectrum and iron line. The source is therefore an
obscured radio-loud quasar.


title: A Dynamical Model for the Globular Cluster G1

abstract:
  We present a comparison between the observational data on the kinematical
structure of G1 in M31, obtained with the Hubble WFPC2 and STIS instruments,
and the results of dynamical simulations carried out using the special-purpose
computer GRAPE-6. We have obtained good fits for models starting with single
cluster King-model initial conditions and even better fits when starting our
simulations with a dynamically constructed merger remnant of two star clusters.
In the latter case, the results from our simulations are in excellent agreement
with the observed profiles of luminosity, velocity dispersion, rotation, and
ellipticity. We obtain a mass-to-light ratio of $M/L = 4.0 \pm 0.4$ and a total
cluster mass of $M=(8\pm 1)\times 10^6 M_\odot$. Given that our dynamical model
can fit all available observational data very well, there seems to be no need
to invoke the presence of an intermediate-mass black hole in the center of G1.


title: Constraints on the binary evolution from chirp mass measurements

abstract:
  We estimate the observed distribution of chirp masses of compact object
binaries for the gravitational wave detectors. The stellar binary evolution is
modeled using the {\em StarTrack} population synthesis code. The distribution
of the predicted "observed" chirp masses vary with variation of different
parameters describing stellar binary evolution. We estimate the sensitivity of
the observed distribution to variation of these parameters and show which of
the parameters can be constrained after observing 20, 100, and 500 compact
object mergers. As a general feature of all our models we find that the
population of observed binaries is dominated by the double black hole mergers.


title: Probing the Physics of Interacting Galaxies

abstract:
  Both Arp 140 and Arp 104 reveal extended tidal tails in the HI. The Halpha
and FIR fluxes of Arp 140 yield similar SFR of ~0.8 solar masses per year. In
contrast the Halpha flux of Arp 104 yields a SFR of ~0.05 solar masses per
year, ~ 20 times smaller than that obtained from the FIR flux. Spectra were
used to examine the changing velocity of atomic and molecular gas in NGC 5218
(Arp 104). The atomic and molecular gas were found to be dynamically similar
with comparable velocities and velocity widths across the galaxy; consistent
with the two phases responding similarly to the interaction, or enhanced HI to
CO conversion in the centre of the galaxy.


title: Red giant depletion in globular cluster cores

abstract:
  We investigate the observed depletion of red giants in the cores of
post-core-collapse globular clusters. In particular, the evolutionary scenario
we consider is a binary consisting of two low-mass stars which undergoes two
common envelope phases. The first common envelope phase occurs when the primary
is a red giant resulting in a helium white dwarf and main sequence star in a
detached binary. The second common envelope phase occurs shortly after the
secondary becomes a red giant. During the second common envelope phase the
degenerate helium cores merge resulting in a core mass greater than the helium
burning limit and the formation of a horizontal branch star. We show that this
evolutionary route is enhanced in post-core-collapse clusters by stellar
encounters. These encounters increase the population of binary secondaries
which would have evolved onto the red giant branch in the recent past.


title:
Detection of 20-30 Mpc-scale Galaxy Structures Embedded in 100 Mpc-scale
  Structures of Quasars and MgII Absorbers at z~0.8 and z~1.2

abstract:
  We report the finding of two large-scale structures of galaxies in a 40'x35'
field embedded in a 25deg^2 area where two 100 Mpc-scale structures of quasars
and MgII absorbers at z~0.8 and z~1.2 have been previously detected. Using deep
optical (V- and I-band) imaging, we are able to select high-redshift
(0.5<z<1.3) early-type galaxies as those redder than the cluster red sequence
at z=0.5 and having I<23.5. Through comparison with a 35'x35' control field, we
find a 30% excess of these red galaxies, corresponding to 563 galaxies across
the field. The colour distribution of the excess galaxies shows a coherent peak
at 2.7<V-I<3.1 and the magnitude distribution is well described by a Schechter
function, showing unambiguously that the galaxy excess is primarily due to a
population of early-type galaxies at z=0.83\pm0.08. In follow-up NIR imaging of
the four best cluster candidates, we identify three clusters at z=0.8\pm0.1,
each having well defined red sequences of ~20 galaxies at I-K~3.4, forming a
structure 20 Mpc across. The fourth candidate, corresponding to a previously
identified cluster at z=1.2\pm0.1 is confirmed with 28 K<20.5 galaxies having
VIJK colours consistent with passively-evolving galaxies at z~1.2 located
within 1' of the cluster centre. The results of this study support the presence
of two sheet-like large-scale galaxy structures extending across the 20-30 Mpc
scales explored by the optical data, one ``sheet'' at z~0.8 with three
associated clusters, and a second ``sheet'' at z~1.2 with one embedded cluster.
Our results confirm that, at least inside the probed region, the two known 100
Mpc-scale structures at z~1 of quasars and MgII absorbers also mark out volumes
with an enhanced density of galaxies.


title:
Small scale structure in molecular gas from multi-epoch observations of
  HD 34078

abstract:
  We present spectroscopic observations of the runaway reddened star HD 34078
acquired during the last three years at Observatoire de Haute Provence and
McDonald Observatory as well as other spectra obtained since 1990. The drift of
the line of sight through the foreground cloud due to the large transverse
velocity of HD 34078 allows us to probe the spatial distribution of CH, CH+, CN
and DIBs carriers at scales ranging from about 1 AU up to 150 AU. In
particular, time variations in the equivalent width of absorption lines are
examined. A few past and recent high resolution observations of CH and CH+
absorption are used to search for line profile variations and to convert
equivalent widths into column densities.
  The data set reveals a 20 % increase in CH column density over the past 10
years with no corresponding variation in the column density of CH+ or in the
strengths of the 5780 and 5797 AA DIBs. CN observations indicate that its
excitation temperature has significantly increased from < 3.1 K in 1993 to 3.6
+- 0.17 K in 1998 while the CN column shows only a modest rise of ~ 12 +- 6 %.
The data also strongly suggest the existence of weak correlated variations in
CH and CH+ columns over periods of 6 - 12 months (or ~ 10 AU).
  These results are discussed in relation to CH+ production mechanisms. A dense
newly intervening clump is considered in order to explain the long-term
increase in the column density of CH, but such a scenario does not account for
all observational constraints. Instead, the observations are best described by
CH+ production in a photodissociation region, like that suggested for the
Pleiades and IC 348.


title:
Chandra observations of the neutron star soft X-ray transient
  RXJ170930.2-263927 returning to quiescence

abstract:
  We present our analysis of Chandra observations obtained when the soft X-ray
transient RX J170930.2-263927 (XTE J1709-267) returned to quiescence after an
outburst. Using the type I burst peak luminosity found by Cocchi et al. (1998)
and the value of N_H we derived from our spectral fits, the distance to RX
J170930.2-263927 can be constrained to 2.5-10 kpc. RX J170930.2-263927 is
probably associated with the low-metalicity Globular Cluster NGC 6293, which
has a tidal radius of 14.2 arcminutes, since the projected distance to the
centre of the cluster is approximately 25 parsec (9-10 arcminutes). If the
association is correct, RX J170930.2-263927 would be at ~8.5 kpc. We determined
that L_outburst / L_quiescence is approximately 10^5 for this outburst. If the
quiescent luminosity is caused by cooling of the neutron star core then
enhanced core cooling processes were at work implying a neutron star mass of
\~1.7-1.8 Msun. Combining our Chandra observations with archival ROSAT
observations we show that the source most likely exhibits periods of sustained
low-level accretion. Variable, low-level activity could provide an alternative
explanation for some of the sources in the recently proposed category of faint
soft X-ray transients. We found excess emission at ~0.6 keV. If such an excess
is a unique feature of ultracompact systems, as was recently proposed, RX
J170930.2-263927 must have a short orbital period as well. From the constraints
on the distance and the non-detection of the optical counterpart with m_V<20.5,
we conclude that this system must have a low-mass companion.


title:
A High Angular Resolution View of Hot Gas in Clusters, Groups, and
  Galaxies

abstract:
  We discuss two themes from Chandra and XMM-Newton observations of galaxies,
groups, and clusters. First, we review observational aspects of cluster
formation and evolution as matter accretes along filaments in A85 and A1367. We
describe Chandra observations that probe the later evolutionary phases where
the effects of mergers -- both subsonic and supersonic -- are observed in
cluster cores as ``cold fronts'' and shocks. Second, we review the interactions
between the hot, intracluster gas with relativistic plasma originating in
active nuclei within the dominant galaxy at the cluster center. As examples of
this interaction, we describe the radio and X-ray observations of M87 where
buoyantly rising bubbles transfer energy and matter within the cluster core. We
describe the Chandra observations of ZW3146 which exhibits both multiple cold
fronts and relativistic plasma interactions. Finally, we describe the X-ray
observations of NGC4636 where energy produced by the central AGN imprints a
unique signature on the surrounding hot corona of the galaxy.


title: The Everchanging Pulsating White Dwarf GD358

abstract:
  We report 323 hours of nearly uninterrupted time series photometric
observations of the DBV star GD 358 acquired with the Whole Earth Telescope
(WET) during May 23rd to June 8th, 2000. We acquired more than 232 000
independent measurements. We also report on 48 hours of time-series photometric
observations in Aug 1996. We detected the non-radial g-modes consistent with
degree l=1 and radial order 8 to 20 and their linear combinations up to 6th
order.We also detect, for the first time, a high amplitude l=2 mode, with a
period of 796s. In the 2000 WET data, the largest amplitude modes are similar
to those detected with the WET observations of 1990 and 1994, but the highest
combination order previously detected was 4th order. At one point during the
1996 observations, most of the pulsation energy was transferred into the radial
order k=8 mode, which displayed a sinusoidal pulse shape in spite of the large
amplitude. The multiplet structure of the individual modes changes from year to
year, and during the 2000 observations only the k=9 mode displays clear normal
triplet structure. Even though the pulsation amplitudes change on timescales of
days and years, the eigenfrequencies remain essentially the same, showing the
stellar structure is not changing on any dynamical timescale.


title: Modest-2: A Summary

abstract:
  This is a summary paper of MODEST-2, a workshop held at the Astronomical
Institute ``Anton Pannekoek'' in Amsterdam, 16-17 December 2002. MODEST is a
loose collaboration of people interested in MOdelling DEnse STellar systems,
particularly those interested in modelling these systems using all the
available physics (stellar dynamics, stellar evolution, hydrodynamics and the
interplay between the three) by defining interfaces between different codes. In
this paper, we summarize 1) the main advances in this endeavour since MODEST-1;
2) the main science goals which can be and should be addressed by these types
of simulations; and 3) the most pressing theoretical and modelling advances
that we identified.


title: Modeling the X-ray Contribution of X-ray Binary Jets

abstract:
  Astrophysical jets exist in both XRBs and AGN, and seem to share common
features, particularly in the radio. While AGN jets are known to emit X-rays,
the situation for XRB jets is not so clear. Radio jets have been resolved in
several XRBs in the low/hard state, establishing that some form of outflow is
routinely present in this state. Interestingly, the flat-to-inverted radio
synchrotron emission associated with these outflows strongly correlates with
the X-ray emission in several sources, suggesting that the jet plasma plays a
role at higher frequencies. In this same state, there is increasing evidence
for a turnover in the IR/optical where the flat-to-inverted spectrum seems to
connect to an optically thin component extending into the X-rays. We discuss
how jet synchrotron emission is likely to contribute to the X-rays, in addition
to inverse Compton up-scattering, providing a natural explanation for these
correlations and the turnover in the IR/optical band. We present model
parameters for fits to several sources, and address some common misconceptions
about the jet model.


title: VLT+UVES Spectroscopy of the CaII LoBAL Quasar SDSS J030000.56+004828.0

abstract:
  We study high-resolution spectra of the `overlapping-trough' low-ionization
broad absorption line (LoBAL) quasar SDSS J030000.56+004828.0. The CaII, MgII
and MgI column densities in this object are the largest reported to date for
any BAL outflow. The broad CaII absorption is mildly blended, but the blending
can be disentangled to measure the CaII column density, which is large enough
that the outflow must include a strong hydrogen ionization front. The outflow
begins at a blueshift of ~1650 km/s from the systemic redshift. The lowest
velocity BAL region produces strong CaII absorption but does not produce
significant excited FeII absorption, while the higher velocity excited FeII
absorption region produces very little CaII absorption. We have found that only
a disk wind outflow can explain this segregation. Whether the outflow is smooth
or clumpy, we conclude that the CaII BAL region has a density high enough to
populate excited levels of FeII, but a temperature low enough to prevent them
from being significantly populated. This requirement means the CaII BAL region
has T<1000 K, and perhaps even T<550 K. This quasar also has an associated
absorption line system (AAL) that exhibits partial covering, and therefore is
likely located near the central engine. Its association with the BAL outflow is
unclear. Blending of the AAL with the BAL trough shows that the spatial region
covered by the BAL outflow can vary over velocity differences of ~1700 km/s.


title:
Infrared Emission of Normal Galaxies from 2.5 to 12 Microns: ISO
  Spectra, Near-Infrared Continuum and Mid-Infrared Emission Features

abstract:
  We present ISO-PHOT spectra of the regions 2.5-4.9um and 5.8-11.6um for a
sample of 45 disk galaxies from the U.S. ISO Key Project on Normal Galaxies.
The spectra can be decomposed into three spectral components: (1) continuum
emission from stellar photospheres, which dominates the near-infrared (2.5-
4.9um; NIR) spectral region; (2) a weak NIR excess continuum, which has a color
temperature of ~ 1000K, carries a luminosity of a few percent of the total
far-infrared luminosity L(FIR), and most likely arises from the ISM; and (3)
the well-known broad emission features at 6.2, 7.7, 8.6 and 11.3 um, which are
generally attributed to aromatic carbon particles. These aromatic features in
emission (AFEs) dominate the mid-infrared (5.8-11.6 um; MIR) part of the
spectrum, and resemble the so-called Type-A spectra observed in many
non-stellar sources and the diffuse ISM in our own Galaxy. The relative
strengths of the AFEs vary by 15-25% among the galaxies. However, little
correlation is seen between these variations and either IRAS 60um-to-100um flux
density ratio R(60/100) or the FIR-to-blue luminosity ratio L(FIR)/L(B),
suggesting that the observed variations are not a direct consequence of the
radiation field differences among the galaxies. We demonstrate that the NIR
excess continuum and AFE emission are correlated, suggesting that they are
produced by similar mechanisms and similar (or the same) material. On the other
hand, as the current star-formation activity increases, the overall strengths
of the AFEs and the NIR excess continuum drop significantly with respect to
that of the far-infrared emission from large dust grains. This is likely a
consequence of the preferential destruction in intense radiation fields of the
small carriers responsible for the NIR/AFE emission.


title:
XMM-Newton observations of the Perseus Cluster I: The temperature and
  surface brightness structure

abstract:
  We present preliminary results of the XMM-Newton 50 ksec observation of the
Perseus cluster. The global east/west asymmetry of the gas temperature and
surface brightness distributions, approximately aligned with the chain of
bright galaxies, suggests an ongoing merger, although the modest degree of the
observed asymmetry certainly excludes a major merger interpretation. The chain
of galaxies probably traces the filament along which accretion has started some
time ago and is continuing at the present time. A cold and dense (low entropy)
cluster core like Perseus is probably well "protected" against the penetration
of the gas of infalling groups and poor clusters whereas in non-cooling core
clusters like Coma and A1367, infalling subclusters can penetrate deeply into
the core region. In Perseus, gas associated with infalling groups may be
stripped completely at the outskirts of the main cluster and only compression
waves (shocks) may reach the central regions. We argue that the passage of such
a wave(s) can qualitatively explain the overall horseshoe shaped appearance of
the gas temperature map (the hot horseshoe surrounds the colder, low entropy
core) as well as other features of the Perseus cluster core. As compression
waves traverse the cluster core, they can induce oscillatory motion of the
cluster gas which can generate multiple sharp "edges", on opposite sides or the
central galaxy. Gas motions induced by mergers may be a natural way to explain
the high frequency of "edges" seen in clusters with cooling cores.


title:
Twofold effect of Alfven waves on the transverse gravitational
  instability

abstract:
  This paper is devoted to the study of the gravitational instability of a
medium permeated by a uniform magnetic field along which a circularly polarized
Alfven wave propagates. We concentrate on the case of perturbations purely
transverse to the ambient field by means of direct numerical simulations of the
MHD equations and of a linear stability analysis performed on a moderate
amplitude asymptotic model. The Alfven wave provides an extra stabilizing
pressure when the scale of perturbations is sufficiently large or small
compared with the Jeans length $L_J$. However, there is a band of scales around
$L_J$ for which the Alfven wave is found to have a destabilizing effect. In
particular, when the medium is stable in absence of waves, the gravitational
instability can develop when the wave amplitude lies in an appropriate range.
This effect appears to be a consequence of the coupling between Alfven and
magnetosonic waves. The prediction based on a WKB approach that the Alfven wave
pressure tensor is isotropic and thus opposes gravity in all directions is only
recovered for large amplitude waves for which the coupling between the
different MHD modes is negligible.


title: High Contrast Imaging with Gaussian Aperture Pupil Masks

abstract:
  Gaussian aperture pupil masks (GAPMs) can in theory achieve the contrast
requisite for directly imaging an extrasolar planet. We outline the process of
fabricating and testing a GAPM for use on the Penn State near-IR Imager and
Spectrograph (PIRIS) at the Mt. Wilson 100$^{\prime\prime}$ telescope. We find
that the initial prototype observations are quite successful, achieving a
contrast similar to a traditional Lyot coronagraph witho ut blocking any light
from a central object and useful for finding faint companions to nearby young
solar analogues. In the lab we can reproduce the expected PSF to within an
order of magnitude and with new designs achieve $\sim5 \times 10^{-5}$ contrast
at 10$\lambda/D$.
  We find that small inaccuracies in the mask fabrication process and
insufficient correction of the atmosphere contribute the most degradation to
contrast. Finally we compare the performance of GAPMs and Lyot coronagraphs of
similar throughput.


title: Chandra Observations of Associates of $\eta$ Car: I. Luminosities

abstract:
  The region around the $\eta$ Car nebula has three OB associations, which
contain a Wolf-Rayet star and several massive O3 stars. An early Chandra ACIS-I
image was centered on $\eta$ Car and includes Trumpler 16 and part of Trumpler
14. The Chandra image confirms the well-known result that O and very early B
stars are X-ray sources with L$_X$ $\simeq$ 10$^{-7} \times$ L$_{bol}$ over an
X-ray luminosity range of about 100. Two new anomalously strong X-ray sources
have been found among the hot star population, Tr 16-244, a heavily-reddened O3
I star, and Tr 16-22, a heavily-reddened O8.5 V star. Two stars have an
unusually large L$_X$/L$_{bol}$: HD 93162, a Wolf-Rayet star (and possible
binary), and Tr 16-22, a possible colliding wind binary In addition, a
population of sources associated with cool stars is detected. In the
color-magnitude diagram, these X-ray sources sit above the sequence of field
stars in the Carina arm. The OB stars are on average more X-ray luminous than
the cool star X-ray sources. X-ray sources among A stars have similar X-ray
luminosities to cooler stars, and may be due to cooler companions. Upper limits
are presented for B stars which are not detected in X-rays. These upper limits
are also the upper limits for any cool companions which the hot stars may have.
Hardness ratios are presented for the most luminous sources in bands 0.5 to 0.9
keV, 0.9 to 1.5 keV, and 1.5 to 2.04 kev. The available information on the
binary nature of the hot stars is discussed, but binarity does not correlate
with X-ray strength in a simple way.


title: The Oort Constants Measured from Proper Motions

abstract:
  The Oort constants describe the local variations of the stellar streaming
field. Classically, they are determined from stellar proper motions. We discuss
problems arising in this procedure. A large, hitherto overlooked, source of
systematic error arises from longitudinal variations of the mean stellar
parallax. Together with the solar reflex motion, these variations create
contributions to the longitudinal proper motions mu_l*(l) that are
indistinguishable from the Oort Constants at the 20% level. Fortunately, we can
correct for this "mode mixing" using the latitudinal proper motions mu_b(l). We
use ~10^6 stars from the ACT/Tycho-2 catalogs with proper motion errors of ~ 3
mas/yr. We find significant deviations from expectations based on a smooth
axisymmetric equilibrium disk, in particular non-zero C for old red giant
stars. We also find variations of the Oort constants with the asymmetric drift
of the sub-sample. These correlations are different in nature than those
expected for an axisymmetric Galaxy. The most reliable tracers for the ``true''
Oort constants are red giants, which are old enough to be in equilibrium and
distant enough to be unaffected by possible local anomalies. For these stars we
find, A ~ 16, B ~- 17, A - B ~ 33, and C ~- 10 km/s/kpc with internal errors of
about 1-2 and external error of perhaps the same order. These values are
consistent with our knowledge of the Milky Way (flat rotation curve and Omega=A
- B ~ 28 +/- 2). Based on observations made with the ESA Hipparcos astrometry
satellite. (Abridged)


title:
Discovery of a new radio galaxy within the error box of the unidentified
  gamma-ray source 3EG J1735-1500

abstract:
  We report the discovery of a new radio galaxy within the location error box
of the gamma-ray source 3EG J1735-1500. The galaxy is a double-sided jet source
forming a large angle with the line of sight. Optical observations reveal a V ~
18 magnitude galaxy at the position of the radio core. Although the association
with the EGRET source is not confirmed at the present stage, because there is a
competing, alternative gamma-ray candidate within the location error contours
which is also studied here, the case deserves further attention. The new radio
galaxy can be used to test the recently proposed possibility of gamma-ray
emitting radio galaxies beyond the already known case of Centaurus A.


title: Dust Grain-Size Distributions From MRN to MEM

abstract:
  Employing the Maximum Entropy Method algorithm, we fit interstellar
extinction measurements which span the wavelength range 0.125-3 micron. We
present a uniform set of MEM model fits, all using the same grain materials,
optical constants and abundance constraints. In addition, we are taking
advantage of improved UV and IR data and better estimates of the gas-to-dust
ratio. The model fits cover the entire range of extinction properties that have
been seen in the Galaxy and the Magellanic Clouds. The grain models employed
for this presentation are the simplistic homogeneous spheres models (i.e.,
Mathis, Rumpl, & Nordsieck 1977) with two (graphite, silicate) or three
(graphite, silicate, amorphous carbon) components. Though such usage is only a
first step, the results do provide interesting insight into the use of grain
size as a diagnostic of dust environment. We find that the SMC Bar extinction
curve cannot be fit using carbon grains alone. This is a challenge to the
recent observational result indicating little silicon depletion in the SMC.


title:
A new clue to the transition mechanism between optical high and low
  states of the supersoft X-ray source RX J0513.9-6951, implied from the
  recurrent nova CI Aquilae 2000 outburst model

abstract:
  We have found a new clue to the transition mechanism between optical
high/X-ray off and optical low/X-ray on states of the LMC supersoft X-ray
source RX J0513.9-6951. A sharp ~1 mag drop is common to the CI Aql 2000
outburst. These drops are naturally attributed to cessation of optically thick
winds on white dwarfs. A detailed light-curve analysis of CI Aql indicates that
the size of a disk drastically shrinks when the wind stops. This causes ~1-2
mag drop in the optical light curve. In RX J0513.9-6951, the same mechanism
reproduces sharp ~1 mag drop from optical high to low states. We predict this
mechanism also works on the transition from low to high states. Interaction
between the wind and the companion star attenuates the mass transfer and drives
full cycles of low and high states.


title: Testing the CMB Data for Systematic Effects

abstract:
  Under the assumption that the concordance Lambda cold dark matter (CDM) model
is the correct model, we test the cosmic microwave background (CMB) anisotropy
data for systematic effects by examining the band pass temperature residuals
with respect to this model. Residuals are plotted as a function of l, galactic
latitude, frequency, calibration source, instrument type and several other
variables that may be associated with potential systematic effects. Linear
fitting to the residuals indicates no significant identifiable systematic
errors associated with these variables, except for the case of galactic
latitude. We find evidence for a trend associated with the absolute galactic
latitude range at more than the 2-sigma level. This may be indicative of
galactic contamination and may require a 2% reduction in the normalisation of
low galactic latitude observations.


title: Archetypal analysis of galaxy spectra

abstract:
  Archetypal analysis represents each individual member of a set of data
vectors as a mixture (a constrained linear combination) of the pure types or
archetypes of the data set. The archetypes are themselves required to be
mixtures of the data vectors. Archetypal analysis may be particularly useful in
analysing data sets comprising galaxy spectra, since each spectrum is,
presumably, a superposition of the emission from the various stellar
populations, nebular emissions and nuclear activity making up that galaxy, and
each of these emission sources corresponds to a potential archetype of the
entire data set. We demonstrate archetypal analysis using sets of composite
synthetic galaxy spectra, showing that the method promises to be an effective
and efficient way to classify spectra. We show that archetypal analysis is
robust in the presence of various types of noise.


title: Nebular Abundances of Nearby Southern Dwarf Galaxies

abstract:
  The results of optical spectroscopy of H II regions in a sample of southern
dwarf irregulars consisting of five dwarf galaxies in the Centaurus A group,
four dwarfs in the Sculptor group, and eight additional dwarf galaxies are
presented. Oxygen abundances are derived using the direct method where [O
III]4363 is detected; otherwise, abundances are derived with the bright-line
method using the McGaugh and the Pilyugin calibrations. ESO358-G060 has the
lowest oxygen abundance (12+log(O/H) = 7.32), which is comparable to the value
for the second most metal-poor galaxy known (SBS0335-052). In all, new oxygen
abundances are reported for nine dwarf galaxies; updated values are presented
for the remaining galaxies. Derived oxygen abundances are in the range from 3%
to 26% of the solar value. Oxygen abundances for dwarfs in the southern sample
are consistent with the metallicity-luminosity relationship defined by a
control sample of dwarf irregulars with [O III]4363 abundances and
well-measured distances. However, NGC5264 appears to have an (upper branch)
oxygen abundance approximately two to three times higher than other dwarfs at
similar luminosities. Nitrogen-to-oxygen and neon-to-oxygen abundance ratios
are also reported; in particular, IC1613 and IC5152 show elevated
nitrogen-to-oxygen ratios for their oxygen abundances.


title: Digital Deblurring of CMB Maps: Performance and Efficient Implementation

abstract:
  Digital deblurring of images is an important problem that arises in
multifrequency observations of the Cosmic Microwave Background (CMB) where,
because of the width of the point spread functions (PSF), maps at different
frequencies suffer a different loss of spatial resolution. Deblurring is useful
for various reasons: first, it helps to restore high frequency components lost
through the smoothing effect of the instrument's PSF; second, emissions at
various frequencies observed with different resolutions can be better studied
on a comparable resolution; third, some map-based component separation
algorithms require maps with similar level of degradation. Because of
computational efficiency, deblurring is usually done in the frequency domain.
But this approach has some limitations as it requires spatial invariance of the
PSF, stationarity of the noise, and is not flexible in the selection of more
appropriate boundary conditions. Deblurring in real space is more flexible but
usually not used because of its high computational cost. In this paper (the
first in a series on the subject) we present new algorithms that allow the use
of real space deblurring techniques even for very large images. In particular,
we consider the use of Tikhonov deblurring of noisy maps with applications to
{\it PLANCK}. We provide details for efficient implementations of the
algorithms. Their performance is tested on Gaussian and non-Gaussian simulated
CMB maps, and PSFs with both circular and elliptical symmetry. Matlab code is
made available.


title: Young Stars in the Outer HI Disc of NGC 6822

abstract:
  We present wide-field optical imaging covering the entire neutral hydrogen
disc of the Local Group dwarf galaxy NGC 6822. These observations reveal the
presence of numerous blue, young stars at large galactocentric radii well
beyond R_25. Blue stars are also found that are associated with NGC 6822's
companion HI cloud, indicating that star formation was triggered in the
companion in the last 10^8 yr. In general, blue stars are present where the HI
surface densities reach values > 5 x 10^20 cm^(-2). However, over one-third of
the blue stars detected are found at lower surface densities. The young stars
trace the distribution of the neutral hydrogen surprisingly well, but seem to
be avoiding the supergiant HI shell in NGC 6822, setting a lower limit for its
age of 10^8 yr. The extended distribution of young stars implies that stars can
form at large galactocentric radii in dwarf galaxies; the HI is therefore not
necessarily much more extended than the stellar population. This finding has
important consequences for the chemical enrichment of the interstellar medium
throughout (dwarf) galaxies


title: Stellar Rotation from GAIA Spectra

abstract:
  Stellar rotation influences our understanding of stellar structure and
evolution, binary systems, clusters etc. and therefore the benefits of a large
and highly accurate database on stellar rotation, obtained by GAIA, will be
manifold.
  To study the prospects of GAIA measurement of projected rotational velocities
v_rot sin i, we use synthetic stellar spectra to simulate the determination of
v_rot sin i at different resolutions (R=5000 - 20000) and S/N (10-300). Results
on the accuracy of v_rot sin i, presented here, show that GAIA will be capable
to measure also low rotational velocities (~10 km/s), provided that the
resolution is higher than 10.000, or preferably even higher.


title: Large-scale HI structures and the origin of radio galaxies

abstract:
  We present the first results of a study aimed to detect large HI structures
in radio galaxies. In two of the three cases presented (Coma A and B2 0648+27),
the detection of a large amount of HI distributed over several tens of kpc
suggests a major merger as origin of the observed system and allows to infer
when this merger must have occurred. The situation is less clear for the third
object (3C 433). We propose an evolutionary sequence for one of the radio
galaxies studied. The implications of this study of neutral hydrogen in nearby
radio galaxies for high-z objects and ``normal'' (i.e. radio-quiet) elliptical
galaxies are also discussed.


title:
On the statistical significance of the GZK feature in the spectrum of
  ultra high energy cosmic rays

abstract:
  The nature of the unknown sources of ultra-high energy cosmic rays can be
revealed through the detection of the GZK feature in the cosmic ray spectrum,
resulting from the production of pions by ultra-high energy protons scattering
off the cosmic microwave background. Here we show that the GZK feature cannot
be accurately determined with the small sample of events with energies $\sim
10^{20}$ eV detected thus far by the largest two experiments, AGASA and HiRes.
With the help of numerical simulations for the propagation of cosmic rays, we
find the error bars around the GZK feature are dominated by fluctuations which
leave a determination of the GZK feature unattainable at present. In addition,
differing results from AGASA and HiRes suggest the presence of $\sim 30%$
systematic errors that may be due to discrepancies in the relative energy
determination of the two experiments. Correcting for these systematics, the two
experiments are brought into agreement at energies below $\sim 10^{20}$ eV.
After simulating the GZK feature for many realizations and different injection
spectra, we determine the best fit injection spectrum required to explain the
observed spectra at energies above $10^{18.5}$ eV. We show that the discrepancy
between the two experiments at the highest energies has low statistical
significance (at the 2 $\sigma$ level) and that the corrected spectra are best
fit by an injection spectrum with spectral index $\sim 2.6$. Our results
clearly show the need for much larger experiments such as Auger, EUSO, and OWL,
that can increase the number of detected events by 2 orders of magnitude. Only
large statistics experiments can finally prove or disprove the existence of the
GZK feature in the cosmic ray spectrum.


title: Chaos in Turbulence Driven by the Magnetorotational Instability

abstract:
  Chaotic flow is studied in a series of numerical magnetohydrodynamical
simulations that use the shearing box formalism. This mimics important features
of local accretion disk dynamics. The magnetorotational instability gives rise
to flow turbulence, and quantitative chaos parameters, such as the largest
Lyapunov exponent, can be measured. Linear growth rates appear in these
exponents even when the flow is fully turbulent. The extreme sensitivity to
initial conditions associated with chaotic flows has practical implications,
the most important of which is that hundreds of orbital times are needed to
extract a meaningful average for the stress. If the evolution time in a disk is
less than this, the classical $\alpha$ formalism will break down.