title:
Massive Star Formation Rates and Radial Distributions from Halpha
  Imaging of 84 Virgo Cluster and Isolated Spiral Galaxies

abstract:
  The massive star formation properties of 55 Virgo Cluster and 29 isolated
S0-Scd bright (M(B) < -18) spiral galaxies are compared via analyses of R and
Halpha surface photometry and integrated fluxes as functions of Hubble type and
central R light concentration (bulge-to-disk ratio). In the median, the total
normalized massive star formation rates (NMSFRs) in Virgo Cluster spirals are
reduced by factors up to 2.5 compared to isolated spiral galaxies of the same
type or concentration, with a range from enhanced (up to 2.5 times) to strongly
reduced (up to 10 times). Within the inner 30% of the optical disk, Virgo
Cluster and isolated spirals have similar ranges in NMSFRs, with similar to
enhanced median NMSFRs for Virgo galaxies. NMSFRs in the outer 70% of the
optical disk are reduced in the median by factors up to 9 for Virgo Cluster
spirals, with more severely reduced star formation at progressively larger disk
radii. Thus the reduction in total star formation of Virgo Cluster spirals is
caused primarily by spatial truncation of the star-forming disks. The
correlation between HI deficiency and R light central concentration is much
weaker than the correlation between HI deficiency and Hubble type. ICM-ISM
stripping of the gas from spiral galaxies is likely responsible for the
truncated star-forming disks of Virgo Cluster spirals. This effect may be
responsible for a significant part of the morphology-density relationship.


title: MHD Simulations of Bondi Accretion to a Star in the "Propeller" Regime

abstract:
  This work investigates Bondi accretion to a rotating magnetized star in the
"propeller" regime using axisymmetric resistive, magnetohydrodynamic
simulations. In this regime accreting matter tends to be expelled from the
equatorial region of the magnetosphere where the centrifugal force on matter
rotating with the star exceeds the gravitational force. The regime is predicted
to occur if the magnetospheric radius larger than the corotation radius and
less than the light cylinder radius. The simulations show that accreting
matters is expelled from the equatorial region of the magnetosphere and that it
moves away from the star in a supersonic, disk-shaped outflow. At larger radial
distances the outflow slows down and becomes subsonic. The equatorial matter
outflow is initially driven by the centrifugal force, but at larger distances
the pressure gradient becomes significant. We find that the star is spun-down
mainly by the magnetic torques at its surface with the rate of loss of angular
momentum $\dot{L}$ proportional to $-\Omega_*^{1.3}\mu^{0.8}$, where $\Omega_*$
is the star's rotation rate and $\mu$ is its magnetic moment. Further, we find
that $\dot{L}$ is approximately independent of the magnetic diffusivity of the
plasma $\eta_m$. The fraction of the Bondi accretion rate which accretes to the
surface of the star is found to be
$\propto\Omega_*^{-1.0}\mu^{-1.7}\eta_m^{0.4}$. Predictions of this work are
important for the observability of isolated old neutron stars and for wind fed
pulsars in X-ray binaries.


title: The SNAP Telescope

abstract:
  The SuperNova/Acceleration Probe (SNAP) mission will require a two-meter
class telescope delivering diffraction limited images spanning a one degree
field in the visible and near infrared wavelength regime. This requirement,
equivalent to nearly one billion pixel resolution, places stringent demands on
its optical system in terms of field flatness, image quality, and freedom from
chromatic aberration.
  We discuss the advantages of annular-field three-mirror anastigmat (TMA)
telescopes for applications such as SNAP, and describe the features of the
specific optical configuration that we have baselined for the SNAP mission. We
discuss the mechanical design and choice of materials for the telescope. Then
we present detailed ray traces and diffraction calculations for our baseline
optical design. We briefly discuss stray light and tolerance issues, and
present a preliminary wavefront error budget for the SNAP Telescope. We
conclude by describing some of tasks to be carried out during the upcoming SNAP
research and development phase.


title: Overview of the SuperNova/Acceleration Probe (SNAP)

abstract:
  The SuperNova / Acceleration Probe (SNAP) is a space-based experiment to
measure the expansion history of the Universe and study both its dark energy
and the dark matter. The experiment is motivated by the startling discovery
that the expansion of the Universe is accelerating. A 0.7 square-degree imager
comprised of 36 large format fully-depleted n-type CCD's sharing a focal plane
with 36 HgCdTe detectors forms the heart of SNAP, allowing discovery and
lightcurve measurements simultaneously for many supernovae. The imager and a
high-efficiency low-resolution integral field spectrograph are coupled to a 2-m
three mirror anastigmat wide-field telescope, which will be placed in a
high-earth orbit. The SNAP mission can obtain high-signal-to-noise calibrated
light-curves and spectra for over 2000 Type Ia supernovae at redshifts between
z=0.1 and 1.7. The resulting data set can not only determine the amount of dark
energy with high precision, but test the nature of the dark energy by examining
its equation of state. In particular, dark energy due to a cosmological
constant can be differentiated from alternatives such as "quintessence", by
measuring the dark energy's equation of state to an accuracy of +/-0.05, and by
studying its time dependence.


title:
A Cold Front in A3667: Hydrodynamics and Magnetic Field in the
  Intracluster Medium

abstract:
  This conference presentation discusses a Chandra observation of the cold
front in Abell 3667. We first review our earlier results which include a
measurement of the front velocity, M~1, using the ratio of exterior and
interior gas pressures; observations of the hydrodynamic effects expected for a
transonic front motion (weak bow shock and gas compression near the leading
edge of the front); direct observation of the suppressed diffusion across the
front, and estimate of the magnetic field strength near the front from
suppression of the Kelvin-Helmholtz instabilities.
  The new results include using the 2-dimensional brightness distribution
inside the cold front (a) to show that the front is stable and (b) to map the
mass distribution in the gas cloud. This analysis confirms the existence of a
dark matter subcluster traveling with the front. We also fix an algebraic error
in our published calculations for the growth rate of the KH instability and
discuss an additional effect which could stabilize the front against the
small-scale perturbations. These updates only strengthen our conclusions
regarding the importance of the magnetic fields for the front dynamics.


title: New subdwarf B star periods

abstract:
  Subdwarf B (sdB) stars are thought to be helium burning stars with low mass
hydrogen envelopes. Several evolutionary paths have been proposed to explain
the formation of these systems. One of these scenarios is the evolution of the
sdB progenitor within a binary system. We have looked systematically at bright
sdB stars from the PG survey. By taking spectra at several different epochs we
have measured the radial velocity shifts caused by the motion of the sdB star
within the binary. Our data have been taken over a long time base line (2
years) which allowed us to find longer period binaries than known before. Here
we present results for 29 sdB systems.


title:
Second Parameter Globulars and Dwarf Spheroidals around the Local Group
  Massive Galaxies: What Can They Evidence?

abstract:
  We suggest that the majority of the "young", so--called "second parameter"
globular clusters (SPGCs) have originated in the outer Galactic halo due to a
process other than a tidal disruption of the dwarf spheroidal (dSph) galaxies.
Basic observational evidence regarding both the dSphs and the SPGCs, coupled
with the latest data about a rather large relative number of such clusters
among globulars in M33 and their low portion in M31, seems to be consistent
with the suspected process. It might have taken place within the system of the
most massive galaxies of the Local Group (LG) at the earliest stages of their
formation and evolution. We argue that the origin and basic characteristics of
the SPGCs can naturally be explained as a result of mass outflow from M31,
during and due to formation of its Pop. II stars, and subsequent accretion of
gas onto its massive companions, the Galaxy and M33. An amount of the gas
accreted onto the Milky Way is expected to have been quite enough for the
formation in the outer Galactic halo not only of the clusters under
consideration but also a number of those dSph galaxies which are as young as
the SPGCs. A less significant, but notable mass transfer from the starbursting
protoGalaxy to the massive members of the LG might have occurred, too.


title: Line-driven winds in presence of strong gravitational fields

abstract:
  We propose a general physical mechanism which could contribute to the
formation of fast line-driven outflows at the vicinity of strong gravitational
field sources. We argue that the gradient of the gravitational potential plays
the same role as the velocity gradient plays in Sobolev approximation. Both
Doppler effect and gravitational redshifting are taken into account in Sobolev
approximation. The radiation force becomes a function of the local velocity
gradient and the gradient of the gravitational potential. The derived equation
of motion has a critical point that is different from that of CAK. A solution
that is continuous through the singular point is obtained numerically. A
comparison with CAK theory is presented. It is shown that the developed theory
predicts terminal velocities which are greater than those obtained from the CAK
theory.


title: Palomar 5 and its tidal tails: New observational results

abstract:
  Sloan Digital Sky Survey data for the field of the globular cluster Pal 5
reveal the existence of a long massive stream of tidal debris spanning an arc
of 10 degrees on the sky. Pal 5 thus provides an outstanding example for tidal
disruption of globular clusters in the Milky Way. Radial velocities from VLT
spectra show that Pal 5 has an extremely low velocity dispersion, in accordance
with the very low mass derived from its total luminosity.


title: IceCube - the next generation neutrino telescope at the South Pole

abstract:
  IceCube is a large neutrino telescope of the next generation to be
constructed in the Antarctic Ice Sheet near the South Pole. We present the
conceptual design and the sensitivity of the IceCube detector to predicted
fluxes of neutrinos, both atmospheric and extra-terrestrial. A complete
simulation of the detector design has been used to study the detector's
capability to search for neutrinos from sources such as active galaxies, and
gamma-ray bursts.


title: The Liverpool-Edinburgh High Proper Motion Survey

abstract:
  We present a catalogue of 6206 stars which have proper motions exceeding 0.18
arcsec/yr with an R-band faint magnitude limit of 19.5 mag. This catalogue has
been produced using SuperCOSMOS digitized R-Band ESO and UK Schmidt Plates in
131 Schmidt fields covering more than 3,000 square degrees (> 7.5% of the whole
sky) at the South Galactic Cap. The survey is > 90% complete within the nominal
limits of the Luyten Two Tenths Catalogue of m_R < 18.5 mag and 0.2 < mu <
2.5arcsec/yr, and is > 80% complete for m_R < 19.5 mag and mu < 2.5arcsec/yr.


title: Dwarf Sphs/First-galaxies connection

abstract:
  I analyze the properties of the first galaxies in cosmological simulations
with radiative feedback. Preliminary results indicate similarities with the
observed properties of the bulk of dwarf spheroidal galaxies (dSphs) in the
Local Group and Andromeda. I briefly discuss observational tests that could
help in understanding the impact of a population of small primordial objects on
the cosmic evolution.


title: Some effects of small-scale metallicity variations in cooling flows

abstract:
  In an attempt to reconcile recent spectral data with predictions of the
standard cooling flow model, it has been suggested that the metals in the
intracluster medium (ICM) might be distributed inhomogeneously on small scales.
We investigate the possible consequences of such a situation within the
framework of the cooling flow scenario. Using the standard isobaric cooling
flow model, we study the ability of such metallicity variations to
preferentially suppress low-temperature line emission in cooling flow spectra.
We then use simple numerical simulations to investigate the temporal and
spatial evolution of the ICM when the metals are distributed in such a fashion.
Simulated observations are used to study the constraints real data can place on
conditions in the ICM. The difficulty of ruling out abundance variations on
small spatial scales with current observational limits is emphasized. We find
that a bimodal distribution of metals may give rise to interesting effects in
the observed abundance profile, in that apparent abundance gradients with
central abundance drops and off-centre peaks, similar to those seen recently in
some clusters, are produced. Different elements behave in different fashion as
governed by the temperature dependence of their equivalent widths. Our overall
conclusion is that, whilst this process alone seems unlikely to be able to
account for the sharp reduction in low temperature emission lines seen in
current spectral data, a contribution at some level is possible and difficult
to rule out. The possibility of small-scale metallicity variations should be
considered when analysing high resolution cluster X-ray spectra.


title:
Application of Monte Carlo Algorithms to the Bayesian Analysis of the
  Cosmic Microwave Background

abstract:
  Power spectrum estimation and evaluation of associated errors in the presence
of incomplete sky coverage; non-homogeneous, correlated instrumental noise; and
foreground emission is a problem of central importance for the extraction of
cosmological information from the cosmic microwave background. We develop a
  Monte Carlo approach for the maximum likelihood estimation of the power
spectrum. The method is based on an identity for the Bayesian posterior as a
marginalization over unknowns. Maximization of the posterior involves the
computation of expectation values as a sample average from maps of the cosmic
microwave background and foregrounds given some current estimate of the power
spectrum or cosmological model, and some assumed statistical characterization
of the foregrounds. Maps of the CMB are sampled by a linear transform of a
Gaussian white noise process, implemented numerically with conjugate gradient
descent. For time series data with N_{t} samples, and N pixels on the sphere,
the method has a computational expense $KO[N^{2} +- N_{t} +AFw-log N_{t}],
where K is a prefactor determined by the convergence rate of conjugate gradient
descent. Preconditioners for conjugate gradient descent are given for scans
close to great circle paths, and the method allows partial sky coverage for
these cases by numerically marginalizing over the unobserved, or removed,
region.


title: Transit Target Selection Using Reduced Proper Motions

abstract:
  In searches for planetary transits in the field, well over half of the survey
stars are typically giants or other stars that are too large to permit
straightforward detection of planets. For all-sky searches of bright V<~11
stars, the fraction is ~90%. We show that the great majority of these
contaminants can be removed from the sample by analyzing their reduced proper
motions (RPMs): giants have much lower RPMs than dwarfs of the same color. We
use Hipparcos data to design a RPM selection function that eliminates most
evolved stars, while rejecting only 9% of viable transit targets. Our method
can be applied using existing or soon-to-be-released all-sky data to stars
V<12.5 in the northern hemisphere and V<12 in the south. The method degrades at
fainter magnitudes, but does so gracefully. For example, at V=14 it can still
be used to eliminate giants redward of V-I~0.95, that is, the blue edge of the
red giant clump.


title: The Black Hole Masses and Host Galaxies of BL Lac Objects

abstract:
  We have measured the central stellar velocity dispersion in the host galaxies
of 11 BL Lac objects with redshifts z <= 0.125. The range of velocity
dispersions, 170-370 km/s, is similar to that of nearby radio galaxies. Using
the correlation between stellar velocity dispersion and black hole mass defined
for nearby galaxies, we derive estimates of the black hole masses in the range
10^7.9 - 10^9.2 solar masses. We do not find any significant difference between
the black hole masses in high-frequency-peaked and low-frequency-peaked BL Lac
objects. Combining the velocity dispersions with previously measured host
galaxy structural parameters, we find that the host galaxies lie on the
fundamental plane of elliptical galaxies. This supports the conclusions of
imaging studies that the majority of BL Lac hosts are normal giant ellipticals.


title: Lyman Break Galaxies and the Lyman-alpha Forest

abstract:
  We use hydrodynamic simulations to predict correlations between Lya forest
absorption and galaxies at redshift z~3. The probability distribution function
(PDF) of Lya flux decrements shifts systematically towards higher values in the
vicinity of galaxies, reflecting the overdense environments in which these
galaxies reside. The predicted signal remains strong in spectra smoothed over
50-200 km/s, allowing tests with moderate resolution quasar spectra. The strong
bias of high redshift galaxies towards high density regions imprints a clear
signature on the flux PDF, but the predictions are not sensitive to galaxy
baryon mass or star formation rate, and they are similar for galaxies and for
dark matter halos. The dependence of the flux PDF on galaxy proximity is
sensitive to redshift determination errors, with rms errors of 150-300 km/s
substantially weakening the predicted trends. On larger scales, the mean galaxy
overdensity in a cube of 5 or 10 Mpc/h (comoving) is strongly correlated with
the mean Lya flux decrement on a line of sight through the cube center. The
slope of the correlation is ~3 times steeper for galaxies than for dark matter
as a result of galaxy bias. The predicted large scale correlation is in
qualitative agreement with recently reported observational results. However,
observations also show a drop in absorption in the immediate vicinity of
galaxies, which our models do not predict even if we allow the galaxies or AGNs
within them to be ionizing sources. This decreased absorption could be a
signature of galaxy feedback on the surrounding IGM, perhaps via galactic
winds. Peculiar velocities often allow gas at comoving distances ~1.5 Mpc/h to
produce saturated absorption at the galaxy redshift, so any feedback mechanism
must suppress neutral hydrogen out to these radii to match the data. (Abridged)


title:
A Study of the Direct-Fitting Method for Measurement of Galaxy Velocity
  Dispersions

abstract:
  We have measured the central stellar velocity dispersions of 33 nearby spiral
and elliptical galaxies, using a straightforward template-fitting algorithm
operating in the pixel domain. The spectra, obtained with the Double
Spectrograph at Palomar Observatory, cover both the Ca triplet and the Mg b
region, and we present a comparison of the velocity dispersion measurements
from these two spectral regions. Model fits to the Ca triplet region generally
yield good results with little sensitivity to the choice of template star. In
contrast, the Mg b region is more sensitive to template mismatch and to details
of the fitting procedure such as the order of a polynomial used to match the
continuum shape of the template to the object. As a consequence of the
correlation of the [Mg/Fe] ratio with velocity dispersion, it is difficult to
obtain a satisfactory model fit to the Mg b lines and the surrounding Fe blends
simultaneously, particularly for giant elliptical galaxies with large velocity
dispersions. We demonstrate that if the metallicities of the galaxy and
template star are not well matched, then direct template-fitting results are
improved if the Mg b lines themselves are excluded from the fit and the
velocity dispersion is determined from the surrounding weaker lines.


title: Supernova remnants and gamma-ray sources

abstract:
  A review of the possible relationship between gamma-ray sources and supernova
remnants (SNRs) is presented. Particular emphasis is given to the analysis of
the observational status of the problem of cosmic ray acceleration at SNR shock
fronts. All positional coincidences between SNRs and unidentified gamma-ray
sources listed in the Third EGRET Catalog at low Galactic latitudes are
discussed on a case by case basis. For several coincidences of particular
interest, new CO(J=1-0) and radio continuum maps are shown, and the mass
content of the SNR surroundings is determined. The contribution to the
gamma-ray flux observed that might come from cosmic ray particles (particularly
nuclei) locally accelerated at the SNR shock fronts is evaluated. We discuss
the prospects for future research in this field and remark on the possibilities
for observations with forthcoming gamma-ray instruments.


title:
Origins of the Highly Ionized Gas along the Line of Sight towards HD
  116852

abstract:
  We present Hubble Space Telescope Imaging Spectrograph (HST/STIS) and Far
Ultraviolet Spectroscopic Explorer (FUSE) observations of high ion interstellar
absorption along the sight line to HD 116852. At a distance of 4.8 kpc, HD
116852 is an O9 III star lying in the low Galactic halo, -1.3 kpc from the
plane of the Galaxy in the direction l = 304.9, b = -16.1. The STIS E140H
grating observations provide high-resolution (FWHM = 2.7 km/s) spectra of the
resonance doublets of Si IV, C IV, and N V. These data are complemented by
medium-resolution (FWHM = 20 km/s) FUSE spectra of O VI. We find evidence for
three distinct types of highly ionized gas present in the data. First, two
narrow absorption components are resolved in the Si IV and C IV profiles, at
approximate LSR velocities of -36 and -10 km/s. These narrow components appear
to be produced in gas associated with the Norma and Sagittarius spiral arms, at
approximate z-distances of -1.0 and -0.5 kpc, respectively. Second, we detect
an intermediate-width component in C IV and Si IV, at 17 km/s, which we propose
could arise at the conductive interface at the boundary between a low column
density neutral or weakly ionized cloud and the surrounding hot medium.
Finally, a broad collisionally ionized component of gas responsible for
producing the smooth N V and O VI profiles is observed; such absorption is also
present to a lesser degree in the profiles of Si IV and C IV. The broad O VI
absorption is observed at a velocity displaced from the broad C IV component by
almost 20 km/s, an amount large enough to suggest that the two ions may not
co-exist in the same physical location.


title:
CMB Anisotropy Constraints on Flat-Lambda and Open CDM Cosmogonies from
  DMR, UCSB South Pole, Python, ARGO, MAX, White Dish, OVRO, and SuZIE Data

abstract:
  We use joint likelihood analyses of combinations of fifteen cosmic microwave
background (CMB) anisotropy data sets from the DMR, UCSB South Pole 1994,
Python I--III, ARGO, MAX 4 and 5, White Dish, OVRO, and SuZIE experiments to
constrain cosmogonies. We consider open and spatially-flat-Lambda cold dark
matter cosmogonies, with nonrelativistic-mass density parameter Omega_0 in the
range 0.1--1, baryonic-mass density parameter Omega_B in the range
(0.005--0.029) h^{-2}, and age of the universe t_0 in the range (10--20) Gyr.
  Marginalizing over all parameters but Omega_0, the data favor Omega_0 \simeq
0.9--1 (0.4--0.6) flat-Lambda (open) models. The range in deduced Omega_0
values is partially a consequence of the different combinations of
smaller-angular-scale CMB anisotropy data sets used in the analyses, but more
significantly a consequence of whether the DMR quadrupole moment is accounted
for or ignored in the analysis. For both flat-Lambda and open models, after
marginalizing over all other parameters, a lower Omega_B h^2 \simeq
0.005--0.009 is favored. This is also marginally at odds with estimates from
more recent CMB anisotropy data and some estimates from standard
nucleosynthesis theory and observed light element abundances. For both sets of
models a younger universe with t_0 \simeq 12--15 Gyr is favored, consistent
with other recent non-CMB indicators. We emphasize that since we consider only
a small number of data sets, these results are tentative. More importantly, the
analyses here do not rule out the currently favored flat-Lambda model with
Omega_0 \sim 0.3, nor the larger Omega_B h^2 values favored by some other data.


title: Sub-Subgiants in the Old Open Cluster M67?

abstract:
  We report the discovery of two spectroscopic binaries in the field of the old
open cluster M67 -- S1063 and S1113 -- whose positions in the color-magnitude
diagram place them approximately 1 mag below the subgiant branch. A ROSAT study
of M67 independently discovered these stars to be X-ray sources. Both have
proper-motion membership probabilities greater than 97%; precise center-of-mass
velocities are consistent with the cluster mean radial velocity. S1063 is also
projected within one core radius of the cluster center. S1063 is a single-lined
binary with a period of 18.396 days and an orbital eccentricity of 0.206. S1113
is a double-lined system with a circular orbit having a period of 2.823094
days. The primary stars of both binaries are subgiants. The secondary of S1113
is likely a 0.9 Mo main-sequence star, which implies a 1.3 Mo primary star. We
have been unable to explain securely the low apparent luminosities of the
primary stars; neither binary contain stars presently limited in radius by
their Roche lobes. We speculate that S1063 and S1113 may be the products of
close stellar encounters involving binaries in the cluster environment, and may
define alternative stellar evolutionary tracks associated with mass-transfer
episodes, mergers, and/or dynamical stellar exchanges.


title: CMB observations using the SKA

abstract:
  We examine the prospects for observations of CMB anisotropy with the SKA; we
discuss the advantages of interferometric SKA imaging, observing strategies,
calibration issues and the achievable sensitivity. Although the SKA will
probably operate at cm wavelengths, where discrete source confusion dominates
the CMB anisotropy, its extreme sensitivity to point sources will make it
possible to subtract the source contamination at these wavelengths and thereby
image the low surface brightness CMB anisotropies on small angular scales. The
SKA, operating at 10-20 GHz, may usefully make high-l observations of the CMB
anisotropy spectrum and survey the sky for Sunyaev-Zeldovich decrements.


title: A Case for Renewed Activity in the Giant Radio Galaxy J0116-473

abstract:
  We present ATCA radio observations of the giant radio galaxy J0116-473 at 12
and 22 cm wavelengths in total intensity and polarization. The images clearly
reveal a bright inner-double structure within more extended edge-brightened
lobe emission. The lack of hotspots at the ends of the outer lobes, the strong
core and the inner-double structure with its edge-brightened morphology lead us
to suggest that this giant radio galaxy is undergoing a renewed nuclear
activity: J0116-473 appears to be a striking example of a radio galaxy where a
young double source is evolving within older lobe material. We also report the
detection of a Mpc-long linear feature which is oriented perpendicular to the
radio axis and has a high fractional polarization.


title:
Infrared study of the eta Chamaeleontis cluster and the longevity of
  circumstellar discs

abstract:
  We have analyzed JHKL observations of the stellar population of the ~9
Myr-old eta Chamaeleontis cluster. Using infrared (IR) colour-colour and
colour-excess diagrams, we find the fraction of stellar systems with near-IR
excess emission is 0.60 pm 0.13 (2_sigma). This results implies considerably
longer disc lifetimes than found in some recent studies of other young stellar
clusters. For the classical T Tauri (CTT) and weak-lined T Tauri (WTT) star
population, we also find a strong correlation between the IR excess and H_alpha
emission. The IR excesses of these stars indicate a wide range of star-disc
activity; from a CTT star showing high levels of accretion, to CTT - WTT
transition objects with evidence for some on-going accretion, and WTT stars
with weak or absent IR excesses. Of the 15 known cluster members, 4 stars with
IR excesses delta(K-L) > 0.4 mag are likely experiencing on-going accretion
owing to strong or variable optical emission. The resulting accretion fraction
(0.27 pm 0.13; 2_sigma) shows that the accretion phase, in addition to the
discs themselves, can endure for at least ~10 Myr.


title:
Radiation drag effects on magnetically dominated outflows around compact
  objects

abstract:
  The effects of radiation drag force on the structure of relativistic
electron-positron and electron-proton outflows are considered within the
one-fluid approximation for quasi-monopole cold outflow. It is shown that for a
Poynting-dominated case the drag force does not change the particle energy
inside the fast magnetosonic surface. In this region the action of the drag
results in a diminishing of the Poynting flux, not the particle flux. Outside
the fast magnetosonic surface, for intermediate photon density the drag force
may result in additional acceleration of the plasma. This acceleration is a
result of the disturbance of magnetic surfaces under the action of the drag. At
even larger distances particles are not frozen into the magnetic field and the
drag force decelerates them efficiently.
  In the case of extreme photon densities, the disturbance of magnetic surfaces
becomes large and the drag force changes the total energy flux significantly,
the particles becoming nonrelativistic.
  We find that for Active Galactic Nuclei the photon density is too low to
disturb the parameters of an ideal MHD outflow. The drag action may result in
additional acceleration of outgoing plasma only for central engines with very
high luminosities. For cosmological gamma-ray bursts the drag force can
strongly affect the process of formation of a Poynting-dominated outflow.


title: Surface Brightness Fluctuations: a theoretical point of view

abstract:
  We present new theoretical evaluations of optical and near-IR Surface
Brightness Fluctuations (SBF) magnitudes for single-burst stellar populations
in the age range t=5-15 Gyr and metallicity from $Z_{\sun}/200$ to $2Z_{\sun}$.
Our theoretical predictions can be successfully used to derive reliable
distance evaluations. They also appear to be a new and valuable tool to trace
the properties of unresolved stellar populations.


title: Some clues on the tilt of the Horizontal Branches in metal-rich clusters

abstract:
  We discuss some clues on the large tilt observed in the Horizontal Branch of
the metal-rich galactic globular clusters NGC 6388 and NGC 6441. This not yet
understood feature is investigated from theoretical and observational sides.


title:
Stability analysis of relativistic jets from collapsars and its
  implications on the short-term variability of gamma-ray bursts

abstract:
  We consider the transverse structure and stability properties of relativistic
jets formed in the course of the collapse of a massive progenitor. Our
numerical simulations show the presence of a strong shear in the bulk velocity
of such jets. This shear can be responsible for a very rapid shear--driven
instability that arises for any velocity profile. This conclusion has been
confirmed both by numerical simulations and theoretical analysis. The
instability leads to rapid fluctuations of the main hydrodynamical parameters
(density, pressure, Lorentz factor, etc.). However, the perturbations of the
density are effectively decoupled from those of the pressure because the beam
of the jet is radiation--dominated. The characteristic growth time of
instability is much shorter than the life time of the jet and, therefore, may
lead to a complete turbulent beam. In the course of the non-linear evolution,
these fluctuations may yield to internal shocks which can be randomly
distributed in the jet. In the case that internal shocks in a ultrarelativistic
outflow are responsible for the observed phenomenology of gamma-ray bursts, the
proposed instability can well account for the short-term variability of
gamma-ray light curves down to milliseconds.


title: The Wave Mechanics of Large-scale Structure

abstract:
  I review the basic ``gravitational instability'' model for the growth of
structure in the expanding Universe. This model requires the existence of small
initial irregularities in the density of a largely uniform universe. These grow
through linear and non-linear stages to form a complex network of clusters,
filaments and voids. The dynamical equations describing the evolution of a
self-gravitating fluid can be rewritten in the form of a Schrodinger equation
coupled to a Poisson equation determining the gravitational potential. This
approach has a number of interesting features, many of which were pointed out
in a seminal paper by Widrow & Kaiser (1993). I argue that this approach has
the potential to yield useful analytic insights into the dynamical growth of
large-scale structure. As a particular example, I show that this approach
yields an elegant reformulation of an idea due to Jones (1999) concerning the
origin of lognormal intermittency in the galaxy distribution.


title: The kinetic temperature of Barnard 68

abstract:
  We have observed the nearby isolated globule Barnard 68 (B68) in the
(J,K)=(1,1) and (2,2) inversion lines of ammonia. The gas kinetic temperature
derived from these is T=10+-1.2 K. The observed line-widths are almost thermal:
DV=0.181+-0.003 km/s (DVtherm=0.164+-0.010 km/s), supporting the earlier
hypothesis that B68 is in hydrostatic equilibrium. The kinetic temperature is
an input parameter to the physical cloud model put forward recently, and we
discuss the impact of the new value in this context.


title: High Energy Emission from the Prompt Gamma-Ray Burst

abstract:
  We study the synchrotron and synchrotron self-Compton (SSC) emission from
internal shocks that are responsible for the prompt gamma-ray emission in GRBs,
and consider the relation between these two components, taking into account the
high energy (HE) cutoff due to pair production and Thomson scattering. We find
that in order for the peak energy of the synchrotron to be E_p\sim 300 keV with
a variability time t_v>1 ms, a Lorentz factor \Gamma<350 is needed, implying no
HE emission above \sim 30 MeV and the synchrotron component would dominate at
all energies. If we want both E_p\sim 300 keV and prompt HE emission up to 2
GeV, as detected by EGRET for GRB 940217, we need \Gamma\sim 600 and t_v\sim
0.1 ms, which might be resolved by super AGILE. If such prompt HE emission is
common in GRBs, as may be tested by GLAST, then for t_v\gtrsim 1 ms we need
\Gamma\gtrsim 350, which implies E_p\lesssim 100 keV. Therefore if X-ray
flashes are GRBs with high values of t_v and \Gamma, they should produce
\gtrsim 1 GeV emission. For an electron power law index p>2, the SSC component
dominates the emission above 100 MeV. Future observations by GLAST may help
determine the value of p and whether the HE emission is consistent with a
single power law (one component--the synchrotron, dominates) or has a break
where the \nuF_\nu slope turns from negative to positive, implying that the SSC
component becomes dominant above \sim 100 MeV. The HE emission is expected to
show similar variability and time structure to that of the soft gamma-ray
emission. Finally, we find that in order to see delayed HE emission from the
prompt GRB due to pair production with the cosmic IR background, extremely
small intergalactic magnetic fields (\lessim 10^{-22} G) are required.


title: An Analytic Model of Black Hole Evolution and Gamma Ray Bursts

abstract:
  An analytic model of the evolution of a rotating black hole (BH) is proposed
by considering the coexistence of disk accretion with the Blandford-Znajek
process. The evolutionary characteristics of the BH are described in terms of
three parameters: the BH spin $a_*$, the ratio $k$ of the angular velocity of
the magnetic field lines to that of the BH horizon and the parameter $\lambda$
indicating the position of the inner edge of the disk. It is shown that the
ratio $k$ being a little greater than 0.5 affects the evolutionary
characteristics of the BH significantly, and the BH spin increases rather than
decreases in its evolutionary process provided that the initial value of the BH
spin is located in an appropriate value range determined by ratio $k$. Our
calculations show that the system of a BH accretion disk with $k=0.6$ might
provide a much higher output energy in a shorter timescale for gamma-ray bursts
than the same system with $k=0.5$.


title: Modelling the Recurrent Nova CI Aql in Quiescence

abstract:
  We present detailed photometric investigations of the recurrent nova CI Aql.
New data obtained after the 2000 outburst are used to derive a 3D geometrical
model of the system. The resulting light curves clearly indicate the existence
of an asymmetric spray around the accretion disk, as claimed in the past e.g.
for the super-soft X-ray source CAL87 in the LMC. The simulated light curves
give us the mass transfer rates varying from \dot M ~ 2.5 x 10^{-8} M_\odot /
yr in 1991-1996 to 5.5 x 10^{-8} < \dot M < 1.5 x 10^{-7}M_\odot / yr in
2001/2002. The distance and the interstellar foreground extinction resulting
from the model are 1.55 kpc and E(B-V) = 0.98 respectively. During fast
photometry sequences in 2002 short timescale variations (t ~ 13 minutes) of the
mass loss are found. Moreover a change in the orbital period of the system is
detectable and results in a mass loss of 2.2 x 10^{-6} < \Delta M < 5.7 x
10^{-6} M_\odot during the nova explosion.


title:
On the formation of Super-AGB stars in intemediate mass close binary
  systems

abstract:
  The evolution of a star of initial mass 9 M_s, and Z = 0.02 in a Close Binary
System is followed in the presence of different mass companions in order to
study their influence on the final evolutionary stages and, in particular, on
the structure and composition of the remnant components. We study two extreme
cases. In the first one the mass of the secondary is 8 M_s, whereas in the
second one the mass was assumed to be 1 M_s. For the first of those cases we
have also explored the possible outcomes of both conservative and
non-conservative mass-loss episodes. During the first mass transfer episode,
several differences arise between the models. The system with the more extreme
mass ratio is not able to survive the 1st. Roche lobe overflow, and spiral-in
of the secondary onto the envelope of the primary is most likely. The system
formed by two stars of comparable mass undergoes two mass transfer episodes in
which the primary is the donor. We have performed two sets of calculations
corresponding to this case in order to account for conservative and
non-conservative mass transfer during the first mass loss episode. One of our
main results is that for the non-conservative case the secondary becomes a
Super-AGB. Such a star undergoes a final dredge-up episode, similar to that of
a single star of comparable mass. The primary components do not undergo a
Super-AGB phase, but instead a carbon-oxygen white dwarf is formed in both
cases, before reversal mass transfer occurs. However, given the extreme mass
ratios at this stage between the components of the binary system, the
possibility of merger episodes remains likely. We also discuss the presumable
final outcomes of the system and possible observational counterparts.


title: Simulated X-ray Cluster Temperature Maps

abstract:
  Temperature maps are presented of the 9 largest clusters in the mock
catalogues of Muanwong et al. for both the Preheating and Radiative models. The
maps show that clusters are not smooth, featureless systems, but contain a
variety of substructure which should be observable. The surface brightness
contours are generally elliptical and features that are seen include cold
clumps, hot spiral features, and cold fronts. Profiles of emission-weighted
temperature, surface brightness and emission-weighted pressure across the
surface brightness discontinuities seen in one of the bimodal clusters are
consistent with the cold front in Abell 2142 observed by Markevitch et al.


title: Flux and spectral variations in the Circinus Galaxy

abstract:
  We report on a dramatic flux (50 % increase in the LECS and MECS band) and
spectral variation between two BeppoSAX observations of the Circinus Galaxy
performed almost three years apart. Through the analysis of all Chandra
observations available in the archive, including a new DDT observation on May
2001, we show that a high flux state of an extremely variable Ultra Luminous
X-ray source (CG X-1: Bauer et al. 2001}, which is within the adopted BeppoSAX
source extraction region of 2", is the most likely explanation for most of the
observed variation. However, the presence of a high flux 6.7 keV line and the
spectral variation of the PDS in the new BeppoSAX data could be partly due to
intrinsic variation of the nucleus. Comparing the longest Chandra observation
and the BeppoSAX one, we find that the long-term flux variability of CG X-1 is
not accompanied by a significant spectral variability. We also re-analysed the
Chandra HEG nuclear spectra and report on the presence of a Compton shoulder
with a flux of about 20% the line core, in agreement with theoretical
expectations for Compton-thick matter.


title: Accelerated expansion without dark energy

abstract:
  The fact that the LambdaCDM model fits the observations does not necessarily
imply the physical existence of `dark energy'. Dropping the assumption that
cold dark matter (CDM) is a perfect fluid opens the possibility to fit the data
without dark energy. For imperfect CDM, negative bulk pressure is favoured by
thermodynamical arguments and might drive the cosmic acceleration. The
coincidence between the onset of accelerated expansion and the epoch of
structure formation at large scales might suggest that the two phenomena are
linked. A specific example is considered in which effective (anti-frictional)
forces, which may be due to dissipative processes during the formation of
inhomogeneities, give rise to accelerated expansion of a CDM universe.


title: The Afterglow of GRB010222: A Case of Continuous Energy Injection

abstract:
  The optical lightcurve of GRB010222 exhibited one of the slowest decays of
any gamma-ray burst to date. Its broadband properties have been difficult to
explain with conventional afterglow models, as they either require the power
law index of the underlying electron energy distribution to be low, $p<2$, or
that the outflow is quasi-spherical thus reviving the energy problem. We argue
that the slow decay of GRB 010222 and a linear polarization of $1.36\pm 0.64$%,
is naturally explained by a jet model with continuous energy injection. The
electron energy distribution then has $p=2.49\pm0.05$, fully consistent with
the expectation from detailed modelling of acceleration in relativistic shocks,
that $p>2$, thus alleviating the ``$p$-problem''.


title: Hot Molecular Gas in the Galactic Center

abstract:
  Using the new 23 GHz receivers at the Very Large Array (VLA), we have
detected NH3(6,6) emission (nu=25.056025 GHz) from hot (>150 K) molecular
clouds in the central 10 pc of the Galaxy. This is the first successful
detection of NH3(6,6) with the VLA. The brightest emission comes from a region
interior to the ``circumnuclear disk'' (CND), less than 1.5 pc in projected
distance from Sgr A*. This region does not show molecular emission from lower
energy transitions such as NH3(1,1) and (2,2), HCN(1-0) and HCO+(1-0). Line
ratios of NH3(6,6) and (3,3) emission as well as NH3(6,6) line widths have peak
values within 1.5 pc of Sgr A*, indicating that the gas is physically close to
the nucleus. NH3(6,6) is also detected towards many features outside the CND
observed in NH3(1,1), (2,2), and (3,3). These features tend to lie along ridges
of gas associated with Sgr A East or the massive ``molecular ridge'' that
connects the ``20 km/s'' and ``50 km/s'' giant molecular clouds (GMCs).


title: XMM-Newton observations of two black hole X-ray transients in quiescence

abstract:
  We report on XMM-Newton observations of GRO J1655-40 and GRS 1009-45, which
are two black hole X-ray transients currently in their quiescent phase. GRO
J1655-40 was detected with a 0.5 - 10 keV luminosity of 5.9 10^{31} erg/s. This
luminosity is comparable to a previous Chandra measurement, but ten times lower
than the 1996 ASCA value, most likely obtained when the source was not yet in a
true quiescent state. Unfortunately, XMM-Newton failed to detect GRS 1009-45. A
stringent upper limit of 8.9 10^{30} erg/s was derived by combining data from
the EPIC-MOS and PN cameras.
  The X-ray spectrum of GRO J1655-40 is very hard as it can be fitted with a
power law model of photon index ~ 1.3 +/- 0.4. Similarly hard spectra have been
observed from other systems; these rule out coronal emission from the secondary
or disk flares as the origin of the observed X-rays. On the other hand, our
observations are consistent with the predictions of the disc instability model
in the case that the accretion flow forms an advection dominated accretion flow
(ADAF) at distances less than a fraction ~ 0.1 - 0.3) of the circularization
radius. This distance corresponds to the greatest extent of the ADAF that is
thought to be possible.


title:
On Measuring the Infrared Luminosity of Distant Galaxies with the Space
  Infrared Telescope Facility

abstract:
  The Space Infrared Telescope Facility (SIRTF) will revolutionize the study of
dust-obscured star formation in distant galaxies. Although deep images from the
Multiband Imaging Photometer for SIRTF (MIPS) will provide coverage at 24, 70,
and 160 micron, the bulk of MIPS-detected objects may only have accurate
photometry in the shorter wavelength bands due to the confusion noise.
Therefore, we have explored the potential for constraining the total infrared
(IR) fluxes of distant galaxies with solely the 24 micron flux density, and for
the combination of 24 micron and 70 micron data. We also discuss the inherent
systematic uncertainties in making these transitions. Under the assumption that
distant star-forming galaxies have IR spectral energy distributions (SEDs) that
are represented somewhere in the local Universe, the 24 micron data (plus
optical and X-ray data to allow redshift estimation and AGN rejection)
constrains the total IR luminosity to within a factor of 2.5 for galaxies with
0.4 < z < 1.6. Incorporating the 70 micron data substantially improves this
constraint by a factor < 6. Lastly, we argue that if the shape of the IR SED is
known (or well constrained; e.g., because of high IR luminosity, or low
ultraviolet/IR flux ratio), then the IR luminosity can be estimated with more
certainty.


title: Possible Transiting Planet Candidates from the EXPLORE Project

abstract:
  The EXPLORE Project is a series of searches for transiting extrasolar planets
using large-format mosaic CCD cameras on 4-m class telescopes. Radial velocity
follow-up is done on transiting planet candidates with 8--10m class telescopes.
We present a summary of transit candidates from the EXPLORE Project for which
we have radial velocity data.


title: Statistical Properties of Cosmological Fluctuations

abstract:
  In this pedagogical lecture, I introduce some of the basic terminology and
description of fluctuating fields as they occur on cosmology. I define various
statistical, cosmological and sample homogeneity and explain what is meant by
the fair sample hypothesis and cosmic variance. I illustrate these concepts
using the simplest second-order statistics, i.e. the two--point correlation
function and its Fourier transform the power-spectrum. I then give a brief
overview of the properties of information relating to the properties of the
phases of the Fourier modes of cosmological fluctuations which is not contained
in these simpler statistics. Specifically, I explain how phase information of a
particular form (called quadratic phase coupling) is encoded in the
three--point correlation function (or, equivalently, the bispectrum).


title:
Extracting cosmic microwave background polarisation from satellite
  astrophysical maps

abstract:
  We present the application of the Fast Independent Component Analysis
({\ica}) technique for blind component separation to polarized astrophysical
emission. We study how the Cosmic Microwave Background (CMB) polarized signal,
consisting of $E$ and $B$ modes, can be extracted from maps affected by
substantial contamination from diffuse Galactic foreground emission and
instrumental noise. {We implement Monte Carlo chains varying the CMB and noise
realizations in order to asses the average capabilities of the algorithm and
their variance.} We perform the analysis of all sky maps simulated according to
the {\sc Planck} satellite capabilities, modelling the sky signal as a
superposition of the CMB and of the existing simulated polarization templates
of Galactic synchrotron. Our results indicate that the angular power spectrum
of CMB $E$-mode can be recovered on all scales up to $\ell\simeq 1000$,
corresponding to the fourth acoustic oscillation, while the $B$-mode power
spectrum can be detected, up to its turnover at $\ell\simeq 100$, if the ratio
of tensor to scalar contributions to the temperature quadrupole exceeds 30%.
The power spectrum of the cross correlation between total intensity and
polarization, $TE$, can be recovered up to $\ell\simeq 1200$, corresponding to
the seventh $TE$ acoustic oscillation.


title: Rarefied Gaseous Disk Around Black Hole in the System of V4641 Sgr

abstract:
  The results of photometric CCD monitoring and spectral observations of the
black hole binary and microquasar V4641 Sgr in the quiet state are presented.
The ellipsoidal light curve with large amplitude of 0.36^m in R band suggests
the influence of a massive object orbiting around a normal B9 star. In the
spectra taken with the 6-m telescope one hour before black hole inferior
conjunction, an absorption component in the red wing of Halpha line is visible.
It is formed by gaseous stream moving in the direction to the normal star. That
suggests the grazing conjunction in this system. Maximum velocity of the stream
is of 650 km/s. Assuming that the stream is moving through the circular
Keplerian orbit around black hole, the mass of the black hole is determined to
be M_{BH}=7.1-9.5Msun, what confirms the model by Orosz et al.


title: The Effect of External Winds on Relativistic Jets

abstract:
  Relativistic jets in Galactic superluminals and extragalactic AGN may be
surrounded by a wind near to the central engine. Theoretical analysis and
numerical simulation reveal considerable stabilization of relativistic jet flow
by a wind to helical and higher order asymmetric modes of jet distortion. When
velocities are measured in the source (inlet) frame, reduction in the absolute
velocity difference between jet and wind, $\Delta v = v_{jet} - v_{wnd}$,
provides stabilization in addition to stabilization provided by a high jet
Lorentz factor, but a high Lorentz factor wind is not needed to stabilize a
high Lorentz factor jet. However, the fundamental pinch mode is not similarly
affected and knots with spacing a few times the jet radius are anticipated to
develop in such flows. Thus, we identify a mechanism that can suppress large
scale asymmetric structures while allowing axisymmetric structures to develop.
Relativistic jets surrounded by outflowing winds will be more stable than if
surrounded by a stationary or backflowing external medium. Knotty structures
along a straight jet like that in 3C 175 could be triggered by pinching of an
initially low Mach number jet surrounded by a suitable wind. As the jet enters
the radio lobe, suppression of any surrounding outflow or backflow associated
with the high pressure lobe triggers exponential growth of helical twisting.


title: Abundance analysis of planetary host stars

abstract:
  We present atmospheric parameters and Fe abundances derived for the majority
of dwarf stars (north of -30 degrees declination) which are up to now known to
host extrasolar planets. High-resolution spectra have been obtained with the
Sandiford Echelle spectrograph on the 2.1m telescope at the University of Texas
McDonald Observatory. We have used the same model atmospheres, atomic data and
equivalent width modeling program for the analysis of all stars. Abundances
have been derived differentially to the Sun, using a solar spectrum obtained
with Callisto as the reflector with the same instrumentation. A similar
analysis has been performed for a sample of stars for which radial velocity
data exclude the presence of a close-in giant planetary companion. The results
are compared to the recent studies found in the literature.


title:
Gamma Ray Large Area Space Telescope (GLAST) Balloon Flight Data
  Handling Overview

abstract:
  The GLAST Balloon Flight Engineering Model (BFEM) represents one of 16 towers
that constitute the Large Area Telescope (LAT), a high-energy (>20 MeV)
gamma-ray pair-production telescope being built by an international partnership
of astrophysicists and particle physicists for a satellite launch in 2006. The
prototype tower consists of a Pb/Si pair-conversion tracker (TKR), a CsI
hodoscopic calorimeter (CAL), an anti-coincidence detector (ACD) and an
autonomous data acquisition system (DAQ). The self-triggering capabilities and
performance of the detector elements have been previously characterized using
positron, photon and hadron beams. External target scintillators were placed
above the instrument to act as sources of hadronic showers. This paper provides
a comprehensive description of the BFEM data-reduction process, from receipt of
the flight data from telemetry through event reconstruction and background
rejection cuts. The goals of the ground analysis presented here are to verify
the functioning of the instrument and to validate the reconstruction software
and the background-rejection scheme.


title:
A Catalog of 157 X-ray Spectra and 84 Spectral Energy Distributions of
  Blazars observed with BeppoSAX

abstract:
  As a special contribution to the proceedings of the BeppoSAX workshop
dedicated to blazar astrophysics we present a catalog of 157 X-ray spectra and
the broad-band Spectral Energy Distribution (SED) of 84 blazars observed by
BeppoSAX during its first five years of operations. The SEDs have been built by
combining BeppoSAX LECS, MECS and PDS data with (mostly) non-simultaneous
multi-frequency photometric data, obtained from NED and from other large
databases, including the GSC2 and the 2MASS surveys. All BeppoSAX data have
been taken from the public archive and have been analysed in a uniform way. For
each source we present a SED plot, and for every BeppoSAX observation we give
the best fit parameters of the spectral model that best describes the data. The
energy where the maximum of the synchrotron power is emitted spans at least six
orders of magnitudes ranging from ~ 0.1 eV to over 100 keV. A wide variety of
X-ray spectral slopes have been seen depending on whether the synchrotron or
inverse Compton component, or both, are present in the X-ray band. The wide
energy bandpass of BeppoSAX allowed us to detect, and measure with good
accuracy, continuous spectral curvature in many objects whose synchrotron
radiation extends to the X-ray band. This convex curvature, which is described
by a logarithmic parabola law better than other models, may be the spectral
signature of a particle acceleration process that becomes less and less
efficient as the particles energy increases. Finally some brief considerations
about other statistical properties of the sample are presented.


title:
Far Infrared Emission from Elliptical Galaxies: NGC 4649, NGC 4472, and
  NGC 4636

abstract:
  We present ISOPHOT P32 oversampled maps and P37/39 sparse maps, of three
bright elliptical galaxies in the Virgo Cluster. The maps reach the limiting
sensitivity of the ISOPHOT instrument at 60, 100, 170 and 200 microns. Two
elliptical galaxies show no emission at all far-IR ISOPHOT wavelengths at a
level of few tens of mJy. The null detection provides a test of the evolution
of dust in elliptical galaxies and its size distribution and composition. As
previous studies have shown, in many elliptical galaxies both IRAS and ISO have
detected mid-IR excess 6-15 micron emission relative to the stellar continuum
indicating emission from circumstellar dust. Under the assumption that these
dusty outflows from evolving red giant stars and planetary nebulae are
continuously supplying dust to the interstellar medium, we have computed the
infrared luminosity at the ISOPHOT bands appropriate for NGC4472. The null
far-IR ISOPHOT observations exceed the far-IR flux expected from dust expelled
from a normal old stellar population.


title:
Three Dimensional MHD Simulations of Accretion to an Inclined Rotator:
  The "Cubed Sphere" Method

abstract:
  We describe a three-dimensional, Godunov-type numerical magnetohydrodynamics
(MHD) method designed for studying disk accretion to a rotating magnetized star
in the general case where the star's rotation axis, its magnetic moment, and
the normal to the disk all have different directions. The numerical method uses
a "cubed sphere" coordinate system which has advantages of Cartesian and
spherical coordinate systems but does not have the singular axis ofthe
spherical system. The grid is formed by a sequence of concentric spheres of
radii $R_j \propto q^j$ with $j=1..N_R$ and $q={\rm const}>1$. The grid on the
surface of the sphere consists of six sectors with the grid on each sector
topologically equivalent to the equidistant grid on the face of a cube.
Simulation results are discussed for the funnel flows (FF) to a star with
dipole moment $\rvecmu$ at an angle $\Theta=30^\circ$ to the star's rotation
axis ${\bf \Omega}$ which is aligned with the normal to the disk. Two important
new 3D features are found in these simulations: (1) The funnel flow to the
stellar surface is mainly in two streams which approach the star from opposite
directions. (2) In the $x-z$ cross section of the flow containing $\rvecmu$ and
${\bf \Omega}$, the funnel flow often takes the longer of the two possible
paths along magnetic field lines to the surface of the star. A subsequent paper
will give a detailed description of the method and results on 3D funnel flows
at different inclination angles $\Theta$.


title:
The detection of variability from the candidate IR counterpart to the
  Anomalous X-ray Pulsar 1E1048.1-5937

abstract:
  We report on the detection of variability from the proposed IR counterpart to
the Anomalous X-ray Pulsar (AXP) 1E1048.1-5937 based on Chandra and ESO
optical/IR deep observations carried out in 2001-2002. Within the narrow
Chandra uncertainty region for 1E1048.1-5937 we found only one relatively faint
(J=22.1+/-0.3, J-Ks=2.4) source, while the recently proposed IR counterpart was
not detected down to a limiting Ks magnitude of about 20.7 (3sigma confidence
level). This implies a remarkable IR brightening of this object, Delta Ks>1.3,
on a timescale of about 50 days. Although our knowledge of the IR properties of
AXPs is rather limited (there is only another source, 1E2259+586, for which IR
variability has been detected), the observed IR variability of the proposed
counterpart strengthens its association with 1E1048.1-5937. Our results make
the IR (and presumably optical) variability a likely common characteristic of
AXPs, and provide new constraints on this class of objects.


title: Stellar wind bubbles around WR and [WR] stars

abstract:
  We study the dynamics of stellar wind bubbles around hydrogen-deficient stars
using numerical simulations with time- and ion dependent cooling. We consider
two types of hydrogen-deficient stars, massive WR stars, producing Ring
Nebulae, and low mass [WR] stars, producing Planetary Nebulae. We show that for
the Planetary Nebulae, the different cooling properties of the
hydrogen-deficient wind lead to a later transition from momentum- to
energy-driven flow, which could explain the observed turbulence of these
nebulae. We find that Ring Nebulae should all be energy-driven, and show how
comparing the bubble's momentum and kinetic energy to the input wind momentum
and kinetic energy, can give misleading information about the dynamics of the
bubble.


title: Evolution of clouds in radio galaxy cocoons

abstract:
  This letter presents a numerical study of the evolution of an emission line
cloud of initial density 10 cm$^{-3}$, temperature $10^4$ K, and size 200 pc,
being overtaken by a strong shock wave. Whereas previous simple models proposed
that such a cloud would either be completely destroyed, or simply shrink in
size, our results show a different and more complex behaviour: due to rapid
cooling, the cloud breaks up into many small and dense fragments, which can
survive for a long time. We show that such rapid cooling behaviour is in fact
expected for a wide range of cloud and shock properties. This process applies
to the evolution of emission line clouds being overtaken by the cocoon of a
radio jet. The resulting small clouds would be Jeans unstable, and form stars.
Our results thus give theoretical credibility to the process of jet induced
star formation, one of the explanations for the alignment of the optical/UV and
radio axis observed in high redshift radio galaxies.


title:
Constraints on Cosmological Parameters from the Analysis of the Cosmic
  Lens All Sky Survey Radio-Selected Gravitational Lens Statistics

abstract:
  We derive constraints on cosmological parameters and the properties of the
lensing galaxies from gravitational lens statistics based on the final Cosmic
Lens All Sky Survey (CLASS) data. For a flat universe with a classical
cosmological constant, we find that the present matter fraction of the critical
density is $\Omega_{\rm m}=0.31^{+0.27}_{-0.14}$ (68%) $^{+0.12}_{-0.10}$
(systematic). For a flat universe with a constant equation of state for dark
energy $w = p_x({pressure})/\rho_x({energy density})$, we find $w <
-0.55^{+0.18}_{-0.11}$ (68%).


title: Determining Bolometric Corrections for BATSE Burst Observations

abstract:
  We compare the energy and count fluxes obtained by integrating over the
finite bandwidth of BATSE with a measure proportional to the bolometric energy
flux, the phi-measure, introduced by Borgonovo & Ryde. We do this on a sample
of 74 bright, long, and smooth pulses from 55 GRBs. The correction factors show
a fairly constant behavior over the whole sample, when the
signal-to-noise-ratio is high enough. We present the averaged spectral
bolometric correction for the sample, which can be used to correct flux data.


title:
A two-streams discrete ordinates solution of radiative transfer in 1-D
  spherical geometry

abstract:
  The analytic solution for the two-streams discrete ordinates equations is
carried out on the spatial domain in one-dimensional spherical geometry. The
solution satisfies all the physical and the geometric conditions, namely: the
natural boundary condition at the surface of the sphere, the symmetry condition
at the center and the reciprocity of path. The solution obeys the inverse
square law and is finite everywhere in the sphere except at the center.
Graphical and numerical data obtained in cold absorbing spheres confirmed the
analytical predictions. The conservation of energy is satisfied with high
accuracy within round-off errors.


title: Vast Antimatter Regions and Scalar Condensate Baryogenesis

abstract:
  The possibility of natural and abundant creation of antimatter in the
Universe in a SUSY-baryogenesis model with a scalar field condensate is
described. This scenario predicts vast quantities of antimatter, corresponding
to galaxy and galaxy cluster scales today, separated from the matter ones by
baryonically empty voids. Theoretical and observational constraints on such
antimatter regions are discussed.


title: Non-Standard Structure Formation Scenarios

abstract:
  Observations on galactic scales seem to be in contradiction with recent high
resolution N-body simulations. This so-called cold dark matter (CDM) crisis has
been addressed in several ways, ranging from a change in fundamental physics by
introducing self-interacting cold dark matter particles to a tuning of complex
astrophysical processes such as global and/or local feedback. All these efforts
attempt to soften density profiles and reduce the abundance of satellites in
simulated galaxy halos. In this contribution we are exploring the differences
between a Warm Dark Matter model and a CDM model where the power on a certain
scale is reduced by introducing a narrow negative feature (''dip''). This dip
is placed in a way so as to mimic the loss of power in the WDM model: both
models have the same integrated power out to the scale where the power of the
Dip model rises to the level of the unperturbed CDM spectrum again. Using
N-body simulations we show that that the new Dip model appears to be a viable
alternative to WDM while being based on different physics: where WDM requires
the introduction of a new particle species the Dip stems from a non-standard
inflationary period. If we are looking for an alternative to the currently
challenged standard LCDM structure formation scenario, neither the LWDM nor the
new Dip model can be ruled out with respect to the analysis presented in this
contribution. They both make very similar predictions and the degeneracy
between them can only be broken with observations yet to come.


title:
Chandra Snapshot Observations of Low-Luminosity AGNs with a Compact
  Radio Source

abstract:
  The results of Chandra snapshot observations of 11 LINERs (Low-Ionization
Nuclear Emission-line Regions), three low-luminosity Seyfert galaxies, and one
HII-LINER transition object are presented. Our sample consists of all the
objects with a flat or inverted spectrum compact radio core in the VLA survey
of 48 low-luminosity AGNs (LLAGNs) by Nagar et al. (2000). An X-ray nucleus is
detected in all galaxies except one and their X-ray luminosities are in the
range 5x10^38 to 8x10^41 erg/s. The X-ray spectra are generally steeper than
expected from thermal bremsstrahlung emission from an advection-dominated
accretion flow (ADAF). The X-ray to Halpha luminosity ratios for 11 out of 14
objects are in good agreement with the value characteristic of LLAGNs and more
luminous AGNs, and indicate that their optical emission lines are predominantly
powered by a LLAGN. For three objects, this ratio is less than expected.
Comparing with properties in other wavelengths, we find that these three
galaxies are most likely to be heavily obscured AGN. We use the ratio RX = \nu
L\nu (5 GHz)/LX, where LX is the luminosity in the 2-10 keV band, as a measure
of radio loudness. In contrast to the usual definition of radio loudness (RO =
L\nu(5 GHz)/L\nu(B)), RX can be used for heavily obscured (NH >~ 10^23 cm^-2,
AV>50 mag) nuclei. Further, with the high spatial resolution of Chandra, the
nuclear X-ray emission of LLAGNs is often easier to measure than the nuclear
optical emission. We investigate the values of RX for LLAGNs, luminous Seyfert
galaxies, quasars and radio galaxies and confirm the suggestion that a large
fraction of LLAGNs are radio loud.


title:
A Spectroscopic Survey of Subarcsecond Binaries in the Taurus-Auriga
  Dark Cloud with the Hubble Space Telescope

abstract:
  We report the results of a spectroscopic survey of 20 close T Tauri binaries
in the Taurus-Auriga dark cloud where the separations between primaries and
their secondaries are less than the typical size of a circumstellar disk around
a young star. Analysis of low-resolution and medium-resolution STIS spectra
yields the stellar luminosities, reddenings, ages, masses, mass accretion
rates, IR excesses, and emission line luminosities for each star in each pair.
We examine the ability of IR color excesses, H-alpha equivalent widths, [O I]
emission, and veiling to distinguish between weak emission and classical T
Tauri stars. Four pairs have one cTTs and one wTTs; the cTTs is the primary in
three of these systems. This frequency of mixed pairs among the close T Tauri
binaries is similar to the frequency of mixed pairs in wider young binaries.
Extinctions within pairs are usually similar; however, the secondary is more
heavily reddened than the primary in some systems, where it may be viewed
through the primary's disk. Mass accretion rates of primaries and secondaries
are strongly correlated, and H-alpha luminosities, IR excesses, and ages also
correlate within pairs. Primaries tend to have somewhat larger accretion rates
than their secondaries do, and are typically slightly older than their
secondaries according to three different sets of modern pre-main-sequence
evolutionary tracks. Age differences for XZ Tau and FS Tau, systems embedded in
reflection nebulae, are striking; the secondary in each pair is less massive
but more luminous than the primary. The stellar masses of the UY Aur and GG Tau
binaries measured from their rotating molecular disks are about 30% larger than
the masses inferred from the spectra and evolutionary tracks.


title: Modern Stellar Evolution Models for Low Mass Stars

abstract:
  The status of the art for evolutionary models of low mass, population II
stars is revisited, stressing the need for the models to be preliminarily
tested with suitable observational data. The uncertainties still affecting the
theory are discussed in the aim of guiding the users in a reasoned choice of
the models. The powerful coupling of evolutionary with pulsational theories is
shortly recalled. A short conclusion and a mention of the problem of tilted HB
close the paper.


title: Matching torsion Lambda - term with observations

abstract:
  Taking into account a torsion field gives rise to a negative pressure
contribution in cosmological dynamics and then to an accelerated behaviour of
Hubble fluid. The presence of torsion has the same effect of a Lambda - term.
We obtain a general exact solution which well fits the data coming from high -
redshift supernovae and Sunyaev - Zeldovich/X - ray method for the
determination of the cosmological parameters. On the other hand, it is possible
to obtain observational constraints on the amount of torsion density. A dust
dominated Friedmann behaviour is recovered as soon as torsion effects are not
relevant.


title: The Dynamical Parameters of the Universe

abstract:
  The results of different analyses of the dynamical parameters of the Universe
are converging towards agreement. Remaining disagreements reflect systematic
errors coming either from the observations or from differences in the methods
of analysis. Compiling the most precise parameter values with our estimates of
such systematic errors added, we find the following best values: the baryonic
density parameter Omega_bh^2 = 0.019 +/- 0.02, the density parameter of the
matter component Omega_m = 0.29 +/- 0.06, the density parameter of the
cosmological constant Omega_lambda = 0.71 +/- 0.07, the spectral index of
scalar fluctuations n_s = 1.02 +/- 0.08, the equation of state of the
cosmological constant w_lambda < -0.86, and the deceleration parameter q_0 =
-0.56 +/- 0.04. We do not modify the published best values of the Hubble
parameter H_0 = 0.73 +/- 0.07 and the total density parameter Omega_0
^{+0.03}_{-0.02}.


title:
Probing the extended emission-line region in 3C171 with high-frequency
  radio polarimetry

abstract:
  I present high-frequency polarimetric radio observations of the radio galaxy
3C171, in which depolarization is associated with an extended emission-line
region. The radio hotspots, known to be depolarized at low radio frequencies,
become significantly polarized above (observer's-frame) frequencies of 15 GHz.
There is some evidence that some of the Faraday rotation structure associated
with the emission-line regions is being resolved at the highest resolutions
(0.1 arcsec, or 400 pc); however, the majority remains unresolved. Using the
new radio data and a simple model for the nature of the depolarizing screen, it
is possible to place some constraints on the nature of the medium responsible
for the depolarization. I argue that it is most likely that the depolarization
is due not to the emission-line material itself but to a second, less dense,
hot phase of the shocked ISM, and derive some limits on its density and
temperature.


title: Models of the formation of the planets in the 47 UMa system

abstract:
  Formation of planets in the 47 UMa system is followed in an evolving
protoplanetary disk composed of gas and solids. The evolution of the disk is
calculated from an early stage, when all solids, assumed to be high-temperature
silicates, are in the dust form, to the stage when most solids are locked in
planetesimals. The simulation of planetary evolution starts with a solid embryo
of ~1 Earth mass, and proceeds according to the core accretion -- gas capture
model. Orbital parameters are kept constant, and it is assumed that the
environment of each planet is not perturbed by the second planet. It is found
that conditions suitable for both planets to form within several Myr are easily
created, and maintained throughout the formation time, in disks with $\alpha
\approx 0.01$. In such disks, a planet of 2.6 Jupiter masses (the minimum for
the inner planet of the 47 UMa system) may be formed at 2.1 AU from the star in
\~3 Myr, while a planet of 0.89 Jupiter masses (the minimum for the outer
planet) may be formed at 3.95 AU from the star in about the same time. The
formation of planets is possible as a result of a significant enhancement of
the surface density of solids between 1.0 and 4.0 AU, which results from the
evolution of a disk with an initially uniform gas-to-dust ratio of 167 and an
initial radius of 40 AU.


title: The properties of Low Surface Brightness galaxies

abstract:
  A description is given of the samples of Low Surface Brightness galaxies
(LSBs) used for comparison with models of their chemical and
spectro-photometric evolution (Boissier et al., this Volume). These samples
show the large variation and scatter in observed global properties of LSBs,
some of which cannot be modeled without adding starbursts or truncations to
their star formation history.


title:
Gamma ray Large Area Space Telescope (GLAST) Balloon Flight Engineering
  Model: Overview

abstract:
  The Gamma Ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT)
is a pair-production high-energy (>20 MeV) gamma-ray telescope being built by
an international partnership of astrophysicists and particle physicists for a
satellite launch in 2006, designed to study a wide variety of high-energy
astrophysical phenomena. As part of the development effort, the collaboration
has built a Balloon Flight Engineering Model (BFEM) for flight on a
high-altitude scientific balloon. The BFEM is approximately the size of one of
the 16 GLAST-LAT towers and contains all the components of the full instrument:
plastic scintillator anticoincidence system (ACD), high-Z foil/Si strip
pair-conversion tracker (TKR), CsI hodoscopic calorimeter (CAL), triggering and
data acquisition electronics (DAQ), commanding system, power distribution,
telemetry, real-time data display, and ground data processing system. The
principal goal of the balloon flight was to demonstrate the performance of this
instrument configuration under conditions similar to those expected in orbit.
Results from a balloon flight from Palestine, Texas, on August 4, 2001, show
that the BFEM successfully obtained gamma-ray data in this high-background
environment.


title:
Halpha surface photometry of galaxies in the Virgo cluster. IV: the
  current star formation in nearby clusters of galaxies

abstract:
  Halpha+[NII] imaging observations of 369 late-type galaxies in the Virgo
cluster and in the Coma/A1367 supercluster are analyzed. They constitute an
optically selected sample (m_p<16.0) observed with 60% c.a. completeness.These
observations provide us with the current (T<10^7 yrs) star formation properties
of galaxies. The expected decrease of the star formation rate (SFR),as traced
by the Halpha E.W., with decreasing clustercentric projected distance is found
only when galaxies brighter than M_p=-19.5 are considered. We also include in
our analysis Near Infrared data, providing us with informations on the old
(T>10^9yrs) stars. Put together, the young and the old stellar indicators give
the ratio of currently formed stars over the stars formed in the past, or
"birthrate" parameter b. We also determine the "global gas content" combining
HI with CO observations. We define the "gas deficiency" parameter as the
logarithmic difference between the gas content of isolated galaxies of a given
Hubble type and the measured gas content.For the isolated objects we find that
b decreases with increasing NIR luminosity. The gas-deficient objects,
primarily members to the Virgo cluster, have their birthrate significantly
lower than the isolated objects with normal gas content and of similar NIR
luminosity. This indicates that the current star formation is regulated by the
gaseous content of spirals.Whatever mechanism (most plausibly ram-pressure
stripping) is responsible for the pattern of gas deficiency observed in spiral
galaxies members to rich clusters, it also produces the observed quenching of
the current star formation.


title: Far infrared observations of pre-protostellar sources in Lynds 183

abstract:
  Using ISOPHOT maps at 100 and 200um and raster scans at 100, 120, 150 and
200um we have detected four unresolved far-infrared sources in the high
latitude molecular cloud L183. Two of the sources are identified with 1.3mm
continuum sources found by Ward-Thompson et al. and are located near the
temperature minimum and the coincident column density maximum of dust
distribution. For these two sources, the ISO observations have enabled us to
derive temperatures (about 8.3 K) and masses (about 1.4 and 2.4 solar masses).
They are found to have masses greater than or comparable to their virial masses
and are thus expected to undergo gravitational collapse. We classify them as
pre-protostellar sources. The two new sources are good candidates for
pre-protostellar sources or protostars within L183.


title: A Fast Algorithm for Solving the Poisson Equation on a Nested Grid

abstract:
  We present a numerical method for solving the Poisson equation on a nested
grid. The nested grid consists of uniform grids having different grid spacing
and is designed to cover the space closer to the center with a finer grid. Thus
our numerical method is suitable for computing the gravity of a centrally
condensed object. It consists of two parts: the difference scheme for the
Poisson equation on the nested grid and the multi-grid iteration algorithm. It
has three advantages: accuracy, fast convergence, and scalability. First it
computes the gravitational potential of a close binary accurately up to the
quadraple moment, even when the binary is resolved only in the fine grids.
Second residual decreases by a factor of 300 or more by each iteration. We
confirmed experimentally that the iteration converges always to the exact
solution of the difference equation. Third the computation load of the
iteration is proportional to the total number of the cells in the nested grid.
Thus our method gives a good solution at the minimum expense when the nested
grid is large. The difference scheme is applicable also to the adaptive mesh
refinement in which cells of different sizes are used to cover a domain of
computation.


title:
Interaction between the Northeastern Boundary of Sgr A East and Giant
  Molecular Clouds

abstract:
  We have detected the v=1-0 S(1) (2.1218 um) and v=2-1 S(1) (2.2477 um) lines
of H_2 in the Galactic centre, in a 90 x 27 arcsec region between the
northeastern boundary of the non-thermal source, Sgr A East, and the giant
molecular cloud (GMC) M-0.02-0.07. The detected H_2 v=1-0 S(1) emission has an
intensity of 1.6 - 21 x 10^-18 W/m^2/arcsec^2 and is present over most of the
region. Along with the high intensity, the broad line widths (FWHM = 40 - 70
km/s) and the 2-1 S(1) / 1-0 S(1) line ratios (0.3 - 0.5) can be best explained
by a combination of C-type shocks and fluorescence. The detection of shocked
H_2 is clear evidence that Sgr A East is driving material into the surrounding
adjacent cool molecular gas. The H_2 emission lines have two velocity
components at about +50 km/s and 0 km/s, which are also present in the
NH_3(3,3) emission mapped by McGary, Coil, and Ho (2001, ApJ, 559, 326). This
two-velocity structure can be explained if Sgr A East is driving C-type shocks
into both the GMC M-0.02-0.07 and the northern ridge of McGary, Coil, and Ho
(2001).


title: Perspectives in Galactic Chemical Evolution studies

abstract:
  In this review I focus on a few selected topics, where recent theoretical
and/or observational progress has been made and important developments are
expected in the future. They include: 1) Evolution of isotopic ratios, 2)
Mixing processes and dispersion in abundance ratios, 3) Abundance gradients in
the Galactic disk (and abundance patterns in the inner Galaxy), 4) The question
of primary Nitrogen and 5) Abundance patterns in extragalactic damped
Lyman-alpha systems (DLAs).


title: Parameter Correlations and Cosmological Properties of BL Lac Objects

abstract:
  Using three complete, radio flux limited, blazar samples we compare the
LogN-LogS and the preliminary radio luminosity function of the general
population of BL Lacs to those of the subclass of high energy synchrotron
peaked (HBL) BL Lacs. We also examine recent results on the cosmological
evolution in different samples of BL Lacs and we investigate the controversial
issue of the correlation between the synchrotron peak frequency and radio
luminosity in BL Lacertae objects. We find that the fraction of HBL objects is
approximately the same at all observed radio fluxes and luminosities implying
that there cannot be any strong correlation between the position of the
synchrotron peak and radio luminosity. The amount of cosmological evolution in
BL Lacs is confirmed to be low and negative at low radio fluxes, although the
large number of objects without redshift prevents a precise estimation. At high
radio fluxes the amount of cosmological evolution is zero or slightly positive
but this could be induced by a possible contamination with Flat Spectrum Radio
Quasars.


title: Far-infrared Emission from Dust in Normal Galaxies

abstract:
  We review the morphological and spectral energy distribution characteristics
of the dust continuum emission (emitted in the 40-200 micron spectral range)
from normal galaxies, as revealed by detailed ISOPHOT mapping observations of
nearby spirals and by ISOPHOT observations of the integrated emissions from
representative statistical samples in the local universe.


title:
Photometry and Spectroscopy of the Type IIP SN 1999em from Outburst to
  Dust Formation

abstract:
  We present photometry and spectra of the type IIP SN1999em in NGC 1637 from
several days after the outburst till day 642. An amount of $\approx 0.02
M_{\odot}$ of ejected $^{56}$Ni is inferred using the recovered bolometric
light curve . The H$\alpha$ and He I 10830 \AA lines at the nebular epoch show
that the distribution of the bulk of $^{56}$Ni can be represented approximately
by a sphere of $^{56}$Ni with a velocity of 1500 km s$^{-1}$, which is shifted
towards the far hemisphere by about 400 km s$^{-1}$. The fine structure of the
H$\alpha$ at the photospheric epoch reminiscent of the "Bochum event" in SN
1987A is analysed . The late time spectra show a dramatic transformation of the
[O I] 6300 \AA line profile between days 465 and 510, which we interpret as an
effect of dust condensation during this period. Late time photometry supports
the dust formation scenario after day 465. The [O I] line profile suggests that
the dust occupies a sphere with velocity $\approx 800$ km s$^{-1}$ and optical
depth $\gg10$. The plateau brightness and duration combined with the expansion
velocity suggest a presupernova radius of $120-150 R_{\odot}$, ejecta mass of
$10-11 M_{\odot}$ and explosion energy of $(0.5-1)\times10^{51}$ erg. The
ejecta mass combined with the neutron star and a conservative assumption about
mass loss implies the main sequence progenitor of $M_{\rm ms}\approx 12-14
M_{\odot}$. From the [O I] 6300,6364 \AA doublet luminosity we infer the oxygen
mass to be a factor four lower than in SN 1987A which is consistent with the
estimated SN 1999em progenitor mass . We note a "second-plateau" behaviour of
the light curve after the main plateau at the beginning of the radioactive
tail. This feature seems to be common to SNe IIP with low $^{56}$Ni mass.


title:
Multiplicity, kinematics and rotation rates of very young brown dwarfs
  in ChaI

abstract:
  We have studied twelve very young (1-5Myr) bona fide and candidate brown
dwarfs in the ChaI star forming region in terms of their kinematic properties,
the occurrence of multiple systems among them as well as their rotational
characteristics. Based on high-resolution spectra taken with UVES at the VLT
(8.2m), radial and rotational velocities have been measured. A kinematic study
of the sample showed that their radial velocity dispersion is relatively small
suggesting that they are not ejected during their formation as proposed in
recent formation scenarios. By means of time-resolved UVES spectra, a radial
velocity survey for close companions to the targets was conducted. The radial
velocities of the targets turned out to be rather constant setting upper limits
for the mass Msini of possible companions to 0.1 - 2 M_Jup. These findings hint
at a rather low (<10%) multiplicity fraction of the studied brown dwarfs.
Furthermore, a photometric monitoring campaign of the targets yielded the
determination of rotational periods for three brown dwarf candidates in the
range of 2.2 to 3.4 days. These are the first rotational periods for very young
brown dwarfs and among the first for brown dwarfs at all.


title: How black holes turn cusps into cores

abstract:
  Collapsing collisionless particle systems form gravitational bound halos with
cuspy density profiles. Also hierarchical merging of these systems produce
remnants with cuspy central density profiles. These results lead to the
assumption of cuspy NFW profiles for the density distribution in dark matter
halos. However, observed rotation curves in disk galaxies suggest dark matter
halos with isothermal core. The same kind of problem can be found for globular
clusters, which show cores in their density profiles but should be cuspy if
they where formed through a cold collapse.We are showing how small, massive,
and compact objects can efficiently transform cuspy stellar systems into
density profiles with an isothermal core.


title: NGC1866: New analysis from HST-WFPC2 observations of the inner regions

abstract:
  We report new results on the LMC globular cluster NGC 1866 obtained by
analyzing F555W and F814W images from WFPC2@HST. On the basis of the CMD we
derive information on the cluster distance and constraints on stellar evolution
theory. Evidence of mass segregation are found in the cluster core.


title: Oxygen, Carbon and Nitrogen evolution in galaxies

abstract:
  We discuss the evolution of oxygen, carbon and nitrogen in galaxies of
different morphological type by adopting detailed chemical evolution models
with different star formation histories (continuous star formation or
starbursts). We start by computing chemical evolution models for the Milky Way
with different stellar nucleosynthesis prescriptions. Then, a comparison
between model results and ``key'' observational constraints allows us to choose
the best set of stellar yields. Once the best set of yields is identified for
the Milky Way, we apply the same nucleosynthesis prescriptions to other spirals
(in particular M101) and dwarf irregular galaxies. We compare our model
predictions with the [C,N,O/Fe] vs. [Fe/H], log(C/O) vs. 12+ log(O/H), log(N/O)
vs. 12+ log(O/H) and [C/O] vs. [Fe/H] relations observed in the solar vicinity,
along the disk and in other galaxies. By taking into account the results
obtained for all the studied galaxies (Milky Way, M101, dwarf galaxies and
DLAs) our main conclusions are: a) once the available observational data are
properly interpreted, there is no compelling evidence for requiring the
production of primary N in massive stars (M>10Msun); b) both C and N we see
today in the ISM come mainly from low- and intermediate-mass stars. In
particular, there is no need to invoke strong stellar winds in massive stars in
order to explain the evolution of C/O ratio in the solar neighborhood, as often
claimed in the literature (abridged).


title: Gemini Near-IR Photometry of the Arches Cluster near the Galactic Center

abstract:
  We present Near-IR photometry of the Arches cluster, a young and massive
stellar cluster near the Galactic center. We have analyzed the high resolution
(FWHM 0.2") H and K' band images in the Galactic Center Demonstration Science
Data Set, which were obtained with the Gemini/Hokupa's adaptive optics (AO)
system. We present the color-magnitude diagram, the luminosity function and the
initial mass function (IMF) of the stars in the Arches cluster in comparison
with the HST/NICMOS data. The IMF slope for the range of 1.0< log(M/M_sun) <2.1
is estimated to be Gamma = -0.79+/-0.16, in good agreements with the earlier
result based on the HST/NICMOS data [Figer et al. 1999, ApJ, 525, 750]. These
results strengthen the evidence that the IMF of the bright stars close to the
Galactic center is much flatter than that for the solar neighborhood. This is
also consistent with a recent finding that the IMFs of the bright stars in
young clusters in M33 get flatter as the galactocentric distance decreases [Lee
et al. 2001, astro-ph 0109258]. It is found that the power of the Gemini/AO
system is comparable, with some limits, to that of the HST/NICMOS.


title: RXTE All-Sky Monitor Detection of the Orbital Period of Scorpius X-1

abstract:
  The orbital period of Scorpius X-1 has been accepted as 0.787313 d since its
discovery in archival optical photometric data by Gottlieb, Wright, & Liller
(1975). This period has been confirmed in both photometric and spectroscopic
optical observations, though to date only marginal evidence has been reported
for modulation of the X-ray intensity at that period. We have used data taken
with the RXTE All Sky Monitor to search for such a modulation. A major
difficulty in detecting the orbit in X-ray data is presented by the flaring
behavior of Sco X-1, which contributes white noise to Fourier transforms of the
intensity time series, and tends to obscure weak modulations. We present a new
technique for substantially reducing the effects of the flaring behavior while
retaining much of any periodic orbital modulation, provided only that the two
temporal behaviors exhibit different spectral signatures. Through such a
search, we have found evidence for orbital modulation at about the 1% level
with a period of 0.78893 d, equal within our accuracy to a period which differs
by 1 cycle per year from the accepted value. If we compare our results with the
period of the 1 year sideband cited by Gottlieb et al. we conclude that the
actual period may be 0.78901 d.


title: The Atacama Large Millimeter Array (ALMA)

abstract:
  The Atacama Large Millimeter Array, or ALMA, is an international telescope
project which will be built over the coming decade in Northern Chile. With over
7000 m^2 of collecting area comprised of 64 12m antennas arrayed over baselines
up to 14 km in extent, ALMA will provide images of unprecedented clarity and
detail. One revolutionary feature of ALMA will be its ability to combine
interferometric and single telescope data, providing complete flux recovery.
ALMA will cover a spectral wavelength range from 7mm to 0.3 mm or shorter
wavelengths, providing astronomy with its first detailed look at the structures
which emit millimeter and submillimeter photons, the most abundant photons in
the Universe.


title:
Prospecting for Heavy Elements with Future Far-IR/Submillimeter
  Observatories

abstract:
  To understand the cosmic history of element synthesis it will be important to
obtain extinction-free measures of the heavy element contents of high-redshift
objects and to chart two monumental events: the collapse of the first
metal-free clouds to form stars, and the initial seeding of the universe with
dust. The information needed to achieve these objectives is uniquely available
in the far-infrared/submillimeter (FIR/SMM) spectral region. Following the
Decadal Report and anticipating the development of the Single Aperture Far-IR
(SAFIR) telescope and FIR/SMM interferometry, we estimate the measurement
capabilities of a large-aperture, background-limited FIR/SMM observatory and an
interferometer on a boom, and discuss how such instruments could be used to
measure the element synthesis history of the universe.


title: LSST: a Complementary Probe of Dark Energy

abstract:
  The number of mass clusters and their distribution in redshift are very
sensitive to the density of matter Omega_m and the equation of state of dark
energy w. Using weak lens gravitational tomography one can detect clusters of
dark matter, weigh them, image their projected mass distribution, and determine
their 3-D location. The degeneracy curve in the Omega_m - w plane is nearly
orthogonal to that from CMB or SN measurements. Thus, a combination of CMB data
with weak lens tomography of clusters can yield precision measurements of
Omega_m and w, independently of the SN observations. The Large Synoptic Survey
Telescope (LSST) will repeatedly survey 30,000 square degrees of the sky in
multiple wavelengths. LSST will create a 3-D tomographic assay of mass
overdensities back to half the age of the universe by measuring the shear and
color-redshift of billions of high redshift galaxies. By simultaneously
measuring several functions of cosmic shear and mass cluster abundance, LSST
will provide a number of independent constraints on the dark energy density and
the equation of state.


title:
X-ray emission from the most luminous z>4 Palomar Digital Sky Survey
  Quasars: the Chandra view

abstract:
  We present the results obtained from exploratory Chandra observations of nine
high-redshift (z=4.09-4.51) quasars, selected from among the optically
brightest Palomar Digital Sky Survey quasars known. Their broad-band spectral
energy distributions are characterized, on average, by steeper alpha_ox values
(<alpha_ox>=-1.81+/-0.03) than those of lower-redshift, lower-luminosity
samples of quasars. We find a significant correlation between AB1450(1+z)
magnitude and soft X-ray flux, suggesting that the engine powering the UV and
X-ray emission is the same. The joint 2-30 keV rest-frame X-ray spectrum is
well parameterized by a Gamma=2.0+/-0.2 power-law model with no evidence for
intrinsic absorption (N_H<8.8 10^{21} cm^-2).


title:
The internal structure of the lens PG1115+080: breaking degeneracies in
  the value of the Hubble Constant

abstract:
  We combine lensing, stellar kinematic and mass-to-light ratio constraints to
build a two-component (luminous plus dark) mass model of the early-type lens
galaxy in PG1115+080. We find a total mass density profile steeper than r^-2,
effectively rho r^-gamma' with gamma'=2.35+-0.1+-0.05 (random + systematic).
The stellar mass fraction is f*=0.67(+0.20/-0.25)+-0.03 inside the Einstein
Radius (R_E 1.2 effective radii). The dynamical mass model breaks the
degeneracies in the mass profile of the lens galaxy and allows us to obtain a
value of the Hubble Constant that is no longer dominated by systematic errors:
H_0=59(+12/-7)+-3 km/s/Mpc (68 percent C.L.; Omega_m=0.3, Omega_L=0.7). The
offset of PG1115+080 from the Fundamental Plane might indicate deviations from
homology of the mass profile of some early-type galaxies.


title: SNAP Focal Plane

abstract:
  The proposed SuperNova/Acceleration Probe (SNAP) mission will have a
two-meter class telescope delivering diffraction-limited images to an
instrumented 0.7 square-degree field sensitive in the visible and near-infrared
wavelength regime. We describe the requirements for the instrument suite and
the evolution of the focal plane design to the present concept in which all the
instrumentation -- visible and near-infrared imagers, spectrograph, and star
guiders -- share one common focal plane.


title: Double degenerates from the supernova Ia progenitor survey (SPY)

abstract:
  We report on follow-up observations of double degenerate (DD) white dwarfs
from the Supernovae Ia Progenitor Survey (SPY). Orbital parameters of four
systems, including a massive short period system, are presented.