title:
Spectroscopic survey of the Galaxy with Gaia I. Design and performance
  of the Radial Velocity Spectrometer

abstract:
  The definition and optimisation studies for the Gaia satellite spectrograph,
the Radial Velocity Spectrometer (RVS), converged in late 2002 with the
adoption of the instrument baseline. This paper reviews the characteristics of
the selected configuration and presents its expected performance. The RVS is a
2.0 by 1.6 degree integral field spectrograph, dispersing the light of all
sources entering its field of view with a resolving power R=11 500 over the
wavelength range [848, 874] nm. The RVS will continuously and repeatedly scan
the sky during the 5 years of the Gaia mission. On average, each source will be
observed 102 times over this period. The RVS will collect the spectra of about
100-150 million stars up to magnitude V~17-18. At the end of the mission, the
RVS will provide radial velocities with precisions of ~2 km/s at V=15 and
\~15-20 km/s at V=17, for a solar metallicity G5 dwarf. The RVS will also
provide rotational velocities, with precisions (at the end of the mission) for
late type stars of sigma_vsini ~5 km/s at V~15 as well as atmospheric
parameters up to V~14-15. The individual abundances of elements such as Silicon
and Magnesium, vital for the understanding of Galactic evolution, will be
obtained up to V~12-13. Finally, the presence of the 862.0 nm Diffuse
Interstellar Band (DIB) in the RVS wavelength range will make it possible to
derive the three dimensional structure of the interstellar reddening.


title: Comptonization in the vicinity of black hole horizon

abstract:
  Using a Monte Carlo method, we derive spectra arising from Comptonization
taking place close to a Kerr black hole. We consider a model consisting of a
hot thermal corona Comptonizing seed photons emitted by a cold accretion disc.
We find that general relativistic effects are crucial for the emerging spectra
in models which involve significant contribution of radiation produced in the
black hole ergosphere. Due to this contribution, spectra of hard X-ray emission
produced in the vicinity of a rapidly rotating black hole strongly depend on
the inclination of the line of sight, with larger inclinations corresponding to
harder spectra. Remarkably, such anisotropy could be responsible for properties
of the X-ray spectra of Seyfert galaxies, which appear to be intrinsically
harder in type 2 objects than in type 1, as reported recently.


title: Atomic carbon at redshift ~2.5

abstract:
  Using the IRAM 30m telescope we detected the lower fine structure line of
neutral carbon towards three high--redshift sources: IRAS FSC10214 (z=2.3),
SMMJ14011+0252 (z=2.5) and H1413+117 (Cloverleaf quasar, z=2.5). SMMJ14011+0252
is the first high--redshift, non--AGN source in which CI has been detected. The
CI(1-0) line from FSC10214 is almost an order of magnitude weaker than
previously claimed, while our detection in the Cloverleaf is in good agreement
with earlier observations. The CI(1-0) linewidths are similar to the CO widths,
indicating that both lines trace similar regions of molecular gas on galactic
scales. Derived CI masses for all three objects are of order few 10^7 solar
masses and the implied CI(1-0)/CO(3-2) line luminosity ratio is about 0.2. This
number is similar to values found in local galaxies. We derive a CI abundance
of 5x10^{-5} which implies significant metal enrichment of the cold molecular
gas at redshifts 2.5 (age of the universe 2.7 Gyr). We conclude that the
physical properties of systems at large lookback times are similar to today's
starburst/AGN environments.


title: Status and future of hydrodynamical model atmospheres

abstract:
  Since about 25 years ago work has been dedicated to the development of
hydrodynamical model atmospheres for cool stars (of A to T spectral type).
Despite their obviously sounder physical foundation in comparison with standard
hydrostatic models, their general application has been rather limited. In order
to understand why this is, and how to progress, we review the present status of
hydrodynamical modelling of cool star atmospheres. The development efforts were
and are motivated by the theoretical interest of understanding the dynamical
processes operating in stellar atmospheres. To show the observational impact,
we discuss examples in the fields of spectroscopy and stellar structure where
hydrodynamical modelling provided results on a level qualitatively beyond
standard models. We stress present modelling challenges, and highlight
presently possible and future observations that would be particularly valuable
in the interplay between model validation and interpretation of observables, to
eventually widen the usage of hydrodynamical model atmospheres within the
astronomical community.


title: Chandra Observations of low velocity dispersion groups

abstract:
  Deviations of galaxy groups from cluster scaling relations can be understood
in terms of an excess of entropy in groups. The main effect of this excess is
to reduce the density and thus luminosity of the intragroup gas. Given this,
groups should also should show a steep relationship between X-ray luminosity
and velocity dispersion. However, previous work suggests that this is not the
case with many measuring slopes flatter than the cluster relation.
  Examining the group L_X:\sigma relation shows that much of the flattening is
caused by a small subset of groups which show very high X-ray luminosities for
their velocity dispersions (or vice versa).
  Detailed Chandra study of two such groups shows that earlier ROSAT results
were subject to significant (~30-40%) point source contamination, but confirm
that a significant hot IGM is present in these groups, although these are two
of the coolest systems in which intergalactic X-ray emission has been detected.
  Their X-ray properties are shown to be broadly consistent with those of other
galaxy groups, although the gas entropy in NGC 1587 is unusually low, and its
X-ray luminosity correspondingly high for its temperature, compared to most
groups.
  This leads us to suggest that the velocity dispersion in these systems has
been reduced in some way, and we consider how this might have come about.


title:
Hydrodynamical simulations of convection-related stellar
  micro-variability

abstract:
  We used a series of COBOLD hydrodynamical model atmospheres covering stellar
objects from white dwarfs to red giants to derive theoretical estimates of the
photometric and photocentric stellar variability in wavelength-integrated light
across the Hertzsprung-Russell diagram. We validated our models against solar
measurements from the SOHO/VIRGO instrument. Within our set of models we find a
systematic increase of the photometric as well as photocentric variability -
which turn out to be closely connected - with decreasing surface gravity. The
estimated absolute levels of the photocentric variability do not affect
astrometric observations on a precision level expected to be achieved by the
GAIA mission - with the exception of close-by giants. The case of supergiants
remains to be investigated. In view of the ongoing debate about the photometric
non-detection of p-modes in Procyon by the Canadian MOST satellite we remark
that we obtain a factor of ca. 3 in amplitude between the granular background
noise in the Sun and Procyon. This statement refers to a particular
representation of temporal power spectra as discussed in Sect. 5.


title: Are all Gamma Ray Bursts like GRB 980425, GRB 030329 and GRB 031203?

abstract:
  We study the probability that three GRBs (980425, 030329, 031203) are found
within z=0.17, given the luminosity functions consistent with the log N-log S
relationship for classical cosmological bursts (i.e., those observed by BATSE).
We show that, in order for the probability of these three low-z events to be
non-negligible (thus making it more likely that they belong to the same class
of the classical cosmological bursts), the bursts' luminosity function must be
a broken powerlaw. By reasoning in analogy with beamed AGNs, we show that
observations are consistent with the expectations if GRB 980425 and GRB 031203
are indeed normal bursts seen sideways. Within this model, no bright burst
within z=0.17 should be observed by a HETE--like instrument within the next
\sim 20 yr.


title: General Relativity and Neutrino-driven Supernova Winds

abstract:
  To date, detailed core-collapse supernova simulations have not succeeded in
elucidating the explosion mechanism. But whatever the mechanism turns out to
be, there will be a neutrino-heated outflow between the hot, newly-born neutron
star and the outgoing supernova shock wave whose neutron richness, low density,
and high temperature could provide promising conditions for the synthesis of
heavy nuclei via rapid neutron capture (the r-process). General relativistic
effects improve the prospects for this outflow as an r-process site. Among
relativistic effects, the enhanced "gravitational potential" is more important
than the gravitational redshift or trajectory bending of neutrinos.


title:
A flash in the dark: UVES/VLT high resolution spectroscopy of GRB
  afterglows

abstract:
  We present the first high resolution (R=20000--45000, corresponding to 14
km/s at 4200A to 6.6 km/s at 9000A) observations of the optical afterglow of
Gamma Ray Bursts. GRB020813 and GRB021004 were observed by UVES@VLT 22.19 hours
and 13.52 hours after the trigger, respectively. These spectra show that the
inter--stellar matter of the GRB host galaxies is complex, with many components
contributing to each main absorption system, and spanning a total velocity
range of up to about 3000 km/s. Several narrow components are resolved down to
a width of a few tens of km/s. In the case of GRB021004 we detected both low
and high ionization lines. Combined with photoionization results obtained with
CLOUDY, the ionization parameters of the various systems are consistent with a
remarkably narrow range with no clear trend with system velocity. This can be
interpreted as due to density fluctuations on top of a regular R^-2 wind
density profile.


title:
XMM-Newton Observations of the Extremely Low Accretion Rate Polars
  SDSSJ15531.12+551614.5 and SDSSJ132411.57+032050.5

abstract:
  XMM-Newton observations of the polar SDSSJ155331.12+551614.5 reveal that all
the X-ray flux emerges at energies less than 2 keV. The best fit to the
spectrum is with a thermal plasma with kT=0.8 keV plus a 20-90 ev black body,
yielding a thermal X-ray luminosity of 8-9.5E28 ergs/s. The low temperature and
X-ray luminosity, together with the lack of variation of the X-ray flux during
the observations, are all consistent with an extremely low accretion rate that
puts the system in the bombardment regime of accretion, rather than accretion
involving a standoff shock. It is likely that the observed X-rays originate
from the M dwarf secondary star, thus providing a base activity level for late
main sequence stars in close binaries. SDSSJ132411.57+032050.5 is detected by
XMM-Newton at the faint EPIC pn count rate of 0.0012 c/s, giving an upper limit
to the X-ray luminosity of 7E28 ergs/s for a distance of 300 pc, which is also
consistent with the above scenario.


title: Dust in 3CR radio galaxies: On the FR1-FR2 difference

abstract:
  We compare three 3CR samples of 11 FR1 galaxies, 17 FR2 galaxies and 18
lobe-dominated quasars contained in the ISO Data Archive. In contrast to the
powerful FR2 galaxies with edge-brightened lobes, the low radio power FR1
galaxies in our sample do not exhibit any high MIR or FIR dust luminosity,
which is typical for a buried, intrinsically more luminous AGN. This
consolidates the fact already inferred from optical studies that their AGNs
have only a relatively low luminosity. Also the FR1 galaxies show a high
FIR/MIR luminosity ratio, compared to quasars, suggesting that their FIR
luminosity is substantially powered by the interstellar radiation field (ISRF)
of the giant elliptical hosts. Finally, we discuss the FR1-FR2 morphological
dichotomy. FR1 galaxies do not have more interstellar matter (ISM) than FR2s as
traced -- on the large scale -- by the cool FIR emitting dust and -- in the
nuclear region -- by the warm MIR emitting dust. Due to the lack of central gas
we suggest that the black holes of our FR1 galaxies are fed at a lower
accretion rate than those of the FR2 galaxies.


title: Microlensing by gas filaments

abstract:
  Gas in the interstellar matter is generally organized in filamentary
structures, which may be also relevant for a complementary explanation of the
dark matter in the Galactic halo. We examine the possibility that such
structures may act as gravitational microlenses on background sources. To this
purpose, we derive the general properties of a cylindrical lens and compare the
light curves produced by such microlensing events with those generated by
spherically symmetric clouds. We find that the establishment of the symmetry of
the lens through the sole analysis of the light curve may be problematic, while
the analysis of the astrometric shift of the centroid of the image can
discriminate between the two classes of clouds. On the basis of our analysis,
we find that only gas filaments with a very high density could be detectable.
Such clouds are unlikely to exist in a long-lived state. Therefore,
microlensing cannot discriminate on the existence and the relevance of gas
filaments in the Halo, which could well be present and escape detection by
ordinary microlensing surveys.


title: A numerical MHD model for the solar tachocline

abstract:
  There are successful approaches to explain the formation of the tachocline by
a poloidal magnetic field in the solar core. We present here the first MHD
simulations of the solar tachocline which self-consistently include the
meridional circulation. We show that the meridional flow significantly changes
the shape and the characteristics of the tachocline. We find that after the
inclusion of the meridional circulation, a tachocline can be formed even when
the poloidal field lines are crossing the boundary between the radiative zone
and the convection zone. We also discuss the effects of the magnetic Prandtl
number as well as of the magnetic Reynolds number on the properties of the
tachocline. The tachocline is much thinner for higher magnetic Reynolds numbers
and/or lower magnetic Prandtl numbers. We expect that a poloidal magnetic seed
field of around 1 G will be sufficient to produce the tachocline of the Sun.
However, the model requires the initial magnetic field to be in a narrow range
for satisfying tachocline solutions. The simulations including a stable
temperature gradient produce a shallower as well as slower meridional
circulation than the ones without it, as desired from the Lithium abundance at
the solar surface.


title: Rotation and Mixing in Massive Stars: Principles and Uncertainties

abstract:
  The main instabilities induced by rotation in stellar interiors are
described. We derive from first principles the general equation describing the
transport of the angular momentum. The case of the transport of the chemical
species is also discussed. As long as the mass loss rates are not too
important, meridional currents, by advecting angular momentum from the inner
regions to the outer layers, accelerate the stellar surface during the Main
Sequence phase. A 9 M$_\odot$ stellar model at solar metallicity with an
equatorial velocity at the beginning of the core H--burning phase equal to 340
km s$^{-1}$ reaches the break--up limit during the MS phase. The model with an
initial velocity of 290 km s$^{-1}$ approaches this limit without reaching it.
The models with 290 km s$^{-1}$ and 340 km s$^{-1}$ predict enhancements of the
N/C ratio at the end of the MS phase equal to 2.8 and 3.2 times the initial
value respectively.


title: Mid-infrared sources in the ELAIS Deep X-ray Survey

abstract:
  We present a cross-correlation of the European Large Area ISO survey (ELAIS)
with the ELAIS Deep X-ray Survey of the N1 and N2 fields. There are 7 Chandra
point sources with matches in the ELAIS Final Analysis 15um catalogue, out of a
total of 28 extragalactic ISO sources present in the Chandra fields. Five of
these are consistent with AGN giving an AGN fraction of ~19 per cent in the
15um flux range 0.8-6 mJy. We have co-added the hard X-ray fluxes of the
individually-undetected ISO sources and find a low significance detection
consistent with star formation in the remaining population. We combine our
point source cross-correlation fraction with the XMM-Newton observations of the
Lockman Hole and Chandra observations of the Hubble Deep Field North to
constrain source count models of the mid-infrared galaxy population. The low
dust-enshrouded AGN fraction in ELAIS implied by the number of
cross-identifications between the ELAIS mid-infrared sample and the Chandra
point sources is encouraging for the use of mid-infrared surveys to constrain
the cosmic star formation history, provided there are not further large
undetected populations of Compton-thick AGN.


title: Coronal Heating versus Solar Wind Acceleration

abstract:
  Parker's initial insights from 1958 provided a key causal link between the
heating of the solar corona and the acceleration of the solar wind. However, we
still do not know what fraction of the solar wind's mass, momentum, and energy
flux is driven by Parker-type gas pressure gradients, and what fraction is
driven by, e.g., wave-particle interactions or turbulence. SOHO has been
pivotal in bringing these ideas back to the forefront of coronal and solar wind
research. This paper reviews our current understanding of coronal heating in
the context of the acceleration of the fast and slow solar wind. For the fast
solar wind, a recent model of Alfven wave generation, propagation, and non-WKB
reflection is presented and compared with UVCS, SUMER, radio, and in-situ
observations at the last solar minimum. The derived fractions of energy and
momentum addition from thermal and nonthermal processes are found to be
consistent with various sets of observational data. For the more chaotic slow
solar wind, the relative roles of steady streamer-edge flows (as emphasized by
UVCS abundance analysis) versus bright blob structures (seen by LASCO) need to
be understood before the relation between streamer heating and and slow-wind
acceleration can be known with certainty. Finally, this presentation summarizes
the need for next-generation remote-sensing observations that can supply the
tight constraints needed to unambiguously characterize the dominant physics.


title: Abundances in a Large Sample of Stars in M3 and M13

abstract:
  We have carried out a detailed abundance analysis for 21 elements in a sample
of 25 stars with a wide range in luminosity from luminous giants to stars near
the main sequence turnoff in the globular cluster M13 and in a sample of 13
stars distributed from the tip to the base of the RGB in the GC M3. Most
elements, including Fe, show no trend with Teff, and low scatter around the
mean between the top of the RGB and near the main sequence turnoff. We have
detected an anti-correlation between O and Na abundances, observed previously
among the most luminous RGB stars in both of these clusters, in both M3 and in
M13 over the full range of luminosity of our samples, i.e. in the case of M13
to near the main sequence turnoff. M13 shows a larger range in both O and Na
abundance than does M3 at all luminosities, in particular having a few stars at
its RGB tip with unusually strongly depleted O. Although CN burning must be
occurring in both M3 and in M13, and ON burning is required for M13, we combine
our new O abundances with published C and N abundances to confirm with quite
high precision that the sum of C+N+O is constant near the tip of the giant
branch, and we extend this down to the bump in the luminosity function. Star
I-5 in M13 has large excesses of Y and of Ba, with no strong enhancement of Eu,
suggesting an s-process event contributed. The mean abundance ratios for M3 and
for M13 are identical to within the errors. The abundance ratios for 13
Galactic GCs with recent detailed abundance analyses are compared to those of
published large surveys of metal-poor halo field stars. For most elements, the
agreement is very good, suggesting a common chemical history for the halo field
and cluster stars.


title:
Modeling of Closure Phase Measurements with AMBER/VLTI - Towards
  Characterization of Exoplanetary Atmospheres

abstract:
  Differential phase observations with a near-IR interferometer offer a way to
obtain spectra of extrasolar planets. The method makes use of the wavelength
dependence of the interferometer phase of the planet/star system, which depends
both on the interferometer geometry and on the brightness ratio between the
planet and the star. The differential phase is strongly affected by
instrumental and atmospheric dispersion effects. Difficulties in calibrating
these effects might prevent the application of the differential phase method to
systems with a very high contrast, such as extrasolar planets. A promising
alternative is the use of spectrally resolved closure phases, which are immune
to many of the systematic and random errors affecting the single-baseline
phases. We have modeled the response of the AMBER instrument at the VLTI to
realistic models of known extrasolar planetary systems, taking into account
their theoretical spectra as well as the geometry of the VLTI. We present a
strategy to determine the geometry of the planetary system and the spectrum of
the extrasolar planet from closure phase observations in two steps. We show
that there is a close relation between the nulls in the closure phase and the
nulls in the corresponding single-baseline phases: every second null of a
single-baseline phase is also a null in the closure phase. In particular, the
nulls in the closure phase do not depend on the spectrum but only on the
geometry. Therefore the geometry of the system can be determined by measuring
the nulls in the closure phase, and braking the remaining ambiguity due to the
unknown system orientation by means of observations at different hour angles.
Based on the known geometry, the planet spectrum can then be directly
synthesized from the closure phases.


title: Fluorescence photons produced in air by extensive air showers

abstract:
  The air fluorescence technique has long been used to detect extensive air
showers and to reconstruct its geometry and energy. The fluorescence photon
yield of an electron in air is of main importance in the reconstruction
procedure. Historically, the fluorescence yield used in the reconstruction of
the showers is approximated at all energies by that of an electron with kinetic
energy of 80 MeV, because these are the most abundant in a shower.
  In this paper, we calculate the fluorescence yield taking into account the
energy spectrum of electrons in showers initiated by proton and iron nuclei as
a function of height. We compare our results with previous calculations based
on mono energetic electrons (80 MeV) and a difference in excess of 8% is found.
Finally, the influence of a more realistic fluorescence yield in the shower
energy reconstruction is also discussed.


title: Inconsistency in theories of violent-relaxation

abstract:
  We examine an inconsistency in theories of violent-relaxation by Lynden-Bell
and Nakamura. The inconsistency arises from the non-transitive nature of these
theories: a system that under goes a violent-relaxation, relaxes and then upon
an addition of energy, undergoes violent-relaxation once again would settle in
an equilibrium state that is different from the one that is predicted had the
system would go directly from the initial to the final states. We conclude that
a proper description of the violent-relaxation process cannot be achieved by
equilibrium statistical mechanics approach, but instead a dynamical theory for
the coarse-grained phase-space density is needed.


title:
Transition (LINER/HII) nuclei as evolved Composite (Seyfert 2/Starburst)
  nuclei

abstract:
  We compare the circumnuclear stellar population and environmental properies
of Seyfert and Composite (Seyfert + Starburst) nuclei with those of LINERs and
LINER/HII transition galaxies (TOs), and discuss evidences for evolution from
Seyfert/Composite to LINER/TO nuclei.


title: Hybrid Mechanisms for Gas/Ice Giant Planet Formation

abstract:
  The effects of gas pressure gradients on the motion of solid grains in the
solar nebula substantially enhances the efficiency of forming protoplanetary
cores in the standard core accretion model in 'hybrid' scenarios for gas/ice
giant planet formation. Such a scenario is enhanced core accretion which
results from Epstein-drag induced inward radial migration of mm-sized grains
and subsequent particle subdisk gravitational instability needed to build up a
population of 1 km planetesimals. Solid/gas ratios can be enhanced by nearly
$\sim 10\times$ over those in Minimum Mass Solar Nebula (MMSN) in the outer
solar nebula (a $>$ 20 AU), increasing the oligarchic core masses and
decreasing formation timescales for protoplanetary cores. A 10 $M_{\oplus}$
core can form on $\sim 10^{6}-10^{7}$ year timescales at 15 - 25 AU compared to
$\sim 10^{8}$ years in the standard model,alleviating the major problem
plaguing the core accretion model for gas/ice giant planet formation.


title: High Energy Astrophysics Tests of Lorentz Invariance Violation

abstract:
  Multi-TeV spectra of Mkn 501 and other BL Lac objects exhibit the high energy
cutoffs predicted to be the result of intergalactic annihilation interactions,
primarily with IR photons having the flux level determined by various
astrophysical observations. After correcting for such intergalactic absorption,
these spectra can be explained within the framework of synchrotron self-Compton
emission models. Stecker and Glashow have shown that the existence of this
annihilation via electron-positron pair production puts strong constriants on
Lorentz invariance violation. Such constriants have important implications for
some quantum gravity and large extra dimension models. A much smaller amount of
Lorentz invariance violation has potential implications for understanding the
spectra of ultrahigh energy cosmic rays.


title:
FUSE Spectroscopy of the Transitional Magnetic Cataclysmic Variable V405
  Aurigae

abstract:
  We present Far Ultraviolet Spectroscopic Explorer observations of the
magnetic cataclysmic variable V405 Aurigae. Together with four other DQ Her
type binaries, V405 Aur forms a small subclass of intermediate polars which are
likely to evolve into low magnetic field strength polars, similar to AM Her.
Our co-added FUSE spectrum exhibits broad O VI and C III emission-lines as well
as a narrow O VI emission-line component which likely forms near the white
dwarf surface. The O VI 1032/1038 narrow emission line flux ratio is near 2.0
throughout the orbit, indicative of its formation in an optically thin gas.
Radial velocity measurements of the narrow O VI emission-lines restrict any
orbital modulation to a very low amplitude (Kwd = 2.5+/- 0.5 km/s) indicating,
along with other single peaked broad disk emission lines in the UV and optical,
that the binary system is at low inclination.


title: Angular power spectrum of the galactic synchrotron radiation

abstract:
  We calculate the angular power spectrum of the galactic synchrotron radiation
induced by the small scale fluctuations of the magnetic field and the cosmic
ray electron density. Using the observed interstellar magnetic field spectrum,
which is consistent with the Komolgorov turbulence model at the relevant
scales, we find that $C_l \propto l^{-3.7}$. We estimate the cosmic ray
electron density fluctuation spectrum with an injection-diffusion model, the
shape of the angular power spectrum in this model depends on the correlations
between the injection sources. For Poisson distribution of sources, $C_l
\propto l^{-4}$. We discuss the implications for the interpretation of cosmic
microwave background (CMB) data and the impact on future 21 cm tomography
experiments.


title:
A Beginner's Guide to the Theory of CMB Temperature and Polarization
  Power Spectra in the Line-of-Sight Formalism

abstract:
  We present here a detailed, self--contained treatment of the mathematical
formalism for describing the theory of polarized anisotropy in the cosmic
microwave background. This didactic review is aimed at researchers who are new
to the field. We first develop the mathematical tools for describing polarized
scattering of CMB photons. Then we take the reader through a detailed
derivation of the line-of-sight formalism, explaining the calculation of both
temperature and polarization power spectra due to the scalar and tensor
perturbations in a flat Universe.


title: Phase-Resolved Infrared H- and K-band Spectroscopy of EF Eridani

abstract:
  We present new phase-resolved H and K-band spectroscopy of the ultra-short
period magnetic cataclysmic variable EF Eri in its current, prolonged ``low''
state obtained using NIRI on Gemini-North, and NIRSPEC on Keck II. These new
data show that the H-band spectrum of EF Eri appears to be dominated by
cyclotron emission during the entire orbital cycle. The {\it K}-band spectrum
of EF Eri is likewise dominated by cyclotron emission during most of an orbital
period, but near binary phase 0.0, the secondary star spectrum may be visible.
We conclude that strong, and highly variable cyclotron emission is responsible
for the photometric variation previously reported for EF Eri. The nature of
this cyclotron emission is complex: the H-band spectra show that the dominant
cyclotron harmonic at phase 0.5 peaks at 1.65 $\mu$m, but at phase 0.0, the
harmonic peaks near 1.72 $\mu$m. At phase 0.5, there is another cyclotron
feature present that peaks in between the H and K bands (near 1.93 $\mu$m), but
at phase 0.0, no such feature is present. These data suggest that cyclotron
emission from both poles is occurring.


title: Lyman-alpha Emission from Structure Formation

abstract:
  The nature of the interaction between galaxies and the intergalactic medium
(IGM) is one of the most fundamental problems in astrophysics. The accretion of
gas onto galaxies provides fuel for star formation, while galactic winds
transform the nearby IGM in a number of ways. One exciting technique to study
this gas is through the imaging of hydrogen Lyman-alpha emission. We use
cosmological simulations to study the Lyman-alpha signals expected from the
growth of cosmic structure from z=0-5. We show that if dust absorption is
negligible, recombinations following the absorption of stellar ionizing photons
dominate the total Lyman-alpha photon production rate. However, galaxies are
also surrounded by "Lyman-alpha coronae" of diffuse IGM gas. These coronae are
composed of a combination of accreting gas and material ejected from the
central galaxy by winds. The Lyman-alpha emission from this phase is powered by
a combination of gravitational processes and the photoionizing background.
While the former dominates at z~0, collisional excitation following
photo-heating may well dominate the total emission at higher redshifts. The
central regions of these systems are dense enough to shield themselves from the
metagalactic ionizing background; unfortunately, in this regime our simulations
are no longer reliable. We therefore consider several scenarios for the
emission from the central cores, including one in which self-shielded gas does
not emit at all. We show that the combination of star formation and cooling IGM
gas can explain most of the observed "Lyman-alpha blobs" at z~3, with the
important exception of the largest sources. On the other hand, except under the
most optimistic assumptions, cooling IGM gas cannot explain the observations on
its own.


title: The Formation of the First Stars in the Universe

abstract:
  In this review, I survey our current understanding of how the very first
stars in the universe formed, with a focus on three main areas of interest: the
formation of the first protogalaxies and the cooling of gas within them, the
nature and extent of fragmentation within the cool gas, and the physics -- in
particular the interplay between protostellar accretion and protostellar
feedback -- that serves to determine the final stellar mass.
  In each of these areas, I have attempted to show how our thinking has
developed over recent years, aided in large part by the increasing ease with
which we can now perform detailed numerical simulations of primordial star
formation. I have also tried to indicate the areas where our understanding
remains incomplete, and to identify some of the most important unsolved
problems.


title: A Magnetic Rotator Wind Disk Model for Be Stars

abstract:
  A Magnetic Rotator Wind-Disk(MRWD) model is considered for the formation of
Keplerian disks around Be stars. Material from low latitudes of the stellar
surface flows along magnetic flux tubes and passes through a shock surface to
form a pre-Keplerian disk region. Initially, the density in this region is
small. After a fill-up time, the density of the disk is significantly larger
and the magnetic force becomes negligible compared with the centrifugal force.
The material then expands to form a Keplerian disk. During disk fill-up, the
meridional component B-star of the magnetic field at the stellar surface must
be larger than a minimum value B-star-min. The radial extent of the Keplerian
region will be larger when B-star is larger or when viscosity plays a role. In
B-type stars, B-star-min must be of order 1 G to 10 G. In faster rotating
stars, the wind speed must be correspondingly larger for the formation of
shock-compressed disk regions.


title: DDO 88: A Galaxy-Sized Hole in the Interstellar Medium

abstract:
  We present an HI and optical study of the gas-rich dwarf irregular galaxy DDO
88. Although DDO 88's global optical and HI parameters are normal for its
morphological type, it hosts a large (3 kpc diameter) and unusually complete
ring of enhanced HI emission. The gas ring is located at approximately
one-third of the total HI radius and one-half the optically-defined Holmberg
radius, and contains 30% of the total HI of the galaxy. The ring surrounds a
central depression in the HI distribution, so it may be a shell formed by a
starburst episode. However, the UBV colors in the HI hole are not bluer than
the rest of the galaxy as would be expected if an unusual star-forming event
had taken place there recently, but there is an old (~1-3 Gyr), red cluster
near the center of the hole that is massive enough to have produced the hole in
the HI. An age estimate for the ring, however, is uncertain because it is not
observed to be expanding. An expansion model produces a lower estimate of 0.5
Gyr, but the presence of faint star formation regions associated with the ring
indicate a much younger age. We also estimate that the ring could have
dispersed by now if it is older than 0.5 Gyr. This implies that the ring is
younger than 0.5 Gyr. A younger age would indicate that the red cluster did not
produce the hole and ring. If this ring and the depression in the gas which it
surrounds were not formed by stellar winds and supernovae, this would indicate
that some other, currently unidentified, mechanism is operating.


title: Instability of Chaplygin gas trajectories in unified dark matter models

abstract:
  In the past few years, the Chaplygin gas (CG) has been considered as an
appealing candidate for unifying dark matter and dark energy into a single
substance. This picture had to face several problems when trying to fit its
predictions with cosmological observations. We point out another potential
problem of this model, showing that, when the CG is described through a
classical scalar field, the corresponding trajectories are strongly unstable.
This implies that an extreme fine tuning must apply to the initial values of
the field in order to end up today with values allowed by observational data.


title:
New insights to the photometric structure of Blue Compact Dwarf Galaxies
  from deep Near-Infrared studies: II. The sample of northern BCDs

abstract:
  This paper is part of a series of publications which present a systematic
study of Blue Compact Dwarf (BCD) Galaxies in the Near Infrared (NIR). Compared
to the visible light, NIR data allow a better separation of the starburst
emission from the light distribution of the old stellar low-surface brightness
(LSB) host galaxy. We analyze deep NIR broad band images of a sample of 11
BCDs, observed with the Calar Alto 3.6m telescope. This work enlarges the
samples presented in preceding papers of this study (Noeske et al. 2003, Cairos
et al. 2003) by BCDs of the most common morphological type, displaying a
regular elliptical LSB host galaxy. The data presented here allow the detection
and quantitative study of the extended stellar LSB host galaxy in all sample
BCDs. The NIR surface brightness profiles (SBPs) of the LSB host galaxies agree
at large galactocentric radii with those from optical studies, showing also an
exponential intensity decrease and compatible scale lengths. Similar to Noeske
et al. (2003), we find centrally flattening exponential (type V) SBPs of the
host galaxy for several BCDs. Such SBPs remain mostly undetected in optical
bands, due to the comparatively stronger starburst emission at these
wavelengths. We apply a modified exponential distribution to decompose and
quantitatively analyze SBPs of LSB hosts with a type V intensity distribution.
We present the results of the surface photometry and the decomposition of SBPs,
and discuss individual objects with respect to morphological details of their
star-forming regions.


title: The Aquarius Superclusters II. Spectroscopic and Photometric Data

abstract:
  We present spectroscopic and photometric data for 920 galaxies selected in 68
fields of the Aquarius Cluster Catalog. Typically the 15 brightest candidate
members with magnitudes in the range 16 < b_J < 21 were selected for
observations, and ~ 71% turn out to be cluster members. Using the new redshift
determinations we assign galaxies to groups and clusters, and by including data
from the literature we calculate systemic velocities and velocity dispersions
for 74 clusters, each with redshifts measured for at least 6 individual
galaxies.


title: A Wide-Field HI Study of the NGC 1566 Group

abstract:
  We report on neutral hydrogen observations of a ~ 5.5 x 5.5 degree field
around the NGC 1566 galaxy group with the multibeam narrow-band system on the
64-m Parkes telescope. We detected thirteen HI sources in the field, including
two galaxies not previously known to be members of the group, bringing the
total number of confirmed galaxies in this group to 26. Each of the HI galaxies
can be associated with an optically catalogued galaxy. No 'intergalactic HI
clouds' were found to an HI mass limit of ~ 3.5 x 10^8 Msun. We have estimated
the expected HI content of the late-type galaxies in this group and find the
total detected HI is consistent with our expectations. However, while no global
HI deficiency is inferred for this group, two galaxies exhibit individual HI
deficiencies. Further observations are needed to determine the gas removal
mechanisms in these galaxies.


title:
Inhomogeneity in the Hot Intracluster Medium of Abell 1060 Observed with
  Chandra

abstract:
  A Chandra observation of the non-cooling flow cluster A 1060 has confirmed
that the hot intracluster medium has fairly uniform distributions of
temperature and metal abundance from a radius of about 230 kpc to the central 5
kpc region (H_0= 75 km/s/Mpc). The radial temperature profile shows a broad
peak at 30-40 kpc from the center at a level ~20% higher than that in the outer
region. Assuming spatially uniform temperature and abundance distributions, we
derived a 3-dimensional density structure by iteratively correcting the beta
model, and obtained the central gas density to be 8.2^{+1.8}_{-1.0} x 10^{-3}
cm^{-3}. The distribution of gravitational mass was estimated from the density
profile, and a central concentration of mass within a radius of 50 kpc was
indicated. The data also suggest several high-abundance regions. The most
significant blob adjacent to the central galaxy NGC 3311 has a radius of about
9 kpc, which indicates a metallicity of ~1.5 solar. We consider that this blob
may be produced by the gas stripped off from NGC 3311.


title: A low upper-limit on the lithium isotope ratio in HD140283

abstract:
  We have obtained a high-S/N (900-1100), high-resolving-power (R=95000)
spectrum of the metal-poor subgiant HD 140283 in an effort to measure its
6Li/7Li isotope ratio. From a 1-D atmospheric analysis, we find a value
consistent with zero, 6Li/7Li = 0.001, with an upper limit of 6Li/7Li < 0.026.
This measurement supersedes an earlier detection (0.040 +/- 0.015(1sigma)) by
one of the authors. HD 140283 provides no support for the suggestion that
Population II stars may preserve their 6Li on the portion of the subgiant
branch where 7Li is preserved. However, this star does not defeat the
suggestion either; being at the cool end of subgiant branch of the Spite
plateau, it may be sufficiently cool that 6Li depletion has already set in, or
the star may be sufficiently metal poor that little Galactic production of 6Li
had occurred. Continued investigation of other subgiants is necessary to test
the idea. We also consider the implications of the HD 140283 upper limit in
conjunction with other measurements for models of 6Li production by cosmic rays
from supernovae and structure formation shocks.


title: X-ray and radio emission from colliding stellar winds

abstract:
  The collision of the hypersonic winds in early-type binaries produces shock
heated gas, which radiates thermal X-ray emission, and relativistic electrons,
which emit nonthermal radio emission. We review our current understanding of
the emission in these spectral regions and discuss models which have been
developed for the interpretation of this emission. Physical processes which
affect the resulting emission are reviewed and ideas for the future are noted.


title:
Monte-Carlo experiments on star-cluster induced integrated-galaxy IMF
  variations

abstract:
  As most if not all stars are born in stellar clusters the shape of the mass
function of the field stars is not only determined by the initial mass function
of stars (IMF) but also by the cluster mass function (CMF). In order to
quantify this Monte-Carlo simulations were carried out by taking cluster masses
randomly from a CMF and then populating these clusters with stars randomly
taken from an IMF. Two cases were studied. Firstly the star masses were added
randomly until the cluster mass was reached. Secondly a number of stars, given
by the cluster mass divided by an estimate of the mean stellar mass and sorted
by mass, were added until the desired cluster mass was reached. Both
experiments verified the analytical results of Kroupa & Weidner (2003) that the
resulting integrated stellar initial mass function is a folding of the IMF with
the CMF and therefore steeper than the input IMF above 1 Msol.


title: GAUDI: a preparatory archive for the COROT mission

abstract:
  The GAUDI database (Ground-based Asteroseismology Uniform Database Interface,
http://sdc.laeff.esa.es/gaudi/) is a preparatory archive for the COROT
(COnvection, ROtation and planetary Transits,
http://www.astrsp-mrs.fr/projets/corot/) mission developed at LAEFF (Laboratory
for Space Astrophysics and Theoretical Physics, http://www.laeff.esa.es). Its
intention is to make the ground-based observations obtained in the preparation
of the asteroseismology programme available in a simple and efficient way. It
contains spectroscopic and photometric data together with inferred physical
parameters for more than 1500 objects gathered since January 1998 in 6 years of
observational campaigns. In this paper, the main functionalities and
characteristics of the system are described. The observations have been
collected at ESO-La Silla, Telescopio Nazionale Galileo, Observatoire de
Haute-Provence, South African Astronomical Observatory, Tautenberg Observatory
and Sierra Nevada Observatory.


title:
Membership, binarity and accretion among very low-mass stars and brown
  dwarfs of the Sigma Orionis cluster

abstract:
  Intermediate resolution (R=7000) spectroscopy is presented for 76
photometrically selected very low mass (0.04<M<0.3M_{sun}) candidate members of
the Sigma Orionis cluster. More than two thirds appear to be genuine cluster
members on the basis of Li I absorption, weak Na I features and radial
velocities. Photometric selection alone therefore appears to be very effective
in identifying cluster members in this mass range. Only 6 objects appear to be
certain non-members, however a substantial subset of 13 have ambiguous or
contradictory indications of membership and lack Li absorption. Four candidate
binary cluster members are identified. Consideration of sampling and precision
leads us to conclude that either the fraction of very low mass stars and brown
dwarfs in small separation (a<1au) binary systems is larger than in field
M-dwarfs, or the distribution of separations is much less skewed towards large
separations. This conclusion hinges critically on the correct identification of
the small number of binary candidates, but is significant even when only
Li-rich candidate members are considered. Broadened H alpha emission,
indicative of circum(sub)stellar accretion discs is found in 5 or 6 of the
candidate cluster members, 3 of which probably have substellar masses. The
fraction of accretors (10+/-5 per cent) is similar to that found in stars of
higher mass in the cluster using H alpha emission as a diagnostic, but much
lower than found for very low mass stars and brown dwarfs of younger clusters.
The timescale for accretion rates to drop to less than 10^{-11} M_sun/yr is
hence less than the age of the Sigma Ori cluster (3 to 7 Myr) for most low-mass
objects (abridged).


title: Young Super Star Clusters in the Starburst of M82: The Catalogue

abstract:
  Recent results from Hubble Space Telescope (HST) have resolved starbursts as
collections of compact young stellar clusters. Here we present a photometric
catalogue of the young stellar clusters in the nuclear starburst of M82,
observed with the HST WFPC2 in Halpha (F656N) and in four optical broad-band
filters. We identify 197 young super stellar clusters. The compactness and high
density of the sources led us to develop specific techniques to measure their
sizes. Strong extinction lanes divide the starburst into five different zones
and we provide a catalogue of young super star clusters for each of these. In
the catalogue we include relative coordinates, radii, fluxes, luminosities,
masses, equivalent widths, extinctions, and other parameters. Extinction values
have been derived from the broad-band images. The radii range between 3 and 9
pc, with a mean value of 5.7 +/- 1.4pc, and a stellar mass between 10e4 and
10e6 Mo. The inferred masses and mean separation, comparable to the size of
super star clusters, together with their high volume density, provides strong
evidence for the key ingredients postulated by Tenorio et al. (2003) as
required for the development of a supergalactic wind.


title: Neutron star cooling

abstract:
  The impact of nuclear physics theories on cooling of isolated neutron stars
is analyzed. Physical properties of neutron star matter important for cooling
are reviewed such as composition, the equation of state, superfluidity of
various baryon species, neutrino emission mechanisms. Theoretical results are
compared with observations of thermal radiation from neutron stars. Current
constraints on theoretical models of dense matter, derived from such a
comparison, are formulated.


title: The massive neutron star or low-mass black hole in 2S0921-630

abstract:
  We report on optical spectroscopy of the eclipsing Halo LMXB 2S0921-630, that
reveals the absorption line radial velocity curve of the K0III secondary star
with a semi-amplitude K_2=92.89 +/- 3.84 km/s, a systemic velocity
$\gamma$=34.9 +/- 3.3 \kms and an orbital period P_orb of 9.0035 +/- 0.0029 day
(1-sigma). Given the quality of the data, we find no evidence for the effects
of X-ray irradiation. Using the previously determined rotational broadening of
the mass donor, and applying conservative limits on the orbital inclination, we
constrain the compact object mass to be 2.0-4.3 Msolar (1-sigma), ruling out a
canonical neutron star at the 99% level. Since the nature of the compact object
is unclear, this mass range implies that the compact object is either a
low-mass black hole with a mass slightly higher than the maximum neutron star
mass (2.9 Msolar) or a massive neutron star. If the compact object is a black
hole, it confirms the prediction of the existence of low-mass black holes,
while if the object is a massive neutron star its high mass severely constrains
the equation of state of nuclear matter.


title:
A new Bohm-Vitense gap in the temperature range 5560 to 5610K in the
  Main Sequence

abstract:
  Highly precise temperatures (sigma = 10-15 K) have been determined from line
depth ratios for a set of 248 F-K field dwarfs of about solar metallicity (-0.5
< [Fe/H] < +0.4), based on high resolution (R=42000), high S/N echelle spectra.
A new gap has been discovered in the distribution of stars on the Main Sequence
in the temperature range 5560 to 5610 K. This gap coincides with a jump in the
microturbulent velocity Vt and the well-known Li depression near 5600 K in
field dwarfs and open clusters. As the principal cause of the observed
discontinuities in stellar properties we propose the penetration of the
convective zone into the inner layers of stars slightly less massive than the
Sun and related to it, a change in the temperature gradient.


title:
Probing the Kinematics of the Narrow-Line Region in Seyfert Galaxies
  with Slitless Spectroscopy: Observational Results

abstract:
  We present slitless spectra of 10 Seyfert galaxies observed with the Space
Telescope Imaging Spectrograph on the Hubble Space Telescope. The spectra cover
the [OIII] 4959, 5007 emission lines at a spectral resolving power of ~9000 and
a spatial resolution of 0.1". We compare the slitless spectra with previous HST
narrow-band images to determine the velocity shifts and dispersions of the
bright emission-line knots in the narrow-line regions (NLRs) of these Seyferts.
Many knots are spatially resolved with sizes of tenths of arcsecs,
corresponding to tens of pcs, and yet they appear to move coherently with
radial velocities between zero and +/- 1200 km/s with respect to the systemic
velocities of their hostgalaxies. The knots also show a broad range in velocity
dispersion, ranging from ~30 km/s (the velocity resolution) to ~1000 km/s FWHM.
Most of the Seyfert galaxies in this sample show an organized flow pattern,
with radial velocities near zero at the nucleus (defined by the optical
continuum peak) and increasing to maximum blueshifts and redshifts within ~1''
of the nucleus, followed by a decline to the systemic velocity. The
emission-line knots also follow a general trend of decreasing velocity
dispersion with increasing distance. In the Seyfert 2 galaxies, the presence of
blueshifts and redshifts on either side of the nucleus indicates that rotation
alone cannot explain the observed radial velocities, and that radial outflow
plays an important role. Each of the Seyfert galaxies in this sample (with the
exception of Mrk 3) shows a bright, compact (FWHM < 0.5") [O III] knot at the
position of its optical nucleus. These nuclear emission-line knots have
radial-velocity centroids near zero, but they typically have the highest
velocity dispersions.


title: Gamma-ray Bursts and Hypernovae

abstract:
  In these proceedings, I discuss recent progress in understanding the nature
of cosmic gamma-ray bursts (GRB), with the focus on the apparent relation of
several GRBs with an energetic subclass of stellar explosions, type Ib/c
core-collapse supernovae. This relation provides the strong case that the GRB
phenomenon is connected with the final stages of massive star evolution and
possibly with the formation of neutron stars and black holes. I speculate that
intrinsically faint, apparently spherically symmetric nearby GRB 980425 and
031203 associated with bright hypernovae SN 1998bw and SN 2003lw, respectively,
can signal the formation of a neutron star in the end of gravitational
collapse, while the bulk of cosmological GRBs with a universal energy release
of $\sim 10^{51}$ ergs in narrow-collimated jets are produced when a black hole
is formed. In the former case, the energy source of GRB is the neutron star
rotational energy; in the latter case the GRB energy is due to non-stationary
accretion onto the black hole.


title:
Chandra observations of X-ray source overdensities in distant galaxy
  cluster fields

abstract:
  The first systematic study of the serendipitous X-ray source density around
10 high z (0.24<z<1.2) clusters performed with Chandra is presented. A factor
\~2 overdensity has been found in 4 cluster fields. The result is statistically
highly significant (at >2sigma per field, and >5sigma overall) only on scale of
8'X8' and peculiar to cluster fields. The blank field fluctuations, i.e. the
most sensitive measurements to date of the X-ray cosmic variance on this scale,
indicate (1 sigma) variations within ~15-25% around the average value. The
first marginal evidence that these overdensities increase with cluster redshift
is also presented. We speculate that the most likely explanation is that the
sources in excess are AGNs tracing filaments connected to the clusters. If the
association of the overdensities with large-scale structures and their positive
relation with cluster redshift is confirmed, these studies could represent a
new, direct, way of mapping the cosmic web and its cosmological parameters at
high z.


title: Effects of Metallicity on the Rotation Rates of Massive Stars

abstract:
  Recent theoretical predictions for low metallicity massive stars predict that
these stars should have drastically reduced equatorial winds (mass loss) while
on the main sequence, and as such should retain most of their angular momentum.
Observations of both the Be/(B+Be) ratio and the blue-to-red supergiant ratio
appear to have a metallicity dependence that may be caused by high rotational
velocities. We have analyzed 39 archival Hubble Space Telescope Imaging
Spectrograph (STIS), high resolution, ultraviolet spectra of O-type stars in
the Magellanic Clouds to determine their projected rotational velocities V sin
i. Our methodology is based on a previous study of the projected rotational
velocities of Galactic O-type stars using International Ultraviolet Explorer
(IUE) Short Wavelength Prime (SWP) Camera high dispersion spectra, which
resulted in a catalog of V sin i values for 177 O stars. Here we present
complementary V sin i values for 21 Large Magellanic Cloud and 22 Small
Magellanic Cloud O-type stars based on STIS and IUE UV spectroscopy. The
distribution of V sin i values for O type stars in the Magellanic Clouds is
compared to that of Galactic O type stars. Despite the theoretical predictions
and indirect observational evidence for high rotation, the O type stars in the
Magellanic Clouds do not appear to rotate faster than their Galactic
counterparts.


title:
Variable stars in the bar of the Large Magellanic Cloud: the photometric
  catalogue

abstract:
  The catalogue of the Johnson-Cousins B,V and I light curves obtained for 162
variable stars (135 RR Lyrae, 4 candidate Anomalous Cepheids, 11 Classical
Cepheids, 11 eclipsing binaries and 1 delta Scuti star) in two areas close to
the bar of the Large Magellanic Cloud is presented along with coordinates,
finding charts, periods, epochs, amplitudes, and mean quantities (intensity-
and magnitude-averaged luminosities) of the variables with full coverage of the
light variations. A star by star comparison is made with MACHO and OGLE II
photometries based on both variable and constant stars in common, and the
transformation relationships to our photometry are provided. The pulsation
properties of the RR Lyrae stars in the sample are discussed in detail.
Parameters of the Fourier decomposition of the light curves are derived for the
fundamental mode RR Lyrae stars with complete and regular curves (29 stars).
They are used to estimate metallicities, absolute magnitudes, intrinsic (B-V)o
colours, and temperatures of the variable stars, according to Jurcsik and
Kovacs (1996), and Kovacs and Walker (2001) method. Quantities derived from the
Fourier parameters are compared with the corresponding observed quantities. In
particular, the "photometric" metallicities are compared with the spectroscopic
metal abundances derived by Gratton et al. (2004) from low resolution spectra
obtained with FORS at the Very Large Telescope.


title:
The spatial clustering of X-ray selected AGN and galaxies in the Chandra
  Deep Field South and North

abstract:
  We investigate the spatial clustering of X-ray selected sources in the two
deepest X-ray fields to date, namely the 2Msec Chandra Deep Field North (CDFN)
and the 1Msec Chandra Deep Field South (CDFS). The projected correlation
function w(r_p), measured on scales ~0.2-10 h^-1 Mpc for a sample of 240
sources with spectroscopic redshift in the CDFN and 124 sources in the CDFS at
a median redshift of z~0.8, is used to constrain the amplitude and slope of the
real space correlation function xi(r)=(r/r0)^-gamma. The clustering signal is
detected at high confidence (>~ 7 sigma) in both fields. The amplitude of the
correlation is found to be significantly different in the two fields, the
correlation length r0 being 8.6 +- 1.2 h^-1 Mpc in the CDFS and 4.2 +- 0.4 h^-1
Mpc in the CDFN, while the correlation slope gamma is found to be flat in both
fields: gamma=1.33 +- 0.11 in the CDFS and gamma=1.42 +- 0.07 in the CDFN (a
flat Universe with Omega_m=0.3 and Omega_L=0.7 is assumed; 1 sigma Poisson
error estimates are considered). The correlation function has been also
measured separately for sources classified as AGN or galaxies. In both fields
AGN have a median redshift of z~0.9 and a median 0.5-10 keV luminosity of
L_x~10^43 erg s^-1, i.e. they are generally in the Seyfert luminosity regime.
As in the case of the total samples, we found a significant difference in the
AGN clustering amplitude between the two fields, the best fit correlation
parameters being r0=10.3 +- 1.7 h^-1 Mpc, gamma=1.33 +- 0.14 in the CDFS, and
r0=5.5 +- 0.6 h^-1 Mpc, gamma=1.50 +- 0.12 in the CDFN. Within each field no
statistically significant difference is found between soft and hard X-ray
selected sources or between type 1 and type 2 AGN. (abridged)


title: A Million-Second Chandra View of Cassiopeia A

abstract:
  We introduce a million-second observation of the supernova remnant Cassiopeia
A with the Chandra X-ray Observatory. The bipolar structure of the Si-rich
ejecta (NE jet and SW counterpart) is clearly evident in the new images, and
their chemical similarity is confirmed by their spectra. These are most likely
due to jets of ejecta as opposed to cavities in the circumstellar medium, since
we can reject simple models for the latter. The properties of these jets and
the Fe-rich ejecta will provide clues to the explosion of Cas A.


title: Asymmetries in Powerful Extragalactic Radio Sources

abstract:
  This review provides the background and current perspective of some of the
striking asymmetries exhibited by extragalactic double-lobed radio sources,
paying special attention to the reported interrelationships among some of them.
We particularly aim to highlight some less discussed aspects pertaining to the
radio lobes and hot-spots for which any relativistic beaming effects are milder
than those imposed on the jets. Various attributes of these features, such as
their geometry, intensity, spectrum, and polarization provide important
underpinnings to models of radio galaxies and quasars, as well as to theories
that attempt to unify them. These contraints are sharpened by exploiting the
asymmetry properties of the extended optical emission-line regions associated
with powerful radio sources, including the giant halos of Lyman-alpha emission
associated with them. We suggest that highly extended disks of dusty gaseous
material, which could also be parts of cosmic filaments, around the host
galaxies of radio sources may hold the key to understanding the correlated
radio--optical asymmetry and perhaps also the depolarization asymmetry of the
twin radio lobes. We also discuss the nature and possible implications of the
extreme type of asymmetry witnessed in the enigmatic quasar 3C273, whose entire
radio emission is observed on just one side of the nucleus. In this context,
theoretical scenarios for the production of one-sided jets are also briefly
recounted. Taking a clue from theobserved one-sidedness of the extended radio
jets even in `weak-headed-quasars', we also propose a scenario for the late
evolutionary stage of double radio sources. We end with a list of key questions
concerning radio source asymmetries which still require final answers.
(Abridged)


title: The planet in M4: implications for planet formation in globular clusters

abstract:
  We consider the formation and evolution of the planetary system PSR B1620-26
in the globular cluster M4. We propose that as M4 is a very-low metallicity
environment the standard model of planet formation around main-sequence stars
through the accretion of gas onto metallic rocky cores should not be applied.
Consequently the previously suggested methods for formation are unlikely. We
propose that the planet formed through the interaction of a passing star with a
circumbinary disc during the common-envelope phase of the inner binary's
evolution. This formation route is favoured by dense stellar systems such as
globular clusters.


title: New VR magnification ratios of QSO 0957+561

abstract:
  We present VR magnification ratios of QSO 0957+561, which are inferred from
the GLITP light curves of Q0957+561A and new frames taken with the 2.56m Nordic
Optical Telescope about 14 months after the GLITP monitoring. From two
photometric approaches and a reasonable range for the time delay in the system
(415-430 days), we do not obtain achromatic optical continuum ratios, but
ratios depending on the wavelength. These new measurements are consistent with
differential extinction in the lens galaxy, the Lyman limit system, the damped
Ly-alpha system, or the host galaxy of the QSO. The possible values for the
differential extinction and the ratio of total to selective extinction in the V
band are reasonable. Moreover, crude probability arguments suggest that the ray
paths of the two components cross a similar dusty environment, including a
network of compact dust clouds and compact dust voids. As an alternative (in
fact, the usual interpretation of the old ratios), we also try to explain the
new ratios as caused by gravitational microlensing in the deflector. From
magnification maps for each of the gravitationally lensed images, using
different fractions of the surface mass density represented by the microlenses,
as well as different sizes and profiles of the V-band and R-band sources,
several synthetic distributions of V-band and R-band ratios are derived. In
some gravitational scenarios, there is an apparent disagreement between the
observed pair of ratios and the simulated distributions. However, several
microlensing pictures work well. To decide between either extinction, or
microlensing, or a mixed scenario (extinction + microlensing), new
observational and interpretation efforts are required.


title: Observation of the Anomalous X-Ray Pulsar 4U 0142+61

abstract:
  We present results of an observation of the anomalous X-ray pulsar 4U 0142+61
with the EPIC cameras on XMM-Newton performed on 2003 January 24. The pulse
phase averaged spectrum can be best described by the sum of a black body with a
temperature of kT_BB = 0.395(5) keV and a power law with photon index Gamma =
3.62(5). The unabsorbed 2-10 keV flux is ~7.2x10^-11 erg s^-1 cm^-2. No
evidence for additional spectral features such as cyclotron lines is present.
These results are consistent with those from an earlier Chandra observation in
2001 May. Phase resolved spectroscopy over the 8.6882(2) s period (MJD
52663.93) shows clear variations with pulse phase of Gamma, while kT_BB shows a
small variation of ~12%. We confirm earlier conclusions by Oezel (2001) that
the emission from AXPs is more likely to originate from neutron stars with one
single and magnetically active region on the neutron star. The significantly
different behavior of the soft and hard spectral components with pulse phase,
however, cannot be fully reconciled with the present magnetar emission models.


title: Changing universe model with applications

abstract:
  Although the current galaxy models yield calculations consistent with much of
the data, many irregularities exist, exceptions have been found to the current
models, the $\Lambda$CDM model apparently fails on galaxy scales, dark matter
remains elusive, the phenomena at the center of galaxies are only beginning to
be addressed, and many observations and empirical relationships are
unexplained. A changing universe model (CUM) is proposed that posits the stuff
of our universe is continually erupting into our universe from sources at the
center of galaxies. In this first test of the CUM, a single equation that
describes the rotation velocity curve of spiral galaxies is derived. The
equation is also used to correlate the measured mass of the theorized, central
supermassive black hole with other galaxy parameters. The equation adds one
parameter for each mature galaxy and one parameter for each particle (atom
nucleus and smaller) species to Newtonian dynamics. Rising, flat, and declining
rotation velocity curves are explained without unknown dark matter. Ten
previously unknown parametric relationships are discovered. Also, the CUM
integrates several heretofore unrelated observations. The CUM model is in an
early development stage and has already predicted new relationships among
galaxy parameters.


title:
Radial Velocity Detectability of Low Mass Extrasolar Planets in Close
  Orbits

abstract:
  Detection of Jupiter mass companions to nearby solar type stars with precise
radial velocity measurements is now routine, and Doppler surveys are moving
towards lower velocity amplitudes. The detection of several Neptune-mass
planets with orbital periods less than a week has been reported. The drive
toward the search for close-in Earth-mass planets is on the agenda. Successful
detection or meaningful upper limits will place important constraints on the
process of planet formation. In this paper, we quantify the statistics of
detection of low-mass planets in-close orbits, showing how the detection
threshold depends on the number and timing of the observations. In particular,
we consider the case of a low-mass planet close to but not on the 2:1 mean
motion resonance with a hot jupiter. This scenario is a likely product of the
core-accretion hypothesis for planet formation coupled with migration of
jupiters in the protoplanetary disk. It is also advantageous for detection
because the orbital period is well-constrained. Detection of few Earth mass
rocky cores will require ~ 1 m/s velocity precision, and most importantly, a
much better understanding of stellar radial velocity jitter.


title:
Faraday Rotation of the Cosmic Microwave Background Polarization by a
  Stochastic Magnetic Field

abstract:
  A primordial cosmological magnetic field induces Faraday rotation of the
cosmic microwave background polarization. This rotation produces a curl-type
polarization component even when the unrotated polarization possesses only
gradient-type polarization, as expected from scalar density perturbations. We
compute the angular power spectrum of curl-type polarization arising from small
Faraday rotation due to a weak stochastic primordial magnetic field with a
power-law power spectrum. The induced polarization power spectrum peaks at
arcminute angular scales. Faraday rotation is one of the few cosmological
sources of curl-type polarization, along with primordial tensor perturbations,
gravitational lensing, and the vector and tensor perturbations induced by
magnetic fields; the Faraday rotation signal peaks on significantly smaller
angular scales than any of these, with a power spectrum amplitude which can be
comparable to that from gravitational lensing. Prospects for detection are
briefly discussed.


title: Constraining Neutrino Masses by CMB Experiments Alone

abstract:
  It is shown that a subelectronvolt upper limit can be derived on the neutrino
mass from the CMB data alone in the Lambda CDM model with the power-law
adiabatic perturbations, without the aid of any other cosmological data.
Assuming the flatness of the universe, the constraint we can derive from the
current WMAP observations is \sum m_nu < 2.0 eV at the 95% confidence level for
the sum over three species of neutrinos (m_nu < 0.66 eV for the degenerate
neutrinos). This constraint modifies little even if we abandon the flatness
assumption for the spatial curvature. We argue that it would be difficult to
improve the limit much beyond \sum m_nu \lesssim 1.5 eV using only the CMB
data, even if their statistics are substantially improved. However, a
significant improvement of the limit is possible if an external input is
introduced that constrains the Hubble constant from below. The parameter
correlation and the mechanism of CMB perturbations that give rise to the limit
on the neutrino mass are also elucidated.


title:
Magnetically Controlled Spasmodic Accretion During Star Formation. I.
  Formulation of the Problem and Method of Solution

abstract:
  We formulate the problem of the late accretion phase of the evolution of an
isothermal magnetic disk surrounding a forming star. The evolution is described
by the six-fluid MHD equations, accounting for the presence of neutrals, atomic
and molecular ions, electrons, and neutral, positively, and negatively charged
grains. Only the electron fluid is assumed to be attached to the magnetic
field, in order to investigate the effect of the detachment of the ions from
the magnetic field lines that begins at densities as low as 10^8 cm^-3. The
"central sink approximation" is used to circumvent the problem of describing
the evolution inside the opaque central region for densities greater than 10^11
cm^-3. In this way, the structure and evolution of the isothermal disk
surrounding the forming star can be studied at late times without having to
implement the numerically costly radiative transfer required by the physics of
the opaque core. The mass and magnetic flux accumulating in the forming star
arecalculated, as are their effects on the structure & evolution of the
surrounding disk. The numerical method of solution first uses an adaptive grid
and later, after a central region a few AU in radius becomes opaque, switches
to a stationary but nonuniform grid with a central sink cell. It also involves
an implicit time integrator, an advective difference scheme that possesses the
transportive property, a second-order difference approximation of forces inside
a cell, an integral approximation of the gravitational and magnetic fields, and
tensor artificial viscosity that permits an accurate investigation of the
formation and evolution of shocks in the neutral fluid.


title: Dynamic X-ray spectra of Chandra cataclysmic variables

abstract:
  In this work we have tested conception of energy dependent power spectra
which can be applied for analysis of X-ray dynamic spectra of cataclysmic
variables. Using this technique we can study properties of variability in
different energy ranges.


title:
Magnetically Controlled Spasmodic Accretion During Star Formation. II.
  Results

abstract:
  The problem of the late accretion phase of the evolution of an axisymmetric,
isothermal magnetic disk surrounding a forming star has been formulated in a
companion paper. The "central sink approximation" is used to circumvent the
problem of describing the evolution inside the opaque central region for
densities greater than 10^11 cm^-3 and radii smaller than a few AUs. Only the
electrons are assumed to be attached to the magnetic field lines, and the
effects of both negatively and positively charged grains are accounted for.
After a mass of 0.1 solar mass accumulates in the central cell (forming star),
a series of magnetically driven outflows and associated outward propagating
shocks form in a quasi-periodic fashion. As a result, mass accretion onto the
protostar occurs in magnetically controlled bursts. We refer to this process as
spasmodic accretion. The shocks propagate outward with supermagnetosonic
speeds. The period of dissipation and revival of the outflow decreases in time,
as the mass accumulated in the central sink increases. We evaluate the
contribution of ambipolar diffusion to the resolution of the magnetic flux
problem of star formation during the accretion phase, and we find it to be very
significant although not sufficient to resolve the entire problem yet. Ohmic
dissipation is completely negligible in the disk during this phase of the
evolution. The protostellar disk is found to be stable against interchange-like
instabilities, despite the fact that the mass-to-flux ratio has temporary local
maxima.


title: Giant Radio Pulses from the Crab Pulsar

abstract:
  Individual giant radio pulses (GRPs) from the Crab pulsar last only a few
microseconds. However, during that time they rank among the brightest objects
in the radio sky reaching peak flux densities of up to 1500 Jy even at high
radio frequencies. Our observations show that GRPs can be found in all phases
of ordinary radio emission including the two high frequency components (HFCs)
visible only between 5 and 9 GHz (Moffett & Hankins, 1996). This leads us to
believe that there is no difference in the emission mechanism of the main pulse
(MP), inter pulse (IP) and HFCs. High resolution dynamic spectra from our
recent observations of giant pulses with the Effelsberg telescope at a center
frequency of 8.35 GHz show distinct spectral maxima within our observational
bandwidth of 500 MHz for individual pulses. Their narrow band components appear
to be brighter at higher frequencies (8.6 GHz) than at lower ones (8.1 GHz).
Moreover, there is an evidence for spectral evolution within and between those
structures. High frequency features occur earlier than low frequency ones.
Strong plasma turbulence might be a feasible mechanism for the creation of the
high energy densities of ~6.7 x 10^4 erg cm^-3 and brightness temperatures of
10^31 K.


title: SZ cluster science with the Planck HFI experiment

abstract:
  In the near future the Planck satellite will gather impressive information
about the anisotropies of the cosmic microwave background and about the galaxy
clusters which perturb that signal. We will here review the ability of Planck
to extract information about these galaxy clusters through the
Sunyaev-Zeldovich imprint. We will conclude that Planck will provide a
catalogue of galaxy clusters, which will be very useful for future targeted
observations. We will explain why Planck will not be very good in extracting
detailed information about individual clusters, except for the dominating
Compton parameter, $y$, which will be measured to a few percent for individual
clusters. In this last point I am being rather conservative, but that will
leave space for pleasant surprises when the Planck data will be analysed.


title: The Subaru Deep Field: The Optical Imaging Data

abstract:
  The Subaru Deep Field (SDF) project is a program of Subaru Observatory to
carry out a deep galaxy survey over a blank field as large as 34'x27'. The
program consists of very deep multi-band optical imaging, near infrared imaging
for smaller portions of the field and follow-up optical spectroscopy. Major
scientific goals of the project are to construct large samples of Lyman-break
galaxies at z~4-5 and Lyman alpha emitters at z~5.7 and 6.6, and to make
detailed studies these very high-redshift galaxy populations. In this paper, we
describe the optical imaging observations and data reduction, presenting
mosaicked images and object catalogs in seven bandpasses.The optical imaging
was made through five broad-band filters, B, V, R, i', z', and two narrow-band
filters, NB816 (lambda_c=8150A) and NB921 (lambda_c=9196A) with almost 10 hours
long integrations for each band. The limiting magnitudes measured at 3-sigma on
a 2" aperture are B=28.45, V=27.74, R=27.80, i'=27.43, z'=26.62, NB816=26.63,
and NB921=26.54 in the AB system. The object catalog constructed for each of
the seven bands contains more than 10^5 objects. The galaxy number counts
corrected for detection incompleteness and star count contribution are found to
be consistent with previous results in the literature. The mosaicked images and
catalogs of all the bands have been made open to the public on Oct. 1, 2004 on
the SDF project website at http://soaps.naoj.org/sdf/.


title: Statistical Imprints of SZ Effects in the Cosmic Microwave Background

abstract:
  We review several aspects of the Sunyaev-Zel'dovich (SZ) effect associated
with the large scale baryon distribution and its characteristic signatures in
the statistics of cosmic microwave background (CMB) anisotropies. We discuss
(1) the contributions to the angular power spectrum from the thermal and
kinetic SZ effects, (2) the effect of SZ non-Gaussianities on cosmological
parameter estimation, and (3) the SZ-induced CMB polarization towards galaxy
clusters. We also discuss the extent to which recent measurements of small
angular scale CMB anisotropy can be accounted for by SZ clusters and the
potential use of SZ polarization towards large samples of galaxy clusters as a
probe of dark energy parameters.


title: The relation between black hole mass and velocity dispersion at z~0.37

abstract:
  The velocity dispersion of 7 Seyfert 1 galaxies at z~0.37 is measured using
high signal-to-noise Keck spectra. Black hole (BH) mass estimates are obtained
via an empirically calibrated photoionization method. We derive the BH mass
velocity dispersion relationship at z~0.37. We find an offset with respect to
the local relationship, in the sense of somewhat lower velocity dispersion at a
fixed BH mass at z~0.37 than today, significant at the 97% level. The offset
corresponds to Delta log sigma = -0.16 with rms scatter of 0.13 dex. If
confirmed by larger samples and independent checks on systematic uncertainties
and selection effects, this result would be consistent with spheroids evolving
faster than BHs in the past 4 Gyrs and inconsistent with pure luminosity
evolution.


title: The FUSE Survey of OVI Absorption in the Galactic Disk

abstract:
  We outline the results from a FUSE Team program designed to characterize OVI
absorption in the disk of the Milky Way. We find that OVI absorption occurs
throughout most of the Galactic plane, at least out to several kpc from the
Sun, and that it is distributed smoothly enough for the column density to
decline with height above the disk and with distance in the plane. However, the
OVI absorbing gas is clumpy, and moves at peculiar velocities relative to that
expected from Galactic rotation. We conclude that the observed absorption is
likely to be a direct indicator of the structures formed when violent,
dynamical processes heat the ISM, such as blowout from multiple supernovae
events.


title: Mercury's Protoplanetary Mass

abstract:
  Major element fractionation among chondrites has been discussed for decades
as ratios relative to Si or Mg. Recently, by expressing ratios relative to Fe,
I discovered a new relationship admitting the possibility that ordinary
chondrite meteorites are derived from two components, a relatively oxidized and
undifferentiated, primitive component and a somewhat differentiated, planetary
component, with oxidation state like the highly reduced enstatite chondrites,
which I suggested was identical to Mercury's complement of lost elements. Here,
on the basis of that relationship, I derive expressions, as a function of the
mass of planet Mercury and the mass of its core, to estimate the mass of
Mercury's lost elements, the mass of Mercury's alloy and rock protoplanetary
core, and the mass of Mercury's gaseous protoplanet. Although Mercury's mass is
well known, its core mass is not, being widely believed to be in the range of
70-80 percent of the planet mass. For a core mass of 75 percent, the mass of
Mercury's lost elements is about 1.32 times the mass of Mercury, the mass of
the alloy and rock protoplanetary core is about 2.32 times the mass of Mercury,
and the mass of the gaseous protoplanet of Mercury is about 700 times the mass
of Mercury. Circumstantial evidence is presented in support of the supposition
that Mercury's lost elements is identical to the planetary component of
ordinary chondrite formation.


title:
Differential Imaging with a Multicolor Detector Assembly: A New
  ExoPlanet Finder Concept

abstract:
  Simultaneous spectral differential imaging is a high contrast technique by
which subtraction of simultaneous images reduces noise from atmospheric
speckles and optical aberrations. Small non-common wave front errors between
channels can seriously degrade its performance. We present a new concept, a
multicolor detector assembly (MCDA), which can eliminate this problem. The
device consists of an infrared detector and a microlens array onto the flat
side of which a checkerboard pattern of narrow-band micro-filters is deposited,
each micro-filter coinciding with a microlens. Practical considerations for
successful implementation of the technique are mentioned. Numerical simulations
predict a noise attenuation of 10^-3 at 0.5" for a 10^5 seconds integration on
a mH=5 star of Strehl ratio 0.9 taken with an 8-m telescope. This reaches a
contrast of 10^-7 at an angular distance of 0.5" from the center of the star
image.


title:
RASS-SDSS galaxy cluster survey. II. A unified picture of the Cluster
  Luminosity Function

abstract:
  We constructed the composite luminosity function (LF) of clusters of galaxies
in the five SDSS photometric bands u,g,r,i and z from the RASS-SDSS galaxy
cluster catalog. Background and foreground galaxies are subtracted using both a
local and a global background correction to take in account the presence of
large scale structures and variations from field to field, respectively. The
composite LF clearly shows two components: a bright-end LF with a classical
slope of -1.25 in each photometric band, and a faint-end LF much steeper (-2.1
<= \alpha <= -1.6) in the dwarf galaxy region. The observed upturn of the faint
galaxies has a location ranging from -16 +5log(h) in the g band to -18.5
+5log(h) in the z band. To study the universality of the cluster LF we compare
the individual cluster LFs with the composite luminosity function. We notice
that, in agreement with the composite LF, a single Schechter component is not a
good fit for the majority of the clusters. We fit a Schechter function to the
bright-end of the individual clusters LFs in the magnitude region brighter than
the observed upturn of the dwarf galaxies. We observe that the distributions of
the derived parameters is close to a Gaussian around the value of the composite
bright-end LF parameters with a dispersion compatible with the statistical
errors. We conclude that the bright-end of the galaxy clusters is universal. To
study the behavior of the individual faint-end LF we define the Dwarf to Giant
galaxy Ratio (DGR) of the single clusters. We notice that the distribution of
DGR has a spread much larger than the statistical errors. Our conclusion is
that the cluster luminosity function is not universal since the cluster
faint-end, differently from the bright-end, varies from cluster to cluster.


title:
Unveiling the composition of radio plasma bubbles in galaxy clusters
  with the Sunyaev-Zel'dovich effect

abstract:
  The Chandra X-ray Observatory is finding a large number of cavities in the
X-ray emitting intra-cluster medium which often coincide with the lobes of the
central radio galaxy. We propose high-resolution Sunyaev-Zel'dovich (SZ)
observations in order to infer the still unknown dynamically dominating
component of the radio plasma bubbles. This work calculates the thermal and
relativistic SZ emission of different compositions of these plasma bubbles
while simultaneously allowing for the cluster's kinetic SZ effect. As examples,
we present simulations of an Atacama Large Millimeter Array (ALMA) observation
and of a Green Bank Telescope (GBT) observation of the cores of the Perseus
cluster and Abell 2052. We predict a 5 sigma detection of the southern radio
bubble of Perseus in a few hours with the GBT and ALMA while assuming a
relativistic electron population within the bubble. In Abell 2052, a similar
detection would require a few ten hours with either telescope, the longer
exposures mainly being the result of the higher redshift and the lower central
temperature of this cluster. Future high-sensitivity multi-frequency SZ
observations will be able to infer the energy spectrum of the dynamically
dominating electron population in order to measure its temperature or spectral
characteristics. This knowledge can yield indirect indications for an
underlying radio jet model.


title: Detecting sub-mJy sources with the EVN

abstract:
  Some microquasars are permanently bright radio sources while others are faint
but produce powerful radio outbursts. Most of the X-ray binaries (XRB) however
are very faint or undetected in the radio regime. The European VLBI Network
(EVN) recently introduced the Mark5 recording system which allows data rates of
up to 1 Gbit/s. This increases the sensitivity of the array significantly. We
briefly describe recent developments in the EVN in terms of reliability of the
network and also data quality. We demonstrate the power of the EVN in detecting
sub-mJy radio sources with modest integration times (order of hours). This high
sensitivity capability will permit the study of variable Galactic sources at
milliarcsecond resolution. An estimate is given for the lowest detectable mass
of hypothetical intermediate-mass black holes (IMBH) in nearby galaxies,
provided these are located in radio-jet systems analogous to microquasars and
active galactic nuclei.


title:
Dynamics and star formation activity of CG J1720-67.8 unveiled through
  integral field spectroscopy and radio observations

abstract:
  CG J1720-67.8 is an ultra compact group of several galaxies with a low
velocity dispersion, and displaying the hallmarks of mutual interaction and
possible tidal dwarf galaxy formation. In hierarchical models, the system is a
possible precursor to a massive elliptical galaxy. In this paper, we use new
optical integral field spectroscopic and radio observations to investigate the
evolutionary status of the group in more detail: global star-formation rates
are estimated using H$\alpha$ and 1.4 GHz radio continuum measurements; H {\sc
i} observations provide an upper limit to the global neutral gas content;
optical broadband colours and spectra provide ages and stellar mass estimates
for the tidal dwarf candidates; the bidimensional H$\alpha$ velocity field is
used to trace the kinematics of the group and its members, which are compared
with numerical simulations of galaxy encounters. The observations suggest a
model in which multiple interactions have occurred, with the latest strong
encounter involving at least two major components within the last 200 Myr.
Debris from the encounter fuels ongoing star formation at the global level of
$\sim20$ M$_{\odot}$ yr$^{-1}$, with self-gravity within the tidal tail
possibly providing a mechanism to enhance the star formation rate of the tidal
dwarf candidates, with bursts of star-formation in clumps of mass $\sim2\times
10^7$ M$_{\odot}$ appearing within the last 10 Myr. The amount of time required
for final merging of all group components remains uncertain.


title:
Detecting gravito-magnetism with rotation of polarization by a
  gravitational lens

abstract:
  We discuss the effects of an isolated gravitational lens on the rotation of
the plane of polarization of linearly polarized light rays, the so called
gravitational Faraday rotation, in metric theories of gravity. By applying the
thin lens approximation, we derive simple expressions for extended, rotating
astrophysical systems deflecting electromagnetic radiation from background
sources. Higher order corrections and the case of a Kerr black hole are also
considered to show how the rotation of polarization is a purely
gravito-magnetic effect. Prospects of a future detection of a gravitational
Faraday rotation are examined.


title: Properties of Hot, Massive Stars: The Impact of FUSE

abstract:
  The impact of FUSE upon the fundamental parameters of OB stars and Wolf-Rayet
stars is reviewed. The stellar wind signatures available in the far-UV provide
us with important additional diagnostics of effective temperature. Together
with improved non-LTE stellar atmosphere models allowing for line blanketing
and stellar winds, this has led to a downward revision in the spectral
type-temperature calibration for O stars versus Vacca et al. (1996) In
addition, the Lyman continuum ionizing fluxes from O dwarfs are compared with
previous calibrations of Panagia (1973) and Vacca et al. We also discuss
mass-loss rates in OB stars, such that agreement between recent theoretical
predictions (Vink et al. 2000, 2001) and observations of O supergiants is
possible, solely if winds are clumped in the far-UV and H-alpha line forming
regions, as favoured by line profile comparisons for PV 1118-28 (early to mid
O) or SIV 1062-1073 (late O to early B) in FUSE datasets. In contrast, B
supergiant wind strengths are predicted to be much higher than observations
indicates, especially if their winds are also clumped. Finally, significant
upward revisions in wind velocities of very late WN stars are indicated by NII
1085 resonance line observations, plus elemental abundances in OB and WR stars
are briefly discussed.


title:
XMM-Newton Observations of G32.45+0.1and G38.55+0.0: diffuse hard X-ray
  sources found with the ASCA Galactic Plane Survey

abstract:
  We report on XMM-Newton observations of G32.45+0.1 and G38.55+0.0. These were
discovered as diffuse hard X-ray sources with the ASCA Galactic plane survey,
but the limited spatial resolution of ASCA could not conclude whether these are
truly diffuse or a group of unresolved point-sources. XMM-Newton, with higher
spatial resolution than ASCA, confirmed that G32.45+0.1 has a diffuse
shell-like structure with a radius of ~4'. The spectrum shows featureless
continuum, hence can be fitted with a power-law model of Gamma ~2.2 with an
absorption of N_H~5.2*10^{22}cm^{-2}. From this N_H value, we estimate the
distance to G32.45+0.1 to be ~17kpc, then the luminosity (in the 0.5-10.0keV
band) and radius of the shell are ~9.5*10^{34}ergs/s and ~20pc, respectively.
The radio complex sources in the NRAO/VLA Sky Survey (NVSS; 1.4GHz) are
globally associated to the X-ray shell of G32.45+0.1. Therefore G32.45+0.1 is
likely to be a synchrotron dominant shell-like SNR. No significant diffuse
structure was found in the XMM-Newton image of another ASCA diffuse source
G38.55+0.0. The upper limit of the observed flux (0.5-10.0keV) is estimated to
be 9.0*10^{-13}ergs/cm^2/s being consistent with the ASCA result.


title: Mode Switching and Subpulse Drifting in PSR B0826-34

abstract:
  We present high-quality observations of PSR B0826-34 at 1374 MHz. The
emission from this pulsar exhibits strong bursts of pulses followed by long
periods of `null' pulses. When it is strong, the radiation extends through the
whole pulse period. We show for the first time that there is weak emission
during the `null' phases, which should therefore be considered to be a
different mode rather than a null. During this weak mode the profile is similar
to that observed in the strong mode at low radio frequency. Using a
phase-tracking method, the pattern of drifting subpulses during the strong mode
is seen to be coherent across the whole profile. The drift rate is variable and
includes positive and negative values. Thirteen subpulse bands have been
directly observed, covering the whole longitude range. The subpulses and their
spacings ($P_2$) are wider in one half of the profile than those in the other
half. This difference, and the variation of observed $P_2$ within the two
regions, can be accounted for if the magnetic pole is inclined to the rotation
axis by about 0.5 degrees. These two regions appear to represent radiation from
outer and inner cones. The intensity modulation of subpulses in all longitude
ranges is related to the magnitude of the drift rate.


title:
An ISOCAM survey through gravitationally lensing galaxy clusters. III.
  New results from mid-infrared observations of th e cluster Abell 2219

abstract:
  The massive cluster of galaxies Abell 2219 (z = 0.228) was observed at 14.3
$\mu$m with the Infrared Space Observatory and results were published by
Barvainis et al. (1999). These observations have been reanalyzed using a method
specifically designed for the detection of faint sources that had been applied
to other clusters. Five new sources were detected and the resulting cumulative
total of ten sources all have optical counterparts. The mid-infrared sources
are identified with three cluster members, three foreground galaxies, an
Extremely Red Object, a star and two galaxies of unknown redshift. The spectral
energy distributions (SEDs) of the galaxies are fit with models from a
selection, using the program GRASIL. Best-fits are obtained, in general, with
models of galaxies with ongoing star formation. For three cluster members the
infrared luminosities derived from the model SEDs are between ~5.7x10^10 Lsun
and 1.4x10^11 Lsun, corresponding to infrared star formation rates between 10
and 24 Msun yr^-1. The two cluster galaxies that have optical classifications
are in the Butcher-Oemler region of the color-magnitude diagramme. The three
foreground galaxies have infrared luminosities between 1.5x10^10 Lsun and
9.4x10^10 Lsun yielding infrared star formation rates between 3 and 16 Msun
yr^-1. Two of the foreground galaxies are located in two foreground galaxy
enhancements (Boschin et al. 2004). Including Abell 2219, six distant clusters
of galaxies have been mapped with ISOCAM and luminous infrared galaxies (LIRGs)
have been found in three of them. The presence of LIRGs in Abell 2219
strengthens the association between luminous infrared galaxies in clusters and
recent or ongoing cluster merger activity.


title: Irradiation-driven mass transfer cycles in compact binaries

abstract:
  We elaborate on the analytical model of Ritter, Zhang, and Kolb (2000, A&A
360, 959) which describes the basic physics of irradiation-driven mass transfer
cycles in semi-detached compact binary systems. In particular, we take into
account a contribution to the thermal relaxation of the donor star which is
unrelated to irradiation and which was neglected in previous studies. We
present results of simulations of the evolution of compact binaries undergoing
mass transfer cycles, in particular also of systems with a nuclear evolved
donor star. These computations have been carried out with a stellar evolution
code which computes mass transfer implicitly and models irradiation of the
donor star in a point source approximation, thereby allowing for more realistic
simulations than were hitherto possible. We find that low-mass X-ray binaries
and cataclysmic variables with orbital periods less than about 6 hours can
undergo mass transfer cycles only for low angular momentum loss rates. CVs
containing a giant donor or one near the terminal age main sequence are more
stable than previously thought, but can possibly also undergo mass transfer
cycles.


title: The evolution of massive stars: a selection of facts and questions

abstract:
  In the present paper we discuss a selection of facts and questions related to
observations and evolutionary calculations of massive single stars and massive
stars in interacting binaries. We focus on the surface chemical abundances, the
role of stellar winds, the early Be-stars, the high mass X-ray binaries, the
effects of rotation on stellar evolution. Finally, we present an
unconventionally formed object scenario (a UFO-scenario) of WR binaries in
dense stellar environments.


title: High velocity HI in NGC 6946 and extra-planar gas in NGC 253

abstract:
  Multi-wavelength observations of nearby spiral galaxies have shown that
neutral and ionized gas are present up to a few kpc from the disk and that star
formation and supernovae probably play an important role in bringing gas into
the halo. We have obtained very sensitive HI observations of the face-on galaxy
NGC 6946 and of the nearly edge-on starburst galaxy NGC 253. We find high
velocity HI clouds in NGC 6946 and extra-planar gas with anomalous velocities
in NGC 253. In both galaxies there seems to be a close connection between the
star-forming disk and the halo HI. In the outer parts of NGC 6946 there is also
evidence for recent gas accretion.


title:
The Low State Temperature Distribution and First Chemical Abundances of
  White Dwarfs in Polars

abstract:
  During the low optical brightness states of AM Herculis systems (polars) when
accretion has declined to a very low value, the underlying magnetic white dwarf
photosphere can be modelled without the complication of thermal bremstrahlung
and cyclotron emission from the luminous accretion column. The far ultraviolet
spectra can be modelled with high gravity solar composition photospheres. In
this way, I present new temperatures and the first chemical abundance estimates
for the white dwarfs in three selected polars from the IUE NEWSIPS archive. For
the white dwarf in V834 Cen with Teff = 16,000$K, Si/H = 0.1 solar, C/H = 0.5
solar, for BY Cam, Teff = 17,000 K, Si/H = 0.1, C/H = 5 solar and for RX
J1313-32, Teff = 22,000 K, Si/H = 0.1 solar, C/H = 0.1 solar. The temperature
distribution of 24 white dwarfs in polars with known temperatures above and
below the period gap is compared with the distribution of the white dwarf
temperatures in dwarf novae during quiescence. In both cases, the magnetic
white dwarfs in polars are significantly cooler than the non-magnetics. For all
CV white dwarfs, magnetic and non-magnetic with Teff < 12,500 K, 91% of the
objects (10 out of 11) are magnetics in polars. This suggests that long term
accretion heating and cooling of white dwarfs in polars differs from the
effects of long term accretion in non-magnetic disk accretors.