title:
Image of Fomalhaut Dust Ring at 350 Microns: Relative Column Density Map
  Shows Pericenter-Apocenter Asymmetry

abstract:
  We have imaged the circumstellar disk of Fomalhaut at 350 microns wavelength,
using SHARC II at the Caltech Submillimeter Observatory. The spatial resolution
of the raw images (9 arcsec) has been enhanced by a factor of three using the
HiRes deconvolution procedure. We find that at this wavelength and signal to
noise ratio (~ 12), the observed morphology is that of a simple inclined ring
(i ~ 70 deg), with little or no other apparent structure; this is the first
observation that shows clearly the ring morphology of the disk. We have
combined our 350 micron data with Spitzer Space Telescope images at 24, 70, and
160 microns in order to estimate the 2-dimensional spatial variation of
relative column density ("tau map") using our DISKFIT procedure. The tau map is
based on the following physical assumptions: (1) the wavelength variation of
opacity is the same throughout the disk, (2) the radial variation of dust
temperature is dictated by the energy balance of individual grains in the
stellar radiation field, and (3) the vertical scale height of the disk follows
a power-law radial variation. The results confirm the ring-like morphology, but
also show that the geometric center is displaced from the star by about 8 AU
and that the ring has an apocentric enhancement of approximately 14% in
integrated column density. If we interpret the displacement in terms of
elliptical orbital motion due to gravitational perturbation by an unseen
planet, then the implied forced eccentricity is ~ 0.06; dynamical modeling then
predicts an apocentric density enhancement consistent with that inferred from
the tau map.


title: Impact of stochastic gas motions on galaxy cluster abundance profiles

abstract:
  The impact of stochastic gas motions on the metal distribution in cluster
core is evaluated. Peaked abundance profiles are a characteristic feature of
clusters with cool cores and abundance peaks are likely associated with the
brightest cluster galaxies (BCGs) which dwell in cluster cores. The width of
the abundance peaks is however significantly broader than the BCG light
distribution, suggesting that some gas motions are transporting metals
originating from within the BCG. Assuming that this process can be treated as
diffusive and using the brightest X-ray cluster A426 (Perseus) as an example,
we estimate that a diffusion coefficient of the order of $2 10^{29} {\rm cm^2
s^{-1}}$ is needed to explain the width of the observed abundance profiles.
Much lower (higher) diffusion coefficients would result in too peaked (too
shallow) profiles. Such diffusion could be produced by stochastic gas motions
and our analysis provides constraints on the product of their characteristic
velocity and their spatial coherence scale. We speculate that the activity of
the supermassive black hole of the BCG is driving the stochastic gas motions in
cluster cores. When combined with the assumption that the dissipation of the
same motions is a key gas heating mechanism, one can estimate both the velocity
and the spatial scale of such a diffusive processes.


title:
Blue Stragglers as Stellar Collision Products: the Angular Momentum
  Question

abstract:
  We investigate the structure and evolution of blue stragglers stars which
were formed from direct stellar collisions between main sequence stars in
globular clusters. In particular, we look at the rotational evolution of the
products of off-axis collisions. As found in previous work, such blue
stragglers initially have too high an angular momentum to contract down to the
main sequence. We consider angular momentum loss through either disc locking or
locking to an outflowing wind and show that both methods allow the merged
object to shed sufficient angular momentum to contract down to the main
sequence.


title:
How is the Diamagnetic Effect (DME) Relevant to Stellar Surface
  Phenomena?

abstract:
  The structure of stellar atmospheres can be modified if they include embedded
diverging magnetic fields. This is due to the presence of speed filters. Here
we examine some of the relevant effects through the numerical simulation of the
motion of charged particles. We introduce the concept of "floating" particles
and point out the relevance of the diamagnetic effet (DME) to the evolution of
Maxwellian velocity distributions into Non-Maxwellian.


title:
GaBoDS: The Garching-Bonn Deep Survey; IV. Methods for the Image
  reduction of multi-chip Cameras

abstract:
  We present our image processing system for the reduction of optical imaging
data from multi-chip cameras. In the framework of the Garching Bonn Deep Survey
(GaBoDS; Schirmer et al. 2003) consisting of about 20 square degrees of
high-quality data from WFI@MPG/ESO 2.2m, our group developed an imaging
pipeline for the homogeneous and efficient processing of this large data set.
Having weak gravitational lensing as the main science driver, our algorithms
are optimised to produce deep co-added mosaics from individual exposures
obtained from empty field observations. However, the modular design of our
pipeline allows an easy adaption to different scientific applications. Our
system has already been ported to a large variety of optical instruments and
its products have been used in various scientific contexts. In this paper we
give a thorough description of the algorithms used and a careful evaluation of
the accuracies reached. This concerns the removal of the instrumental
signature, the astrometric alignment, photometric calibration and the
characterisation of final co-added mosaics. In addition we give a more general
overview on the image reduction process and comment on observing strategies
where they have significant influence on the data quality.


title:
Planets in Stellar Clusters Extensive Search. III. A search for
  transiting planets in the metal-rich open cluster NGC 6791

abstract:
  We have undertaken a long-term project, Planets in Stellar Clusters Extensive
Search (PISCES), to search for transiting planets in open clusters. In this
paper we present the results for NGC 6791 -- a very old, populous, metal rich
cluster. We have monitored the cluster for over 300 hours, spread over 84
nights. We have not detected any good transiting planet candidates. Given the
photometric precision and temporal coverage of our observations, and current
best estimates for the frequency and radii of short-period planets, the
expected number of detectable transiting planets in our sample is 1.5. We have
discovered 14 new variable stars in the cluster, most of which are eclipsing
binaries, and present high precision light curves, spanning two years, for
these new variables and also the previously known variables.


title: Radiative transfer problem in dusty galaxies: ray-tracing approach

abstract:
  A new code for evaluation of light absorption and scattering by interstellar
dust grains is presented. The radiative transfer problem is solved using
ray-tracing algorithm in a self-consistent and highly efficient way. The code
demonstrates performance and accuracy similar or better than that of previously
published results, achieved using Monte-Carlo methods, with accuracy better
than ~ 3% for most cases. The intended application of the code is
spectrophotometric modelling of disk galaxies, however, it can be easily
adapted to other cases that require a detailed spatial evaluation of
scattering, such as circumstellar disks and shells containing both point and
distributed light sources.


title: IGM metal enrichment through dust sputtering

abstract:
  We study the motion of dust grains into the Intergalactic Medium (IGM) around
redshift z=3, to test the hypothesis that grains can efficiently pollute the
gas with metals through sputtering. We use the results available in the
literature for radiation-driven dust ejection from galaxies as initial
conditions, and follow the motion onward. Via this mechanism, grains are
ejected into the IGM with velocities >100 km/s; as they move supersonically,
grains can be efficiently eroded by non-thermal sputtering. However, Coulomb
and collisional drag forces effectively reduce the charged grain velocity.
Up-to-date sputtering yields for graphite and silicate (olivine) grains have
been derived using the code TRIM, for which we provide analytic fits. After
training our method on a homogeneous density case, we analyze the grain motion
and sputtering in the IGM density field as derived from a LambdaCDM
cosmological simulation at z = 3.27. We found that only large (a >~ 0.1-um)
grains can travel up to considerable distances (few times 100 kpc physical)
before being stopped. Resulting metallicities show a well defined trend with
overdensity delta. The maximum metallicities are reached for 10<delta<100
(corresponding to systems, in QSO absorption spectra, with 14.5 < log N_HI <
16). However the distribution of sputtered metals is very inhomogeneous, with
only a small fraction of the IGM volume polluted by dust sputtering (filling
factors of 18 per cent for Si and 6 per cent for C). For the adopted size
distribution, grains are never completely destroyed; nevertheless, the
extinction and gas photo-electric heating effects due to this population of
intergalactic grains are well below current detection limits.


title:
A NICMOS Direct Imaging Search for Giant Planets around the Single White
  Dwarfs in the Hyades

abstract:
  We report preliminary results from our search for massive giant planets (6-12
Jupiter masses) around the known seven single white dwarfs in the Hyades
cluster at sub-arcsec separations. At an age of 625 Myr, the white dwarfs had
progenitor masses of about 3 solar masses, and massive gaseous giant planets
should have formed in the massive circumstellar disks around these ex-Herbig A0
stars, probably at orbital separations similar or slightly larger than that of
Jupiter. Such planets would have survived the post-Main-Sequence mass loss of
the parent star and would have migrated outward adiabatically to a distance of
about 25 AU. At the distance of the Hyades (45 pc) this corresponds to an
angular separation of 0.5 arcsec. J and H magnitudes of these giants are in the
range of 20.5-23.3 mag, which can be resolved with NICMOS. The achieved
sensitivities and contrast ratios agree well with simulations. Preliminary
evaluation of the NICMOS data set did not reveal any evidence for neither
planetary mass companions with masses down to about 10 Jupiter masses nor brown
dwarfs around any of the seven white dwarfs for separations larger than 0.5
arcsec.


title: Massive elliptical galaxies in X-rays: the role of late gas accretion

abstract:
  We present a new chemical evolution model meant to be a first step in the
self-consistent study of both optical and X-ray properties of elliptical
galaxies. Detailed cooling and heating processes in the interstellar medium are
taken into account using a mono-phase one-zone treatment which allows a more
reliable modelling of the galactic wind regime with respect to previous work.
The model successfully reproduces simultaneously the mass-metallicity,
colour-magnitude, the L_X - L_B and the L_X - T relations, as well as the
observed trend of the [Mg/Fe] ratio as a function of sigma, by adopting the
prescriptions of Pipino & Matteucci (2004) for the gas infall and star
formation timescales. We found that a late secondary accretion of gas from the
environment plays a fundamental role in driving the L_X - L_B and L_X - T
relations and can explain their large observational scatter. The iron
discrepancy, namely the too high predicted iron abundance in X-ray haloes of
ellipticals compared to observations, still persists. On the other hand, we
predict [O/Fe] in the ISM which is in good agreement with the most recent
observations. We suggest possible mechanisms acting on a galactic scale which
may solve the iron discrepancy. In particular, mixing of gas driven by AGNs may
preserve the gas mass (and thus the X-ray luminosity) while diluting the iron
abundance. New predictions for the amounts of iron, oxygen and energy ejected
into the intracluster medium (ICM) are presented and we conclude that Type Ia
supernovae (SNe Ia) play a fundamental role in the ICM enrichment. SNe Ia
activity, in fact, may power a galactic wind lasting for a considerable amount
of the galactic lifetime, even in the case for which the efficiency of energy
transfer into the ISM per SN Ia event is less than unity.


title:
HST/ACS weak lensing analysis of the galaxy cluster RDCS 1252.9-2927 at
  z=1.24

abstract:
  We present a weak lensing analysis of one of the most distant massive galaxy
cluster known, RDCS 1252.9-2927 at z=1.24, using deep images from the Advanced
Camera for Survey (ACS) on board the Hubble Space Telescope (HST). By taking
advantage of the depth and of the angular resolution of the ACS images, we
detect for the first time at z>1 a clear weak lensing signal in both the i
(F775W) and z (F850LP) filters. We measure a 5-\sigma signal in the i band and
a 3-\sigma signal in the shallower z band image. The two radial mass profiles
are found to be in very good agreement with each other, and provide a
measurement of the total mass of the cluster inside a 1Mpc radius of M(<1Mpc) =
(8.0 +/- 1.3) x 10^14 M_\odot in the current cosmological concordance model h
=0.70, \Omega_m=0.3, \Omega_\Lambda=0.7, assuming a redshift distribution of
background galaxies as inferred from the Hubble Deep Fields surveys. A weak
lensing signal is detected out to the boundary of our field (3' radius,
corresponding to 1.5Mpc at the cluster redshift). We detect a small offset
between the centroid of the weak lensing mass map and the brightest cluster
galaxy, and we discuss the possible origin of this discrepancy. The cumulative
weak lensing radial mass profile is found to be in good agreement with the
X-ray mass estimate based on Chandr and XMM-Newton observations, at least out
to R_500=0.5Mpc.


title: Spherical galaxy models with power law logarithmic slope

abstract:
  We present a new family of spherically symmetric models for the luminous
components of elliptical and spiral galaxies and their dark matter haloes. Our
starting point is a general expression for the logarithmic slope $\alpha(r) =
d\log{\rho}/d\log{r}$ from which most of the cuspy models yet available in
literature may be derived. We then dedicate our attention to a particular set
of models whose logarithmic slope is a power law function of the radius $r$
investigating in detail their dynamics assuming isotropy in the velocity space.
While the basic properties (such as the density profile and the gravitational
potential) may be expressed analytically, both the distribution function and
the observable quantities (surface brightness and line of sight velocity
dispersion) have to be evaluated numerically. We also consider the extension to
anisotropic models trying two different parameterization. Since the model
recently proposed by Navarro et al. (2004) as the best fit to their sample of
numerically simulated haloes belongs to the family we present here, analytical
approximations are given for the most useful quantities.


title:
The Effect of Inhomogeneities on the Luminosity Distance-Redshift
  Relation: is Dark Energy Necessary in a Perturbed Universe?

abstract:
  The luminosity distance-redshift relation is one of the fundamental tools of
modern cosmology. We compute the luminosity distance-redshift relation in a
perturbed flat matter-dominated Universe, taking into account the presence of
cosmological inhomogeneities up to second order in perturbation theory.
Cosmological observations implementing the luminosity distance-redshift
relation tell us that the Universe is presently undergoing a phase of
accelerated expansion. This seems to call for a mysterious Dark Energy
component with negative pressure. Our findings suggest that the need of a Dark
Energy fluid may be challenged once a realistic inhomogeneous Universe is
considered and that an accelerated expansion may be consistent with a
matter-dominated Universe.


title: Particle acceleration in astrophysical shear flows

abstract:
  We consider the acceleration of particles due to a velocity shear in
relativistic astrophysical flows. The basic physical picture and the formation
of power law momentum spectra is discussed for a non-relativistic velocity
field using a microscopic approach. We identify possible sites for shear
acceleration in relativistic astrophysical jets and analyze their associated
acceleration timescales. It is shown in particular that for a mean scattering
time $\tau$ scaling with the gyro-radius, the acceleration timescale for
gradual shear scales in the same manner as the synchrotron cooling timescale,
so that losses may no longer be able to stop the acceleration once it has
started to work efficiently. Finally, the possible role of shear acceleration
is discussed with reference to the relativistic jet in the quasar 3C~273.


title: Stability of density-stratified viscous Taylor-Couette flows

abstract:
  The stability of density-stratified viscous Taylor-Couette flows is
considered using the Boussinesq approximation but without any use of the
short-wave approximation. The flows which are unstable after the Rayleigh
criterion (\hat \mu<\hat \eta^2, with \hat \mu=\Omega_{out}/\Omega_{in} and
\hat \eta= R_{in}/R_{out}) now develop overstable axisymmetric Taylor vortices.
For the considered wide-gap container we find the nonaxisymmetric modes as the
most unstable ones. The nonaxisymmetric modes are unstable also beyond the
Rayleigh line. For such modes the instability condition seems simply to be
\hat\mu<1 as stressed by Yavneh, McWilliams & Molemaker (2001). However, we
never found unstable modes for too flat rotation laws fulfilling the condition
\hat \mu >\hat \eta. The Reynolds numbers rapidly grow to very high values if
this limit is approached (see Figs. 3 and 4).
  Also striking is that the marginal stability lines for the higher $m$ do less
and less enter the region beyond the Rayleigh line so that we might have to
consider the stratorotational instability as a 'low-$m$ instability'. The
applicability of these results to the stability problem of accretion disks with
their strong stratification and fast rotation is shortly discussed.


title:
Results from observations of AGNs with the H.E.S.S. telescope system and
  Future plans

abstract:
  The H.E.S.S. (High Energy Stereoscopic System) phase I is comprised of four
Imaging Atmospheric Cherenkov telescopes, for observation of galactic and
cosmic sources of very high energy gamma rays. Its installation in the Khomas
highlands, Namibia has been completed in December, 2003. The first of these
telescopes was installed in June 2003, and data-taking has proceeded since that
time. The HESS telescope system provides a significant improvement in
sensitivity and a threshold for detection below that of previous Imaging
Atmospheric Cherenkov Telescopes. The characteristics for the phase-I will be
presented, together with plans for phase-II of the experiment, comprised of a
large telescope in the centre of the current phase-I providing a lowered
threshold and increased sensitivity. We can observe AGNs up to redshift 0.5
with HESS and 2-3 with HESS Phase-2, which provides a unique capability for
study of spectral and temporal characteristics on timescales of several hours
or even less than 1 h (depending on the strength of flares). We will present
the first results from a number of southern AGN observed during the
installation of the phase-I, in particular concerning the detection and
spectral properties of the AGN PKS2155$-$305.


title:
Spectral and temporal signatures of ultrarelativistic protons in compact
  sources

abstract:
  We present calculations of the spectral and temporal radiative signatures
expected from ultrarelativistic protons in compact sources. The coupling
between the protons and the leptonic component is assumed to occur via
Bethe-Heitler pair production. This process is treated by modeling the results
of Monte-Carlo simulations and incorporating them in a time-dependent kinetic
equation, that we subsequently solve numerically. Thus, the present work is, in
many respects, an extension of the leptonic `one-zone' models to include
hadrons. Several examples of astrophysical importance are presented, such as
the signature resulting from the cooling of relativistic protons on an external
black-body field and that of their cooling in the presence of radiation from
injected electrons. We also investigate and refine the threshold conditions for
the 'Pair Production/Synchrotron' feedback loop which operates when
relativistic protons cool efficiently on the synchrotron radiation of the
internally produced Bethe-Heitler pairs. We demonstrate that an additional
component of injected electrons lowers the threshold for this instability.


title: The relation between optical and X-ray variability in Seyfert galaxies

abstract:
  Studying simultaneous optical and X-ray light curves of radio-quiet AGN can
help to probe the relationship between very different physical components - the
cool, optically thick disk and hot, optically thin corona. Here, we review the
relationship between optical and X-ray variability in Seyfert galaxies, which
due to observing constraints was difficult to study for many years, but was
given a huge boost with the launch of the RXTE satellite in 1995. We summarise
the diverse results of several monitoring campaigns, which pose a challenge for
standard theories relating optical and X-ray variability, with sources showing
either correlated optical and X-ray flux variations, correlated optical flux
and X-ray spectral variations, or no correlation at all. We discuss possible
explanations for these results, some of which may be explained using a more
standard AGN picture, while others may require additional components, such as
the 2-phase accretion flows suggested to explain black hole X-ray binary
behaviour.


title: Extinction curves expected in young galaxies

abstract:
  We investigate the extinction curves of young galaxies in which dust is
supplied from Type II supernovae (SNe II) and/or pair instability supernovae
(PISNe). We adopt Nozawa et al. (2003) for compositions and size distribution
of grains formed in SNe II and PISNe. We find that the extinction curve is
quite sensitive to internal metal mixing in supernovae (SNe). The extinction
curves predicted from the mixed SNe are dominated by SiO2 and is characterised
by steep rise from infrared to ultraviolet (UV). The dust from unmixed SNe
shows shallower extinction curve, because of the contribution from large-sized
(~ 0.1 um) Si grains. However, the progenitor mass is important in unmixed SNe
II: If the progenitor mass is smaller than ~ 20 Msun, the extinction curve is
flat in UV; otherwise, the extinction curve rises toward the short wavelength.
The extinction curve observed in a high-redshift quasar (z=6.2) favours the
dust production by unmixed SNe II. We also provide some useful observational
quantities, so that our model might be compared with future high-z extinction
curves.


title: The sub-arcsecond dusty environment of Eta Carinae

abstract:
  The core of the nebula surrounding Eta Carinae has been observed with the VLT
Adaptive Optics system NACO and with the interferometer VLTI/MIDI to constrain
spatially and spectrally the warm dusty environment and the central object. In
particular, narrow-band images at 3.74 and 4.05 micron reveal the butterfly
shaped dusty environment close to the central star with unprecedented spatial
resolution. A void whose radius corresponds to the expected sublimation radius
has been discovered around the central source. Fringes have been obtained in
the Mid-IR which reveal a correlated flux of about 100Jy situated 0.3"
south-east of the photocenter of the nebula at 8.7 micron, which corresponds
with the location of the star as seen in other wavelengths. This correlated
flux is partly attributed to the central object, and these observations provide
an upper limit for the SED of the central source from 2.2 to 13.5 micron.
Moreover, we have been able to spectrally disperse the signal from the nebula
itself at PA=318 degree, i.e. in the direction of the bipolar nebula 310
degree) within the MIDI field of view of 3". A large amount of corundum (Al2O3)
is discovered, peaking at 0.6-1.2" south-east from the star, whereas the dust
content of the Weigelt blobs is dominated b silicates. We discuss the
mechanisms of dust formation which are closely related to the geometry of this
Butterfly nebulae.


title: Photoionising feedback in star cluster formation

abstract:
  We present the first ever hydrodynamic calculations of star cluster formation
that incorporate the effect of feedback from ionising radiation. In our
simulations, the ionising source forms in the cluster core at the intersection
of several dense filaments of inflowing gas. We show that these filaments
collimate ionised outflows and suggest such an environmental origin for at
least some observed outflows in regions of massive star formation. Our
simulations show both positive feedback (i.e. promotion of star formation in
neutral gas compressed by expanding HII regions) and negative feedback (i.e.
suppression of the accretion flow in to the central regions). We show that the
volume filling factor of ionised gas is very different in our simulations than
would result from the case where the central source interacted with an
azimuthally smoothed gas density distribution. As expected, gas density is the
key parameter in determining whether clusters are unbound by photoionising
radiation. Nevertheless, we find - on account of the acceleration of a small
fraction of the gas to high velocities in the outflows - that the deposition in
the gas of an energy that exceeds the binding energy of the cluster is not a
sufficient criterion for unbinding the bulk of the cluster mass.


title:
Magnetic Field Clumping in Massive Star-Forming Regions as Determined
  from Excited-State OH Absorption and Maser Emission

abstract:
  We have observed six high-mass star-forming regions in the 2 Pi 3/2, J = 7/2
lines of OH using the GBT in order to investigate whether the magnetic field,
and hence the density, measured in absorption differs from that implied by
maser Zeeman splitting. We detect absorption in both the 13441 and 13434 MHz
main lines in all six sources. Zeeman splitting in the F = 3-3 absorption line
in W3(OH) implies a line-of-sight magnetic field strength of 3.0 +/- 0.3 mG.
This is significantly less than full magnetic field strengths detected from OH
maser Zeeman splitting, suggesting that OH maser regions may be denser than the
non-masing OH material by a factor of several. Zeeman splitting is not detected
in other sources, but we are able to place upper limits on B_parallel of 1.2 mG
in G10.624-0.385 and 2.9 mG in K3-50. These results are consistent with a
density enhancement of the masers, but other explanations for the lower
magnetic field in absorption compared to maser emission are possible for these
two sources. Absorption in one or both of the 13442 and 13433 MHz satellite
lines is also seen in four sources. This is the very first detection of the 2
Pi 3/2, J = 7/2 satellite lines. Ratios of satellite-line to main-line
absorption suggest enhancement of the satellite lines from local thermodynamic
equilibrium values. Masers are seen in the F = 4-4 and 3-3 transitions of
W3(OH) and the 4-4 transition of ON 1. A previously undetected 4-4 maser is
seen near -44.85 km/s in W3(OH).


title: First VLTI/MIDI observations of a Be star: Alpha Ara

abstract:
  We present the first VLTI/MIDI observations of the Be star Alpha Ara, showing
a nearly unresolved circumstellar disk in the N band. The interferometric
measurements made use of the UT1 and UT3 telescopes. The projected baselines
were 102 and 74 meters with position angles of 7 degres and 55 degres,
respectively. These measurements put an upper limit to the envelope size in the
N band under the Uniform disk approximation of $\phi_{\rm max}= 4\pm1.5$ mas,
corresponding to 14 $R_{\star}$, assuming $R_{\star}$=4.8${\rm R}_\odot$ and
the Hipparcos distance of 74pc. On the other hand the disk density must be
large enough to produce the observed strong Balmer line emission. In order to
estimate the possible circumstellar and stellar parameters we have used the
SIMECA code developed by Stee (1995) and Stee & Bittar (2001). Optical spectra
taken with the echelle instrument Heros and the ESO-50cm telescope, as well as
infrared ones from the 1.6m Brazilian telescope have been used together with
the MIDI spectra and visibilities. These observations put complementary
constraints on the density and geometry of Alpha Ara circumstellar disk. We
discuss on the potential truncation of the disk by a companion and we present
spectroscopic indications of a periodic perturbation of some Balmer lines.


title: Photometric properties and origin of bulges in SB0 galaxies

abstract:
  We have derived the photometric parameters for the structural components of a
sample of fourteen SB0 galaxies by applying a parametric photometric
decomposition to their observed $I$-band surface brightness distribution.
  We find that SB0 bulges are similar to bulges of the early-type unbarred
spirals, i.e. they have nearly exponential surface brightness profiles
($<n>=1.48\pm0.16$) and their effective radii are strongly coupled to the scale
lengths of their surrounding discs ($<r_e/h>=0.20\pm0.01$). The photometric
analysis alone does not allow us to differentiate SB0 bulges from unbarred S0
ones.
  However, three sample bulges have disc properties typical of pseudobulges.
The bulges of NGC 1308 and NGC 4340 rotate faster than bulges of unbarred
galaxies and models of isotropic oblate spheroids with equal ellipticity. The
bulge of IC 874 has a velocity dispersion lower than expected from the
Faber--Jackson correlation and the fundamental plane of the elliptical galaxies
and S0 bulges. The remaining sample bulges are classical bulges, and are
kinematically similar to lower-luminosity ellipticals. In particular, they
follow the Faber--Jackson correlation, lie on the fundamental plane and those
for which stellar kinematics are available rotate as fast as the bulges of
unbarred galaxies.


title:
Helium recombination spectra as temperature diagnostics for planetary
  nebulae

abstract:
  Electron temperatures derived from the \ion{He}{1} recombination line ratios,
designated $T_{\rm e}$(\ion{He}{1}), are presented for 48 planetary nebulae
(PNe). We study the effect that temperature fluctuations inside nebulae have on
the $T_{\rm e}$(\ion{He}{1}) value. We show that a comparison between $T_{\rm
e}$(\ion{He}{1}) and the electron temperature derived from the Balmer jump of
the \ion{H}{1} recombination spectrum, designated $T_{\rm e}$(\ion{H}{1}),
provides an opportunity to discriminate between the paradigms of a chemically
homogeneous plasma with temperature and density variations, and a two-abundance
nebular model with hydrogen-deficient material embedded in diffuse gas of a
``normal'' chemical composition (i.e. $\sim$ solar), as the possible causes of
the dichotomy between the abundances that are deduced from collisionally
excited lines to those deduced from recombination lines. We find that $T_{\rm
e}$(\ion{He}{1}) values are significantly lower than $T_{\rm e}$(\ion{H}{1})
values, with an average difference of $<T_{\rm e}$(\ion{H}{1})-$T_{\rm
e}$(\ion{He}{1})$>=4000$ K. The result is consistent with the expectation of
the two-abundance nebular model but is opposite to the prediction of the
scenarios of temperature fluctuations and/or density inhomogeneities. From the
observed difference between $T_{\rm e}$(\ion{He}{1}) and $T_{\rm
e}$(\ion{H}{1}), we estimate that the filling factor ofhydrogen-deficient
components has a typical value of $10^{-4}$. In spite of its small mass, the
existence of hydrogen-deficient inclusions may potentially have a profound
effect in enhancing the intensities of \ion{He}{1} recombination lines and
thereby lead to apparently overestimated helium abundances for PNe.


title: Time-series Paschen-beta spectroscopy of SU Aurigae

abstract:
  We present time-series echelle spectra of the Pa-beta line of the T Tauri
star SU Aur, observed over three consecutive nights. The line shows strong
variability (~10 per cent) over the velocity range (100 km/s, 420 km/s) in the
red broad absorption component, and weaker variability (~2 per cent) over the
velocity range (-200 km/s, 0 km/s) in the blue wing. The variability in the
velocity range (-200 km/s, 0 km/s) is correlated with that in (200 km/s, 400
km/s), and the variability in these velocity ranges anti-correlates with that
in (0 km/s, 100 km/s). The mean spectrum from the second night shows a
suggestion of a blue-shifted absorption component at about -150 km/s, similar
to that found in the H-alpha and H-beta lines. We find the position of the
subpeak in the red absorption component changes steadily with time, and its
motion modulates on half the rotational period. We also find that the
modulation of the line equivalent width is associated with a half and a third
of the rotational period, which is consistent with the surface Doppler images
of SU Aur. Radiative transfer models of a rotationally modulated Pa-beta line,
produced in the shock-heated magnetospheric accretion flow, are also presented.
Models with a magnetic dipole offset reproduce the overall characteristics of
the observed line variability, including the line equivalent width and the
motion of the subpeak in the red absorption trough.


title: The Outer Cluster System of NGC 1399: Preliminary Results

abstract:
  We present preliminary results of our dynamical study of the outer globular
cluster system of NGC 1399, the central galaxy in the Fornax Cluster. About 160
new radial velocities for globular clusters at projected galactocentric
distances between 8 and 18 arcminutes indicate that the constant velocity
dispersion of 276 km/s (for all clusters) already found for the inner region
can be traced out to 80 kpc. We find that the kinematical properties of the
blue (metal-poor) and the red (metal-rich) globular cluster subpopulations
appear to be different: While the velocity distribution of the red clusters is
symmetric with respect to the systemic velocity of NGC 1399, the blue clusters
show a somewhat asymmetric distribution, with more velocities above the
systemic velocity.


title: CMB B-mode polarization from Thomson scattering in the local universe

abstract:
  [Abridged] The polarization of the CMB is widely recognized as a potential
source of information about primordial gravitational waves. The gravitational
wave contribution can be separated from the dominant CMB polarization created
by density perturbations because it generates both E and B polarization modes,
whereas the density perturbations create only E polarization. The limits of our
ability to measure gravitational waves are thus determined by statistical and
systematic errors, foregrounds, and nonlinear evolution effects such as lensing
of the CMB. Usually it is assumed that most foregrounds can be removed because
of their frequency dependence, however Thomson scattering of the CMB quadrupole
by electrons in the Galaxy or nearby structures shares the blackbody frequency
dependence of the CMB. If the optical depth from these nearby electrons is
anisotropic, the polarization generated can include B modes even without tensor
perturbations. We estimate this effect for the Galactic disk and nearby
extragalactic structures, and find that it contributes to the B polarization at
the level of ~(1--2)x10^-4\mu K per logarithmic interval in multipole L for
L<30. This is well below the detectability level even for a future CMB
polarization satellite. Depending on its structure and extent, the Galactic
corona may be a source of B-modes comparable to the residual large-scale
lensing B-mode after the latter has been cleaned using lensing reconstruction
techniques. For an extremely ambitious post-Planck CMB experiment, Thomson
scattering in the Galactic corona is thus a potential contaminant of the
gravitational wave signal; conversely, if the other foregrounds can be cleaned
out, such an experiment might be able to constrain models of the corona.


title:
On variations in the fine-structure constant and stellar pollution of
  quasar absorption systems

abstract:
  At redshifts z_abs < 2, quasar absorption-line constraints on space-time
variations in the fine-structure constant, alpha, rely on the comparison of
MgII and FeII transition wavelengths. One potentially important uncertainty is
the relative abundance of Mg isotopes in the absorbers which, if different from
solar, can cause spurious shifts in the measured wavelengths and, therefore,
alpha. Here we explore chemical evolution models with enhanced populations of
intermediate-mass (IM) stars which, in their asymptotic giant branch (AGB)
phase, are thought to be the dominant factories for heavy Mg isotopes at the
low metallicities typical of quasar absorption systems. By design, these models
partially explain recent Keck/HIRES evidence for a smaller alpha in z_abs < 2
absorption clouds than on Earth. However, such models also over-produce N,
violating observed abundance trends in high-z_abs damped Lyman-alpha systems
(DLAs). Our results do not support the recent claim of Ashenfelter, Mathews &
Olive (2004b) that similar models of IM-enhanced initial mass functions (IMFs)
may simultaneously explain the HIRES varying-alpha data and DLA N abundances.
We explore the effect of the IM-enhanced model on Si, Al and P abundances,
finding it to be much-less pronounced than for N. We also show that the 13C/12C
ratio, as measured in absorption systems, could constitute a future diagnostic
of non-standard models of the high-redshift IMF.


title:
Correlations between bright submillimetre sources and low-redshift
  galaxies

abstract:
  We present evidence for a positive angular correlation between bright
submillimetre sources and low-redshift galaxies. The study was conducted using
39 sources selected from 3 contiguous, flux-limited SCUBA surveys,
cross-correlated with optical field galaxies with magnitudes R<23 (with a
median redshift of z~0.5). We find that the angular distribution of submm
sources is skewed towards overdensities in the galaxy population, consistent
with 25+-12 per cent being associated with dense, low-redshift structure. The
signal appears to be dominated by the brightest sources with a flux density
S_850>10mJy. We conduct Monte-Carlo simulations of clustered submm populations,
and find that the probability of obtaining these correlations by chance is less
than 0.4 per cent. The results may suggest that a larger than expected fraction
of submm sources lie at z~0.5. Alternatively, we argue that this signal is most
likely caused by gravitational lensing bias, which may be entirely expected
given the steep submm source counts. Implications for future submm surveys are
discussed.


title:
West-Side Story (On the History of Density-Wave Spiral Theories in the
  1960s)

abstract:
  This paper deals with the history of Density-Wave Spiral Theories in the
1960s. The motivation to write the paper was the publication of two papers on
the history of these theories (Pasha 2004a,b). Pasha's papers tell only a part
of the story that took place on the Western side of the Iron Curtain in the
1960s. But giving only a part of the full story is a distortion of historical
truth. Important work done on the Eastern side of the Iron Curtain is still
little known in the West. In this paper, I fill the gaps and correct
chronological inaccuracies in Pasha's story and mention facts that are still
unknown (or little known) to the astronomical community in the West. I also
give my recollection of the development of Density-Wave Spiral Theories in the
1960s.


title:
Detection of the Baryon Acoustic Peak in the Large-Scale Correlation
  Function of SDSS Luminous Red Galaxies

abstract:
  We present the large-scale correlation function measured from a spectroscopic
sample of 46,748 luminous red galaxies from the Sloan Digital Sky Survey. The
survey region covers 0.72 h^{-3} Gpc^3 over 3816 square degrees and
0.16<z<0.47, making it the best sample yet for the study of large-scale
structure. We find a well-detected peak in the correlation function at
100h^{-1} Mpc separation that is an excellent match to the predicted shape and
location of the imprint of the recombination-epoch acoustic oscillations on the
low-redshift clustering of matter. This detection demonstrates the linear
growth of structure by gravitational instability between z=1000 and the present
and confirms a firm prediction of the standard cosmological theory. The
acoustic peak provides a standard ruler by which we can measure the ratio of
the distances to z=0.35 and z=1089 to 4% fractional accuracy and the absolute
distance to z=0.35 to 5% accuracy. From the overall shape of the correlation
function, we measure the matter density Omega_mh^2 to 8% and find agreement
with the value from cosmic microwave background (CMB) anisotropies. Independent
of the constraints provided by the CMB acoustic scale, we find Omega_m = 0.273
+- 0.025 + 0.123 (1+w_0) + 0.137 Omega_K. Including the CMB acoustic scale, we
find that the spatial curvature is Omega_K=-0.010+-0.009 if the dark energy is
a cosmological constant. More generally, our results provide a measurement of
cosmological distance, and hence an argument for dark energy, based on a
geometric method with the same simple physics as the microwave background
anisotropies. The standard cosmological model convincingly passes these new and
robust tests of its fundamental properties.


title: Proper Motion of the Irradiated Jet HH 399 in the Trifid Nebula

abstract:
  HH 399 is one of the first Herbig Haro flows recognized to be irradiated by
the UV radiation of the massive O7.5 star in the Trifid nebula. We present the
proper motion of the first irradiated jet based on two epochs of HST
observations of HH 399 separated nearly by five years using H$\alpha$ and [SII]
line filters. High proper motion with continuous velocities between 200$\pm$55
and 528$\pm24$ \kms are detected in both lines along the 18$''$ extent of the
jet axis. The irradiated fully-ionized jet consists of numerous knots along the
jet but also shows the evidence for a number of isolated blob-like structures
running immediately outside the jet with lower transverse velocities. The
transverse velocities combined with radial velocity measurements indicate that
the jet axis lies away from the plane of the sky by only few degrees. We argue
that the jet is fully ionized based on [SII]/H$\alpha$ line ratio as well as
radio continuum emission detected from the full extent of the jet at 3.6cm
wavelength. The stellar mass-loss rate producing HH 399 is estimated to be
$\approx 2\times10^{-6} \msol $yr$^{-1}$.


title: The Disk and Extraplanar Regions of NGC 55

abstract:
  The stellar content of the nearby SB(s)m galaxy NGC 55 is investigated using
images covering the visible and near-infrared wavelength regions. A
well-defined plume, which stellar evolution models suggest contains stars with
masses near the RSG - AGB transition, is detected in CMDs of the disk, and it
is concluded that star formation in the thin disk of NGC 55 has ocurred at a
significant rate for at least the past 0.1 - 0.2 Gyr. The disk also contains a
large population of old (log(t_yr) ~ 10) stars, and it is argued that a stable
disk has been in place in NGC 55 for a significant fraction of the age of the
Universe. At projected distances in excess of 2 kpc off of the disk plane the
brightest AGB stars have ages 10(+3)(-2) Gyr. Thus, despite indications that
dust and gas are present in the envelope surrounding the NGC 55 disk, the AGB
content suggests that recently formed stars do not occur in large numbers in
the extraplanar region. The mean metallicity of extraplanar RGB stars is in
excellent agreement with that measured in the extraplanar HII regions EHR 1 and
2, suggesting that the age-metallicity relation in this part of NGC 55 has been
flat for at least a few Gyr. Finally, the RGB-tip occurs near i' = 23.1 in the
extraplanar region, and a distance modulus of 26.5 is computed from this
feature.


title:
The 2dF Galaxy Redshift Survey: Power-spectrum analysis of the final
  dataset and cosmological implications

abstract:
  We present a power spectrum analysis of the final 2dF Galaxy Redshift Survey,
employing a direct Fourier method. The sample used comprises 221,414 galaxies
with measured redshifts. We investigate in detail the modelling of the sample
selection. A new angular mask is derived, based on revisions to the photometric
calibration. The redshift selection function is determined by dividing the
survey according to rest-frame colour, and deducing a self-consistent treatment
of k-corrections and evolution for each population. The covariance matrix for
the power-spectrum estimates is determined using two different approaches to
the construction of mock surveys which are used to demonstrate that the input
cosmological model can be correctly recovered. We are confident that the 2dFGRS
power spectrum can be used to infer the matter content of the universe. On
large scales, our estimated power spectrum shows evidence for the `baryon
oscillations' that are predicted in CDM models. Fitting to a CDM model,
assuming a primordial $n_{s}=1$ spectrum, $h=0.72$ and negligible neutrino
mass, the preferred parameters are $\Omega_{M} h = 0.168 \pm 0.016$ and a
baryon fraction $\Omega_{b} /\Omega_{M} = 0.185\pm0.046$ (1$\sigma$ errors).
The value of $\Omega_{M} h$ is $1\sigma$ lower than the $0.20 \pm 0.03$ in our
2001 analysis of the partially complete 2dFGRS. This shift is largely due to
the signal from the newly-sampled regions of space, rather than the refinements
in the treatment of observational selection. This analysis therefore implies a
density significantly below the standard $\Omega_{M} =0.3$: in combination with
CMB data from WMAP, we infer $\Omega_{M} =0.231\pm 0.021$. (Abridged.)


title: AGN heating and dissipative processes in galaxy clusters

abstract:
  Recent X-ray observations reveal growing evidence for heating by active
galactic nuclei (AGN) in clusters and groups of galaxies. AGN outflows play a
crucial role in explaining the riddle of cooling flows and the entropy problem
in clusters. Here we study the effect of AGN on the intra-cluster medium in a
cosmological simulation using the adaptive mesh refinement FLASH code. We pay
particular attention to the effects of conductivity and viscosity on the
dissipation of weak shocks generated by the AGN activity in a realistic galaxy
cluster. Our 3D simulations demonstrate that both viscous and conductive
dissipation play an important role in distributing the mechanical energy
injected by the AGN, offsetting radiative cooling and injecting entropy to the
gas. These processes are important even when the transport coefficients are at
a level of 10% of the Spitzer value. Provided that both conductivity and
viscosity are suppressed by a comparable amount, conductive dissipation is
likely to dominate over viscous dissipation. Nevertheless, viscous effects may
still affect the dynamics of the gas and contribute a significant amount of
dissipation compared to radiative cooling. We also present synthetic Chandra
observations. We show that the simulated buoyant bubbles inflated by the AGN,
and weak shocks associated with them, are detectable with the Chandra
observatory.


title:
Supernova Ia without Accelerated Expansion The First Global Failure of
  Relativity Theory

abstract:
  A new cosmological model has been developed that shows great promise for
solving many of the present problems of physics. A new concept of space and its
production, spatial condensation (SC) is the cause of the expansion. Dark mass
(not matter) scales with the expansion differently than matter. Many other
non-relativistic concepts predict a simple beginning, absence of singularities,
a definition of energy and the cause of space curvature and gravity. Predicted
cosmological parameters agree with recent measurements including t0=13.5 Gy,
H0=68.6 km/(s Mpc), Omega (mass)=0.28 and no dark energy. Other predictions
include: Hubble flow at the Planck level, vacuum energy (no mass),
Evac/Emass=10^123 in agreement with quantum mechanics, and the pattern in the
CMB is the distribution of very early dark mass black holes of average mass
10^8 Msun. Excellent agreement with supernova Ia data is obtained with no
acceleration of the expansion rate. It is concluded that the SC-model announces
the first global failure of relativity theory.


title: Discovery of an Unbound Hyper-Velocity Star in the Milky Way Halo

abstract:
  We have discovered a star, SDSS J090745.0+024507, leaving the Galaxy with a
heliocentric radial velocity of +853+-12 km/s, the largest velocity ever
observed in the Milky Way halo. The star is either a hot blue horizontal branch
star or a B9 main sequence star with a heliocentric distance ~55 kpc. Corrected
for the solar reflex motion and to the local standard of rest, the Galactic
rest-frame velocity is +709 km/s.
  Because its radial velocity vector points 173.8 deg from the Galactic center,
we suggest that this star is the first example of a hyper-velocity star ejected
from the Galactic center as predicted by Hills and later discussed by Yu &
Tremaine. The star has [Fe/H]~0, consistent with a Galactic center origin, and
a travel time of <80 Myr from the Galactic center, consistent with its stellar
lifetime. If the star is indeed traveling from the Galactic center, it should
have a proper motion of 0.3 mas/yr observable with GAIA. Identifying additional
hyper-velocity stars throughout the halo will constrain the production rate
history of hyper-velocity stars at the Galactic center.


title: SDSS J210014.12+004446.0: A New Dwarf Nova with Quiescent Superhumps?

abstract:
  We report follow-up observations of the Sloan Digital Sky Survey Cataclysmic
Variable SDSS J210014.12+004446.0 (hereafter SDSS J2100). We obtained
photometry and spectroscopy in both outburst and quiescent states, providing
the first quiescent spectrum of this source. In both states, non-sinusoidal
photometric modulations are apparent, suggestive of superhumps, placing SDSS
J2100 in the SU UMa subclass of dwarf novae. However, the periods during
outburst and quiescence differ significantly, being 2.099 plus or minus 0.002
hr and 1.96 plus or minus 0.02 hr respectively. Our phase-resolved spectroscopy
during outburst yielded an estimate of about 2 hr for the orbital period,
consistent with the photometry. The presence of the shorter period modulation
at quiescence is unusual, but not unique. Another atypical feature is the
relative weakness of the Balmer emission lines in quiescence. Overall, we find
a close similarity between SDSS J2100 and the well-studied superhump
cataclysmic Variable V503 Cygni. By analogy, we suggest that the quiescent
modulation is due to a tilted accretion disk -- producing negative superhumps
-- and the modulation in outburst is due to positive superhumps from the
precession of an elliptical disk.


title: Secular evolution of galactic discs: constraints on phase-space density

abstract:
  It was argued in the past that bulges of galaxies cannot be formed through
collisionless secular evolution because that would violate constraints on the
phase-space density: the phase-space density in bulges is several times larger
than in the inner parts of discs. We show that these arguments against secular
evolution are not correct. Observations give estimates of the coarsely grained
phase-space densities of galaxies, f'=rho_s/(sigma_R sigma_phi sigma_z), where
rho_s is stellar density and sigma_R, sigma_phi, sigma_z are the radial,
tangential, and vertical rms velocities of stars. Using high-resolution N-body
simulations, we study the evolution of f' in discs of Galaxy-size models.
During the secular evolution, the discs, which are embedded in live CDM haloes,
form a bar and then a thick, dynamically hot, central mass concentration. In
the course of evolution f' declines at all radii, not just in the central
region. However, the decline is different in different parts of the disc. In
the inner disc, f'(R) develops a valley with a minimum around the end of the
central mass concentration. The final result is that the values of f' in the
central regions are significantly larger than those in the inner disc. The
minimum, which gets deeper with time, seems to be due to a large phase mixing
produced by the outer bar. We find that the shape and the amplitude of f'(R)
for different simulations agree qualitatively with the observed f'(R) in our
Galaxy. Curiously enough, the fact that the coarsely grained phase-space
density of the bulge is significantly larger than the one of the inner disc
turns out to be an argument in favor of secular formation of bulges, not
against it.


title: The optical spectroscopy of extraterrestrial molecules

abstract:
  The ongoing quest to identify molecules in the interstellar medium by their
electronic spectra in the visible region is reviewed. Identification of
molecular absorption is described in the context of the elucidation of the
carriers of the unidentified diffuse interstellar bands while molecular
emission is discussed with reference to the unidentified Red Rectangle bands.
The experimental techniques employed in undertaking studies on the optical
spectroscopy of extraterrestrial molecules are described and critiqued in the
context of their application.


title:
A New Algorithm for the Detection of Inter-cluster Galaxy Filaments
  using Galaxy Orientation Alignments

abstract:
  We present a new algorithm to detect inter-cluster galaxy filaments based
upon the assumption that the orientations of constituent galaxies along such
filaments are non-isotropic. We apply the algorithm to the 2dF Galaxy Redshift
Survey catalogue and find that it readily detects many straight filaments
between close cluster pairs. At large inter-cluster separations (>15 Mpc), we
find that the detection efficiency falls quickly, as it also does with more
complex filament morphologies. We explore the underlying assumptions and
suggest that it is only in the case of close cluster pairs that we can expect
galaxy orientations to be significantly correlated with filament direction.


title: Galaxy Groups at 0.3 <= z <= 0.55. I. Group Properties

abstract:
  The evolution of galaxies in groups may have important implications for the
evolution of the star formation history of the universe, since many processes
which operate in groups may suppress star formation and the fraction of
galaxies in bound groups grows rapidly between z=1 and the present day. In this
paper, we present an investigation of the properties of galaxies in galaxy
groups at intermediate redshift (z ~ 0.4). The groups were selected from the
CNOC2 redshift survey as described in Carlberg et al., 2001, with further
spectroscopic follow-up undertaken at the Magellan telescope in order to
improve the completeness and depth of the sample. We present the data for the
individual groups, and find no clear trend in the fraction of passive galaxies
with group velocity dispersion and group concentration. We stack the galaxy
groups in order to compare the properties of group galaxies with those of field
galaxies at the same redshift. The groups contain a larger fraction of passive
galaxies than the field, this trend being particularly clear for galaxies
brighter than M_{B_J} < -20 in the higher velocity dispersion groups. In
addition, we see evidence for an excess of bright passive galaxies in the
groups relative to the field. In contrast, the luminosity functions of the star
forming galaxies in the groups and the field are consistent. These trends are
qualitatively consitent with the differences between group and field galaxies
seen in the local universe.


title: Galaxy Groups at 0.3 <= z <= 0.55. II. Evolution to z ~ 0

abstract:
  We compare deep Magellan spectroscopy of 26 groups at 0.3 <= z <= 0.55,
selected from the Canadian Network for Observational Cosmology 2 field survey
(CNOC2), with a large sample of nearby groups from the 2PIGG catalogue (Eke et
al., 2004). We find that the fraction of group galaxies with significant [OII]
emission (>=5\AA) increases strongly with redshift, from ~29% in 2dFGRS to ~58%
in CNOC2, for all galaxies brighter than ~ M*+1.75. This trend is parallel to
the evolution of field galaxies, where the equivalent fraction of emission line
galaxies increases from ~ 53% to ~ 75%. The fraction of emission-line galaxies
in groups is lower than in the field, across the full redshift range,
indicating that the history of star formation in groups is influenced by their
environment. We show that the evolution required to explain the data is
inconsistent with a quiescent model of galaxy evolution; instead, discrete
events in which galaxies cease forming stars (truncation events) are required.
We constrain the probability of truncation (P_trunc) and find that a high value
is required in a simple evolutionary scenario neglecting galaxy mergers
(P_trunc >~ 0.3 Gyr^{-1}). However, without assuming significant density
evolution, P_trunc is not required to be larger in groups than in the field,
suggesting that the environmental dependence of star formation was embedded at
redshifts z >~ 0.45.


title:
Optical Monitoring of BL Lac Object S5 0716+714 with High Temporal
  Resolution

abstract:
  Optical monitoring of S5 0716+714 was performed with a 60/90 Schmidt
telescope in 2003 November and December and 2004 January for studying the
variability of the object on short timescales. Due to the high brightness of
the source we could carry out quasi-simultaneous measurements in three bands
with a temporal resolution of about 20 minutes by using one single telescope.
Intraday and intranight variations were observed with an overall change of ~0.9
mag during the whole campaign. Two outbursts were recorded on JD 2453005 and JD
2453009. Minimum timescales of a few hours were derived from the light curves
of individual nights but were different from night to night. A
bluer-when-brighter chromatism was present when the object was in fast flare,
but was absent when it was in a relatively quiescent state. Our results are
basically consistent with the shock-in-jet model and demonstrate that the
geometrical effects can sometimes play an important role in the variability of
blazars.


title: Accurate numerical potential and field in razor-thin axisymmetric discs

abstract:
  We demonstrate the high accuracy of the density splitting method to compute
the gravitational potential and field in the plane of razor-thin, axially
symmetric discs, as preliminarily outlined in Pierens & Hure (2004).
  Because residual kernels in Poisson integrals are not C^infinity-class
functions, we use a dynamical space mapping in order to increase the efficiency
of advanced quadrature schemes. In terms of accuracy, results are better by
orders of magnitude than for the classical FFT-methods.


title: The distribution of kHz QPO frequencies in bright LMXBs

abstract:
  We analyzed all published frequencies, nu_1 and nu_2, of the twin kilohertz
quasi-periodic oscillations (kHz QPOs) in bright neutron star low-mass X-ray
binaries. The two frequencies are well correlated but, contrary to recent
suggestions, the frequency-frequency correlation is significantly different
from a nu_2 = (3/2) nu_1 relation. To check whether, although not following the
the 3/2 relation, the QPO frequencies cluster around a region where nu_2/nu_1 ~
3/2, we re-analyzed the Sco X-1 data that were used to report that ratio and
show that, because the distribution of ratios of linearly correlated
measurements is intrinsically biased, although the significance of the
clustering around nu_2/nu_1 ~ 3/2 previously reported in the case of Sco X-1 is
formally correct, it does not provide any useful information about a possible
underlying resonance mechanism in this source. Using the same data, we then
show that the (unbiased) distribution of QPO frequencies is consistent with a
uniform distribution at a 2.4 sigma level. To investigate this further, we
analyzed a larger data set of Sco X-1 and four other sources, 4U 1608-52, 4U
1636-53, 4U 1728-34 and 4U 1820-30. We find that for all five sources the
distribution of the kHz QPO frequencies is not uniform and has multiple peaks,
which have no analogy in the distribution of points in the spectral color-color
diagrams of these sources. Finally, we demonstrate that a simple random walk of
the QPO frequencies can reproduce qualitatively the observed distributions in
frequency and frequency ratio. This result weakens the support for resonance
models of kHz QPOs in neutron stars.


title:
The Mid-IR spatially resolved environment of OH26.5+0.6 at maximum
  luminosity

abstract:
  We present observations of the famous OH/IR star OH26.5+0.6 obtained using
the Mid-Infrared Interferometric Instrument MIDI at the European Southern
Observatory (ESO) Very Large Telescope Interferometer VLTI. The emission of the
dusty envelope, spectrally dispersed at a resolution of 30 from 8 to 13.5
micron, appears resolved by a single dish UT telescope. In particular the
angular diameter increases strongly within the silicate absorption band.
Moreover an acquisition image taken at 8.7 micron exhibits, after
deconvolution, a strong asymmetry. The axis ratio is 0.75+/-0.07 with the FWHM
of the major and minor axis which are 286mas and 214mas respectively. The
measured PA angle, 95 degrees +/-6 degrees is reminiscent of the asymmetry in
the OH maser emission detected at 1612MHz by Bowers & Johnston (1990) for this
star. In interferometric mode the UT1-UT3 102m baseline was employed to detect
the presence of the star. No fringes have been found with a detection threshold
estimated to be of the order of 1% of the total flux of the source, i.e. 5-8
Jy. These observations were carried out during the phase of maximum luminosity
of the star, when the dust shell is more diluted and therefore the chance to
detect the central source maximized. We modeled the dusty environment based on
the work of Justannont et al. (1996). In particular, the failure to detect
fringes provides strong constraints on the opacities in the inner regions of
the dust shell or in the close vicinity of the star.


title:
The optical-to-radio spectral energy distributions of low-metallicity
  blue compact dwarf galaxies

abstract:
  We present global spectral energy distributions (SEDs) from 0.3$\mu$m to 90cm
for a sample of seven low-metallicity blue compact dwarf galaxies (BCDs). In
addition to data compiled from the literature, we report new SCUBA data for the
galaxies in the sample, including the two most metal-poor star-forming galaxies
known, IZw18 and SBS0335-052. The standard starburst templates, M82 and Arp220,
do not give a good approximation to any of the BCD SEDs in our sample. Several
SEDs are instead characterized by: (i) approximately flat radio spectra
suggesting dominant thermal processes; (ii) far-infrared (FIR) spectra which
peak at or shortward of 60 $\mu$m; (iii) a significant warm dust component and
absence of Aromatic Features in Emission (or PAHs) in the mid-infrared (MIR).
The SEDs of low-metallicity BCDs do not follow ``canonical'' scaling relations,
and the ``standard'' star-formation indicators based on radio continuum, FIR,
and MIR luminosities can be discrepant by factors of $\simgt10$. We present new
models of the dust SEDs from 5$\mu$m to 1cm, and derive infrared luminosities,
dust distributions, temperatures, and masses. The observed SEDs and dust models
are interpreted in terms of the active/passive regimes of star formation and
trends with metallicity. Finally, we discuss the implications of our results on
the $z\simgt6$ starburst populations which will be detected by forthcoming
submm and radio facilities.


title: The Shape of Space after WMAP data

abstract:
  What is the shape of space is a long-standing question in cosmology. In this
talk I review recent advances in cosmic topology since it has entered a new era
of experimental tests. High redshift surveys of astronomical sources and
accurate maps of the Cosmic Microwave Background radiation (CMB) are beginning
to hint at the shape of the universe, or at least to limit the wide range of
possibilities. Among those possibilites are surprising "wrap around" universe
models in which space, whatever its curvature, may be smaller than the
observable universe and generate topological lensing effects on a detectable
cosmic scale. In particular, the recent analysis of CMB data provided by the
WMAP satellite suggests a finite universe with the topology of the Poincare
dodecahedral spherical space. Such a model of a "small universe", the volume of
which would represent only about 80% the volume of the observable universe,
offers an observational signature in the form of a predictable topological lens
effect on one hand, and rises new issues on the early universe physics on the
other hand.


title: Neutral Hydrogen Gas in Interacting Galaxies: The NGC 1511 galaxy group

abstract:
  We present HI line and 20-cm radio continuum observations of the NGC 1511
galaxy group obtained with the Australia Telescope Compact Array. The data
reveal an extended, rather disturbed HI distribution for the peculiar starburst
galaxy NGC 1511 and a narrow bridge to its small companion galaxy, NGC 1511B,
which has been severely distorted by the interaction/collision between the two
galaxies. No stellar counterpart to the gaseous bridge has been detected. In
addition, we find that the peculiar optical ridge to the east of NGC 1511 is
probably the stellar remnant of a galaxy completed disrupted by interactions
with NGC 1511. The slightly more distant neighbour, NGC 1511A, shows a regular
HI velocity field and no obvious signs of interactions. Radio continuum
emission from NGC 1511 reveals three prominent sources on top of a more
diffuse, extended distribution. We derive an overall star formation rate of 7
Msun/yr. The most enhanced star formation is found in the south-eastern part of
the disk, coincident with several bright HII regions, and closest to the
peculiar optical ridge. No continuum emission was detected in the companions,
but NGC 1511B appears to show an HII region at its faint western edge, closest
to NGC 1511. The group displays a prime example of interaction-induced star
formation activity.


title: Kilo-gauss Magnetic Fields in three DA White Dwarfs

abstract:
  We have detected longitudinal magnetic fields between 2 and 4kG in three
normal DA white dwarfs (WD0446-790, WD1105-048, WD2359$-$434) out of a sample
of 12 by using optical spectropolarimetry done with the VLT Antu 8 m telescope
equipped with FORS1. With the exception of 40 Eri B (4kG) these are the first
positive detections of magnetic fields in white dwarfs below 30kG. A detection
rate of 25% (3/12) may indicate now for the firsttime that a substantial
fraction of white dwarfs have a weak magnetic field.This result, if confirmed
by future observations, would form a cornerston for our understanding of the
evolution of stellar magnetic fields.


title:
On dynamics of relativistic shock waves with losses in gamma-ray burst
  sources

abstract:
  Generalization of the self-similar solution for ultrarelativistic shock waves
(Blandford & McKee, 1976) is obtained in presence of losses localized on the
shock front or distributed in the downstream medium. It is shown that there are
two qualitatively different regimes of shock deceleration, corresponding to
small and large losses. We present the temperature, pressure and density
distributions in the downstream fluid as well as Lorentz factor as a function
of distance from the shock front.


title: A Multiwavelength Investigation of Unidentified EGRET Sources

abstract:
  Statistical studies indicate that the 271 point sources of high-energy gamma
rays belong to two groups: a Galactic population and an isotropic extragalactic
population. Many unidentified extragalactic sources are certainly blazars, and
it is the intention of this work to uncover gamma-ray blazars missed by
previous attempts. Until recently, searches for blazar counterparts to
unidentified EGRET sources have focused on finding AGN that have 5-GHz radio
flux densities S_5 near or above 1 Jy. However, the recent blazar
identification of 3EG J2006-2321 (S_5 = 260 mJy) and other work suggest that
careful studies of weaker flat-spectrum sources may be fruitful. In this
spirit, error circles of 4 high-latitude unidentified EGRET sources have been
searched for 5-GHz sources. The gamma-ray sources are 3EG J1133+0033, 3EG
J1212+2304, 3EG J1222+2315, and 3EG J1227+4302. Within the error contours of
each of the four sources are found 6 radio candidates; by observing the
positions of the radio sources with the 0.81-m Tenagra II telescope it is
determined that 14 of these 24 radio sources have optical counterparts with R <
22. Eight of these from two different EGRET sources have been observed in the
B, V, and R bands in more than one epoch and the analysis of these data is
ongoing. Any sources that are found to be variable will be the objects of
multi-epoch polarimetry studies.


title:
Intergalactic stars in z~0.25 galaxy clusters: systematic properties
  from stacking of Sloan Digital Sky Survey imaging data

abstract:
  We analyse the spatial distribution and colour of the intracluster light
(ICL) in 683 clusters of galaxies between z=0.2 and 0.3, selected from approx
1500 deg^2 of the SDSS-DR1. Surface photometry in the g, r and i bands is
conducted on stacked images of the clusters, after rescaling them to the same
metric size and masking out resolved sources. We are able to trace the average
surface brightness profile of the ICL out to 700 kpc, where it is less than
1/10,000 of the mean surface brightness of the dark night sky. The ICL appears
as a clear surface brightness excess with respect to an inner R^1/4 profile
which characterises the mean profile of the BCG. The surface brightness (SB) of
the ICL ranges from 27.5 mag/arcsec^2 at 100 kpc to roughly 32 at 700 kpc in
the observed r-band (26.5 to 31 in the rest-frame g-band). We find that, on
average, the ICL contributes only a small fraction of the total optical
emission in a cluster (10.9+-5.0% within 500 kpc). The radial distribution of
the ICL is more centrally concentrated than that of the cluster galaxies, but
the colours of the two components are identical within the statistical
uncertainties. In the mean the ICL is aligned with and more flattened than the
BCG itself. This alignment is substantially stronger than that of the cluster
light as a whole. The SB of the ICL correlates both with BCG luminosity and
with cluster richness, while the fraction of the total light in the ICL is
almost independent of these quantities. These results support the idea that the
ICL is produced by stripping and disruption of galaxies as they pass through
the central regions of clusters. Our measurements of the diffuse light also
constrain the faint-end slope of the cluster LF. Slopes alpha<-1.35 would imply
more light from undetected galaxies than is observed in the diffuse component.


title: Outstanding Problems in Particle Astrophysics

abstract:
  The general features of the cosmic-ray spectrum have been known for a long
time. Although the basic approaches to understanding cosmic-ray propagation and
acceleration have also been well understood for many years, there are several
questions of great interest that motivate the current intense experimental
activity in the field. The purpose of this lecture is to introduce the main
topics of the School and to relate the theoretical questions to the experiments
that can answer them.


title: Dynamical Evolution of Barred Galaxies

abstract:
  Angular momentum redistribution within barred galaxies drives their dynamical
evolution. Angular momentum is emitted mainly by near-resonant material in the
bar region and absorbed by resonant material mainly in the outer disc and in
the halo. This exchange determines the strength of the bar, the decrease of its
pattern speed, as well as its morphology. If the galaxy has also a gaseous
component and/or a companion or satellite, then these also take part in the
angular momentum exchange. During the evolution a bar structure forms in the
inner parts of the halo as well. This bar is shorter and fatter than the disc
bar and stays so all through the simulation, although its length grows
considerably with time. Viewed edge-on, the bar in the disc component acquires
a boxy or peanut shape. I describe the families of periodic orbits that explain
such structures and review the observations showing that boxy/peanut `bulges'
are in fact just bars seen edge-on.


title: High-energy emission from off-axis relativistic jets

abstract:
  We analyze how the spectrum of synchrotron and inverse Compton radiation from
a narrow relativistic jet changes with the observation angle. It is shown that
diversity of acceleration mechanisms (in particular, taking the converter
mechanism (Derishev et al. 2003) into account) allows for numerous
modifications of the observed spectrum. In general, the off-axis emission in
GeV-TeV energy range appears to be brighter, has a much harder spectrum and a
much higher cut-off frequency compared to the values derived from Doppler
boosting considerations alone. The magnitude of these effects depends on the
details of particle acceleration mechanisms, what can be used to discriminate
between different models.
  One of the implications is the possibility to explain high-latitude
unidentified EGRET sources as off-axis but otherwise typical relativistic-jet
sources, such as blazars. We also discuss the broadening of beam pattern in
application to bright transient jet sources, such as Gamma-Ray Bursts.


title:
The Effects of Photon Bubble Instability in Radiation-Dominated
  Accretion Disks

abstract:
  We examine the effects of photon bubble instability in radiation-dominated
accretion disks such as those found around black holes in active galactic
nuclei and X-ray binary star systems. Two- and 3-D numerical radiation MHD
calculations of small patches of disk are used. Modes with wavelengths shorter
than the gas pressure scale height grow faster than the orbital frequency in
the surface layers. The fastest growth rate observed is five times the orbital
frequency and occurs on nearly-vertical magnetic fields. The spectrum of linear
modes agrees with a WKB analysis indicating still faster growth at unresolved
scales, with a maximum proportional to the gravity and inversely proportional
to the gas sound speed. Disturbances reaching non-linear amplitudes steepen
into trains of shocks similar to a 1-D periodic non-linear analytic solution.
Variations in propagation speed result in merging of adjacent fronts, and over
time the shock spacing and amplitude increase. Growth is limited by the
strength of the field, and the structure is disrupted when the ram pressure
exceeds the magnetic pressure. The largest horizontal density variations are
similar to the ratio of magnetic to gas pressure, and in our calculations are
more than 100. Under the conditions considered, radiation diffuses through the
inhomogeneneous flow 5x faster than through the initial hydrostatic
equilibrium, and the net cooling rate is several times greater than in a
similar calculation without magnetic fields showing the effects of convection.
These results indicate photon bubbles may be important in cooling
radiation-dominated disks.


title: SGARFACE: A Novel Detector For Microsecond Gamma Ray Bursts

abstract:
  The Short GAmma Ray Front Air Cherenkov Experiment (SGARFACE) is operated at
the Whipple Observatory utilizing the Whipple 10m gamma-ray telescope. SGARFACE
is sensitive to gamma-ray bursts of more than 100MeV with durations from 100ns
to 35us and provides a fluence sensitivity as low as 0.8 gamma-rays per m^2
above 200MeV (0.05 gamma-rays per m^2 above 2GeV) and allows to record the
burst time structure.


title:
An Open Inflationary Model for Dimensional Reduction and its Effects on
  the Observable Parameters of the Universe

abstract:
  Assuming that higher dimensions existed in the early stages of the universe
where the evolution was inflationary, we construct an open, singularity-free,
spatially homogeneous and isotropic cosmological model to study the effects of
dimensional reduction that may have taken place during the early stages of the
universe. We consider dimensional reduction to take place in a stepwise manner
and interpret each step as a phase transition. By imposing suitable boundary
conditions we trace their effects on the present day parameters of the
universe.


title:
Systematic errors in weak lensing: application to SDSS galaxy-galaxy
  weak lensing

abstract:
  Weak lensing is emerging as a powerful observational tool to constrain
cosmological models, but is at present limited by an incomplete understanding
of many sources of systematic error. Many of these errors are multiplicative
and depend on the population of background galaxies. We show how the commonly
cited geometric test, which is rather insensitive to cosmology, can be used as
a ratio test of systematics in the lensing signal at the 1 per cent level. We
apply this test to the galaxy-galaxy lensing analysis of the Sloan Digital Sky
Survey (SDSS), which at present is the sample with the highest weak lensing
signal to noise and has the additional advantage of spectroscopic redshifts for
lenses. This allows one to perform meaningful geometric tests of systematics
for different subsamples of galaxies at different mean redshifts, such as
brighter galaxies, fainter galaxies and high-redshift luminous red galaxies,
both with and without photometric redshift estimates. We use overlapping
objects between SDSS and the DEEP2 and 2SLAQ spectroscopic surveys to establish
accurate calibration of photometric redshifts and to determine the redshift
distributions for SDSS. We use these redshift results to compute the projected
surface density contrast DeltaSigma around 259 609 spectroscopic galaxies in
the SDSS; by measuring DeltaSigma with different source samples we establish
consistency of the results at the 10 per cent level (1-sigma). We also use the
ratio test to constrain shear calibration biases and other systematics in the
SDSS survey data to determine the overall galaxy-galaxy weak lensing signal
calibration uncertainty. We find no evidence of any inconsistency among many
subsamples of the data.


title:
When Darwin Met Einstein: Gravitational Lens Inversion with Genetic
  Algorithms

abstract:
  Gravitational lensing can magnify a distant source, revealing structural
detail which is normally unresolvable. Recovering this detail through an
inversion of the influence of gravitational lensing, however, requires
optimisation of not only lens parameters, but also of the surface brightness
distribution of the source. This paper outlines a new approach to this
inversion, utilising genetic algorithms to reconstruct the source profile. In
this initial study, the effects of image degradation due to instrumental and
atmospheric effects are neglected and it is assumed that the lens model is
accurately known, but the genetic algorithm approach can be incorporated into
more general optimisation techniques, allowing the optimisation of both the
parameters for a lensing model and the surface brightness of the source.


title:
On highly eccentric stellar trajectories interacting with a
  self-gravitating disc in Sgr A*

abstract:
  We propose that Kozai's phenomenon is responsible for the long-term evolution
of stellar orbits near a supermassive black hole. We pursue the idea that this
process may be driven by a fossil accretion disc in the centre of our Galaxy,
causing the gradual orbital decay of stellar trajectories, while setting some
stars on highly elliptic orbits. We evolve model orbits that undergo repetitive
transitions across the disc over the period of ~10^7 years. We assume that the
disc mass is small compared to the central black hole, and its gravitational
field comparatively weak, yet non-zero, and we set the present values of
orbital parameters of the model star consistent with those reported for the S2
star in Sagittarius A*. We show how a model trajectory decays and circularizes,
but at some point the mean eccentricity is substantially increased by Kozai's
resonance. In consequence the orbital decay of highly eccentric orbits is
accelerated. A combination of an axially symmetric gravitational field and
dissipative environment can provide a mechanism explaining the origin of stars
on highly eccentric orbits tightly bound to the central black hole. In the
context of other S-stars, we can conclude that an acceptable mass of the disc
(i.e., M_d<=1 percent of the black hole mass) is compatible with their
surprisingly young age and small pericentre distances, provided these stars
were formed at r<=10^5 gravitational radii.


title:
Evolutionary Stellar Population Synthesis at High Spectral Resolution:
  Optical Wavelengths

abstract:
  We present the single stellar population (SSP) synthesis results of our new
synthetic stellar atmosphere models library with a spectral sampling of 0.3 A,
covering the wavelength range from 3000 A to 7000 A for a wide range of
metallicities (twice solar, solar, half and 1/10 solar). The stellar library is
composed of 1650 spectra computed with the latest improvements in stellar
atmospheres. In particular it incorporates non-LTE line-blanketed models for
hot (Teff >= 27500 K) and LTE line-blanketed models (Phoenix) for cool (3000 K
=< Teff =< 4500 K) stars. Because of the high spectral resolution of this
library, evolutionary synthesis models can be used to predict the strength of
numerous weak absorption lines, and the evolution of the profiles of the
strongest lines over a wide range of ages. The SSP results have been calculated
for ages 1 Myr to 17 Gyr using the stellar evolutionary provided by the Geneva
and Padova-tracks groups. For young stellar populations, our results have a
very detailed coverage of high-temperature stars with similar results for
Padova and Geneva isochrones. For intermediate and old stellar populations, our
results, once degraded to a lower resolution, are similar to the ones obtained
by other groups apart from limitations imposed by the stellar evolutionary
physics. The limitations and advantages of our library for the analysis of
integrated populations are described. The full set of the stellar library and
the evolutionary models are available for retrieval at the websites
http://www.iaa.csic.es/~rosa and http://www.iaa.csic.es/~mcs/Sed@, or on
request from the first two authors.


title:
Structure and kinematics of edge-on galaxy discs -- IV. The kinematics
  of the stellar discs

abstract:
  The stellar disc kinematics in a sample of fifteen intermediate- to late-type
edge-on spiral galaxies are studied using a dynamical modeling technique. The
sample covers a substantial range in maximum rotation velocity and deprojected
face-on surface brightness and contains seven spirals with either a boxy- or
peanut-shaped bulge. Dynamical models of the stellar discs are constructed
using the disc structure from $I$-band surface photometry and rotation curves
observed in the gas. The differences in the line-of-sight stellar kinematics
between the models and absorption line spectroscopy are minimized using a
least-squares approach. The modeling constrains the disc surface density and
stellar radial velocity dispersion at a fiducial radius through the free
parameter $\sqrt{M/L}$ $(\sigma_{\rm z}/\sigma_{\rm R})^{-1}$, where
$\sigma_{\rm z}/\sigma_{\rm R}$ is the ratio of vertical and radial velocity
dispersion and $M/L$ the disc mass-to-light ratio. For thirteen spirals a
transparent model provides a good match to the mean line-of-sight stellar
velocity dispersion. Models that include a realistic radiative transfer
prescription confirm that the effect of dust on the observable stellar
kinematics is small at the observed slit positions. We discuss possible sources
of systematic error and conclude that most of these are likely to be small. The
exception is the neglect of the dark halo gravity, which has probably caused an
overestimate of the surface density in the case of low surface brightness
discs.


title: The transient hard X-ray tail of GX 17+2: new BeppoSAX results

abstract:
  We report on results of two BeppoSAX observations of the Z source GX 17+2. In
both cases the source is in the horizontal branch of the colour-intensity
diagram. The persistent continuum can be fit by two-component models consisting
of a blackbody plus a Comptonization spectrum. With one of these models, two
solutions for the blackbody temperature of both the observed and seed photons
for Comptonization are equally accepted by the data. In the first observation,
when the source is on the left part of the horizontal branch, we observe a hard
tail extending up to 120 keV, while in the second observation, when the source
moves towards right in the same branch, the tail is no longer detected. The
hard ($\ga 30$ keV) X-ray emission can be modeled either by a simple power-law
with photon index $\Gamma \sim$ 2.7, or assuming Comptonization of $\sim$ 1 keV
soft photons off a hybrid thermal plus non-thermal electron plasma. The
spectral index of the non-thermal injected electrons is $p \sim 1.7$. The
observation of hard {X-ray} emission only in the left part of the horizontal
branch could be indicative of the presence of a threshold in the accretion rate
above which the hard tail disappears. An emission line at 6.7 keV with
equivalent width $\sim 30$ eV is also found in both observations. We discuss
these results and their physical implications


title: X-rays and young clusters: Membership, IMFs and distances

abstract:
  Sensitive imaging X-ray observations of young stellar clusters (YSCs, ages
less than about 10 Myr) are valuable tools for the acquisition of an unbiased
census of cluster members needed for Initial Mass Function (IMF) studies.
Several dozen YSCs, both nearby and across the Galactic disk, have been
observed with the Chandra and XMM-Newton satellites, detecting >10,000 low-mass
cluster members. Many of these samples should be nearly complete down to about
1 Mo. An important additional benefit is that the YSC X-ray luminosity function
appears to be universal with a lognormal shape, providing a new standard candle
for measurement of YSC distances.


title: Circumstellar discs around solar-mass stars in NGC 6611

abstract:
  We have performed IZJHKL' observations in NGC 6611, the young cluster that
ionises the Eagle Nebula. We have discovered a rich pre-main sequence
concentrated around the O-stars in the cluster. As measured by their L'-band
excesses, at least 58% +/- 5% of the pre-main sequence objects (0.45 Msun < M <
2 Msun) have circumstellar discs. By comparing this disc frequency with
frequencies determined for regions where the pre-main sequence stars are
subject to less ionising radiation, we find no evidence that the harsher
environment of NGC 6611 (approximately an order of magnitude more ionising
Lyman continuum radiation than the Trapezium cluster) significantly hastens the
dissipation of circumstellar discs around solar-mass stars.


title: Geometric model of dark energy

abstract:
  A cosmological model with a gravitational Lagrangian $L_g(R)\propto R+A R^n$
is set up to account for the presently observed re-acceleration of the
universe. The evolution equation for the scale factor $a$ of the universe is
analyzed in detail for the two parameters $n=2$ and $n=4/3$, which were
preferred by previous studies of the early universe. The initial conditions are
specified at a red-shift parameter $z\approx 0$. The fit to the observable data
fixes the free parameter $A$. The analysis shows that the model with $n=2$
agrees better with present data. Then, if we set $w(q)=-1$ at $z=0$,
corresponding to the deceleration parameter $q\approx -1/2$, we find that at
$z\approx 0.5$, $w(q)$ has evolved to $w\approx -0.72$, corresponding to
$q\approx 0$. At $z\approx 1$ we find $w\approx 0$ corresponding to $q\approx
1/2$. These results are compared with the flat Friedmann model with cold matter
and Lambda-term (LCDM model) for the same initial conditions at $z\approx 0$.
The other choice of the model with $n=4/3$ allows for big crunch. However this
possibility is eliminated by the fit of $A$ to the present data.


title: Search for pulsating PMS stars in NGC 6383

abstract:
  A search for pulsating pre-main sequence (PMS) stars was performed in the
young open cluster NGC 6383 using CCD time series photometry in Johnson B & V
filters. With an age of only ~1.7 million years all cluster members later than
spectral type A0 have not reached the ZAMS yet, hence being ideal candidates
for investigating PMS pulsation among A and F type stars. In total 286 stars
have been analyzed using classical Fourier techniques. From about a dozen of
stars within the boundaries of the classical instability strip, two stars were
found to pulsate: NGC 6383 #170, with five frequencies simultaneously, and NGC
6383 #198, with a single frequency. In addition, NGC 6383 #152 is a suspected
PMS variable star, but our data remain inconclusive. Linear, non-adiabatic
models assuming PMS evolutionary phase and purely radial pulsation were
calculated for the two new PMS pulsators. NGC 6383 #170 appears to pulsate
radially in third and fifth overtones, while the other three frequencies seem
to be of non-radial nature. NGC 6383 #198 pulsates monoperiodically, most
probably in the third radial overtone. Magnitudes and B-V colours were
available in the literature for only one third of all stars and we used them
for calibrating the remaining.


title:
A Bayesian view on Faraday rotation maps - Seeing the magnetic power
  spectra in galaxy clusters

abstract:
  We present a Bayesian maximum likelihood analysis of Faraday rotation measure
(RM) maps of extended radio sources to determine magnetic field power spectra
in clusters of galaxies. Using this approach, it is possible to determine the
uncertainties in the measurements. We apply this approach to the RM map of
Hydra A and derive the power spectrum of the cluster magnetic field. For Hydra
A, we measure a spectral index of -5/3 over at least one order of magnitude
implying Kolmogorov type turbulence. We find a dominant scale of about 3 kpc on
which the magnetic power is concentrated, since the magnetic autocorrelation
length is lambda_B = 3 +/- 0.5 kpc. Furthermore, we investigate the influences
of the assumption about the sampling volume (described by a window function) on
the magnetic power spectrum. The central magnetic field strength was determined
to be about 7 +/- 2 muG for the most likely geometries.


title: Kinematics of Nearby Subdwarf Stars

abstract:
  We present an analysis of the space motions of 742 subdwarf stars based on
the sample of Carney et al. (1994, CLLA). Hipparcos parallaxes, TYC2+HIP proper
motions and Tycho2 proper motions were combined with radial velocities and
metallicities from CLLA. The kinematical behavior is discussed in particular in
relation to their metallicities. The majority of these sample stars have metal
abundances of [Fe/H] >-1 and represent the thick disk population. The halo
component, with [Fe/H] <-1.6, is characterized by a low mean rotation velocity
and a radially elongated velocity ellipsoid. In the intermediate metallicity
range (-1.6 < [Fe/H] <-1), we find a significant number of subdwarfs with
disklike kinematics. We interpret this population of stars as a metal-weak
thick disk population.


title: A Study of the Near-Ultraviolet Spectrum of Vega

abstract:
  UV, optical, and near-IR spectra of Vega have been combined to test our
understanding of stellar atmospheric opacities, and to examine the possibility
of constraining chemical abundances from low-resolution UV fluxes. We have
carried out a detailed analysis assuming Local Thermodynamic Equilibrium (LTE)
to identify the most important contributors to the UV continuous opacity: H,
H$^{-}$, C I, and Si II. Our analysis also assumes that Vega is spherically
symmetric and its atmosphere is well described with the plane parallel
approximation. Comparing observations and computed fluxes we have been able to
discriminate between two different flux scales that have been proposed, the
IUE-INES and the HST scales, favoring the latter. The effective temperature and
angular diameter derived from the analysis of observed optical and near-UV
spectra are in very good agreement with previous determinations based on
different techniques. The silicon abundance is poorly constrained by the UV
observations of the continuum and strong lines, but the situation is more
favorable for carbon and the abundances inferred from the UV continuum and
optical absorption lines are in good agreement. Some spectral intervals in the
UV spectrum of Vega that the calculations do not reproduce well are likely
affected by deviations from LTE, but we conclude that our understanding of UV
atmospheric opacities is fairly complete for early A-type stars.


title: The merging cluster Abell 85 caught between meals by XMM-Newton

abstract:
  Our XMM-Newton observations of Abell 85 confirm the extended 4 Mpc filament
first detected with ROSAT, which has an X-ray temperature of about 2 keV and is
probably made of groups falling on to the cluster. A comparison of the
temperature map with numerical simulations show that Abell 85 had intense
merging activity in the past and is not fully relaxed, even in the central
region. Finally, a deprojected temperature profile has been calculated and
used, together with the suface brightness, to estimate the entropy and pressure
profiles. Abell 85 only presents a mild flattening of the entropy profile in
the center, showing no evidence of an ``entropy floor''.


title: X-ray variability, viscous time scale and Lindblad resonances in LMXBs

abstract:
  Based on RXTE/ASM and EXOSAT/ME data we studied X-ray variability of
persistent LMXBs in the 1e-8 - 1e-1 Hz frequency range, aiming to detect
features in their power density spectra (PDS) associated with the viscous time
scale of the accretion disk tvisc. As this is the longest intrinsic time scale
of the disk, the power density of its Mdot variations is expected to be
independent on the frequency at f<1/tvisc. Indeed, in the PDS of 11 sources out
of 12 we found very low frequency break, below which the spectra are nearly
flat. At higher frequencies they approximately follow the Pnu ~ nu^{-1.3} law.
  The break frequency correlates very well with the binary orbital frequency in
a broad range of binary periods Porb ~ 12 min - 33.5 days, in accord with
theoretical expectations for the viscous time scale of the disk. However, the
value of fbreak/forb is at least by an order of magnitude larger than predicted
by the standard disk theory. This suggests that a significant fraction of the
accretion Mdot occurs through the optically thin and hot coronal flow with the
aspect ratio of H/R>0.1 The predicted parameters of this flow, T ~ 1e4-1e6 K
and Ne ~ 1e12-1e15 cm^-3, are in qualitative agreement with recent Chandra and
XMM-Newton observations of complex absorption/emission features in the spectra
of LMXBs with high inclination angle.
  We find a clear dichotomy in the value of tvisc/Porb between wide and compact
systems, the compact systems having ~10 times shorter viscous time. The
boundary lies at the mass ratio q ~ 0.3, suggesting that this dichotomy is
caused by the excitation of the 3:1 inner Lindblad resonance in low-q LMXBs.


title:
Analysis of historical meteor and meteor shower records: Korea, China,
  and Japan

abstract:
  We have compiled and analyzed historical Korean meteor and meteor shower
records in three Korean official history books, Samguksagi which covers the
three Kingdoms period (57 B.C -- A.D. 935), Goryeosa of Goryeo dynasty (A.D.
918 -- 1392), and Joseonwangjosillok of Joseon dynasty (A.D. 1392 -- 1910). We
have found 3861 meteor and 31 meteor shower records. We have confirmed the
peaks of Perseids and an excess due to the mixture of Orionids, north-Taurids,
or Leonids through the Monte-Carlo test. The peaks persist from the period of
Goryeo dynasty to that of Joseon dynasty, for almost one thousand years. Korean
records show a decrease of Perseids activity and an increase of
Orionids/north-Taurids/Leonids activity. We have also analyzed seasonal
variation of sporadic meteors from Korean records. We confirm the seasonal
variation of sporadic meteors from the records of Joseon dynasty with the
maximum number of events being roughly 1.7 times the minimum. The Korean
records are compared with Chinese and Japanese records for the same periods.
Major features in Chinese meteor shower records are quite consistent with those
of Korean records, particularly for the last millennium. Japanese records also
show Perseids feature and Orionids/north-Taurids/Leonids feature, although they
are less prominent compared to those of Korean or Chinese records.


title: Reconstruction of primordial density fields

abstract:
  The Monge-Ampere-Kantorovich (MAK) reconstruction is tested against
cosmological N-body simulations. Using only the present mass distribution
sampled with particles, and the assumption of homogeneity of the primordial
distribution, MAK recovers for each particle the non-linear displacement field
between its present position and its Lagrangian position on a primordial
uniform grid. To test the method, we examine a standard LCDM N-body simulation
with Gaussian initial conditions and 6 models with non-Gaussian initial
conditions: a chi-squared model, a model with primordial voids and four weakly
non-Gaussian models. Our extensive analyses of the Gaussian simulation show
that the level of accuracy of the reconstruction of the nonlinear displacement
field achieved by MAK is unprecedented, at scales as small as about 3 Mpc. In
particular, it captures in a nontrivial way the nonlinear contribution from
gravitational instability, well beyond the Zel'dovich approximation. This is
also confirmed by our analyses of the non-Gaussian samples. Applying the
spherical collapse model to the probability distribution function of the
divergence of the displacement field, we also show that from a
well-reconstructed displacement field, such as that given by MAK, it is
possible to accurately disentangle dynamical contributions induced by
gravitational clustering from possible initial non-Gaussianities, allowing one
to efficiently test the non-Gaussian nature of the primordial fluctuations. In
addition, a simple application of MAK using the Zel'dovich approximation allows
one to also recover accurately the present-day peculiar velocity field on
scales of about 8 Mpc.