title: Evidence for a Massive Post-Starburst Galaxy at z ~ 6.5

abstract:
  We present results from a search for high-redshift J--band ``dropout''
galaxies in the portion of the GOODS southern field that is covered by
extremely deep imaging from the Hubble Ultradeep Field (HUDF).Using
observations at optical, near-infrared and mid-infrared wavelengths from the
Hubble and Spitzer Space Telescopes and the ESO-VLT, we search for very massive
galaxies at high redshifts and find one particularly remarkable candidate. Its
spectral energy distribution is consistent with a galaxy at z ~ 6.5 and a
stellar mass of 6x10e11 M(sun) (for a Salpeter IMF). We interpret a prominent
photometric break between the near-infrared and Spitzer bandpasses as the 3646A
Balmer discontinuity. The best-fitting models have low reddening and ages of
several hundred Myr, placing the formation of the bulk of the stars at z > 9.
Alternative models of dusty galaxies at z ~ 2.5 are possible but provide
significantly poorer fits. The object is detected with Spitzer at 24 micron.
This emission originats from an obscured active nucleus or star formation. We
present optical and near-infrared spectroscopy which has, thus far, failed to
detect any spectral features. This helps limit the solution in which the galaxy
is a starburst or active galaxy at z ~ 2.5. If the high-redshift interpretation
is correct, this object would be an example of a galaxy that formed by a
process strongly resembling traditional models of monolithic collapse, in a way
which a very large mass of stars formed within a remarkably short period of
time, at very high redshift.


title: Search for a Shock Wave around the Crab Nebula

abstract:
  We have searched the region surrounding the Crab Nebula for the existence of
a shock wave with the imaging instruments of the Einstein Observatory. The
search is complicated by the scattering of nebula and pulsar X-rays from the
imperfectly polished surfaces of the telescope mirror, as well as from
interstellar grains along the line of sight. Both of these effects lead to the
appearance of X-ray emission, in the form of an X-ray halo, beyond the
boundaries of the nebula filaments.
  We show that the size, shape, and intensity of the halo around the Crab
Nebula, above the contribution of mirror scattering, is consistent with what is
expected from the scattering from interstellar grains. The upper limit on the
X-ray emission from a shock wave is about 1% of the total 0.5-4 keV luminosity
of the Crab or about 2E35 erg/s (assuming a distance of 2.2 kpc). This figure
applies to a shell whose angular radius is 9 arcminutes. The upper limit is
smaller (larger) for a shell of larger (smaller) size. This upper limit is an
order of magnitude or more below the flux of Cas A, Tycho, and Kepler SNRs,
which are 2 to 3 times younger, but it is still above that of SN 1006.


title:
HI Detection in two Dwarf S0 Galaxies in Nearby Groups: ESO384-016 and
  NGC 59

abstract:
  An \hi survey of 10 dE/dS0 galaxies in the nearby Sculptor and Centaurus A
groups was made using the Australia Telescope Compact Array (ATCA). The
observed galaxies have accurate distances derived by Jerjen et al (1998; 2000b)
using the surface brightness fluctuation technique. Their absolute magnitudes
are in the range $-9.5 > M_B > -15.3$. Only two of the ten galaxies were
detected at our detection limit ($\sim 1.0 \times 10^6$ \msol for the Centaurus
group and $\sim 5.3 \times 10^5$ \msol for the Sculptor group), the two dS0
galaxies ESO384-016 in the Centaurus A Group and NGC 59 in the Sculptor Group,
with \hi masses of $6.0 \pm 0.5 \times 10^6$ \msol and $1.4 \pm 0.1 \times
10^7$ \msol respectively. Those two detections were confirmed using the Green
Bank Telescope. These small \hi reservoirs could fuel future generations of low
level star formation and could explain the bluer colors seen at the center of
the detected galaxies. Similarly to what is seen with the Virgo dEs, the two
objects with \hi appear to be on the outskirt of the groups.


title:
Submillimeter Array 440$\mu$m/690GHz line and continuum observations of
  Orion-KL

abstract:
  Submillimeter Array observations of Orion-KL at 1'' resolution in the
440mu/690GHz band reveal new insights about the continuum and line emission of
the region. The 440mu continuum flux density measurement from source I allows
us to differentiate among the various proposed physical models: Source I can be
well modeled by a ``normal'' protostellar SED consisting of a proton-electron
free-free emission component at low frequencies and a strong dust component in
the submillimeter bands. Furthermore, we find that the protostellar object SMA1
is clearly distinct from the hot core. The non-detection of SMA1 at cm and
infrared wavelengths suggests that it may be one of the youngest sources in the
entire Orion-KL region. The molecular line maps show emission mainly from the
sources I, SMA1 and the hot core peak position. An analysis of the
CH$3CN(37_K-36_K) K-ladder (K=0...3) indicates a warm gas component of the
order 600+-200K. In addition, we detect a large fraction (~58%) of unidentified
lines and discuss the difficulties of line identifications at these
frequencies.


title:
New Candidate EHB Stars in the Open Cluster NGC 6791: Looking Locally
  into the UV-upturn Phenomenon

abstract:
  Relying on U,B imagery at the Italian Telescopio Nazionale Galileo (TNG), we
report here the discovery of a sample of 13 new UV-bright post-HB candidate
stars in the field of the galactic open cluster NGC 6791. Owing to its
super-solar metal content ([Fe/H]>0.2 dex) and estimated age (t> 8 Gyr), this
cluster represents the nearest and ideal stellar aggregate to match the
distinctive properties of the evolved stellar populations possibly ruling the
UV-upturn phenomenon in elliptical galaxies and bulges of spirals.
  Our ongoing spectroscopic follow-up of this unique UV-bright sample will
allow us to assess - once cluster membership of the candidates is properly
checked - the real nature (e.g. SdB, SdO, AGB-manque' or EHB stars) of these
hot sources, and their link with the ultraviolet excess emerging from low-mass,
metal-rich evolutionary environments of external galaxies.


title: Cool Gas and Massive Stars - the Nuclear Ring in M100

abstract:
  The SAURON integral field spectrograph was used to observe the central area
of the barred spiral galaxy M100 (NGC 4321). M100 contains a nuclear ring of
star formation, fueled by gas channeled inward by the galaxy's bar. We present
maps of emission line strengths, absorption line strength indices, and the gas
velocity dispersion across the field. The H beta emission is strongest in the
ring, along two curved bar dustlanes and at the ends of the bar. The Mg b
absorption line strength shows a younger population of stars within the ring as
compared to the surrounding area. The gas velocity dispersion is notably
smaller than elsewhere in the field both in the ring and along the leading edge
of the dustlanes. Low gas dispersion is correlated spatially with the H beta
emission. We thus see stars being formed from cold (low dispersion) gas which
is being channeled inward along the dustlanes under the influence of a large
bar, and accumulated into a ring near the location of the inner Lindblad
resonances. This lends further strong support to the interpretation of nuclear
rings in barred galaxies as resonance phenomena.


title: A cosmological test for general relativity

abstract:
  The effect of spatial variations of the Newton constant on the cosmic
microwave background is studied. Constraints on the strong equivalence
principle violation at the recombination time are then obtained with the help
of WMAP data and of the standard theory of big-bang nucleosynthesis.


title:
Scattering of Polarized Radiation by Atoms in Magnetic and Electric
  Fields

abstract:
  The polarization of radiation by scattering on an atom embedded in combined
external quadrupole electric and uniform magnetic fields is studied
theoretically. Analytic formulae are derived for the scattering phase matrix.
Limiting cases of scattering under Zeeman effect, and Hanle effect in weak
magnetic fields are discussed.


title:
Improved Correlation between the Variability and Peak Luminosity of
  Gamma-Ray Bursts

abstract:
  A new procedure for smoothing a gamma-ray burst (GRB) lightcurve and
calculating its variability is presented. Applying the procedure to a sample of
25 long GRBs, we have obtained a very tight correlation between the variability
and the peak luminosity. The only significant outlier in the sample is GRB
030329. With this outlier excluded, the data scatter is reduced by a factor of
\sim 3 compared to that of Guidorzi et al. (2005), measured by the deviation of
fit. Possible causes for the outlier are discussed.


title: Composition, collimation, contamination: the jet of Cygnus X-1

abstract:
  We model the observed size and brightness of the VLBA radio core of the jet
in Cygnus X-1 to derive an expression for the jet power as a function of basic
jet parameters. We apply this expression to recent constraints on the jet power
from observations of a large scale shocked shell around the source by Gallo et
al. 2005, which leads us to a set of alternative conclusions: either (a) the
jet contains large amounts of protons: more than 2000 protons per radio
emitting electron, (b) it has a very low radio volume filling factor of f <
3x10^(-5), (c) the steady, radio emitting VLBA jet is not the source of the
kinetic energy powering the ISM shell, or (d) its asymptotic behavior differs
fundamentally from a broad set of plausible analytic jet models.


title: Diffusion and pulsations in slowly rotating B stars

abstract:
  Diffusion in cool B stars of the main sequence has been shown to strongly
affect opacities and convection in cool B stars of the main sequence. We show
here that diffusion in B stars maintains or enhances the excitation of
pulsations in these stars. This result conflicts with observations as cool B
stars that show evidence of diffusion, the HgMn stars, are stable to the
current detection level. We discuss possible implications of this discrepancy
for the models.


title:
Predictions and Strategies for Integral-Field Spectroscopy of
  High-Redshift Galaxies

abstract:
  We investigate the ability of infrared integral-field spectrographs to map
the velocity fields of high redshift galaxies, presenting a formalism which may
be applied to any telescope and imaging spectrograph system. We discuss the
5-sigma limiting line fluxes which current integral-field spectrographs will
reach, and extend this discussion to consider future large aperture telescopes
with cryogenically cooled adaptive reimaging optics. In particular, we simulate
observations of spectral line emission from star-forming regions at redshifts z
= 0.5 to 2.5 using a variety of spatial sampling scales and give predictions
for the signal-to-noise ratio expected as a function of redshift. Using values
characteristic of the W.M. Keck II telescope and the new OH-Suppressing
InfraRed Imaging Spectrograph (OSIRIS) we calculate integral-field
signal-to-noise ratio maps for a sample of U_nGR color-selected star-forming
galaxies at redshift z ~ 2 - 2.6 and demonstrate that OSIRIS will be able to
reconstruct the two-dimensional projected velocity fields of these galaxies on
scales of 100 mas (~ 1 kpc at redshift z ~ 2). With signal-to-noise ratios per
spatial sample up to ~ 20, OSIRIS will in some cases be able to distinguish
between merger activity and ordered disk rotation. Structures on scales smaller
than 1 kpc may be detected by OSIRIS for particularly bright sources, and will
be easy targets for future 30m class telescopes.


title:
Probing Reionization with the Cosmological Proximity Effect and
  High-Redshift Supernovae Rates

abstract:
  We develop and assess the potential of several powerful techniques, designed
to investigate the details of reionization. First, we present a procedure to
probe the neutral fraction, x_HI, using the Lyman alpha transmission statistics
of high-redshift (z > 6) sources. We find that only tens of bright quasar
spectra could distinguish between x_HI ~ 1 and x_HI < 0.01. A rudimentary
application of such a technique on quasar SDSS J1030+0524 has yielded
compelling evidence of a large neutral fraction (x_HI > 0.2) at z ~ 6. We also
generate the observable, high-z supernovae (SNe) rates and quantify the
prospects of detecting the suppression of star-formation in low-mass galaxies
at reionization from such SNe rates, specifically from those obtainable from
the James Webb Space Telescope (JWST). Our analysis suggests that searches for
SNe could yield thousands of SNe per unit redshift at z ~ 6, and be a valuable
tool at studying reionization features and feedback effects out to z < 13.


title: Chandra Multiwavelength Plane (ChaMPlane) Survey: an Introduction

abstract:
  We introduce the Chandra Multiwavelength Plane (ChaMPlane) Survey, designed
to measure or constrain the populations of low-luminosity (Lx > ~10^31 erg/s)
accreting white dwarfs, neutron stars and stellar mass black holes in the
Galactic Plane and Bulge. ChaMPlane incorporates two surveys, X-ray (Chandra)
and optical (NOAO 4m-Mosaic imaging), and a followup spectroscopy and IR
identification program. The survey has now extended through the first 6 years
of Chandra data using serendipitous sources detected in 105 distinct ACIS-I and
-S fields observed in 154 pointings and covered by 65 deep Mosaic images in V,
R, I, and H-alpha. ChaMPlane incorporates fields with galactic latitude |b| <~
12 deg and selected to be devoid of bright point or diffuse sources, with
exposure time > ~20 ksec, and (where possible) minimum NH. We describe the
scientific goals and introduce the X-ray and optical/IR processing and
databases. We derive preliminary constraints on the space density or luminosity
function of cataclysmic variables from the X-ray/optical data for 14 fields in
the Galactic Anticenter. The lack of ChaMPlane CVs in these Anticenter fields
suggests their space density is ~ 3x below the value (3 x 10^-5 pc^-3) found
for the solar neighborhood by previous X-ray surveys. Companion papers describe
the X-ray and optical processing in detail, optical spectroscopy of ChaMPlane
sources in selected Anticenter fields and IR imaging results for the Galactic
Center field. An Appendix introduces the ChaMPlane Virtual Observatory (VO) for
online access to the X-ray and optical images and source catalogs for ready
display and further analysis.


title:
X-ray Processing of ChaMPlane Fields: Methods and Initial Results for
  Selected Anti-Galactic Center Fields

abstract:
  We describe the X-ray analysis procedure of the on-going Chandra
Multiwavelength Plane (ChaMPlane) survey and report the initial results from
the analysis of 15 selected anti-Galactic center observations (90 deg < l < 270
deg). We describe the X-ray analysis procedures for ChaMPlane using
custom-developed analysis tools appropriate for Galactic sources but also of
general use: optimum photometry in crowded fields using advanced techniques for
overlapping sources, rigorous astrometry and 95% error circles for combining
X-ray images or matching to optical/IR images, and application of quantile
analysis for spectral analysis of faint sources. We apply these techniques to
15 anti-Galactic center observations (of 14 distinct fields) in which we have
detected 921 X-ray point sources. We present logN-logS distributions and
quantile analysis to show that in the hard band (2 - 8 keV) active galactic
nuclei dominate the sources. Complete analysis of all ChaMPlane anti-Galactic
center fields will be given in a subsequent paper, followed by papers on
sources in the Galactic center and Bulge regions.


title: Constraining the Nature of the Galactic Center X-ray Source Population

abstract:
  We searched for infrared counterparts to the cluster of X-ray point sources
discovered by Chandra in the Galactic Center Region (GCR). While the sources
could be white dwarfs, neutron stars, or black holes accreting from stellar
companions, their X-ray properties are consistent with magnetic Cataclysmic
Variables, or High Mass X-ray Binaries (HMXB) at low accretion-rates. A direct
way to decide between these possibilities and hence between alternative
formation scenarios is to measure or constrain the luminosity distribution of
the companions. Using infrared (J, H, K, Br-gamma) imaging, we searched for
counterparts corresponding to typical HMXB secondaries: spectral type B0V with
K<15 at the GCR. We found no significant excess of bright stars in Chandra
error circles, indicating that HMXBs are not the dominant X-ray source
population, and account for fewer than 10% of the hardest X-ray sources.


title:
Imprint of Inhomogeneous Reionization on the Power Spectrum of Galaxy
  Surveys at High Redshifts

abstract:
  We consider the effects of inhomogeneous reionization on the distribution of
galaxies at high redshifts. Modulation of the formation process of the ionizing
sources by large scale density modes makes reionization inhomogeneous and
introduces a spread to the reionization times of different regions with the
same size. After sources photo-ionize and heat these regions to a temperature
$\ga 10^4$K at different times, their temperatures evolve as the ionized
intergalactic medium (IGM) expands. The varying IGM temperature makes the
minimum mass of galaxies spatially non-uniform with a fluctuation amplitude
that increases towards small scales. These scale-dependent fluctuations modify
the shape of the power spectrum of low-mass galaxies at high redshifts in a way
that depends on the history of reionization. The resulting distortion of the
primordial power spectrum is significantly larger than changes associated with
uncertainties in the inflationary parameters, such as the spectral index of the
scalar power spectrum or the running of the spectral index. Future surveys of
high-redshift galaxies will offer a new probe of the thermal history of the IGM
but might have a more limited scope in constraining inflation.


title: ChaMPlane Optical Survey: Mosaic Photometry

abstract:
  The ChaMPlane survey to identify and analyze the serendipitous X-ray sources
in deep Galactic plane fields incorporates the ChaMPlane Optical Survey, which
is one of NOAO's Long-term Survey Programs. We started this optical imaging
survey in March 2000 and completed it in June 2005. Using the NOAO 4-m
telescopes with the Mosaic cameras at CTIO and KPNO, deep images of the
ChaMPlane fields are obtained in V, R, I and H-alpha bands. This paper
describes the process of observation, data reduction and analysis of fields
included in the ChaMPlane Optical Survey, and describes the search for H-alpha
emission objects and Chandra optical counterparts. We illustrate these
procedures using the ChaMPlane field for the black hole X-ray binary GRO
J0422+32 as an example.


title:
Spitzer Space Telescope detection of the young supernova remnant 1E
  0102.2-7219

abstract:
  We present infrared observations of the young, oxygen-rich supernova remnant
1E 0102.2-7219 (E0102) in the Small Magellanic Cloud, obtained with the Spitzer
Space Telescope. The remnant is detected at 24 um but not at 8 or 70 um and has
a filled morphology with two prominent filaments. We find evidence for the
existence of up to 8x10^-4 Msolar of hot dust (T~120 K) associated with the
remnant. Most of the hot dust is located in the central region of E0102 which
appears significantly enhanced in infrared and radio continuum emission
relative to the X--ray emission. Even if all of the hot dust was formed in the
explosion of E0102, the estimated mass of dust is at least 100 times lower that
what is predicted by some recent theoretical models.


title: Gravitational Wave Background from Neutrino-Driven Gamma-Ray Bursts

abstract:
  We discuss the gravitational wave background (GWB) from a cosmological
population of gamma-ray bursts (GRBs). Among various emission mechanisms for
the gravitational waves (GWs), we pay a particular attention to the vast
anisotropic neutrino emissions from the accretion disk around the black hole
formed after the so-called failed supernova explosions. The produced GWs by
such mechanism are known as burst with memory, which could dominate over the
low-frequency regime below \sim 10Hz. To estimate their amplitudes, we derive
general analytic formulae for gravitational waveform from the axisymmetric
jets. Based on the formulae, we first quantify the spectrum of GWs from a
single GRB. Then, summing up its cosmological population, we find that the
resultant value of the density parameter becomes roughly \Omega_{GW} \approx
10^{-20} over the wide-band of the low-frequency region, f\sim 10^{-4}-10^1Hz.
The amplitude of GWB is sufficiently smaller than the primordial GWBs
originated from an inflationary epoch and far below the detection limit.


title:
Enrichment of Very Metal-Poor Stars with Both r-Process and s-Process
  Elements from 8-10 M_\odot Stars

abstract:
  Recent spectroscopic studies have revealed the presence of numerous
carbon-enhanced, metal-poor stars with [Fe/H] < -2.0 that exhibit strong
enhancements of s-process elements. These stars are believed to be the result
of a binary mass-transfer episode from a former asymptotic giant-branch (AGB)
companion that underwent s-process nucleosynthesis. However, several such stars
exhibit significantly lower Ba/Eu ratios than solar s-process abundances. This
might be explained if there were an additional contribution from the r-process,
thereby diluting the Ba/Eu ratio by extra production of Eu. We propose a model
in which the double enhancements of r-process and s-process elements originate
from a former 8-10 M_\odot companion in a wide binary system, which may undergo
s-processing during an AGB phase, followed by r-processing during its
subsequent supernova explosion. The mass of Eu (as representative of r-process
elements) captured by the secondary through the wind from the supernova is
estimated, which is assumed to be proportional to the geometric fraction of the
secondary (low-mass, main-sequence) star with respect to the primary
(exploding) star. We find that the estimated mass is in good agreement with a
constraint on the Eu yield per supernova event obtained from a Galactic
chemical evolution study, when the initial orbital separation is taken to be
\sim 1 year. If one assumes an orbital period on the order of five years, the
efficiency of wind pollution from the supernova must be enhanced by a factor of
\sim 10. This may, in fact, be realized if the expansion velocity of the
supernova's innermost ejecta, in which the r-process has taken place, is
significantly slow, resulting in an enhancement of accretion efficiency by
gravitational focusing.


title:
Relativistic Gross-Pitaevskii equation and the cosmological Bose
  Einstein Condensation

abstract:
  We do not know 96% of the total matter in the universe at present. In this
paper, a cosmological model is proposed in which Dark Energy (DE) is identified
as Bose-Einstein Condensation (BEC) of some boson field. Global cosmic
acceleration caused by this BEC and multiple rapid collapses of BEC into black
holes etc. (=Dark Matter (DM)) are examined based on the relativistic version
of the Gross-Pitaevskii equation. We propose (a) a novel mechanism of inflation
free from the slow-rolling condition, (b) a natural solution for the cosmic
coincidence ('Why Now?') problem through the transition from DE into DM, (c)
very early formation of highly non-linear objects such as black holes, which
might trigger the first light as a form of quasars, and (d) log-z periodicity
in the subsequent BEC collapsing time. All of these are based on the steady
slow BEC process.


title: Observational Constraints on Variable Chaplygin Gas

abstract:
  We investigate observational constraints on the variable Chaplygin gas model
from the gold sample of type Ia supernova data and the recent measurements of
the X-ray gas mass fractions in galaxy clusters. Combining these databases, we
obtain a tight constraint on the two model parameters. Our results indicate
that the original Chaplygin gas model is ruled out by the data at 99.7%
confidence level.


title: EUVE Observations of VW Hydri in Superoutburst

abstract:
  EUVE observed the SU UMa-type dwarf nova VW Hydri in superoutburst for an
interval of nearly 2 days in 1994 June and produced EUV light curves and the
first EUV spectrum of this important CV.


title: Downsizing Scaling Relations

abstract:
  Faber-Jackson and Tully-Fisher scaling relations for elliptical and spiral
galaxy samples up to z=1 provide evidence for a differential behaviour of
galaxy evolution with mass. In compliance with the downsizing scenario, the
stellar populations of less massive galaxies display a stronger evolution than
the more massive ones. For spirals, this may be attributed to a suppressed star
formation efficiency in small dark matter halos. For ellipticals, star
formation must have been negligible at least during the past ~4Gyr in all
environments.


title: Conservation of nonlinear curvature perturbations on super-Hubble scales

abstract:
  We consider general, non-linear curvature perturbations on scales greater
than the Hubble horizon scale by invoking an expansion in spatial gradients,
the so-called gradient expansion. After reviewing the basic properties of the
gradient expansion, we derive the conservation law for non-linear curvature
perturbations for an isentropic fluid. We also define the gauge-invariant
curvature perturbation under a finite shift of time-slicing, and derive the
non-linear genralization of the $\delta N$ formalism. The results obtained are
straight-forward generalisations of those already proven in linear perturbation
theory, and the equations are simple, resembling closely the first-order
equations.


title: A Search for PNe in Nearby Galaxies with SDSS Imaging Data

abstract:
  We present the latest results from our project to search for new planetary
nebulae in nearby galaxies using Sloan Digital Sky Survey (SDSS) imaging data.
Our method is based on photometric criteria and can be applied to galaxies
where PNe appear as point sources. We applied these criteria to the whole area
of M31 as scanned by SDSS, detecting 130 new PN candidates and 30 known PNe.
All selected PNe candidates are located in the outer regions of M31. For 85
candidates follow-up spectroscopy was obtained with the 2.2m telescope at Calar
Alto Observatory. The observations show that our method has a detection
efficiency of about 82%. We discuss the 2D velocity field of the outer part of
M31 based on our observed PN data. The PNe suggest an exponential disk scale
length of 13 kpc along the minor axis. We discovered two PNe along the line of
sight to Andromeda NE, a very low surface brightness giant stellar structure in
the outer halo of M31. These two PNe are located at projected distances of ~48
kpc and ~41 kpc from the center of M31 and are the most distant PNe in M31
found up to now. Our data support the idea that Andromeda NE is located at the
distance of M31. No PNe associated with other M31 satellites observed by the
SDSS were found. Applying our method to other SDSS regions we checked data for
the Local Group galaxies Sextans, Draco, Leo I, Pegasus, Sextans B and Leo A
and recovered a known PN in Leo A. We re-measured its O/H and for the first
time determined abundances of N/H, S/H, He/H as well as the electron number
density Ne. We argue that the PN progenitor was formed ~1.5 Gyr ago during the
strongest episode of star formation in Leo A.


title:
A Hubble Space Telescope ACS Search for Brown Dwarf Binaries in the
  Pleiades Open Cluster

abstract:
  We present the results of a high-resolution imaging survey for brown dwarf
binaries in the Pleiades open cluster. The observations were carried out with
the Advance Camera for Surveys onboard the Hubble Space Telescope. Our sample
consists of 15 bona-fide brown dwarfs. We confirm 2 binaries and detect their
orbital motion, but we did not resolve any new binary candidates in the
separation range between 5.4AU and 1700AU and masses in the range
0.035--0.065~Msun. Together with the results of our previous study (Martin et
al., 2003), we can derive a visual binary frequency of 13.3$^{+13.7}_{-4.3}$\%
for separations greater than 7~AU masses between 0.055--0.065~M$_{\sun}$ and
mass ratios between 0.45--0.9$<q<$1.0. The other observed properties of
Pleiades brown dwarf binaries (distributions of separation and mass ratio)
appear to be similar to their older counterparts in the field.


title:
A variable Quasi-Periodic Ocillation in M82 X-1. Timing and spectral
  analysis of XMM-Newton and RossiXTE observations

abstract:
  We report results from a spectral and timing analysis of M82 X-1, one of the
brightest known ultraluminous X-ray sources. Data from a new 105 ks {\it
XMM-Newton} observation of M82 X-1, performed in April 2004, and of archival
{\it RossiXTE} observations are presented. A very soft thermal component is
present in the {\it XMM} spectrum. Although it is not possible to rule out a
residual contamination from the host galaxy, modelling it with a standard
accretion disk would imply a black hole mass of $\approx 10^3 M_{\odot}$. An
emission line was also detected at an energy typical for fluorescent Fe
emission. The power density spectrum of the {\it XMM} observation shows a
variable QPO at frequency of 113 mHz with properties similar to that discovered
by Strohmayer & Mushotzky (2003). The QPO was also found in 7 archival {\it
RXTE} observations, that include those analyzed by Strohmayer & Mushotzky
(2003) and Fiorito & Titarchuk (2004). A comparison of the properties of this
QPO with those of the various types of QPOs observed in Galactic black hole
candidates strongly suggests an association with the type-C, low frequency
QPOs. Scaling the frequency inversely to the black hole mass, the observed QPO
frequency range (from 50 to 166 mHz) would yield a black hole mass anywhere in
the interval few tens to 1000 $M_\odot$.


title:
Cluster AgeS Experiment (CASE): Dwarf Novae and a Probable Microlensing
  Event in the Globular Cluster M22

abstract:
  We report the identification of a new cataclysmic variable (denoted as CV2)
and a probable microlensing event in the field of the globular cluster M22. Two
outbursts were observed for CV2. During one of them superhumps with
P_sh=0.08875 d were present in the light curve. CV2 has an X-ray counterpart
detected by XMM-Newton. A very likely microlensing event at a radius of 2.3
arcmin from the cluster center was detected. It had an amplitude of
Delta_V=0.75 mag and a characteristic time of 15.9 days. Based on model
considerations we show that the most likely configuration has the source in the
Galactic bulge with the lens in the cluster. Two outbursts were observed for
the already known dwarf nova CV1.


title: Review on low-mass stars and brown dwarfs

abstract:
  In this review, we examine the successes and weaknesses of modern low-mass
star and brown dwarf theory.(1) We first focus on the mechanical (equation of
state) and thermal (atmosphere) properties and on the evolution. We then
examine the current shortcomings of the theory and we discuss recent
observational analysis which have suggested discrepancies between models and
observations.(2) We then examine the stellar and brown dwarf IMF and suggest
that a power-law above the average thermal Jeans mass (about 1 Msol) rolling
over a lognormal form below this limit adequately reproduces the observations
of field and young cluster stellar and brown dwarf distributions. This yields a
reasonably accurate estimate of the stellar and brown dwarf Galactic census.
Finally (3) we argue that the combination of turbulence driven fragmentation at
large scale and gravity at small scales provides an appealing solution for the
general star and brown dwarf formation mechanism. It also provides a physical
ground for the aforementioned power-law + lognormal form for the IMF, whereas a
series of different power laws lacks such a physical motivation. At last, we
argue that the deuterium-burning limit as the distinction between stars and
planets has no physical foundation in this modern star formation scheme.
Opacity limited fragmentation extending down to a few (< 10) jupiter masses,
due to shocks, anisotropy or magnetic fields, provides a much more robust
limit, even though difficult to determine accurately. Therefore, the various
"direct" detections of exoplanets claimed recently in the literature are most
likely regular low-mass brown dwarfs and the direct detection of an extrasolar
planet remains for now elusive.


title: A universal density slope - velocity anisotropy relation

abstract:
  One can solve the Jeans equation analytically for equilibrated dark matter
structures, once given two pieces of input from numerical simulations. These
inputs are 1) a connection between phase-space density and radius, and 2) a
connection between velocity anisotropy and density slope, the \alpha-\beta
relation. The first (phase-space density v.s. radius) has been analysed through
several different simulations, however the second (\alpha-\beta relation) has
not been quantified yet. We perform a large set of numerical experiments in
order to quantify the slope and zero-point of the \alpha-\beta relation. When
combined with the assumption of phase-space being a power-law in radius this
allows us to conclude that equilibrated dark matter structures indeed have zero
central velocity anisotropy, central density slope of \alpha_0 = -0.8, and
outer anisotropy of approximately \beta_\infinity = 0.5.


title: Conceptual Problems of the Standard Cosmological Model

abstract:
  The physics of the expansion of the universe is still a poorly studied
subject of the standard cosmological model. This because the concept of
expanding space can not be tested in the laboratory and because ``expansion''
means continuous creation of space, something that leads to several paradoxes.
We re-consider and expand here the discussion of conceptual problems, already
noted in the literature, linked to the expansion of space. In particular we
discuss the problem of the violation of energy conservation for local comoving
volumes, the exact Newtonian form of the Friedmann equations, the receding
velocity of galaxies being greater than the speed of light, and the Hubble law
inside inhomogeneous galaxy distribution. Recent discussion by Kiang, Davis \&
Lineweaver, and Whiting of the non-Doppler nature of the Lemaitre cosmological
redshift in the standard model is just a particular consequence of the
paradoxes mentioned above. The common cause of these paradoxes is the
geometrical description of gravity (general relativity), where there is not a
well defined concept of the energy-momentum tensor for the gravitational field
and hence no energy-momentum conservation for matter plus gravity.


title: On the most metal-poor PN and its binary central star

abstract:
  PN G135.9+55.9 is the most metal-poor PN known in our Galaxy. The central
star resides in a short-period binary system with a compact component, probably
a white dwarf. We describe new observations, which allowed us to determine the
orbital period. The lower limit for the combined mass of both stars is close to
the Chandrasekhar limit for white dwarfs, making this binary a possible
progenitor of a supernova type Ia. The binary system must have recently emerged
from a common envelope phase.


title:
XMM-Newton and optical follow-up observations of SDSS
  J093249.57+472523.0 and SDSS J102347.67+003841.2

abstract:
  We report follow-up XMM-Newton and ground-based optical observations of the
unusual X-ray binary SDSS J102347.67+003841.2 (=FIRST J102347.6+003841), and a
new candidate intermediate polar found in the Sloan Digital Sky Survey: SDSS
J093249.57+472523.0. SDSS J1023 was observed in its low-state, with similar
magnitude/color (V=17.4 and B=17.9), and smooth orbital modulation as seen in
most previous observations. We further refine the ephemeris (for photometric
minimum) to: HJD(TT)_min= 2453081.8546(3) + E* 0.198094(1) d. It is easily
detected in X-rays at an unabsorbed flux (0.01-10.0 keV) of 5x10e-13
erg/cm^2/s. Fitting a variety of models we find that: (i) either a hot (kT>~15
keV) optically thin plasma emission model (bremsstrahlung or MEKAL) or a simple
power law can provide adequate fits to the data; (ii) these models prefer a low
column density ~10e19 cm^-2; (iii) a neutron star atmosphere plus power law
model (as found for quiescent low-mass X-ray binaries) can also produce a good
fit (for plausible distances), though only for a much higher column of about
4x10e20 cm^-2 and a very cool atmosphere kT<~50eV. These results support the
case that SDSS J1023 is a transient LMXB, and indeed places it in the subclass
of such systems whose quiescent X-ray emission is dominated by a hard power law
component. Our optical photometry of SDSS J0932 reveals that it is an high
inclination eclipsing system. Combined with its optical characteristics -- high
excitation emission lines, and brightness, yielding a large F_X/F_opt ratio --
its highly absorbed X-ray spectrum argues that SDSS J0932 is a strong IP
candidate. However, only more extensive optical photometry and a detection of
its spin or spin-orbit beat frequency can confirm this classification.
(abridged)


title:
Evolution of X-ray cluster scaling relations in simulations with
  radiative cooling and non-gravitational heating

abstract:
  We investigate the redshift dependence of X-ray cluster scaling relations
drawn from three hydrodynamic simulations of the LCDM cosmology: a Radiative
model that incorporates radiative cooling of the gas, a Preheating model that
additionally heats the gas uniformly at high redshift, and a Feedback model
that self-consistently heats cold gas in proportion to its local star-formation
rate. While all three models are capable of reproducing the observed local
Lx-Tx relation, they predict substantially different results at high redshift
(to z=1.5), with the Radiative, Preheating and Feedback models predicting
strongly positive, mildly positive and mildly negative evolution, respectively.
  The physical explanation for these differences lies in the structure of the
intracluster medium. All three models predict significant temperature
fluctuations at any given radius due to the presence of cool subclumps and, in
the case of the Feedback simulation, reheated gas. The mean gas temperature
lies above the dynamical temperature of the halo for all models at z=0, but
differs between models at higher redshift with the Radiative model having the
lowest mean gas temperature at z=1.5.
  We have not attempted to model the scaling relations in a manner that mimics
the observational selection effects, nor has a consistent observational picture
yet emerged. Nevertheless, evolution of the scaling relations promises to be a
powerful probe of the physics of entropy generation in clusters. First
indications are that early, widespread heating is favored over an extended
period of heating that is associated with galaxy formation.


title: Probing disk properties with open clusters

abstract:
  We use the open clusters (OCs) with known parameters available in the WEBDA
database and in recently published papers to derive properties related to the
disk structure. The sample totals 654 OCs, consisting basically of Trumpler
types I to III clusters. Because of the completeness effects, the observed
radial distribution of OCs with respect to Galactocentric distance does not
follow the expected exponential profile. We simulate the effects of
completeness assuming that the observed distribution of the number of OCs with
a given number of stars above the background, measured in a restricted zone
outside the Solar circle, is representative of the intrinsic distribution of
OCs throughout the Galaxy. As a result we derive completeness-corrected radial
distributions which agree with exponential disks throughout the observed
Galactocentric distance range 5--14\,kpc, with scale lengths in the range $1.5
- 1.9\,kpc$. In particular we retrieve the expected exponential-disk radial
profile for the highly depleted regions internal to the Solar circle.
Extrapolation of the completeness-corrected radial distributions down to the
Galactic center indicates a total number of OCs in the range $\rm(1.8 -
3.7)\times10^5$. These estimates are upper-limits because they do not take into
account depletion in the number of OCs by dynamical effects in the inner parts
of the Galaxy. The observed and completeness-corrected age-distributions of the
OCs can be fitted by a combination of two exponential-decay profiles
characterized by age scales of $\rm\sim100\,Myr$ and $\rm\sim1.9\,Gyr$,
respectively. This rules out evolutionary scenarios based on constant
star-formation and OC-disruption rates. We estimate that 3.4--8\% of the
embedded clusters do actually emerge from the parent molecular clouds as OCs.


title: Mass functions and structure of the young open cluster NGC\,6611

abstract:
  We use 2MASS photometry to study colour-magnitude and colour-colour diagrams,
structure and mass distribution in the ionizing open cluster NGC\,6611.
Reddening variation throughout the cluster region is taken into account
followed by field-star decontamination of the CMDs. The field-star
decontamination showed that the lower limit of the main sequence (MS) occurs at
$\rm\approx5\,\ms$. Based on the fraction of Ks excess stars in the
colour-colour diagram we estimate an age of $1.3\pm0.3$\,Myr which is
consistent with the presence of a large number of pre-main sequence (PMS)
stars. The radial density distribution including MS and PMS stars is fitted by
a King profile with a core radius $0.70\pm0.08\,pc$. The cluster density
profile merges into the background at a limiting radius $6.5\pm0.5\,pc$. In the
halo and through the whole cluster the MFs have slopes $\rm\chi=1.52\pm0.13$
and $\rm\chi=1.45\pm0.12$, respectively, thus slightly steeper than Salpeter's
IMF. In the core the MF is flat, $\rm\chi=0.62\pm0.16$, indicating some degree
of mass segregation since the cluster age is a factor $\sim2$ larger than the
relaxation time. Because of the very young age of NGC\,6611, part of this
effect appears to be related to the molecular cloud-fragmentation process
itself. We detect $362\pm120$ PMS stars. The total observed mass including
detected MS (in the range $\rm5-85\,\ms$) and PMS stars amounts to
$\sim1\,600\,\ms$, thus more massive than the Trapezium cluster. Compared to
older open clusters of different masses, the overall NGC\,6611 fits in the
relations involving structural and dynamical parameters. However, the core is
atypical in the sense that it looks like an old/dynamically evolved core.
Again, part of this effect must be linked to formation processes.


title:
Phase transitions in rotating neutron stars cores: back bending,
  stability, corequakes and pulsar timing

abstract:
  The back-bending phenomenon for compact stars is studied by means of
analytical equations of state, for both constant-pressure phase transitions and
the transitions through the mixed-phase region. We restrict ourselves to the
case of normal rotating configurations, with baryon mass below the maximum
allowable baryon mass for non-rotating stars. We use high-precision 2-D
multi-domain spectral code LORENE to search the parameter space for possible
instability regions, and possible changes in the stability character of
rotating stars with phase transitions in their cores. Conditions on the density
jump in constant-pressure phase transitions, leading to the existence of the
unstable segments in the evolutionary sequences of spinning down isolated
normal neutron stars, are derived. Conjectures concerning the existence of two
disjoint families of non-rotating and rotating stationary configurations of
neutron stars are formulated. Particular case of EOSs leading to marginal
instability of static and rotating configurations is also studied: marginal
instability point in non-rotating configurations continues to exist in all
evolutionary spin-down tracks. The fate of rotating stars entering the region
of instability is discussed. The change in radius, energy release, and spin-up
associated with the corequake in rotating neutron star, triggered by the
instability, are calculated. The energy release is found to be very weakly
dependent on the angular momentum of collapsing star.


title:
CMBR distortion concerned with recombination of the primordial hydrogen
  plasma

abstract:
  CMBR distortion concerned with recombination of the primordial plasma is
calculated in frequency band from 1 GHz to 100 GHz in the frame of the standard
cosmological model for different values of cosmological density parameters:
nonrelativistic matter density $\Omega_m$ and baryonic matter density
$\Omega_b$. Comparison of these results with observational data which will be
obtained from planned experiments may be used for independent determination of
the cosmological parameters $\Omega_m$ and $\Omega_b$.


title: Statistical mechanics of the self-gravitating gases

abstract:
  The self-gravitating systems are formed by particles interacting through
gravity. They describe structure formation in the universe. As a consequence of
the long range interaction of gravity, they are inhomogeneous even at thermal
equilibrium. We study the self-gravitating systems with several kinds of
particles and the self-gravitating systems in the presence of the cosmological
constant $ Lambda$. We formulate the statistical mechanics and the mean field
approach describing the gaseous phase. We explicitely compute the density of
particles and thermodynamic quantities. The presence of $ Lambda$ extends the
domain of stability of the gaseous phase. Monte Carlo simulations show that the
mean field describes the gaseous phase with an excellent accuracy. Scalling law
of the self-gravitating systems with several kinds of particles is found. At
the critical point the fractal dimension is independant of their composition
and is $1.6...$~.


title:
Spiral shocks, triggering of star formation and the velocity dispersion
  in Giant Molecular Clouds

abstract:
  We present numerical simulations of the passage of clumpy gas through a
galactic spiral shock and the subsequent formation of giant molecular clouds
(GMCs). The spiral shock forms dense clouds while dissipating kinetic energy,
producing regions that are locally gravitationally bound and collapse to form
stars. The effect of the clumpiness of gas as it passes through the shock is to
generate chaotic internal motions in the gas. The kinematics of these motions
are found to agree with the observed velocity-dispersion/size relation found in
star-forming regions. In contrast to the standard picture where continuously
driven turbulence generates the density inhomogeneities in star-forming clouds,
we find here that it is the clumpiness of the interstellar gas that produces
the chaotic motions as it passes through the spiral shock and initiates the
star formation process. The velocity dispersion can be understood as being due
to the random mass loading of clumps as they converge in the spiral shock. In
this model there is no need for any internal or external continuous driving
mechanism for the 'turbulence'. The coupling of the clouds' internal kinematics
to their externally triggered formation removes the need for the clouds to be
self-gravitating. Indeed, while clearly some parts of the clouds are
self-gravitating and able to form stars, most of the molecular material remains
gravitationally unbound. This can provide a simple explanation for the low
efficiency of star formation.


title:
Planetary Nebula Studies of Face-On Spiral Galaxies: Is the Disk
  Mass-to-Light Ratio Constant?

abstract:
  When astronomers study the dark matter halos of spiral galaxies, they
normally assume that the disk mass-to-light ratio is *constant*. We describe a
method of analyzing the kinematics of planetary nebulae (PNe) in nearby face-on
spiral galaxies to test this assumption. Since the restoring force for stellar
motions perpendicular to the galactic disk is proportional to the disk mass
surface density, measurements of the vertical velocity dispersion can be used
to produce an independent measure of the total amount of matter in the disk.
Our steps are: (1) to identify a population of PNe by imaging the host spiral
in several filters, and (2) to isolate the vertical velocity dispersion from
spectroscopic observations of the PNe. Our first results for the PNe of M33
indicate that the mass-to-light ratio of the galaxy's disk actually *increases*
by more than a factor of 5 over the inner 6 disk scale lengths. We have begun
similar studies of the PNe in five more face-on galaxies: M83, M101, M94, NGC
6946, and M74. These data will also produce additional science such as galaxy
distances and constraints on the disk transparency.


title: Globular Clusters in Dwarf Galaxies

abstract:
  Data are presently available on the luminosities and half-light radii of 101
globular clusters associated with low-luminosity parent galaxies. The
luminosity distribution of globulars embedded in dwarf galaxies having $M_{v} >
-16$ is found to differ dramatically from that for globular clusters
surrounding giant host galaxies with $M_{v} < -16$. The luminosity distribution
of globular clusters in giant galaxies peaks at $M_{v} \sim -7.5$, whereas that
for dwarfs is found to increases monotonically down to the completeness limit
of the cluster data at $M_{v} \sim -5.0$. Unexpectedly, the power law
distribution of the luminosities of globular clusters hosted by dwarf galaxies
is seen to be much flatter than the that of bright unevolved part of the
luminosity distribution of globular clusters associated with giant galaxies.
The specific frequency of globular clusters that are fainter than $M_{v} =
-7.5$ is found to be particularly high in dwarf galaxies. The luminosity
distribution of the LMC globular clusters is similar to that in giant galaxies,
and differs from those of the globulars in dwarf galaxies. The present data
appear to show no strong dependence of globular cluster luminosity on the
morphological types of their parent galaxies. No attempt is made to explain the
unexpected discovery that the luminosity distribution of globular clusters is
critically dependent on parent galaxy luminosity (mass?), but insensitive to
the morphological type of their host galaxy.


title:
A Spectroscopic Study of the Ancient Milky Way: F- and G-Type Stars in
  the Third Data Release of the Sloan Digital Sky Survey

abstract:
  (Abridged) We perform an analysis of spectra and photometry for 22,770 stars
included in the third data release (DR3) of the SDSS. We measure radial
velocities and, based on a model-atmosphere analysis, derive estimates ofthe
atmospheric parameters (effective temperature, surface gravity, and [Fe/H]) for
each star. Stellar evolution models are then used to estimate distances. The
SDSS sample covers a range in stellar brightness of 14 < V < 22, and comprises
large numbers of F- and G-type stars from the thick-disk and halo populations
(up to 100 kpc from the galactic plane), therefore including some of the oldest
stars in the Milky Way. In agreement with previous results from the literature,
we find that halo stars exhibit a broad range of iron abundances, with a peak
at [Fe/H] ~ -1.4. This population exhibits essentially no galactic rotation.
Thick-disk G-dwarf stars at distances from the galactic plane in the range
1<|z|<3 kpc show a much more compact metallicity distribution, with a maximum
at [Fe/H] ~ -0.7, and a median galactic rotation velocity at that metallicity
of 157 +/- 4 km/s (a lag relative to the thin disk of 63 km/s). A comparison of
color indices and metal abundances with isochrones indicates that no
significant star formation has taken place in the halo in the last ~ 11 Gyr,
but there are thick-disk stars which are at least 2 Gyr younger. We find the
metallicities of thick-disk stars to be nearly independent of galactocentric
distance between 5 and 14 kpc, in contrast with the marked gradients found in
the literature for the thin disk. No vertical metallicity gradient is apparent
for the thick disk, but we detect a gradient inits rotational velocity of -16
+/- 4 km/s/kpc between 1 and 3 kpc from the plane.


title: LISA double black holes: Dynamics in gaseous nuclear discs

abstract:
  We study the inspiral of double black holes, with masses in the LISA window
of detectability, orbiting inside a massive circum-nuclear disc. Using
high-resolution SPH simulations, we follow the black hole dynamics in the early
phase when gas-dynamical friction acts on the black holes individually, and
continue our simulation until they form a close binary. We find that in the
early sinking the black holes lose memory of their initial orbital eccentricity
if they co-rotate with the gaseous disc, forming a binary with a low
eccentricity, consistent with zero within our numerical resolution limit. The
cause of circularization resides in the rotation present in the gaseous
background where dynamical friction operates. Circularization may hinder
gravitational waves from taking over and leading the binary to coalescence. In
the case of counter-rotating orbits the initial eccentricity does not decrease,
and the black holes may bind forming an eccentric binary. When dynamical
friction has subsided, for equal mass black holes and regardless their initial
eccentricity, angular momentum loss, driven by the gravitational torque exerted
on the binary by surrounding gas, is nevertheless observable down to the
smallest scale probed. In the case of unequal masses, dynamical friction
remains efficient down to our resolution limit, and there is no sign of
formation of any ellipsoidal gas distribution that may further harden the
binary. During inspiral, gravitational capture of gas by the black holes occurs
mainly along circular orbits: eccentric orbits imply high relative velocities
and weak gravitational focusing. Thus, AGN activity may be excited during the
black hole pairing process and double active nuclei may form when
circularization is completed, on distance-scales of tens of pcs.


title: Relativistic three-body effects in black hole coalescence

abstract:
  Three-body interactions are expected to be common in globular clusters and in
galactic cores hosting supermassive black holes. Here we consider an equal-mass
binary-black-hole system in the presence of a third black hole. Using
numerically generated binary-black-hole initial-data sets, and first- and
second-order post-Newtonian (1PN and 2PN) techniques, we find that the presence
of the third black hole has non-negligible relativistic effects on the location
of the innermost stable circular orbit (ISCO), and that these effects arise at
2PN order. In particular, we study the more astrophysically realistic situation
of a stellar-mass black-hole binary in orbit about a third supermassive black
hole. In general, the proximity of the massive black hole has stabilizing
effects on the orbiting binary, leading to an increase in merger time and a
decrease of the terminal orbital frequency, and an amplification of the
gravitational radiation emitted from the binary system by up to 6 percent.


title: Wideband Spectroscopy of Two Radio Bursts on AD Leonis

abstract:
  We report high-time-resolution, broadband spectroscopic observations of two
radio bursts on the classical flare star AD Leonis. The observations were
acquired by the 305 m telescope at Arecibo Observatory on 2003 June 13-14.
Using the Wideband Arecibo Pulsar Processor, these observations sampled a total
bandwidth of 400 MHz, distributed over a 500 MHz frequency range, 1120--1620
MHz, with a frequency resolution of 0.78 MHz and a time resolution of 10 ms. A
radio burst observed on June 13 is characterized by the presence of multitudes
of short duration ($\Delta t \sim$30 ms), high brightness temperature
($T_{b}>10^{14}$K), highly circularly polarized, fast-drift radio sub-bursts,
with median bandwidths $\Delta \nu/\nu \sim$5%. The inverse drift rates are
small, and have a symmetric distribution (both positive and negative frequency
drifts) with a Gaussian FWHM inverse drift rate of 4.5$\times10^{-4}$ s/MHz.
The fast-drift sub-bursts occur at a mean rate of 13 s$^{-1}$ and show no
evidence for periodic recurrence. The fast-drift radio events on AD Leo are
highly reminiscent of solar decimetric spike bursts. We suggest the emission is
due to fundamental plasma radiation. A second highly circularly polarized radio
burst, recorded June 14, has markedly different properties: a smoothly varying
intensity profile characterized by a slow drift in frequency with time (-52 MHz
s$^{-1}$). Under the assumption that the source is due to a disturbance
propagating through the low corona, a source size of 0.1--1 R$_{\star}$ is
inferred, implying a brightness temperature range
6$\times10^{11}$--6$\times10^{13}$K: another example of a coherent radio burst.


title: The Non-Homologous Nature of Solar Diameter Variations

abstract:
  We show in this paper that the changes of the solar diameter in response to
variations of large scale magnetic fields and turbulence are not homologous.
For the best current model, the variation at the photospheric level is over
1000 times larger than the variation at a depth of 5 Mm, which is about the
level at which f-mode solar oscillations determine diameter variations. This
model is supported by observations that indicate larger diameter changes for
high degree f-modes than for low degree f-modes, since energy of the former are
concentrated at shallower layers than the latter.


title:
A Pre-Protostellar Core in L1551. II. State of Dynamical and Chemical
  Evolution

abstract:
  Both analytic and numerical radiative transfer models applied to high
spectral resolution CS and N2H+ data give insight into the evolutionary state
of L1551 MC. This recently discovered pre-protostellar core in L1551 appears to
be in the early stages of dynamical evolution. Line-of-sight infall velocities
of >0.1km/s are needed in the outer regions of L1551 MC to adequately fit the
data. This translates to an accretion rate of ~ 1e-6 Msun/yr, uncertain to
within a factor of 5 owing to unknown geometry. The observed dynamics are not
due to spherically symmetric gravitational collapse and are not consistent with
the standard model of low-mass star formation. The widespread, fairly uniform
CS line asymmetries are more consistent with planar infall. There is modest
evidence for chemical depletion in the radial profiles of CS and C18O
suggesting that L1551 MC is also chemically young. The models are not very
sensitive to chemical evolution. L1551 MC lies within a quiescent region of
L1551 and is evidence for continued star formation in this evolved cloud.


title: Point Source Confusion in SZ Cluster Surveys

abstract:
  We examine the effect of point source confusion on cluster detection in
Sunyaev-Zel'dovich (SZ) surveys. A filter matched to the spatial and spectral
characteristics of the SZ signal optimally extracts clusters from the
astrophysical backgrounds. We calculate the expected confusion (point source
and primary cosmic microwave background [CMB]) noise through this filter and
quantify its effect on the detection threshold for both single and multiple
frequency surveys. Extrapolating current radio counts, we estimate that
confusion from sources below 100 microJy limits single-frequency surveys to
1-sigma detection thresholds of Y 3.10^{-6} arcmin^2 at 30 GHz and Y 10^{-5}
arcmin^2 at 15 GHz (for unresolved clusters in a 2 arcmin beam); these numbers
are highly uncertain, and an extrapolation with flatter counts leads to much
lower confusion limits. Bolometer surveys must contend with an important
population of infrared point sources. We find that a three-band matched filter
with 1 arcminute resolution (in each band) efficiently reduces confusion, but
does not eliminate it: residual point source and CMB fluctuations contribute
significantly the total filter noise. In this light, we find that a 3-band
filter with a low-frequency channel (e.g, 90+150+220 GHz) extracts clusters
more effectively than one with a high frequency channel (e.g, 150+220+300 GHz).


title: A Catalog of 1022 Bright Contact Binary Stars

abstract:
  In this work we describe a large new sample of contact binary stars extracted
in a uniform manner from sky patrol data taken by the ROTSE-I telescope.
Extensive ROTSE-I light curve data is combined with J, H, and K band
near-infrared data taken from the Two Micron All-Sky Survey (2MASS) to add
color information. Contact binaries candidates are selected using the observed
period-color relation. Candidates are confirmed by visual examination of the
light curves. To enhance the utility of this catalog, we derive a new J-H
period-color-luminosity relation and use this to estimate distances for the
entire catalog. From these distance estimates we derive an estimated contact
binary space density of (1.7 +/- 0.6) x 10^-5 pcs^-3.


title: A ROSAT Survey of Contact Binary Stars

abstract:
  Contact binary stars are common variable stars which are all believed to emit
relatively large fluxes of x-rays. In this work we combine a large new sample
of contact binary stars derived from the ROTSE-I telescope with x-ray data from
the ROSAT All-Sky Survey (RASS) to estimate the x-ray volume emissivity of
contact binary stars in the galaxy. We obtained x-ray fluxes for 140 contact
binaries from the RASS, as well as 2 additional stars observed by the
XMM-Newton observatory. From these data we confirm the emission of x-rays from
all contact binary systems, with typical luminosities of approximately 1.0 x
10^30 erg s^-1. Combining calculated luminosities with an estimated contact
binary space density, we find that contact binaries do not have strong enough
x-ray emission to account for a significant portion of the galactic x-ray
background.


title:
The Properties of Intergalactic CIV Absorption II: Which Systems Are
  Associated With Galaxy Outflows?

abstract:
  Using the extremely high S/N quasar absorption-line sample described in the
first paper of the series, we investigate which intergalactic CIV absorption
line systems could be directly associated with galactic outflows at z = 2 - 3.5
from an analysis of the velocity widths of the CIV absorption line systems.
Only about half the systems with a peak tau(CIV) above 0.4 in the 1548 Angstrom
line (roughly a column density of CIV above about 2 x 10^13 cm^-2) have
velocity widths large enough to originate in this way, and very few of the
weaker systems do. The median velocity full width at a tenth max is found to be
50 km/s for systems with peak tau(CIV) in the range 0.1--0.4 and 160 km/s for
systems with a peak tau(CIV) in the range 0.4--3. We show that this critical
value of tau(CIV) also separates systems that could be ionized by galaxy-like
spectra from those in which the ionization is clearly AGN-dominated. Together
the results are consistent with a picture in which almost all the lower column
density, and at least half the higher column density, systems lie in the more
general IGM whereas about half of the higher column density systems could be
produced directly by the outflows and possibly be ionized by their parent
galaxies.


title: The Galaxy Environment of O VI Absorption Systems

abstract:
  We combine a FUSE sample of OVI absorbers (z < 0.15) with a database of 1.07
million galaxy redshifts to explore the relationship between absorbers and
galaxy environments. All 37 absorbers with N(OVI) > 10^{13.2} cm^-2 lie within
800 h_70^-1 kpc of the nearest galaxy, with no compelling evidence for OVI
absorbers in voids. The OVI absorbers often appear to be associated with
environments of individual galaxies. Gas with 10 +/- 5% of solar metallicity
(OVI and CIII) has a median spread in distance of 350-500 kpc around L*
galaxies and 200-270 kpc around 0.1 L* galaxies (ranges reflect uncertain
metallicities of gas undetected in Lya absorption). In order to match the OVI
line frequency, dN/dz = 20 for N(OVI) > 10^{13.2} cm^-2, galaxies with L < 0.1
L* must contribute to the cross section. The Lya absorbers with N(HI) >
10^{13.2} cm^-2 cover ~50% of the surface area of typical galaxy filaments.
Two-thirds of these show OVI and/or CIII absorption, corresponding to a 33-50%
covering factor at 0.1 Z_sun and suggesting that metals are spread to a maximum
distance of 800 kpc, within typical galaxy supercluster filaments.
Approximately 50% of the OVI absorbers have associated Lya line pairs with
separations Delta V = 50-200 km/s. These pairs could represent shocks at the
speeds necessary to create copious OVI, located within 100 kpc of the nearest
galaxy and accounting for much of the two-point correlation function of low-z
Lya forest absorbers.


title:
PSR J1833-1034: Discovery of the Central Young Pulsar in the Supernova
  Remnant G21.5-0.9

abstract:
  We have discovered the pulsar associated with the supernova remnant
G21.5-0.9. PSR J1833-1034, with spin period P = 61.8 ms and dispersion measure
169 pc/cc, is very faint, with pulse-averaged flux density of approximately 70
microJy at a frequency of 1.4 GHz, and was first detected in a deep search with
the Parkes telescope. Subsequent observations with Parkes and the Green Bank
Telescope have confirmed this detection, and yield a period derivative dP/dt =
2.02e-13. These spin parameters imply a characteristic age tau_c = 4.8 kyr and
a spin-down luminosity dE/dt = 3.3e37 ergs/s, the latter value exceeded only by
the Crab pulsar among the rotation-powered pulsars known in our Galaxy. The
pulsar has an unusually steep radio spectrum in the 0.8-2.0 GHz range, with
power law index ~3.0, and a narrow single-peaked pulse profile with full-width
at half maximum of 0.04P. We have analyzed 350 ks of archival Chandra X-ray
Observatory High Resolution Camera (HRC) data, and find a point-like source of
luminosity approximately 3e-5dE/dt, offset from the center of an elliptical
region of size ~7"x5" and luminosity approximately 1e-3dE/dt within which
likely lies the pulsar wind termination shock. We have searched for X-ray
pulsations in a 30 ks HRC observation without success, deriving a pulsed
fraction upper limit for a sinusoidal pulse shape of about 70% of the pulsar
flux. We revisit the distance to G21.5-0.9 based on HI and CO observations,
arguing that it is 4.7+-0.4 kpc. We use existing X-ray and radio observations
of the pulsar wind nebula, along with the measured properties of its engine and
a recent detection of the supernova remnant shell, to argue that G21.5-0.9 and
PSR J1833-1034 are much younger than tau_c, and likely their true age is ~<1000
yr. In that case, the initial spin period of the pulsar was >~55 ms.


title: Systems of Galaxies in the SDSS: the fundamental plane

abstract:
  We analyse a subsample of the galaxy groups obtained by Merch\'an &
Zandivarez (2005) from the SDSS DR3 to study the fundamental plane and the mass
to light ratio of galaxy groups. We find a fundamental plane given by $L_R
\propto R^{1.3} \sigma^{0.7}$. We do not find differences when different
dynamical sates or redshift ranges are analysed. We find that the mass to light
ratio increases with group mass as $M/L_R \propto M^{0.36}$.


title:
Continuum emission in NGC1068 and NGC3147: Indications for a turnover in
  the core spectra

abstract:
  We present new interferometric observations of the continuum emission at mm
wavelengths in the Seyfert galaxies NGC1068 and NGC3147. Three mm continuum
peaks are detected in NGC1068, one centered on the core, one associated with
the jet and the third one with the counter-jet. This is the first significant
detection of the radio jet and counter-jet at mm wavelengths in NGC1068. While
the fluxes of the jet components agree with a steep spectral index extrapolated
from cm-wavelengths, the core fluxes indicate a turnover of the inverted cm-
into a steep mm-spectrum at roughly 50GHz which is most likely caused by
electron-scattered synchrotron emission. As in NGC 1068, the spectrum of the
pointlike continuum source in NGC3147 also shows a turnover between cm and
mm-wavelengths at 25GHz resulting from synchrotron self-absorption different to
NGC1068. This strongly resembles the spectrum of SgrA*, the weakly active
nucleus of our own galaxy, and M81*, a link between SgrA* and Seyfert galaxies
in terms of activity sequence, which may display a similar turnover.


title: A Faraday Rotation Search for Magnetic Fields in Large Scale Structure

abstract:
  Faraday rotation of radio source polarization provides a measure of the
integrated magnetic field along the observational lines of sight. We compare a
new, large sample of Faraday rotation measures (RMs) of polarized extragalactic
sources with galaxy counts in Hercules and Perseus-Pisces, two nearby
superclusters. We find that the average of RMs in these two supercluster areas
are larger than in control areas in the same galactic latitude range. This is
the first RM detection of magnetic fields that pervade a supercluster volume,
in which case the fields are at least partially coherent over several
megaparsecs. Even the most conservative interpretation of our observations,
according to which Milky Way RM variations mimic the background supercluster
galaxy overdensities, puts constraints on the IGM magneto-ionic ``strength'' in
these two superclusters. We obtain an approximate typical upper limit on the
field strength of about 0.3 microGauss l/(500 kpc), when we combine our RM data
with fiducial estimates of electron density from the environments of giant
radio galaxies, and of the warm-hot intergalactic medium (WHIM).


title:
First Results from the CHARA Array. III. Oblateness, Rotational Velocity
  and Gravity Darkening of Alderamin

abstract:
  We present observations of the A7IV-V star Alderamin ($\alpha$ Cep, HR 8162,
HD 203280) from the Georgia State University CHARA Array. These infrared
interferometric angular size measurements indicate a non-circular projected
disk brightness distribution for this known rapid rotator. The interferometric
observations are modeled as arising from an elongated rigid atmosphere, with
apparent polar and equatorial radii of $r_p=0.6753^{+0.0119}_{-0.0135}$
milliarcseconds (mas) and $r_e=0.8767^{+0.0293}_{-0.0183}$ mas, respectively,
for a difference of $201\pm 32$ microarcseconds ($\mu$as), and with an axial
ratio of $r_e/r_p =1.298\pm 0.051$. Using the Hipparcos distance of $14.96\pm
0.11$ pc, these angular measures translate to $2.18\pm0.05$ and $2.82\pm0.10$
$R_\odot$. The inclination of Alderamin to the line of sight indicated by this
modeling is effectively edge-on ($i=88.2^{+1.8}_{-13.3}$). The star has a true
rotational velocity of $283\pm 10$ km/s ($\sim83$% of breakup velocity), and a
polar temperature of roughly 8400 K. Significantly, a necessary aspect of this
modeling is a determination of the gravity darkening coefficient, which at a
value of $\beta=0.084^{+0.026}_{-0.049}$ is consistent with a convective
photosphere, as expected for an A7IV-V star. Our detailed characterization of
this object allows us to investigate various scenarios for the angular momentum
history of Alderamin and the appropriateness of certain stellar evolution
models.


title:
A flux tube solar dynamo model based on the competing role of buoyancy
  and downflows

abstract:
  A magnetic flux tube may be considered both as a separate body and as a
confined field. As a field, it is affected both by differential rotation
($\Omega$-effect) and cyclonic convection ($\alpha$-effect). As a body, the
tube experiences not only a buoyant force, but also a dynamic pressure due to
downflows above the tube. These two competing dynamic effects are incorporated
into the $\alpha$-$\Omega$ dynamo equations through the total magnetic
turbulent diffusivity, leading to a flux tube dynamo operating in the
convection zone. We analyze and solve the extended dynamo equations in the
linear approximation by adopting the observed solar internal rotation and
assuming a downflow effect derived from numerical simulations of solar
convection zone. The model reproduces: the 22-year cycle period; the extended
butterfly diagram with the confinement of strong activity to low heliographic
latitudes $|\Phi|\le 35^\circ$; the evidence that at low latitudes the radial
field is in an approximately $\pi$ phase lag compared to the toroidal field at
the same latitude; the evidence that the poleward branch is in a $\pi/2$ phase
lag with respect to the equatorward branch; and the evidence that most of the
magnetic flux is present in an intermittent form, concentrated into strong flux
tubes.


title:
Chemical and Photometric Evolution of the Local Group Galaxy NGC 6822 in
  a Cosmological Context

abstract:
  Based on the photometric properties of NGC 6822 we derive a robust star
formation history. Adopting this history we compute 15 models of galactic
chemical evolution. All of them match present-day photometric properties. The
dark halo mass in all models evolves according to the mass assembly history
predicted by a $\Lambda$CDM cosmology. We model the evolution of the baryonic
mass aggregation history in this cosmological context assuming that part of the
gas available for accretion never falls into the system due to two different
physical processes. For seven models we assume that during accretion the
universal baryon fraction is reduced by reionization only. The best model of
this first group, a complex model with an early outflow, fits the observed
gaseous mass, and the O/H, C/O, and Fe/O present-day values. This model
requires a lower upper mass limit for the IMF than that of the solar vicinity,
in agreement with recent results by other authors. We have also computed eight
models where, in addition to reionization, the accreted baryon fraction is
reduced by large-scale shock heating.The best model of this series, that also
requires and early outflow and a lower upper mass limit for the IMF,can
marginally fit the gaseous mass and the O/H and C/O observed values.


title:
Eclipse Prediction and Orbit Improvement for Asteroids: Theory and
  Application to Near Earth Asteroids

abstract:
  Asteroids can be eclipsed by other bodies in the Solar System, but no direct
observation of an asteroid eclipse has been reported to date. We describe a
statistical method to predict an eclipse for an asteroid based on the analysis
of the orbital elements covariance matrix. By propagating a set of Virtual
Asteroids to an epoch correspondent to a close approach with a Solar System
planet or natural satellite, it is possible to estimate the probability of a
partial or total eclipse.
  The direct observation of an eclipse can provide data useful to improve the
asteroid orbit, especially for dim asteroids typically observed only for a few
days. We propose two different methods: the first, based on the inclusion of
the apparent magnitude residuals into the orbit's least squares minimization
process, capable of improving the asteroid's nominal orbit and the related
covariance matrix; the second, based on weighting different Virtual Asteroids
in relation to their apparent magnitude during the eclipse, useful for recovery
purposes.
  As an application, we have numerically investigated the possibility of a Near
Earth Asteroid eclipsed by the Moon or the Earth in the 1990-2050 period. A
total of 74 distinct eclipses have been found, involving 59 asteroids. In
particular, the asteroid (99942) Apophis has a probability of about 74% to
enter the Moon's penumbra cone and a probability of about 6% to enter the umbra
cone on April 14, 2029, less than six hours after a very close approach to
Earth.


title:
Planetary nebulae and stellar kinematics in the flattened elliptical
  galaxy NGC 1344

abstract:
  We present photometric and kinematic information obtained by measuring 197
planetary nebulae (PNs) discovered in the flattened Fornax elliptical galaxy
NGC 1344 (also known as NGC 1340) with an on-band, off-band, grism + on-band
filter technique. We build the PN luminosity function (PNLF) and use it to
derive a distance modulus m-M=31.4, slightly smaller than, but in good
agreement with, the surface brightness fluctuation distance. The PNLF also
provides an estimate of the specific PN formation rate: 6x10^-12 PNs per year
per solar luminosity. Combining the positional information from the on-band
image with PN positions measured on the grism + on-band image, we can measure
the radial velocities of 195 PNs, some of them distant more than 3 effective
radii from the center of NGC 1344. We complement this data set with stellar
kinematics derived from integrated spectra along the major and minor axes, and
parallel to the major axis of NGC 1344. The line-of-sight velocity dispersion
profile indicates the presence of a dark matter halo around this galaxy.


title: PKS 1622-253: A Weakly Accreting, Powerful Gamma Ray Source

abstract:
  In this Letter, we discuss new deep radio observations of PKS 1622-253 and
their implications for the energetics of the central engine that powers this
strong high energy gamma-ray source. Combining archival infrared and optical
measurements with new millimeter observations, we show that even though the
accretion flow in PKS 1622-253 is under-luminous by quasar standards, a
powerful super-luminal jet is launched with a higher kinetic luminosity than
most EGRET blazars. Only a few percent of the total jet kinetic luminosity is
required to power even the most powerful gamma ray flares that are observed.
The implication is that a high accretion system is not required to power the
strongest high energy gamma ray sources.


title: Efficient analysis in planet transit surveys

abstract:
  With the growing number of projects dedicated to the search for extrasolar
planets via transits, there is a need to develop fast, automatic, robust
methods with a statistical background in order to efficiently do the analysis.
We propose a modified analysis of variance (AoV) test particularly suitable for
the detection of planetary transits in stellar light curves. We show how
savings of labor by a factor of over 10 could be achieved by the careful
organization of computations. Basing on solid analytical statistical
formulation, we discuss performance of our and other methods for different
signal-to-noise and number of observations.


title: Implications of Elemental Abundances in Dwarf Spheroidal Galaxies

abstract:
  Unusual elemental abundance patterns observed for stars belonging to nearby
dwarf spheroidal (dSph) galaxies are discussed. Analysis of the [alpha/H] vs.
[Fe/H] diagrams where alpha represents Mg or average of alpha-elements reveals
that Fe from Type Ia supernovae (SNe Ia) does not contribute to the stellar
abundances in the dSph galaxies where the member stars exhibit low alpha/Fe
ratios except for the most massive dSph galaxy, the Sagitarrius. The more
massive dwarf (irregular) galaxy, the Large Magellanic Cloud, also have an SNe
Ia signature in the stellar abundances. These findings suggest that the
condition of whether SNe Ia contribute to chemical evolution in dwarf galaxies
is likely to depend on the mass scale of galaxies. Unusual Mg abundances in
some dSph stars are also found to be the origin of the large scatter in the
[Mg/Fe] ratios and responsible for a seemingly decreasing [Mg/Fe] feature with
increasing [Fe/H]. In addition, the lack of massive stars in the dSph galaxies
does not satisfactorily account for the low-alpha signature. Considering the
assemblage of deficient elements (O, Mg, Si, Ca, Ti, and Zn), all of which are
synthesized in pre-SN massive stars and in SN explosions, the low-alpha
signature appears to reflect the heavy-element yields of massive stars with
smaller rotation compared to solar neighborhood stars.


title:
Dust and Molecules in Early Galaxies: Prediction and Strategy for
  Observations

abstract:
  The interplay between dust and molecules is of fundamental importance in
early galaxy evolution. First we present the prediction for the dust emission
from forming galaxies. Then we discuss the observational strategy for molecules
in early galaxies by infrared absorption lines of a bright continuum source
behind the clouds. By combining these two approaches, we will be able to have a
coherent picture of the very early stage of galaxy evolution.


title:
Outflows from young objects observed with the ISO-LWS I. Fine structure
  lines [O I] 63, [O I]145 and [C II]157 micron

abstract:
  Far infrared fine structure line data from the ISO archive have been
extracted for several hundred YSOs and their outflows, including molecular (CO)
outflows, optical jets and Herbig-Haro (HH) objects. Given the importance of
these lines to astrophysics, their excitation and transfer ought to be
investigated in detail and, at this stage, the reliability of the diagnostic
power of the fine structure transitions of O I and C II has been examined.
Several issues, such as the extremely small intensity ratios of the oxygen 63
micron to 145 micron lines, are still awaiting an explanation. It is
demonstrated that, in interstellar cloud conditions, the 145 micron line is
prone to masing, but that this effect is likely an insufficient cause of the
line ratio anomaly observed from cold dark clouds. Very optically thick
emission could in principle also account for this, but would need similar,
prohibitively high column densities and must therefore be abondoned as a viable
explanation. One is left with [O I] 63 micron self absorption by cold and
tenuous foreground gas, as has been advocated for distant luminous sources.
Recent observations with the submillimeter observatory Odin support this
scenario also in the case of nearby dark molecular clouds. On the basis of this
large statistical material we are led to conclude that in star forming regions,
the [O I] and [C II] lines generally have only limited diagnostic value.


title:
A faster algorithm for smoothed particle hydrodynamics with radiative
  transfer in the flux-limited diffusion approximation

abstract:
  We describe a new, faster implicit algorithm for solving the radiation
hydrodynamics equations in the flux-limited diffusion approximation for
smoothed particle hydrodynamics. This improves on the method elucidated in
Whitehouse & Bate by using a Gauss-Seidel iterative method rather than
iterating over the exchange of energy between pairs of particles. The new
algorithm is typically many thousands of times faster than the old one, which
will enable more complex problems to be solved. The new algorithm is tested
using the same tests performed by Turner & Stone for ZEUS-2D, and repeated by
Whitehouse & Bate.


title: A class of self-gravitating, magnetized accretion disks

abstract:
  The steady-state structure of self-gravitating, magnetized accretion disks is
studied using a set of self-similar solutions which are appropriate in the
outer regions. The disk is assumed to be isothermal and the magnetic field
outside of the disk is treated in a phenomenological way. However, the internal
field is determined self-consistently. The behaviour of the solutions are
investigated by changing the input parameters of the model, i.e. mass accretion
rate, coefficients of viscosity and resistivity, and the magnetic field
configuration.


title:
HST STIS spectroscopy of the triple nucleus of M31: two nested disks in
  Keplerian rotation around a Supermassive Black Hole

abstract:
  We present HST spectroscopy of the nucleus of M31 obtained with STIS. Spectra
taken around the CaT lines at 8500 see only the red giants in the double
bright- ness peaks P1 and P2. In contrast, spectra taken at 3600-5100 A are
sensitive to the tiny blue nucleus embedded in P2, the lower surface brightness
red nucleus. P2 has a K-type spectrum, but the embedded blue nucleus has an
A-type spectrum with strong Balmer absorption lines. Given the small likelihood
for stellar collisions, a 200 Myr old starburst appears to be the most
plausible origin of the blue nucleus. In stellar population, size, and velocity
dispersion, the blue nucleus is so different from P1 and P2 that we call it P3.
The line-of-sight velocity distributions of the red stars in P1+P2 strengthen
the support for Tremaine s eccentric disk model. The kinematics of P3 is
consistent with a circular stellar disk in Keplerian rotation around a
super-massive black hole with M_bh = 1.4 x 10^8 M_sun. The P3 and the P1+P2
disks rotate in the same sense and are almost coplanar. The observed velocity
dispersion of P3 is due to blurred rotation and has a maximum value of sigma =
1183+-201 km/s. The observed peak rotation velocity of P3 is V = 618+-81 km/s
at radius 0.05" = 0.19 pc corresponding to a circular rotation velocity at this
radius of ~1700 km/s. Any dark star cluster alternative to a black hole must
have a half-mass radius <= 0.03" = 0.11 pc. We show that this excludes clusters
of brown dwarfs or dead stars on astrophysical grounds.


title: The Production of Magnetically Dominated Star Forming Regions

abstract:
  We consider the dynamical evolution of an interstellar cloud that is
initially in thermal equilibrium in the warm phase and is then subjected to a
sudden increase in the pressure of its surroundings. We find that if the
initial plasma beta of the cloud is of order unity, then there is a
considerable period during which the material in the cloud both has a small
beta and is in the thermally unstable temperature range. These conditions are
not only consistent with observations of star forming regions, but are also
ideally suited to the production of density inhomogeneities by
magnetohydrodynamic waves. The end result should be a cloud whose size and
average density are typical of Giant Molecular Clouds (GMCs) and which contains
denser regions whose densities are in the range inferred for the translucent
clumps in GMCs.


title:
The extragalactic nature of the serendipitous BeppoSAX source 2MASX
  J14585116-1652223

abstract:
  As a follow-up of the X-ray serendipitous detection of the source 2MASX
J14585116-1652223, medium-resolution optical spectroscopic observations
collected at the 1.5-metre "Cassini" telescope of the Astronomical Observatory
of Bologna were performed. This allowed us to determine the extragalactic
nature of this X-ray source, which is a Type 2 Seyfert galaxy at redshift z =
0.068 +- 0.001. This result points to the fact that 2MASX J14585116-1652223
hosts one of the very few Active Galactic Nuclei detected so far in the hard
X-ray band above 20 keV, in particular at z > 0.05. Other optical and X-ray
properties of this object are also discussed.


title:
B, V, I photometry of the complete sample of 23 Cepheids in the field of
  NGC 1866

abstract:
  We present the result of BVI photometry, obtained by using FORS@VLT, of the
Cepheids present in the field of the Large Magellanic Cloud cluster NGC 1866.
We found the 22 known variables plus an additional new Cepheid located about
10' from the cluster center. The accuracy of the photometry allowed us to
derive B, V and I mean magnitudes with an uncertainty lower than 0.02 mag for
22 out of the 23 objects, with the exception of only one Cepheid (WS9) which
presents a noisy light curve due to the probable occurrence of image blending.
As a result, we provide accurate observational data for a substantial sample of
variables all lying at the same distance and with a common original
composition. The resulting period-luminosity relations are presented and
briefly discussed.


title: Local and Large scale Environment of Seyfert Galaxies

abstract:
  We present a three-dimensional study of the local (<100 h^-1} kpc) and the
large scale (<1 h^{-1} Mpc) environment of the two main types of Seyfert AGN
galaxies. For this purpose we use 48 Sy1 galaxies (with redshifts in the range
0.007<z<0.036) and 56 Sy2 galaxies (with 0.004<z<0.020), located at high
galactic latitudes, as well as two control samples of non-active galaxies
having the same morphological, redshift, and diameter size distributions as the
corresponding Seyfert samples. Using the Center for Astrophysics (CfA2) and
Southern Sky Redshift Survey (SSRS) galaxy catalogues (m_B~15.5) and our own
spectroscopic observations (m_B~18.5), we find that within a projected distance
of 100 h^-1 kpc and a radial velocity separation of dv<600 km/sec around each
of our AGNs, the fraction of Seyfert 2 galaxies with a close neighbor is
significantly higher than that of their control (especially within 75 h^{-1}
kpc) and Seyfert 1 galaxy samples, confirming a previous two-dimensional
analysis of Dultzin-Hacyan et al. We also find that the large-scale environment
around the two types of Seyfert galaxies does not vary with respect to their
control sample galaxies. However, in the Seyfert 2 and control galaxy samples
do differ significantly when compared to the corresponding Seyfert 1 samples.
Since the main difference between these samples is their morphological type
distribution, we argue that the large-scale environmental difference cannot be
attributed to differences in nuclear activity but rather to their different
type of host galaxies.


title: V4332 Sgr in 'Quiescence'

abstract:
  In 1994 V4332 Sgr underwent a mysterious eruption. Somehow its fast evolution
towards a red giant star was, lacking alternative classifications, connected to
the red variable M31 RV, which had its eruption in 1988. The red eruptive
variable V838~Mon draw in February 2002 the attention back to its 'older twin'
V4332~Sgr. The new precise photometry of the progenitor given here shows that
the object started to rise years before the 1994 event. Post outburst
photometry and spectroscopy from 2002 and 2003 show that the object stopped
it's decline and seem to reheat now. The progenitor data and the new high
quality spectra provide a supplement and completion to the data around the
outburst given by Martini et al. (1999). It thus allows theorists to give new
boundaries for modelling of this unusual object.


title: Scaling law of the plasma turbulence with non conservative fluxes

abstract:
  It is shown that in the presence of anisotropic kinetic dissipation existence
of scale invariant power law spectrum of plasma turbulence is possible.
Obtained scale invariant spectrum is not associated with the constant flux of
any physical quantity. Application of the model to the high frequency part of
the solar wind turbulence is discussed.


title: Surface gravity waves in deep fluid at vertical shear flows

abstract:
  Special features of surface gravity waves in deep fluid flow with constant
vertical shear of velocity is studied. It is found that the mean flow velocity
shear leads to non-trivial modification of surface gravity wave modes
dispersive characteristics. Moreover, the shear induces generation of surface
gravity waves by internal vortex mode perturbations. The performed analytical
and numerical study provides, that surface gravity waves are effectively
generated by the internal perturbations at high shear rates. The generation is
different for the waves propagating in the different directions. Generation of
surface gravity waves propagating along the main flow considerably exceeds the
generation of surface gravity waves in the opposite direction for relatively
small shear rates, whereas the later wave is generated more effectively for the
high shear rates. From the mathematical point of view the wave generation is
caused by non self-adjointness of the linear operators that describe the shear
flow.


title:
Torsion effects on vortex filaments and Hasimoto soliton transformation
  in magnetars

abstract:
  The role played by torsion of magnetic vortex line curves or filaments, in
the equilibrium state of magnetars is investigated. When the magnetars
equilibrium equations are written in terms Frenet-Serret frame it is shown that
in regions of the magnetic star where the Frenet torsion is constant it induces
an oscillation in the vortex filaments. By solving the magnetar equilibrium
equation we shown the this behaviour also appears in the magnetic field. The
first derivative of the gravitational potential with respect to the arc lenght
of the vortex filament is shown to coincide with the Hasimoto soliton
transformation of the Schroedinger equation for the constant torsion.


title:
Wind-wind collision in the Carinae binary system II: Constrains to the
  binary orbital parameters from radio emission near periastron passage

abstract:
  In this paper we use the 7 mm and 1.3 mm light curves obtained during the
2003.5 low excitation phase of the eta Carinae system to constrain the possible
parameters of the binary orbit. To do that we assumed that the mm wave emission
is produced in a dense disk surrounding the binary system; during the low
excitation phase, which occurs close to periastron, the number of ionizing
photons decreases, producing the dip in the radio emission. On the other hand,
due to the large eccentricity, the density of the shock region at periastron is
very high and the plasma is optically thick for free-free radiation at 7 mm,
explaining the sharp peak that was observed at this frequency and lasted for
about 10 days. From the shape and duration of the peak we were able to
determine the orbital parameters of the binary system, independently of the
stellar parameters, such as mass loss rates, wind velocities or temperature at
the post-shock region.


title:
Properties of Intra-group Stars and Galaxies in Galaxy Groups: "Normal"
  versus "Fossil" Groups

abstract:
  Cosmological LCDM simulations of 12 M_vir~10^14 Msun galaxy groups have been
performed, invoking star formation, chemical evolution with non-instantaneous
recycling, metallicity dependent radiative cooling, strong star-burst driven
galactic super-winds and effects of a meta-galactic UV field. At z=0,
intra-group light (IGL) fractions are found to be 12-45%. Low values refer to
groups with only a small difference between the R-band magnitudes of the first
and second ranked group galaxy, large are typical of "fossil" groups (FGs). The
IG stars in the 4 FGs are 0.3-0.5 Gyr older than in the 8 nonFGs. For the IGL,
B-R=~1.4, in good agreement with observations. For FGs/nonFGs the iron
abundance of the IG stars is slightly sub-solar in the central parts (r~100
kpc) decreasing to about 40% solar at about 0.5 r_vir The IG stars are
alpha-element enhanced with [O/Fe] increasing with r, and an overall
[O/Fe]~0.45, indicating predominant SNII enrichment. The velocity distributions
of the IG stars and group galaxies are, at r>~30 kpc, significantly more
radially anisotropic for FGs than for nonFGs. So a characteristic of FG
formation, apart from formation time (D'Onghia et al.), may be the "initial"
velocity distribution of the group galaxies. For FGs one can dynamically infer
the (dark matter dominated) mass distribution of the groups all the way to
r_vir, from the kinematics of the IG stars or group galaxies. For the nonFGs
this method overestimates the group mass at r>~200 kpc, by up to a factor of
two at r_vir. This is interpreted as FGs being, in general, more relaxed than
nonFGs. Finally, FGs of the above M_vir should host ~500 planetary nebulae at
projected distances between 100 and 1000 kpc from the first ranked galaxy. All
results appear consistent with the FG formation scenario of D'Onghia et al.


title: SWAS observations of comet 9P/Tempel 1 and Deep Impact

abstract:
  On 4 July 2005 at 1:52 UT the Deep Impact mission successfully completed its
goal to hit the nucleus of 9P/Tempel 1 with an impactor, forming a crater on
the nucleus and ejecting material into the coma of the comet. The 370 kg
impactor collided with the sunlit side of the nucleus with a relative velocity
of 10.2 km/s. NASA's Submillimeter Wave Astronomy Satellite (SWAS) observed the
1(10)-1(01) ortho-water ground-state rotational transition in comet 9P/Tempel 1
before, during, and after the impact. No excess emission from the impact was
detected by SWAS. However, the water production rate of the comet showed large
natural variations of more than a factor of three during the weeks before the
impact.


title: The broad-band spectrum of Cygnus X-1 measured by INTEGRAL

abstract:
  The INTEGRAL satellite extensively observed the black hole binary Cygnus X-1
from 2002 November to 2004 November during calibration, open time and core
program (Galactic Plane Scan) observations. These data provide evidence for
significant spectral variations over the period. In the framework of the
accreting black hole phenomenology, the source was most of the time in the Hard
State and occasionally switched to the so-called "Intermediate State". Using
the results of the analysis performed on these data, we present and compare the
spectral properties of the source over the whole energy range (5 keV - 1 MeV)
covered by the high-energy instruments on board INTEGRAL, in both observed
spectral states. Fe line and reflection component evolution occurs with
spectral changes in the hard and soft components. The observed behaviour of
Cygnus X-1 is consistent with the general picture of galactic black holes. Our
results give clues to the physical changes that took place in the system (disc
and corona) at almost constant luminosity during the spectral transitions and
provide new measures of the spectral model parameters. In particular, during
the Intermediate State of 2003 June, we observe in the Cygnus X-1 data a
high-energy tail at several hundred keV in excess of the thermal Comptonization
model which suggests the presence of an additional non-thermal component.


title: An abundance analysis of the symbiotic star CH Cyg

abstract:
  The photospheric abundances for the cool component of the symbiotic star CH
Cyg were calculated for the first time using high-resolution near-infrared
spectra and the method of of standard LTE analysis and atmospheric models. The
iron abundance for CH Cyg was found to be solar, [Fe/H] = 0.0+/-0.19. The
atmospheric parameters and metallicity for CH Cyg are found to be approximately
equal to those for nearby field M7 giants. The calculated [C/H] = -0.15, [N/H]
= +0.16, [O/H] = -0.07, and the isotopic ratios of 12C/13C and 16O/17O are
close to the mean values for single M giants that have experienced the first
dredge-up. A reasonable explanation for the absence of barium star-like
chemical peculiarities seems to be the high metallicity of CH Cyg. The emission
line technique was explored for estimating CNO ratios in the wind of the giant.