title: Gamma-ray bursts and terrestrial planetary atmospheres

abstract:
  We describe results of modeling the effects on Earth-like planets of
long-duration gamma-ray bursts (GRBs) within a few kiloparsecs. A primary
effect is generation of nitrogen oxide compounds which deplete ozone. Ozone
depletion leads to an increase in solar UVB radiation at the surface, enhancing
DNA damage, particularly in marine microorganisms such as phytoplankton. In
addition, we expect increased atmospheric opacity due to buildup of nitrogen
dioxide produced by the burst and enhanced precipitation of nitric acid. We
review here previous work on this subject and discuss recent developments,
including further discussion of our estimates of the rates of impacting GRBs
and the possible role of short-duration bursts.

categories: astro-ph physics.ao-ph physics.geo-ph q-bio.PE


title:
Measurement of the orbital and superhump periods of the eclipsing
  cataclysmic variable SDSS J170213.26+322954.1

abstract:
  The orbital period of the eclipsing cataclysmic variable SDSS
J170213.26+322954.1 has been measured as 0.10008215+/-0.00000001d using
observations of eclipses during the first recorded superoutburst in October
2005 together with eclipses observed in quiescence in July 2003. This period
puts the system in the centre of the period gap. Observation of superhumps
during the October 2005 outburst with a period of 0.10496+/-0.00015d confirms
this to be a UGSU-type system with a period excess of 4.9%.


title:
The Detection of a 3.5-h Period in the Classical Nova Velorum 1999 (V382
  Vel) and the Long Term Behavior of the Nova Light Curve

abstract:
  We present CCD photometry, light curve and time series analysis of the
classical nova V382 Vel (N Vel 1999). The source was observed for 2 nights in
2000, 21 nights in 2001 and 7 nights in 2002 using clear filters. We report the
detection of a distinct period in the light curve of the nova P=0.146126(18) d
(3.5 h). The period is evident in all data sets, and we interpret it as the
binary period of the system. We also measured an increase in the amplitude
modulation of the optical light (in magnitude) by more than 55% from 2000 to
2001 and about 64% from 2001 to 2002. The pulse profiles in 2001 show
deviations from a pure sinusoidal shape which progressively become more
sinusoidal by 2002. The main cause of the variations in 2001 and 2002 can be
explained with the occultation of the accretion disk by the secondary star. We
interpret the observed deviations from a pure sinusoidal shape as additional
flux resulting from the aspect variations of the irradiated face of the
secondary star.


title:
Pregalactic Black Hole Formation with an Atomic Hydrogen Equation of
  State

abstract:
  The polytropic equation of state of an atomic hydrogen gas is examined for
primordial halos with baryonic masses of M_h~10^7-10^9 Mo. For roughly
isothermal collapse around 10^4 K, we find that line trapping of Lyman alpha
(HI and HeII) photons causes the polytropic exponent to stiffen to values
significantly above unity. Under the assumptions of zero H2 abundance and very
modest pollution by metals (<10^-4 Solar), fragmentation is likely to be
inhibited for such an equation of state. We argue on purely thermodynamic
grounds that a single black hole of ~0.02-0.003M_h can form at the center of a
halo for z=10-20 when the free-fall time is less than the time needed for a
resonantly scattered Lyman alpha photon to escape from the halo. The absence of
H2 follows naturally from the high, 10^4 K, temperatures that are attained when
Lyman alpha photons are trapped in the dense and massive halos that we
consider. An H2 dissociating UV background is needed if positive feedback
effects on H2 formation from X-rays occur. The black hole to baryon mass
fraction is suggestively close to what is required for these intermediate mass
black holes, of mass M_BH~10^4-10^6 Mo, to act as seeds for forming the
supermassive black holes of mass ~0.001M_spheroid found in galaxies today.


title:
Kinematic Dynamos using Constrained Transport with High Order Godunov
  Schemes and Adaptive Mesh Refinement

abstract:
  We propose to extend the well-known MUSCL-Hancock scheme for Euler equations
to the induction equation modeling the magnetic field evolution in kinematic
dynamo problems. The scheme is based on an integral form of the underlying
conservation law which, in our formulation, results in a ``finite-surface''
scheme for the induction equation. This naturally leads to the well-known
``constrained transport'' method, with additional continuity requirement on the
magnetic field representation. The second ingredient in the MUSCL scheme is the
predictor step that ensures second order accuracy both in space and time. We
explore specific constraints that the mathematical properties of the induction
equations place on this predictor step, showing that three possible variants
can be considered. We show that the most aggressive formulations (referred to
as C-MUSCL and U-MUSCL) reach the same level of accuracy as the other one
(referred to as Runge-Kutta), at a lower computational cost. More
interestingly, these two schemes are compatible with the Adaptive Mesh
Refinement (AMR) framework. It has been implemented in the AMR code RAMSES. It
offers a novel and efficient implementation of a second order scheme for the
induction equation. We have tested it by solving two kinematic dynamo problems
in the low diffusion limit. The construction of this scheme for the induction
equation constitutes a step towards solving the full MHD set of equations using
an extension of our current methodology.


title:
New Precision Orbits of Bright Double-Lined Spectroscopic Binaries. I:
  RR Lyncis, 12 Bootis, and HR 6169

abstract:
  Radial velocities from the 2.1 m telescope at McDonald Observatory
supplemented with radial velocities from the coude' feed telescope at KPNO
provide new precise orbits for the double-lined spectroscopic binaries RR Lyn
(A3/A8/A6), 12 Boo (F8IV), and HR 6169 (A2V). We derive orbital dimensions and
minimum masses with accuracies of 0.06 to 0.9 %. The three systems, which have
V magnitudes of 5.54, 4.83, and 6.42, respectively, are all sufficiently bright
that they are easily within the grasp of modern optical interferometers and so
afford the prospect, when our spectroscopic observations are complemented by
interferometric observations, of fully-determined orbits, precise masses, and
distances. In the case of RR Lyn, which is also a detached eclipsing binary
with a well-determined orbital inclination, we are able to determine the
semimajor axis of the relative orbit, a = 29.32 +/- 0.04 Rsun, primary and
secondary radii of 2.57 +/- 0.02 Rsun and 1.59 +/- 0.03 Rsun, respectively; and
primary and secondary masses of 1.927 +/- 0.008 Msun and 1.507 +/- 0.004 Msun,
respectively. Comparison of our new systemic velocity determination, gamma =
-12.03 +/- 0.04 km/s, with an earlier one, gamma = -11.61 +/- 0.30 km/s, shows
no evidence of any change in the systemic velocity in the 40 years separating
the two measurements, a null result that neither confirms nor contradicts the
presence of the low-mass third component proposed by Khaliullin & Khaliullina
(2002). Our spectroscopic orbit of 12 Boo is more precise that that of Boden et
al. (2005), but confirms their results about this system. Our analysis of HR
6169 has produced a major improvement in its orbital elements. The minimum
masses of the primary and secondary are 2.20 +/- 0.01 and 1.64 +/- 0.02 Msun,
respectively.


title: The Spatial Clustering of Low Luminosity AGN

abstract:
  We present the first multi-parameter analysis of the narrow line AGN
clustering properties. Estimates of the two-point correlation function (CF)
based on SDSS DR2 data reveal that Seyferts are clearly less clustered than
normal galaxies, while the clustering amplitude (r_0) of LINERs is consistent
with that of the parent galaxy population. The similarities in the host
properties (color and concentration index) of Seyferts and LINERs suggest that
the difference in their r_0 is not driven by the morphology-density relation.
We find that the luminosity of [O I] emission shows the strongest influence on
AGN clustering, with low L([O I]) sources having the highest r_0. This trend is
much stronger than the previously detected dependence on L([O III]), which we
confirm. There is a strong correspondence between the clustering patterns of
objects of given spectral type and their physical properties. LINERs, which
exhibit high r_0, show the lowest luminosities and obscuration levels, and
relatively low gas densities (n_e), suggesting that these objects harbor black
holes that are relatively massive yet weakly active or inefficient in their
accretion, probably due to the insufficiency of their fuel supply. Seyferts,
which have low r_0, are luminous and show large n_e, suggesting that their
black holes are less massive but accrete quickly and efficiently enough to
clearly dominate the ionization. The low r_0 of the H II galaxies can be
understood as a consequence of both the morphology-density and star formation
rate-density relations, however, their spectral properties suggest that their
centers hide amidst large amounts of obscuring material black holes of
generally low mass whose activity remains relatively feeble. Our own Milky Way
may be a typical such case.[abridged]


title:
Radio continuum and molecular line observations of four bright-rimmed
  clouds

abstract:
  We present the results of radio continuum and molecular line observations
conducted using the Mopra millimetre-wave telescope and Australia Telescope
Compact Array. These observations reveal the presence of a dense core embedded
within each cloud, and the presence of a layer of hot ionised gas coincided
with their bright-rims. The ionised gas has electron densities significantly
higher than the critical density above which an ionised boundary layer can form
and be maintained, strongly supporting the hypothesis that these clouds are
being photoionised by the nearby OB star(s). From an evaluation of the pressure
balance between the ionised and molecular gas, SFO 58 and SFO 68 are identified
as being in a post-pressure balance state, while SFO 75 and SFO 76 are more
likely to be in a pre-pressure balance state. We find secondary evidence for
the presence of ongoing star formation within SFO 58 and SFO 68, such as
molecular outflows, OH, H$_2$O and methanol masers, and identify a potential
embedded UC HII region, but find no evidence for any ongoing star formation
within SFO 75 and SFO 76. Our results are consistent with the star formation
within SFO 58 and SFO 68 having been triggered by the radiatively driven
implosion of these clouds.


title:
The Properties and Redshift Evolution of Intermediate-Luminosity
  Off-Nuclear X-ray Sources in the Chandra Deep Fields

abstract:
  We analyze a population of intermediate-redshift (z ~ 0.05-0.3), off-nuclear
X-ray sources located within optically-bright galaxies in the Great
Observatories Origins Deep Survey (GOODS) and Galaxy Evolution from Morphology
and SEDs (GEMS) fields. A total of 24 off-nuclear source candidates are
classified using deep Chandra exposures from the Chandra Deep Field-North,
Chandra Deep Field-South, and Extended Chandra Deep Field-South; 15 of these
are newly identified. These sources have average X-ray spectral shapes and
optical environments similar to those observed for off-nuclear
intermediate-luminosity (L_X >~ 10^{39} erg/s in the 0.5-2.0 keV band) X-ray
objects (IXOs; sometimes referred to as ultraluminous X-ray sources [ULXs]) in
the local universe. This sample improves the available source statistics for
intermediate-redshift, off-nuclear sources with L_X >~ 10^{39.5} erg/s, and it
places significant new constraints on the redshift evolution of the off-nuclear
source frequency in field galaxies. The fraction of intermediate-redshift field
galaxies containing an off-nuclear source with L_X >~ 10^{39} erg/s is
suggestively elevated (~80% confidence level) with respect to that observed for
IXOs in the local universe; we calculate this elevation to be a factor of
1.9^{+1.4}_{-1.3}. A rise in this fraction is plausibly expected as a
consequence of the observed increase in global star-formation density with
redshift, and our results are consistent with the expected magnitude of the
rise in this fraction.


title: Streaming Motions Towards the Supermassive Black Hole in NGC 1097

abstract:
  We have used GMOS-IFU and high resolution HST-ACS observations to map, in
unprecedented detail, the gas velocity field and structure within the 0.7 kpc
circumnuclear ring of the SBb LINER/Seyfert 1 galaxy NGC 1097. We find clear
evidence of radial streaming motions associated with spiral structures leading
to the unresolved (<3.5 parsecs) nucleus, which we interpret as part of the
fueling chain by which gas is transported to the nuclear starburst and
supermassive black hole.


title: The age dependence of galaxy clustering

abstract:
  We construct mock galaxy catalogues to analyse clustering properties of a
Lambda cold dark matter (LCDM) universe within a cosmological dark matter
simulation of sufficient resolution to resolve structure down to the scale of
dwarfs. We show that there is a strong age-clustering correlation for objects
likely to host luminous galaxies, which includes the satellite halo (subhalo)
population. Older mock galaxies are significantly more clustered in our
catalog, which consists of satellite haloes as well as the central peaks of
discrete haloes, selected solely by peak circular velocity. This age dependence
is caused mainly by the age-clustering relation for discrete haloes, recently
found by Gao et al., acting mostly on field members, combined with the tendency
for older mock galaxies to lie within groups and clusters, where galaxy
clustering is enhanced. Our results suggest that the clustering age dependence
is manifested in real galaxies. At small scales (less than ~5 Mpc/h), the very
simple assumption that galaxy colour depends solely on halo age is inconsistent
with the strength of the observed clustering colour trends, where red galaxies
become increasingly more clustered than blue galaxies toward smaller scales,
suggesting that luminosity weighted galaxy ages do not closely trace the
assembly epoch of their dark matter hosts. The age dependence is present but is
much weaker for satellite haloes lying within groups and clusters than for the
global population.


title: The Afterglows and Host Galaxies of Short GRBs: An Overview

abstract:
  Despite a rich diversity in observational properties, gamma-ray bursts (GRBs)
can be divided into two broad categories based on their duration and spectral
hardness -- the long-soft and the short-hard GRBs. The discovery of afterglows
from long GRBs in 1997, and their localization to arcsecond accuracy, was a
watershed event. The ensuing decade of intense study led to the realization
that long-soft GRBs are located in star forming galaxies, produce about 10^51
erg in collimated relativistic ejecta, are accompanied by supernovae, and
result from the death of massive stars. While theoretical arguments suggest
that short GRBs have a different physical origin, the lack of detectable
afterglows prevented definitive conclusions. The situation changed dramatically
starting in May 2005 with the discovery of the first afterglows from short GRBs
localized by Swift and HETE-2. Here I summarize the discovery of these
afterglows and the underlying host galaxies, and draw initial conclusions about
the nature of the progenitors and the properties of the bursts.


title: How galaxies lose their angular momentum

abstract:
  The processes are investigated by which gas loses its angular momentum during
the protogalactic collapse phase, leading to disk galaxies that are too compact
with respect to the observations. High-resolution N-body/SPH simulations in a
cosmological context are presented including cold gas and dark matter. A halo
with quiet merging activity since z~3.8 and with a high spin parameter is
analysed that should be an ideal candidate for the formation of an extended
galactic disk. We show that the gas and the dark matter have similar specific
angular momenta until a merger event occurs at z~2 with a mass ratio of 5:1.
All the gas involved in the merger loses a substantial fraction of its specific
angular momentum due to tidal torques and falls quickly into the center.
Dynamical friction plays a minor role,in contrast to previous claims. In fact,
after this event a new extended disk begins to form from gas that was not
involved in the 5:1 merger event and that falls in subsequently. We argue that
the angular momentum problem of disk galaxy formation is a merger problem: in
cold dark matter cosmology substantial mergers with mass ratios of 1:1 to 6:1
are expected to occur in almost all galaxies. We suggest that energetic
feedback processes could in principle solve this problem, however only if the
heating occurs at the time or shortly before the last substantial merger event.
Good candidates for such a coordinated feedback would be a merger-triggered
star burst or central black hole heating. If a large fraction of the low
angular momentum gas would be ejected as a result of these processes, late-type
galaxies could form with a dominant extended disk component, resulting from
late infall, a small bulge-to-disk ratio and a low baryon fraction, in
agreement with observations.


title: Microlensing Sensitivity to Earth-mass Planets in the Habitable Zone

abstract:
  Microlensing is one of the most powerful methods that can detect extrasolar
planets and a future space-based survey with a high monitoring frequency is
proposed to detect a large sample of Earth-mass planets. In this paper, we
examine the sensitivity of the future microlensing survey to Earth-mass planets
located in the habitable zone. For this, we estimate the fraction of Earth-mass
planets that will be located in the habitable zone of their parent stars by
carrying out detailed simulation of microlensing events based on standard
models of the physical and dynamic distributions and the mass function of
Galactic matter. From this investigation, we find that among the total
detectable Earth-mass planets from the survey, those located in the habitable
zone would comprise less than 1% even under a less-conservative definition of
the habitable zone. We find the main reason for the low sensitivity is that the
projected star-planet separation at which the microlensing planet detection
efficiency becomes maximum (lensing zone) is in most cases substantially larger
than the median value of the habitable zone. We find that the ratio of the
median radius of the habitable zone to the mean radius of the lensing zone is
roughly expressed as $d_{\rm HZ}/r_{\rm E}\sim 0.2(m/0.5 M_\odot)^{1/2}$.


title: A simple model for quasar density evolution

abstract:
  It is widely agreed upon that AGN and Quasars are driven by gas accretion
onto a supermassive black hole. The origin of the latter however still remains
an open question. In this work we present the results of an extremely simple
cosmological model combined with an evolutionary scenario in which both the
formation of the black hole as well as the gas accretion onto it are triggered
by major mergers of gas-rich galaxies. Despite its very generous approximations
our model reproduces the quasar density evolution in remarkable agreement with
observations.


title: From Protoplanets to Protolife: The Emergence and Maintenance of Life

abstract:
  Despite great advances in our understanding of the formation of the Solar
System, the evolution of the Earth, and the chemical basis for life, we are not
much closer than the ancient Greeks to an answer of whether life has arisen and
persisted on any other planet. The origin of life as a planetary phenomenon
will probably resist successful explanation as long as we lack an early record
of its evolution and additional examples. It is widely thought that the
geologic record shows that life emerged quickly after the end of prolonged
bombardment of the Earth. New data and simulations contradict that view and
suggest that more than half a billion years of unrecorded Earth history may
have elapsed between the origin of life and LUCA. The impact-driven exchange of
material between the inner planets may have allowed earliest life to be more
cosmopolitan. Indeed, terrestrial life may not have originated on the Earth, or
even on any planet. Smaller bodies, e.g. the parent bodies of primitive
meteorites, offer alternative environments for the origin of life in our Solar
System. The search for past or present life on Mars is an obvious path to
greater enlightenment. The subsurface oceans of some icy satellites of the
outer planets represent the best locales to search for an independent origin of
life in the Solar System because of the high dynamical barriers for transfer,
intense radiation at their surfaces, and thick ice crusts. The ``ultimate''
answer to the abundance of life in the Cosmos will remain the domain of
speculation until we develop observatories capable of detecting habitable
planets - and signs of life - around the nearest million or so stars.


title: The Cosmogony of Super-Massive Black Holes

abstract:
  We report results of a project investigating the growth of super-massive
black holes (BHs) by disk accretion. We find that the BH mass growth is quick
enough to account for the inferred masses in the highest-redshift quasars, and
the growth time is an inverse function of the final BH mass as seems to be
required by recent X-ray surveys.


title: Diffuse Far-ultraviolet Observations of the Taurus Region

abstract:
  Diffuse far-ultraviolet (FUV: 1370-1670 A) flux from the Taurus molecular
cloud region has been observed with the SPEAR/FIMS imaging spectrograph. An FUV
continuum map of the Taurus region, similar to the visual extinction maps,
shows a distinct cloud core and halo region. The dense cloud core, where the
visual extinction is A_v > 1.5, obscures the background diffuse FUV radiation,
while a scattered FUV radiation is seen in and beyond the halo region where A_v
< 1.5. The total intensity of H2 fluorescence in the cloud halo is I_{H2} = 6.5
x 10^4 photons cm^{-2} s^{-1} sr^{-1} in the 1370-1670 A wavelength band. A
synthetic model of the H2 fluorescent emission fits the present observation
best with a hydrogen density n_H = 50 cm^{-3}, H2 column density N(H2) = 0.8 x
10^{20} cm^{-2}, and an incident FUV intensity I_{UV} = 0.2. H2 fluorescence is
not seen in the core presumably because the required radiation flux to induce
fluorescence is unable to penetrate the core region.


title: Notes to Saturn satellites Ijiraq and Kiviuq mutual close encounters

abstract:
  The problem of origin of outer irregular satellites of large planets is
considered. The capture way of their origin most probable, however there is not
detail theory. There are a number of irregular satellites, discovered in recent
time. It gives an ability to investigate the statistics of orbital interaction
and try to reconstruct real collision history of these objects We restrict this
consideration by pair of orbits with close elements: Kiviuq and Ijiraq and
determine period of close encounters between this satellites. It may be
considered as a first step on road to the construction of theory of origin of
the abundant class of irregular satellites.


title: The Formation of Massive Stars

abstract:
  Massive stars have a profound influence on the Universe, but their formation
remains poorly understood. We review the current status of observational and
theoretical research in this field, describing the various stages of an
evolutionary sequence that begins with cold, massive gas cores and ends with
the dispersal and ionization of gas by the newly-formed star. The physical
processes in massive star formation are described and related to their
observational manifestations. Feedback processes and the relation of massive
stars to star cluster formation are also discussed. We identify key
observational and theoretical questions that future studies should address.


title: Inspiral of double black holes in gaseous nuclear disks

abstract:
  We study the inspiral of double black holes orbiting inside a massive
rotationally supported gaseous disk, with masses in the Laser Interferometer
Space Antenna (LISA) window of detectability. 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 the form a close binary. We find that in the early sinking the
black holes loose memory of their initial orbital eccentricity if they
co-rotate with the gaseous disk. As a consequence the massive black holes form
a binary with very low eccentricity. During the inspiral, gravitational capture
of gas by the black holes occurs mainly when they move on circular orbits and
may ignite AGN activity: eccentric orbits imply instead high relative
velocities and weak gravitational focusing.


title:
SPITZER IRS spectra of Virgo early type galaxies: detection of stellar
  silicate emission

abstract:
  We present high signal to noise ratio Spitzer Infrared Spectrograph
observations of 17 Virgo early-type galaxies. The galaxies were selected from
those that define the colour-magnitude relation of the cluster, with the aim of
detecting the silicate emission of their dusty, mass-losing evolved stars. To
flux calibrate these extended sources we have devised a new procedure that
allows us to obtain the intrinsic spectral energy distribution and to
disentangle resolved and unresolved emission within the same object. We have
found that thirteen objects of the sample (76%) are passively evolving galaxies
with a pronounced broad silicate feature which is spatially extended and likely
of stellar origin, in agreement with model predictions. The other 4 objects
(24%) are characterized by different levels of activity. In NGC 4486 (M 87) the
line emission and the broad silicate emission are evidently unresolved and,
given also the typical shape of the continuum, they likely originate in the
nuclear torus. NGC 4636 shows emission lines superimposed on extended (i.e.
stellar) silicate emission, thus pushing the percentage of galaxies with
silicate emission to 82%. Finally, NGC 4550 and NGC 4435 are characterized by
polycyclic aromatic hydrocarbon (PAH) and line emission, arising from a central
unresolved region. A more detailed analysis of our sample, with updated models,
will be presented in a forthcoming paper.


title:
Systematic bias in the estimate of cluster mass and the fluctuation
  amplitude from cluster abundance statistics

abstract:
  We revisit the estimate of the mass fluctuation amplitude, sigma_8, from the
observational X-ray cluster abundance. In particular, we examine the effect of
the systematic difference between the cluster virial mass estimated from the
X-ray spectroscopy, M_{vir, spec}, and the true virial mass of the
corresponding halo, M_{vir}. Mazzotta et al. (2004) recently pointed out the
possibility that alpha_M = M_{vir, spec}/M_{vir} is systematically lower than
unity. We perform the statistical analysis combining the latest X-ray cluster
sample and the improved theoretical models and find that sigma_8 \sim 0.76 +/-
0.01 + 0.50 (1-alpha_M) for 0.5 \le alpha_M \le 1, where the quoted errors are
statistical only. Thus if alpha_M \sim 0.7, the value of sigma_8 from cluster
abundance alone is now in better agreement with other cosmological data
including the cosmic microwave background, the galaxy power spectrum and the
weak lensing data. The current study also illustrates the importance of
possible systematic effects in mapping real clusters to underlying dark halos
which changes the interpretation of cluster abundance statistics.


title:
The source of variable optical emission is localized in the jet of the
  radio galaxy 3C 390.3

abstract:
  We present observational evidence for the link between variability of the
radio emission of the relativistic jet and optical continuum emission in the
radio galaxy 3C 390.3 which indicates that the source of variable non-thermal
continuum radiation is located in the innermost part of the relativistic jet.
We suggest that the continuum emission from the jet ionizes material in a
subrelativistic outflow surrounding the jet, which results in a formation of a
conical region with broad emission lines at a distance of about 0.4 parsecs
from the central nucleus.


title:
The old anticentre open cluster Berkeley 32: membership and fundamental
  parameters

abstract:
  We have obtained medium-low resolution spectroscopy and BVI CCD imaging of
Berkeley 32, an old open cluster which lies in the anticentre direction. From
the radial velocities of 48 stars in the cluster direction we found that 31 of
them, in crucial evolutionary phases, are probable cluster members, with an
average radial velocity of +106.7 (sigma = 8.5) km/s. From isochrone fitting to
the colour magnitude diagrams of Berkeley 32 we have obtained an age of 6.3
Gyr, (m-M)0 = 12.48 and E(B-V) = 0.10. The best fit is obtained with Z=0.008. A
consistent distance, (m-M)0 ~= 12.6 +/- 0.1, has been derived from the mean
magnitude of red clump stars with confirmed membership; we may assume (m-M)0 ~=
12.55 +/- 0.1. The colour magnitude diagram of the nearby field observed to
check for field stars contamination looks intriguingly similar to that of the
Canis Major overdensity.


title:
The Optical Gravitational Lensing Experiment. Internet Access to the
  OGLE Photometry Data Set: OGLE-II BVI maps and I-band data

abstract:
  We present on-line, interactive interface to the whole I-band photometry data
set obtained in the second phase of the OGLE project (OGLE-II). The raw
photometric database is accessed through an additional database using MySQL
engine, allowing to select objects fulfilling any set of criteria including
RA/Dec coordinates, mean brightness, error etc. The results of the queries can
be browsed on-line, the light curves can be plotted interactively, the
photometric data can be downloaded for the total of over 10^10 measurements of
more than 40 million objects in the Galactic bulge and the Magellanic Clouds
collected during OGLE-II. The MySQL database of parameters also includes the
complete data set of the previously published photometric BVI maps of OGLE-II
targets, allowing to interactively select objects from these maps.


title:
Shrinking of Cluster Ellipticals: a Tidal Stripping explanation and
  Implications for the Intra-Cluster Light

abstract:
  We look for evidence of tidal stripping in elliptical galaxies through the
analysis of homogeneous CCD data corresponding to a sample of 228 elliptical
galaxies belonging to 24 clusters of galaxies at $0.015<z<0.080$. We
investigate departures from the standard magnitude-isophotal size relation, as
a function of environmental (cluster-centric distance, local galaxy density)
and structural (cluster velocity dispersion, Bautz-Morgan type) properties. We
find that, for any particular galaxy luminosity, the ellipticals in the inner
and denser regions of the clusters are about 5% smaller than those in the outer
regions, which is in good agreement with the finding of Strom & Strom (1978)
based on photographic photometry. The null hypothesis (ie., galaxy sizes are
independent of the cluster-centric distance or density) is rejected at a
significance level of better than 99.7%. Numericals models of Aguilar & White
(1986) predict that tidal stripping can lead to changes in the whole structure
of ellipticals producing shrinkage and brightening of the galaxy, qualitatively
consistent with our measurements and also with the findings of Trujillo et al.
(2002), that more centrally concentrated ellipticals populate denser regions.
Our observational results can be interpreted as evidence for stripping of stars
from ellipticals in the central/denser regions of clusters, contributing to the
intra-cluster light observed in these structures.


title:
SDSS J143030.22-001115.1: A misclassified narrow-line Seyfert 1 galaxy
  with flat X-ray spectrum

abstract:
  We used multi-component profiles to model H$\beta$ and [O III]$\lambda
\lambda $4959,5007 lines for SDSS J143030.22-001115.1, a narrow-line Seyfert 1
galaxy (NLS1) in a sample of 150 NLS1s candidates selected from the Sloan
Digital Sky Survey (SDSS) Early Data Release (EDR). After subtracting the
H$\beta$ contribution from narrow line regions (NLRs), we found that its full
width half maximum (FWHM) of broad H$\beta$ line is nearly 2900 \kms,
significantly larger than the customarily adopted criterion of 2000 \kms. With
its weak Fe II multiples, we think that SDSS J143030.22-001115.1 can't be
classified as a genuine NLS1. When we calculate the virial black hole masses of
NLS1s, we should use the H$\beta$ linewidth after subtracting the H$\beta$
contribution from NLRs.


title: An optical-IR jet in 3C133

abstract:
  We report the discovery of a new optical-IR synchrotron jet in the radio
galaxy 3C133 from our HST/NICMOS snapshot survey. The jet and eastern hotspot
are well resolved, and visible at both optical and IR wavelengths. The IR jet
follows the morphology of the inner part of the radio jet, with three distinct
knots identified with features in the radio. The radio-IR SED's of the knots
are examined, along with those of two more distant hotspots at the eastern
extreme of the radio feature. The detected emission appears to be synchrotron,
with peaks in the NIR for all except one case, which exhibits a power-law
spectrum throughout.


title: Photon Bubbles and the Vertical Structure of Accretion Disks

abstract:
  We consider the effects of "photon bubble" shock trains on the vertical
structure of radiation pressure-dominated accretion disks. These density
inhomogeneities are expected to develop spontaneously in radiation-dominated
accretion disks where magnetic pressure exceeds gas pressure, even in the
presence of magnetorotational instability. They increase the rate at which
radiation escapes from the disk, and may allow disks to exceed the Eddington
limit by a substantial factor. We first generalize the theory of photon bubbles
to include the effects of finite optical depths and radiation damping.
Modifications to the diffusion law at low optical depth tend to fill in the
low-density regions of photon bubbles, while radiation damping inhibits the
formation of photon bubbles at large radii, small accretion rates, and small
heights above the equatorial plane. Accretion disks dominated by photon bubble
transport may reach luminosities of 10 to >100 times the Eddington limit (L_E),
depending on the mass of the central object, while remaining geometrically
thin. However, photon bubble-dominated disks with alpha-viscosity are subject
to the same thermal and viscous instabilities that plague standard radiation
pressure-dominated disks, suggesting that they may be intrinsically unsteady.
Photon bubbles can lead to a "core-halo" vertical disk structure. In
super-Eddington disks the halo forms the base of a wind, which carries away
substantial energy and mass, but not enough to prevent the luminosity from
exceeding L_E. Photon bubble-dominated disks may have smaller color corrections
than standard accretion disks of the same luminosity. They remain viable
contenders for some ultraluminous X-ray sources and may play a role in the
rapid growth of supermassive black holes at high redshift.


title: No Higher Criticism of the Bianchi Corrected WMAP Data

abstract:
  Motivated by the success of the Bianchi VII_h model in addressing many of the
anomalies observed in the WMAP data (Jaffe et al.), we present calculations in
real and in wavelet space of the Higher Criticism statistic of the Bianchi
corrected Wilkinson Microwave Anisotropy Probe (WMAP) first year data. At the
wavelet scale of 5 degrees the Higher Criticism of the WMAP map drops from a
value above the 99% c.l. to a value below the 68% c.l. when corrected by the
Bianchi template. An important property of the Higher Criticism statistic is
its ability to locate the pixels that account for the deviation from
Gaussianity. The analysis of the uncorrected WMAP data pointed to a cold spot
in the southern hemisphere centered at (l,b)~ (209, -57). The Higher Criticism
of the Bianchi corrected map indicates that this spot remains prominent, albeit
at a level completely consistent with Gaussian statistics. Consequently, it is
debatable how much emphasis should be placed on this residual feature, but we
consider the effect of modestly increasing the scaling of the template. A
factor of only 1.2 renders the spot indistinguishable from the background
level, with no noticeable impact on the results published in Jaffe et al. for
the low-l anomalies, large-scale power asymmetry or wavelet kurtosis. A trivial
interpretation would be that the Bianchi template may require a small
enhancement of power on scales corresponding to the wavelet scale of 5 degrees.


title:
On the Formation and Progenitor of PSR J0737-3039: New Constraints on
  the Supernova Explosion Forming Pulsar B

abstract:
  We revisit the formation of PSR J0737-3039, taking into account the most
recent observational constraints. We show that the most likely kick velocity
and progenitor parameters depend strongly on the consideration of the full
five-dimensional PDF for the magnitude and direction of the kick velocity
imparted to pulsar B at birth, the mass of pulsar B's pre-supernova helium star
progenitor, and the pre-supernova orbital separation, and on the adopted prior
assumptions. The priors consist of the transverse systemic velocity, the age of
the system, and the treatment of the unknown radial velocity. Since the latter
cannot be determined from observation, we adopt a statistical approach and use
theoretical radial-velocity distributions obtained from population synthesis
calculations for coalescing double neutron stars. We find that the prior
assumptions about the pre-supernova helium star mass affect the derived most
likely parameters significantly: when the minimum helium star mass required for
neutron star formation is assumed to be 2.1Msun, the most likely kick velocity
ranges from 70-180km/s; when masses lower than 2.1Msun are assumed to allow
neutron star formation, the most likely kick velocity can be as low as a few
km/s, although the majority of the considered models still yield most likely
kick velocities of 50-170km/s. We also show that the proximity of the double
pulsar to the Galactic plane and the small proper motion do not pose stringent
constraints on the kick velocity and progenitor mass of pulsar B. Instead, the
constraints imposed by the orbital dynamics of asymmetric supernova explosions
turn out to be much more restrictive. We conclude that the currently available
observational constraints cannot be used to favor a specific core-collapse and
neutron star formation mechanism. (abridged)


title: Observations of high energy neutrinos with water/ice neutrino telescopes

abstract:
  The search for high energy neutrinos of astrophysical origin is being
conducted today with two water/ice Cherenkov experiments. New instruments of
higher performance are now in construction and more are in the R&D phase. No
sources have been found to date. Upper limits on neutrino fluxes are
approaching model predictions. Results are reported on the search for point
sources, diffuse fluxes, gamma ray bursts, dark matter and other sources.


title: Spatial clustering of USS sources and galaxies

abstract:
  We present measurements of the clustering properties of galaxies in the field
of redshift range $0.5 \lesssim z \lesssim 1.5$ Ultra Steep Spectrum (USS)
radio sources selected from Sydney University Molonglo Sky Survey and NRAO VLA
Sky Survey. Galaxies in these USS fields were identified in deep near-IR
observations, complete down to $K_s=20$, using {\tt IRIS2} instrument at the
AAT telescope. We used the redshift distribution of $K_{s} < 20$ galaxies taken
from Cimatti et al. (2002) to constrain the correlation length $r_0$. We find a
strong correlation signal of galaxies with $K_{s} < 20$ around our USS sample.
A comoving correlation length $r_{0}=14.0\pm2.8$ $h^{-1}$ Mpc and
$\gamma=1.98\pm0.15$ are derived in a flat cosmological model Universe. We
compare our findings with those obtained in a cosmological N--body simulation
populated with GALFORM semi-analytic galaxies. We find that clusters of
galaxies with masses in the range $M=10^{13.4-14.2}$ $h^{-1}$ M$_{\sun}$ have a
cluster--galaxy cross--correlation amplitude comparable to those found between
USS hosts and galaxies. These results suggest that distant radio galaxies are
excellent tracers of galaxy overdensities and pinpoint the progenitors of
present day rich clusters of galaxies.


title:
Dark and Baryonic Matter in Bright Spiral Galaxies: II. Radial
  Distributions for 34 Galaxies

abstract:
  We decompose the rotation curves of 34 bright spiral galaxies into baryonic
and dark matter components. Stellar mass profiles are created by applying
color-M/L relations to near-infrared and optical photometry. We find that the
radial profile of the baryonic-to-dark-matter ratio is self-similar for all
galaxies, when scaled to the radius where the contribution of the baryonic mass
to the rotation curve equals that of the dark matter (R_X). We argue that this
is due to the quasi-exponential nature of disks and rotation curves that are
nearly flat after an initial rise. The radius R_X is found to correlate most
strongly with baryonic rotation speed, such that galaxies with R_X measurements
that lie further out in their disks rotate faster. This quantity also
correlates very strongly with stellar mass, Hubble type, and observed rotation
speed; B-band central surface brightness is less related to R_X than these
other galaxy properties. Most of the galaxies in our sample appear to be close
to maximal disk. For these galaxies, we find that maximum observed rotation
speeds are tightly correlated with maximum rotation speeds predicted from the
baryon distributions, such that one can create a Tully-Fisher relation based on
surface photometry and redshifts alone. Finally, we compare our data to the NFW
parameterization for dark matter profiles with and without including adiabatic
contraction as it is most commonly implemented. Fits are generally poor, and
all but 2 galaxies are better fit if adiabatic contraction is not performed. In
order to have better fits, and especially to accommodate adiabatic contraction,
baryons would need to contribute very little to the total mass in the inner
parts of galaxies, seemingly in contrast with other observational constraints.


title:
Dark and Baryonic Matter in Bright Spiral Galaxies: I.Near-infrared and
  Optical Broadband Surface Photometry of 30 Galaxies

abstract:
  We present photometrically calibrated images and surface photometry in the B,
V, R, J, H, and K-bands of 25, and in the g, r, and K-bands of 5 nearby bright
(Bo_T<12.5 mag) spiral galaxies with inclinations between 30-65 degrees
spanning the Hubble Sequence from Sa to Scd. Data are from The Ohio State
University Bright Spiral Galaxy Survey, the Two Micron All Sky Survey, and the
Sloan Digital Sky Survey Second Data Release. Radial surface brightness
profiles are extracted, and integrated magnitudes are measured from the
profiles. Axis ratios, position angles, and scale lengths are measured from the
near-infrared images. A 1-dimensional bulge/disk decomposition is performed on
the near-infrared images of galaxies with a non-negligible bulge component, and
an exponential disk is fit to the radial surface brightness profiles of the
remaining galaxies.


title:
Multi-scale simulations of merging galaxies with supermassive black
  holes

abstract:
  We present the results of the first multi-scale N-Body+SPH simulations of
merging galaxies containing central supermassive black holes (SMBHs) and having
a spatial resolution of only a few parsecs. Strong gas inflows associated with
equal-mass mergers produce non-axisymmetric nuclear disks with masses of order
$10^9 M_{\odot}$, resolved by about $10^6$ SPH particles. Such disks have sizes
of several hundred parsecs but most of their mass is concentrated within less
than $50$ pc. We find that a close SMBH pair forms after the merger. The
separation of the two SMBHs then shrinks further owing to dynamical friction
against the predominantly gaseous background. The orbits of the SMBHs decay
down to the minimum resolvable scale in a few million years for an ambient gas
temperature and density typical of a region undergoing a starburst. These
results suggest the initial conditions necessary for the eventual coalescence
of the two holes arise naturally from the merging of two equal-mass galaxies
whose structure and orbits are consistent with the predictions of the
$\Lambda$CDM model. Our findings have important implications for planned
gravitational wave detection experiments such as {\it LISA}.


title: Microwave emission from spinning dust in circumstellar disks

abstract:
  In the high density environments of circumstellar disks dust grains are
expected to grow to large sizes by coagulation. Somewhat unexpectedly, recent
near-IR observations of PAH features from disks around Herbig Ae/Be stars
demonstrate that substantial amount of dust mass in these disks (up to several
tens of per cent of the total carbon content) can be locked up in particles
with sizes ranging from several to tens of nanometers. We investigate the
possibility of detecting the electric dipole emission produced by these
nanoparticles as they spin at thermal rates (tens of GHz) in cold gas. We show
that such emission peaks in the microwave range and dominates over the thermal
disk emission at \nu < 50 GHz typically by a factor of several if > 5 % of the
total carbon abundance is locked up in nanoparticles. We test the sensitivity
of this prediction to various stellar and disk parameters and show that if the
potential contamination of the spinning dust component by the free-free and/or
synchrotron emission can be removed, then the best chances of detecting this
emission would be in disks with small opacity, having SEDs with steep sub-mm
slopes (which minimizes thermal disk emission at GHz frequencies). Detection of
the spinning dust emission would provide important evidence for the existence,
properties, and origin of the population of small dust particles in
protoplanetary disks, with possible ramifications for planet formation.


title: The matter power spectrum in f(R) gravity

abstract:
  Modified gravity can be considered as an alternative to dark energy. In a
generalized theory of gravity, the universe may accelerate while containing
only baryonic and dark matter. We study, in particular, the evolution of matter
fluctuations in f(R) models within the Palatini approach, and find that the
resulting matter power spectrum is sensitive to a nonlinear dependence on the
curvature scalar in the gravitational action. The constraints that arise from
comparison to the form of the observed matter power spectrum tighten the
previous constraints derived from background expansion by several orders of
magnitude. Models in the allowed parameter space are practically
indistinguishable from general relativity with a cosmological constant when the
backround expansion is considered.


title:
CIRS: Cluster Infall Regions in the Sloan Digital Sky Survey I. Infall
  Patterns and Mass Profiles

abstract:
  We use the Fourth Data Release of the Sloan Digital Sky Survey to test the
ubiquity of infall patterns around galaxy clusters and measure cluster mass
profiles to large radii. We match X-ray cluster catalogs with SDSS, search for
infall patterns, and compute mass profiles for a complete sample of X-ray
selected clusters. Very clean infall patterns are apparent in most of the
clusters, with the fraction decreasing with increasing redshift due to
shallower sampling. All 72 clusters in a well-defined sample limited by
redshift (ensuring good sampling) and X-ray flux (excluding superpositions)
show infall patterns sufficient to apply the caustic technique. This sample is
by far the largest sample of cluster mass profiles extending to large radii to
date. Similar to CAIRNS, cluster infall patterns are better defined in
observations than in simulations. Further work is needed to determine the
source of this difference. We use the infall patterns to compute mass profiles
for 72 clusters and compare them to model profiles. Cluster scaling relations
using caustic masses agree well with those using X-ray or virial mass
estimates, confirming the reliability of the caustic technique. We confirm the
conclusion of CAIRNS that cluster infall regions are well fit by NFW and
Hernquist profiles and poorly fit by singular isothermal spheres. This much
larger sample enables new comparisons of cluster properties with those in
simulations. The shapes (specifically, NFW concentrations) of the mass profiles
agree well with the predictions of simulations. The mass inside the turnaround
radius is on average 2.19$\pm$0.18 times that within the virial radius. This
ratio agrees well with recent predictions from simulations of the final masses
of dark matter haloes.


title: A low density of 0.8 g/cc for the Trojan binary asteroid 617 Patroclus

abstract:
  The Trojan population consists of two swarms of asteroids following the same
orbit as Jupiter and located at the L4 and L5 Lagrange points of the
Jupiter-Sun system (leading and following Jupiter by 60 degrees). The asteroid
617 Patroclus is the only known binary Trojan (Merline et al. 2001). The orbit
of this double system was hitherto unknown. Here we report that the components,
separated by 680 km, move around the system centre of mass, describing roughly
a circular orbit. Using the orbital parameters, combined with thermal
measurements to estimate the size of the components, we derive a very low
density of 0.8 g/cc. The components of Patroclus are therefore very porous or
composed mostly of water ice, suggesting that they could have been formed in
the outer part of the solar system.


title: Evolution of Rotating Molecular Cloud Core with Oblique Magnetic Field

abstract:
  We studied the collapse of rotating molecular cloud cores with inclined
magnetic fields, based on three-dimensional numerical simulations.The numerical
simulations start from a rotating Bonnor-Ebert isothermal cloud in a uniform
magnetic field. The magnetic field is initially taken to be inclined from the
rotation axis. As the cloud collapses, the magnetic field and rotation axis
change their directions. When the rotation is slow and the magnetic field is
relatively strong, the direction of the rotation axis changes to align with the
magnetic field, as shown earlier by Matsumoto & Tomisaka. When the magnetic
field is weak and the rotation is relatively fast, the magnetic field inclines
to become perpendicular to the rotation axis. In other words, the evolution of
the magnetic field and rotation axis depends on the relative strength of the
rotation and magnetic field. Magnetic braking acts to align the rotation axis
and magnetic field, while the rotation causes the magnetic field to incline
through dynamo action. The latter effect dominates the former when the ratio of
the angular velocity to the magnetic field is larger than a critical value
\Omega_0/ B_0 > 0.39 G^1/2 c_s^-1, where B_0, \Omega_0, G, and c_s^-1 denote
the initial magnetic field, initial angular velocity, gravitational constant,
and sound speed, respectively. When the rotation is relatively strong, the
collapsing cloud forms a disk perpendicular to the rotation axis and the
magnetic field becomes nearly parallel to the disk surface in the high density
region. A spiral structure appears due to the rotation and the wound-up
magnetic field in the disk.


title:
Gravitational Microlensing Influence on X-ray Radiation from Accretion
  Disk of Active Galaxies

abstract:
  Gravitational microlensing is a very useful tool for investigating the
innermost part of lensed quasars, especially for studying a relativistic
accretion disk around a massive black hole (BH) supposed to exist in a quasar's
center. Here we present a short overview of our recent investigations in this
field.


title:
delta Ceti is not monoperiodic: seismic modeling of a beta Cephei star
  from MOST spacebased photometry

abstract:
  The beta Cephei star delta Ceti was considered one of the few monoperiodic
variables in the class. Despite (or perhaps because of) its apparently simple
oscillation spectrum, it has been challenging and controversial to identify
this star's pulsation mode and constrain its physical parameters seismically.
Broadband time-resolved photometry of delta Ceti spanning 18.7 days with a duty
cycle of about 65% obtained by the MOST (Microvariability & Oscillations of
STars) satellite -- the first scientific observations ever obtained by MOST --
reveals that the star is actually multiperiodic. Besides the well-known
dominant frequency of f1 = 6.205886/d, we have discovered in the MOST data its
first harmonic 2f1 and three other frequencies (f2 = 3.737/d, f3 = 3.673/d and
f4 = 0.318/d), all detected with S/N > 4. In retrospect, f2 was also present in
archival spectral line profile data but at lower S/N. We present seismic models
whose modes match exactly the frequencies f1 and f2. Only one model falls
within the common part of the error boxes of the star's observed surface
gravity and effective temperature from photometry and spectroscopy. In this
model, f1 is the radial (l = 0) first overtone and f2 is the g2 (l = 2, m = 0)
mode. This model has a mass of 10.2+/-0.2 Msun and an age of 17.9+/-0.3 million
years, making delta Ceti an evolved beta Cephei star. If f2 and f3 are
rotationally split components of the same g2 mode, then the star's equatorial
rotation velocity is either 27.6 km/s or half this value. Given its vsini of
about 1 km/s, this implies we are seeing delta Ceti nearly pole-on.


title:
Amplitude variability or close frequencies in pulsating stars? The Delta
  Scuti star FG Vir

abstract:
  The nature of the observed amplitude variability of several modes in the
Delta Scuti star FG Vir is examined. In this star, three frequencies show
strong amplitude and phase variations. In the power spectrum, these frequencies
also show up as frequency doublets. However, since true amplitude variability
of a single frequency can also lead to (false) frequency doublets in the power
spectrum, a specific test examining in detail the observed amplitude and phase
variations of an assumed single frequency is applied. For the frequencies at
12.15 and 23.40 cycle/day it is shown that amplitude variability of a single
mode can be ruled out. In particular, an important property of beating between
two modes is fulfilled: the amplitude and phase vary synchronously with a phase
shift close to 90 degrees. The origin of the amplitude variability of a third
mode, viz. near 19.86 c/d, is not clear due to the long beat period of 20+
years, for which the amplitude/phase test suffers from gaps in the coverage.
However, even for this frequency the amplitude variations can be expressed well
by a mathematical two-mode model.
  If we examine these three close frequency pairs together with other (usually
more widely separated) close frequencies in FG Vir, 18 pairs of frequencies
with separations closer than 0.10 c/d have been detected. It is shown that the
majority of the pairs occur near the theoretically expected frequencies of
radial modes. Mode identifications are available for only a few modes: the only
detected radial mode at 12.15 c/d is part of a close pair.
  It is shown that accidental agreements between the frequencies of excited
modes can be ruled out because of the large number of detected close frequency
doublets.


title: The merger rate of massive galaxies

abstract:
  We calculate the projected two point correlation function for samples of
luminous and massive galaxies in the COMBO-17 photometric redshift survey,
focusing particularly on the amplitude of the correlation function at small
projected radii and exploring the constraints such measurements can place on
the galaxy merger rate. For nearly volume-limited samples with 0.4<z<0.8, we
find that 4+/-1% of luminous M_B<-20 galaxies are in close physical pairs (with
real space separation of <30 proper kpc). The corresponding fraction for
massive galaxies with M_*>2.5e10 M_sun is 5+/-1%. Incorporating close pair
fractions from the literature, the 2dFGRS and the SDSS, we find a fairly rapid
evolution of the merger fraction of massive galaxies between z=0.8 and the
present day. Assuming that the major merger timescale is of order the dynamical
timescale for close massive galaxy pairs, we tentatively infer that ~50% (70%)
of all galaxies with present-day masses M_*>5e10 M_sun (remnants of mergers
between galaxies with M_*>2.5e10 M_sun) have undergone a major merger since
z=0.8(1): major mergers between massive galaxies are a significant driver of
galaxy evolution over the last eight billion years.


title: The Tully-Fisher relations of the Eridanus group of galaxies

abstract:
  The Tully-Fisher (TF) or the luminosity line-width relations of the galaxies
in the Eridanus group are constructed using the HI rotation curves and the
luminosities in the optical and in the near-infrared bands. The slopes of the
TF relations (absolute magnitude vs log2V_{flat}) are -8.6\pm1.1, -10.0\pm1.5,
-10.7\pm2.1, and -9.7\pm1.3 in the R, J, H, and K bands respectively for
galaxies having flat HI rotation curves. These values of the slopes are
consistent with those obtained from studies of other groups and clusters. The
scatter in the TF relations is in the range 0.5 - 1.1 mag in different bands.
This scatter is considerably larger compared to those observed in other groups
and clusters. It is suggested that the larger scatter in the TF relations for
the Eridanus group is related to the loose structure of the group. If the TF
relations are constructed using the baryonic mass (stellar + HI + Helium mass)
instead of the stellar luminosity, nearly identical slopes are obtained in the
R and in the near-infrared bands. The baryonic TF (baryonic mass vs
log2V_{flat}) slope is in the range 3.5 - 4.1.


title:
The dynamics of the radiative envelope of rapidly rotating stars. I. A
  spherical Boussinesq model

abstract:
  Context: The observations of rapidly rotating stars are increasingly detailed
and precise thanks to interferometry and asteroseismology; two-dimensional
models taking into account the hydrodynamics of these stars are very much
needed.
  Aims: A model for studying the dynamics of baroclinic stellar envelope is
presented.
  Methods: This models treats the stellar fluid at the Boussinesq approximation
and assumes that it is contained in a rigid spherical domain. The temperature
field along with the rotation of the system generate the baroclinic flow.
  Results: We manage to give an analytical solution to the asymptotic problem
at small Ekman and Prandtl numbers. We show that, provided the Brunt-Vaisala
frequency profile is smooth enough, differential rotation of a stably
stratified envelope takes the form a fast rotating pole and a slow equator
while it is the opposite in a convective envelope. We also show that at low
Prandtl numbers and without $\mu$-barriers, the jump in viscosity at the
core-envelope boundary generates a shear layer staying along the tangential
cylinder of the core. Its role in mixing processes is discussed.
  Conclusions: Such a model provides an interesting tool for investigating the
fluid dynamics of rotating stars in particular for the study of the various
instabilities affecting baroclinic flows or, even more, of a dynamo effect.


title: Dust in Proto-Planetary Disks: Properties and Evolution

abstract:
  We review the properties of dust in protoplanetary disks around optically
visible pre-main sequence stars obtained with a variety of observational
techniques, from measurements of scattered light at visual and infrared
wavelengths to mid-infrared spectroscopy and millimeter interferometry. A
general result is that grains in disks are on average much larger than in the
diffuse interstellar medium (ISM). In many disks, there is evidence that a
large mass of dust is in grains with millimeter and centimeter sizes, more
similar to "sand and pebbles" than to grains. Smaller grains (with
micron-sizes) exist closer to the disk surface, which also contains much
smaller particles, e.g., polycyclic aromatic hydrocarbons. There is some
evidence of a vertical stratification, with smaller grains closer to the
surface. Another difference with ISM is the higher fraction of crystalline
relative to amorphous silicates found in disk surfaces. There is a large
scatter in dust properties among different sources, but no evidence of
correlation with the stellar properties, for samples that include objects from
intermediate to solar mass stars and brown dwarfs. There is also no apparent
correlation with the age of the central object, over a range roughly between 1
and 10 Myr. This suggests a scenario where significant grain processing may
occur very early in the disk evolution, possibly when it is accreting matter
from the parental molecular core. Further evolution may occur, but not
necessarily rapidly, since we have evidence that large amounts of grains, from
micron to centimeter size, can survive for periods as long as 10 Myr.


title: Collisions and close encounters involving massive main-sequence stars

abstract:
  We study close encounters involving massive main sequence stars and the
evolution of the exotic products of these encounters as common--envelope
systems or possible hypernova progenitors. We show that parabolic encounters
between low-- and high--mass stars and between two high--mass stars with small
periastrons result in mergers on timescales of a few tens of stellar freefall
times (a few tens of hours). We show that such mergers of unevolved low--mass
stars with evolved high--mass stars result in little mass loss ($\sim0.01$
M$_{\odot}$) and can deliver sufficient fresh hydrogen to the core of the
collision product to allow the collision product to burn for several million
years. We find that grazing encounters enter a common--envelope phase which may
expel the envelope of the merger product. The deposition of energy in the
envelopes of our merger products causes them to swell by factors of $\sim100$.
If these remnants exist in very densely-populated environments
($n\gtrsim10^{7}$ pc$^{-3}$), they will suffer further collisions which may
drive off their envelopes, leaving behind hard binaries. We show that the
products of collisions have cores rotating sufficiently rapidly to make them
candidate hypernova/gamma--ray burst progenitors and that $\sim0.1%$ of massive
stars may suffer collisions, sufficient for such events to contribute
significantly to the observed rates of hypernovae and gamma--ray bursts.


title:
The Source of Mass Accreted by the Central Black Hole in Cooling Flow
  Clusters

abstract:
  This paper reports the study of the cold-feedback heating in cooling flow
clusters. In the cold-feedback model the mass accreted by the central black
hole originates in non-linear over-dense blobs of gas residing in an extended
region (r ~ 5-30 kpc); these blobs are originally hot, but then cool faster
than their environment and sink toward the center. The intra-cluster medium
(ICM) entropy profile must be shallow for the blobs to reach the center as cold
blobs. I build a toy model to explore the role of the entropy profile and the
population of dense blobs in the cold-feedback mechanism. The mass accretion
rate by the central black hole is determined by the cooling time of the ICM,
the entropy profile, and the presence of inhomogeneities. The mass accretion
rate determines the energy injected by the black hole back to the ICM. These
active galactic nucleus (AGN) outbursts not only heat the ICM, but also change
the entropy profile in the cluster and cause inhomogeneities that are the seeds
of future dense blobs. Therefore, in addition to the ICM temperature (or
energy), the ICM entropy profile and ICM inhomogeneities are also ingredients
in the feedback mechanism.


title: Post-Outburst Phase of McNeil's Nebula (V1647 Orionis)

abstract:
  We present a detailed study of the post-outburst phase of McNeil's nebula
(V1647 Ori) using optical B,V,R,I and NIR J,H,K photometric and low resolution
optical spectroscopic observations. The observations were carried out with the
HFOSC, NIRCAM, TIRCAM and NICMOS cameras on the 2m HCT and 1.2m PRL telescopes
during the period 2004 Feb-2005 Dec. The optical/NIR observations show a
general decline in brightness of the exciting source of McNeil's nebula (V1647
Ori). Our recent optical images show that V1647 Ori has faded by more than 3
mags since Feb 2004. The optical/NIR photometric data also show a significant
variation in the mags (Delta V = 0.78 mag, Delta R = 0.44 mag, Delta I = 0.21
mag, Delta J = 0.24 mag and Delta H = 0.20 mag) of V1647 Ori within a period of
one month, which is possibly undergoing a phase similar to eruptive variables,
like EXors or FUors. The optical spectra show a few features such as strong
Halpha emission with blue-shifted absorption and the CaII IR triplet (8498A,
8542A and 8662A) in emission. As compared to the period just after outburst,
there is a decrease in the depth and extent of the blue-shifted absorption
component, indicating a weakening in the powerful stellar wind. The presence of
the CaII IR triplet in emission confirms that V1647 Ori is a PMS star. The
long-term, post-outburst photometric observations of V1647 Ori suggest an EXor,
rather than an FUor event. An optical/IR comparison of the region surrounding
McNeil's nebula shows that the optical nebula is more widely and predominantly
extended to the north, whereas the IR nebula is relatively confined (dia ~ 60
arcsec), but definitely extended, to the south, too.


title: Luminosity function of contact binaries based on the ASAS survey

abstract:
  The luminosity function for contact binary stars of the W~UMa-type is
evaluated on the basis of the ASAS photometric project covering all stars south
of delta= +28 within a magnitude range 8<V<13. Lack of colour indices enforced
a limitation to 3373 systems with P<0.562 days (i.e. 73% of all systems with
P<1 day) where a simplified Mv(log P) calibration could be used. The spatial
density relative to the main sequence FGK stars of 0.2%, as established
previously from the Hipparcos sample to V=7.5, is confirmed. While the numbers
of contact binaries in the ASAS survey are large and thus the statistical
uncertainties small, derivation of the luminosity function required a
correction for missed systems with small amplitudes and with orbital periods
longer than 0.562 days; the correction, by a factor of 3 times, carries an
uncertainty of about 30%.


title:
Relative velocities among accreting planetesimals in binary systems: the
  circumprimary case

abstract:
  We investigate classical planetesimal accretion in a binary star system of
separation ab<50AU by numerical simulations, with particular focus on the
region at a distance of 1 AU from the primary. The planetesimals orbit the
primary, are perturbed by the companion and are in addition subjected to a gas
drag force. We concentrate on the problem of relative velocities dv among
planetesimals of different sizes. For various stellar mass ratios and binary
orbital parameters we determine regions where dv exceed planetesimal escape
velocities v_esc (thus preventing runaway accretion) or even the threshold
velocity v_ero for which erosion dominates accretion. Gaseous friction has two
crucial effects on the velocity distribution: it damps secular perturbations by
forcing periastron alignment of orbits, but at the same time the
size--dependence of this orbital alignment induces a significant dv increase
between bodies of different sizes. This differential phasing effect proves very
efficient and almost always increases dv to values preventing runaway
accretion, except in a narrow domain of almost circular companion orbits. The
erosion threshold dv>v_ero is reached in a wide (ab,eb) space for small (<10km)
planetesimals, but in a much more limited region for bigger ~50km objects. In
the intermediate v_esc<dv < v_ero domain, a possible growth mode would be the
type II runaway growth identified by Kortenkmap et al.(2001)


title: Strangeness in Compact Stars

abstract:
  Astrophysicists distinguish between three different types of compact stars.
These are white dwarfs, neutron stars, and black holes. The former contain
matter in one of the densest forms found in the Universe. This feature,
together with the unprecedented progress in observational astronomy, makes such
stars superb astrophysical laboratories for a broad range of exciting physical
studies. This article studies the role of strangeness for compact star
phenomenology. Strangeness is carried by hyperons, mesons, H-dibaryons, and
strange quark matter, and may leave its mark in the masses, radii, cooling
behavior, surface composition and the spin evolution of compact stars.


title:
Hubble Space Telescope Observations of SV Cam: II. First Derivative
  Lightcurve Modelling using PHOENIX and ATLAS Model Atmospheres

abstract:
  The variation of the specific intensity across the stellar disc is essential
input parameter in surface brightness reconstruction techniques such as Doppler
imaging, where the relative intensity contributions of different surface
elements are important in detecting starspots. We use PHOENIX and ATLAS model
atmospheres to model lightcurves derived from high precision (S/N ~ 5000) HST
data of the eclipsing binary SV Cam (F9V + K4V), where the variation of
specific intensity across the stellar disc will determine the contact points of
the binary system lightcurve. For the first time we use chi^2 comparison fits
to the first derivative profiles to determine the best-fitting model
atmosphere. We show the wavelength dependence of the limb darkening and that
the first derivative profile is sensitive to the limb-darkening profile very
close to the limb of the primary star. It is concluded that there is only a
marginal difference (< 1sigma) between the chi^2 comparison fits of the two
model atmospheres to the HST lightcurve at all wavelengths. The usefulness of
the second derivative of the light-curve for measuring the sharpness of the
primary's limb is investigated, but we find that the data are too noisy to
permit a quantitative analysis.


title: Evolution of Class0 protostars: Models vs. Observations

abstract:
  The rates at which mass accumulates into protostellar cores can now be
predicted in numerical simulations. Our purpose here is to develop methods to
compare the statistical properties of the predicted protostars with the
observable parameters. This requires (1) an evolutionary scheme to convert
numerically-derived mass accretion rates into evolutionary tracks and (2) a
technique to compare the tracks to the observed statistics of protostars. Here,
we use a 3D-Kolmogorov-Smirnov test to quantitatively compare model
evolutionary tracks and observations of Class0 protostars.
  We find that the wide range of accretion functions and timescales associated
with gravoturbulent simulations naturally overcome difficulties associated with
schemes that use a fixed accretion pattern. This implies that the location of a
protostar on an evolutionary track does not precisely determine the present age
or final accrued mass. Rather, we find that predictions of the final mass for
protostars from observed Tbol-Lbol values are uncertain by a factor of two and
that the bolometric temperature is not always a reliable measure of the
evolutionary stage. Furthermore, we constrain several parameters of the
evolutionary scheme and estimate a lifetime of Class0 sources of 2-6*10^4yrs,
which is related to the local free-fall time and thus to the local density at
the onset of the collapse. Models with Mach numbers smaller than six are found
to best explain the observational data. Generally, only a probability of 70%
was found that our models explain the current observations. This is caused by
not well understood selection effects in the observational sample and the
simplified assumptions in the models.


title:
Hubble Space Telescope Observations of SV Cam: I. The Importance of
  Unresolved Starspot Distributions in Lightcurve Fitting

abstract:
  We have used maximum entropy eclipse mapping to recover images of the visual
surface brightness distribution of the primary component of the RS CVn
eclipsing binary SV Cam, using high-precision photometry data obtained during
three primary eclipses with STIS aboard the Hubble Space Telescope. These were
augmented by contemporaneous ground-based photometry secured around the rest of
the orbit. The goal of these observations was to determine the filling factor
and size distribution of starspots too small to be resolved by Doppler imaging.
The information content of the final image and the fit to the data were
optimised with respect to various system parameters using the chi^2 landscape
method, using an eclipse mapping code that solves for large-scale spot
coverage. It is only with the unprecedented photometric precision of the HST
data (0.00015 mag) that it is possible to see strong discontinuities at the
four contact points in the residuals of the fit to the lightcurve. These
features can only be removed from the residual lightcurve by the reduction of
the photospheric temperature, to synthesise high unresolvable spot coverage,
and the inclusion of a polar spot. We show that this spottedness of the stellar
surface can have a significant impact on the determination of the stellar
binary parameters and the fit to the lightcurve by reducing the secondary
radius from 0.794 +/- 0.009 Rsun to 0.727 +/- 0.009 Rsun. This new technique
can also be applied to other binary systems with high precision
spectrophotometric observations.


title:
Measuring the Three-Dimensional Structure of Galaxy Clusters. II. Are
  clusters of galaxies oblate or prolate?

abstract:
  The intrinsic shape of galaxy clusters can be obtained through a combination
of X-ray and Sunyaev-Zeldovich effect observations once cosmological parameters
are assumed to be known. In this paper we discuss the feasibility of modelling
galaxy clusters as either prolate or oblate ellipsoids. We analyze the
intra-cluster medium distribution for a sample of 25 X-ray selected clusters,
with measured Sunyaev-Zeldovich temperature decrements. A mixed population of
prolate and oblate ellipsoids of revolution fits the data well, with prolate
shapes preferred on a 60-76% basis. We observe an excess of clusters nearly
aligned along the line of sight, with respect to what is expected from a
randomly oriented cluster population, which might imply the presence of a
selection bias in our sample. We also find signs that a more general triaxial
morphology might better describe the morphology of galaxy clusters. Additional
constraints from gravitational lensing could disentangle the degeneracy between
an ellipsoidal and a triaxial morphology, and could also allow an unbiased
determination of the Hubble constant.


title:
Hydrostatic Modeling of the Integrated Soft X-Ray and EUV Emission in
  Solar Active Regions

abstract:
  Many studies of the solar corona have shown that the observed X-ray
luminosity is well correlated with the total unsigned magnetic flux.
  In this paper we present results from the extensive numerical modeling of
active regions observed with the \textit{Solar and
  Heliospheric Observatory} (\textit{SOHO}) Extreme Ultraviolet
  Telescope (EIT), the \textit{Yohkoh} Soft X-ray Telescope (SXT), and the
\textit{SOHO} Michelson Doppler Imager (MDI). We use potential field
extrapolations to compute magnetic field lines and populate these field lines
with solutions to the hydrostatic loop equations assuming steady, uniform
heating. Our volumetric heating rates are of the form $\epsilon_H\sim
\bar{B}^\alpha/L^\beta$, where $\bar{B}$ is the magnetic field strength
averaged along a field line and $L$ is the loop length. Comparisons between the
observed and simulated emission for 26 active regions suggest that coronal
heating models that scale as $\epsilon_H\sim \bar{B}/L$ are in the closest
argreement the observed emission at high temperatures. The field-braiding
reconnection model of Parker, for example, is consistent with our results. We
find, however, that the integrated intensities alone are insufficent to
uniquely determine the parameterization of the volumetric heating rate.
Visualizations of the emission are also needed. We also find that there are
significant discrepancies between our simulation results and the lower
temperature emission observed in the EIT channels.


title:
Evolving Newton's Constant, Extended Gravity Theories and SnIa Data
  Analysis

abstract:
  If Newton's constant G evolves on cosmological timescales as predicted by
extended gravity theories then Type Ia supernovae (SnIa) can not be treated as
standard candles. The magnitude-redshift datasets however can still be useful.
They can be used to simultaneously fit for both H(z) and G(z) (so that local
G(z) constraints are also satisfied) in the context of appropriate
parametrizations. Here we demonstrate how can this analysis be done by applying
it to the Gold SnIa dataset. We compare the derived effective equation of state
parameter w(z) at best fit with the corresponding result obtained by neglecting
the evolution G(z). We show that even though the results clearly differ from
each other, in both cases the best fit w(z) crosses the phantom divide w=-1. We
then attempt to reconstruct a scalar tensor theory that predicts the derived
best fit forms of H(z) and G(z). Since the best fit G(z) fixes the scalar
tensor potential evolution F(z), there is no ambiguity in the reconstruction
and the potential U(z) can be derived uniquely. The particular reconstructed
scalar tensor theory however, involves a change of sign of the kinetic term
$\Phi'(z)^2$ as in the minimally coupled case.


title:
The Effect of Porosity on X-ray Emission Line Profiles from Hot-Star
  Winds

abstract:
  We investigate the degree to which the nearly symmetric form of X-ray
emission lines seen in Chandra spectra of early-type supergiant stars could be
explained by a possibly porous nature of their spatially structured stellar
winds. Such porosity could effectively reduce the bound-free absorption of
X-rays emitted by embedded wind shocks, and thus allow a more similar
transmission of red- vs. blue-shifted emission from the back vs. front
hemispheres. For a medium consisting of clumps of size l and volume filling
factor f, in which the `porosity length' h=l/f increases with local radius as h
= h' r, we find that a substantial reduction in wind absorption requires a
quite large porosity scale factor h' > 1, implying large porosity lengths h >
r. The associated wind structure must thus have either a relatively large scale
l~ r, or a small volume filling factor f ~ l/r << 1, or some combination of
these. The relatively small-scale, moderate compressions generated by intrinsic
instabilities in line-driving seem unlikely to give such large porosity
lengths, leaving again the prospect of instead having to invoke a substantial
(ca. factor 5) downward revision in assumed mass-loss rates.


title:
New Metallicities of RR Lyrae Stars in omega Centauri: Evidence for a
  Non He-Enhanced Metal-Intermediate Population

abstract:
  We present new spectroscopic metal abundances for 74 RR Lyrae stars in omega
Cen obtained with FLAMES. The well-known metallicity spread is visible among
the RR Lyrae variables. The metal-intermediate (MInt) RR Lyrae stars ([Fe/H] ~
-1.2) are fainter than the bulk of the dominant metal-poor population ([Fe/H] ~
-1.7), in good agreement with the corresponding zero-age horizontal branch
models with cosmological helium abundance Y = 0.246. This result conflicts with
the hypothesis that the progenitors of the MInt RR Lyrae stars correspond to
the anomalous blue main-sequence stars, which share a similar metallicity but
whose properties are currently explained by assuming for them a large helium
enhancement. Therefore, in this scenario, the coexistence within the cluster of
two different populations with similar metallicities ([Fe/H] ~ -1.2) and
different helium abundances has to be considered.


title: Molecular Gas in the Low Metallicity, Star Forming Dwarf IC 10

abstract:
  We present a complete survey of CO 1->0 emission in the Local Group dwarf
irregular IC 10. The survey, conducted with the BIMA interferometer, covers the
stellar disk and a large fraction of the extended HI envelope with the
sensitivity and resolution necessary to detect individual giant molecular
clouds (GMCs) at the distance of IC 10 (950 kpc). We find 16 clouds with a
total CO luminosity of 1 x 10^6 K km s^-1 pc^2, equivalent to 4 x 10^6 Msun of
molecular gas using the Galactic CO-to-H2 conversion factor. Observations with
the ARO 12m find that BIMA may resolve out as much as 50% of the CO emission,
and we estimate the total CO luminosity as 2.2 x 10^6 K km s^-1 pc^2. We
measure the properties of 14 GMCs from high resolution OVRO data. These clouds
are very similar to Galactic GMCs in their sizes, line widths, luminosities,
and CO-to-H2 conversion factors despite the low metallicity of IC 10 (Z ~ 1/5
Zsun). Comparing the BIMA survey to the atomic gas and stellar content of IC 10
we find that most of the CO emission is coincident with high surface density
HI. IC 10 displays a much higher star formation rate per unit molecular (H2) or
total (HI+H2) gas than most galaxies. This could be a real difference or may be
an evolutionary effect - the star formation rate may have been higher in the
recent past.


title: Turbulence from localized random expansion waves

abstract:
  In an attempt to determine the outer scale of turbulence driven by localized
sources, such as supernova explosions in the interstellar medium, we consider a
forcing function given by the gradient of gaussian profiles localized at random
positions. Different coherence times of the forcing function are considered. In
order to isolate the effects specific to the nature of the forcing function we
consider the case of a polytropic equation of state and restrict ourselves to
forcing amplitudes such that the flow remains subsonic. When the coherence time
is short, the outer scale agrees with the half-width of the gaussian. Longer
coherence times can cause extra power at large scales, but this would not yield
power law behavior at scales larger than that of the expansion waves. At scales
smaller than the scale of the expansion waves the spectrum is close to power
law with a spectral exponent of -2. The resulting flow is virtually free of
vorticity. Viscous driving of vorticity turns out to be weak and
self-amplification through the nonlinear term is found to be insignificant. No
evidence for small scale dynamo action is found in cases where the magnetic
induction equation is solved simultaneously with the other equations.


title:
Constraints on the Diverse Progenitors of GRBs from the Large-Scale
  Environments

abstract:
  The pursuit of the progenitors of short duration-hard spectrum gamma-ray
bursts (SHBs) draws strongly upon similar quests for the origin of supernovae
(SNe) and long duration-soft spectrum GRBs(LSBs). Indeed the notion that, in
the absence of smoking guns, the progenitors of cosmic explosions betray their
identities both on the global and local scale, motivates the study of SHB
redshifts, host galaxies, and locations with respect to hosts. To this end, we
suggest both a historical and emergent physical analogy of GRBs with SNe:
long-soft GRBs are to core-collapsed supernovae as short-hard GRBs are to Type
Ia supernovae ("LSB:CC::SHB:Ia''). Still, the SHB progenitor pursuit is just
beginning and we caution that while there are some substantive differences
between observations of LSBs and SHBs on large-scales, particularly in host
demographics, neither the offset nor the redshift distributions of SHBs are
statistically inconsistent with those of LSBs.


title:
The stellar mass-accretion rate relation in T Tauri stars and brown
  dwarfs

abstract:
  Recent observations show a strong correlation between stellar mass and
accretion rate in young stellar and sub-stellar objects, with the scaling
$\dot{M}_{acc} \propto M_*^2$ holding over more than four orders of magnitude
in accretion rate. We explore the consequences of this correlation in the
context of disk evolution models. We note that such a correlation is not
expected to arise from variations in disk angular momentum transport efficiency
with stellar mass, and suggest that it may reflect a systematic trend in disk
initial conditions. In this case we find that brown dwarf disks initially have
rather larger radii than those around more massive objects. By considering disk
evolution, and invoking a simple parametrization for a shut-off in accretion at
the end of the disk lifetime, we show that such models predict that the scatter
in the stellar mass-accretion rate relationship should increase with increasing
stellar mass, in rough agreement with current observations.


title:
A unified picture for gamma-ray burst prompt and X-ray afterglow
  emissions

abstract:
  Data from the Swift satellite has enabled us for the first time to provide a
complete picture of the gamma-ray burst emission mechanism and its relationship
with the early afterglow emissions. We show that gamma-ray photons for two
bursts, 050126 & 050219A, for which we have carried out detailed analysis were
produced as a result of the synchrotron self-Compton process in the material
ejected in the explosion when it was heated to a mildly relativistic
temperature at a distance from the center of explosion of order the
deceleration radius. Both of these bursts exhibit rapidly declining early X-ray
afterglow lightcurves; this emission is from the same source that produced the
gamma-ray burst. The technique we exploit to determine this is very general and
makes no assumption about any particular model for gamma-ray generation except
that the basic radiation mechanism is some combination of synchrotron and
inverse-Compton processes in a relativistic outflow. For GRB 050219A we can
rule out the possibility that energy from the explosion is carried outward by
magnetic fields, and that the dissipation of this field produced the
$\gamma$-ray burst.


title: Information of Structures in Galaxy Distribution

abstract:
  We introduce an information-theoretic measure, the Renyi information, to
describe the galaxy distribution in space. We discuss properties of the
information measure, and demonstrate its relationship with the probability
distribution function and multifractal descriptions. Using the First Look
Survey galaxy samples observed by the Infrared Array Camera onboard Spitzer
Space Telescope, we present measurements of the Renyi information, as well as
the counts-in-cells distribution and multifractal properties of galaxies in
mid-infrared wavelengths. Guided by multiplicative cascade simulation based on
a binomial model, we verify our measurements, and discuss the spatial selection
effects on measuring information of the spatial structures. We derive structure
scan functions at scales where selection effects are small for the Spitzer
samples. We discuss the results, and the potential of applying the Renyi
information to measuring other spatial structures.


title: Forecasting Solar Wind Speeds

abstract:
  By explicitly taking into account effects of Alfven waves, I derive from a
simple energetics argument a fundamental relation which predicts solar wind
(SW) speeds in the vicinity of the earth from physical properties on the sun.
Kojima et al. recently found from their observations that a ratio of surface
magnetic field strength to an expansion factor of open magnetic flux tubes is a
good indicator of the SW speed. I show by using the derived relation that this
nice correlation is an evidence of the Alfven wave which accelerates SW in
expanding flux tubes. The observations further require that fluctuation
amplitudes of magnetic field lines at the surface should be almost universal in
different coronal holes, which needs to be tested by future observations.


title: Multiwavelength star formation indicators: Observations

abstract:
  We present a compilation of multiwavelength data on different star formation
indicators for a sample of nearby star forming galaxies. Here we discuss the
observations, reductions and measurements of ultraviolet images obtained with
STIS, on board the Hubble Space Telescope, ground-based Halpha, and VLA 8.46
GHz radio images. These observations are complemented with infrared fluxes, as
well as large aperture optical radio and ultraviolet data from the literature.
This database will be used in a forthcoming paper to compare star formation
rates at different wavebands. We also present spectral energy distributions
(SEDs) for those galaxies with at least one far-infrared measurements from ISO,
longward of 100 um. These SEDs are divided in two groups, those which are
dominated by the far-infrared emission, and those where the contribution from
the far-infrared and optical emission is comparable. These SEDs are useful
tools to study the properties of high redshift galaxies.


title: Ultraviolet-to-Far-Infrared Properties of Local Star-Forming Galaxies

abstract:
  We present the results of a multiwavelength study of nearby galaxies, aimed
at understanding the relation between the ultraviolet and far-infrared emission
in star-forming galaxies. The dataset comprises new ultraviolet (from
HST/STIS), ground-based Halpha, and radio continuum observations, together with
archival infrared data (from IRAS and ISO). The local galaxies are used as
benchmarks for comparison of the infrared-to-ultraviolet properties with two
populations of high-redshift galaxies: the sub-millimeter star-forming galaxies
detected by SCUBA and the ultraviolet-selected Lyman Break galaxies. In
addition, the long wavelength baseline covered by the present data enables us
to compare the star formation rates (SFRs) derived from the observed
ultraviolet, Halpha, infrared, and radio luminosities, and to gauge the impact
of dust opacity in the local galaxies. We also derive a new calibration for the
non-thermal part of the radio SFR estimator, based on the comparison of 1.4 GHz
measurements with a new estimator of the bolometric luminosity of the star
forming regions. We find that more actively star forming galaxies show higher
dust opacities, in line with previous results. We find that the local
star-forming galaxies have lower F(205um)/F(UV) ratio, by two-three orders of
magnitude than the submillimeter-selected galaxies, and may have similar or
somewhat higher F(205um)/F(UV) than Lyman Break Galaxies. The F(205um)/F(UV)
ratio of the local galaxy population may be influenced by the cool dust
emission in the far-infrared heated by non-ionizing stellar populations, which
may be reduced or absent in the LBGs.


title:
Erratum - The many lives of AGN: cooling flows, black holes and the
  luminosities and colours of galaxies

abstract:
  In Figure 6 we inadvertently labeled the proxy circular velocity as the
virial velocity of the dark matter halo instead of what is actually plotted,
the maximum circular velocity of the dark matter halo. The maximum halo
circular velocity is a much better estimate of the disk V_c than is V_vir. This
confusion influenced the discussion of the Tully-Fisher relation in our paper.
In fact, Figure 6 demonstrates that it is possible to simultaneously reproduce
both the local Tully-Fisher relation and luminosity function using
semi-analytic techniques applied to the standard LCDM cosmology, thus
contradicting previous studies of this issue and our own discussion in Section
3.6.


title: Determination of Stellar Ellipticities in Future Microlensing Surveys

abstract:
  We propose a method that can determine the ellipticities of source stars of
microlensing events produced by binary lenses. The method is based on the fact
that the products of the caustic-crossing timescale, $\Delta t$, and the cosine
of the caustic incidence angle of the source trajectory, $\kappa$, of the
individual caustic crossings are different for events involving an elliptical
source, while the products are the same for events associated with a circular
source. The product $\Delta t_\perp =\Delta t \cos\kappa$ corresponds to the
caustic-crossing timescale when the incidence angle of the source trajectory is
$\kappa=0$. For the unique determination of the source ellipticity, resolutions
of at least three caustic crossings are required. Although this requirement is
difficult to achieve under the current observational setup based on
alert/follow-up mode, it will be possible with the advent of future lensing
experiments that will survey wide fields continuously at high cadence. For
typical Galactic bulge events, the difference in $\Delta t_\perp$ between
caustic crossings is of the order of minutes depending on the source
orientations and ellipticities. Considering the monitoring frequency of the
future lensing surveys of $\sim 6$ times/hr and the improved photometry
especially of the proposed space-based survey, we predict that ellipticity
determinations by the proposed method will be possible for a significant
fraction of multiple caustic-crossing binary lens events involving source stars
having non-negligible ellipticities.


title:
A Search for wide visual companions of exoplanet host stars - The Calar
  Alto Survey

abstract:
  We have carried out a search for co-moving stellar and substellar companions
around 18 exoplanet host stars with the infrared camera MAGIC at the 2.2m Calar
Alto telescope, by comparing our images with images from the all sky surveys
2MASS, POSS I and II. Four stars of the sample namely HD80606, 55Cnc, HD46375
and BD-103166, are listed as binaries in the Washington Visual Double Star
Catalogue (WDS). The binary nature of HD80606, 55Cnc, and HD46375 is confirmed
with both astrometry as well as photometry, thereby the proper motion of the
companion of HD46375 was determined here for the first time. We derived the
companion masses as well as the longterm stability regions for additional
companions in these three binary systems. We can rule out further stellar
companions around all stars in the sample with projected separations between
270AU and 2500AU, being sensitive to substellar companions with masses down to
\~60MJup (S/N=3). Furthermore we present evidence that the two components of
the WDS binary BD-103166 are unrelated stars, i.e this system is a visual pair.
The spectrophotometric distance of the primary (a K0 dwarf) is ~67pc, whereas
the presumable secondary BD-103166B (a M4 to M5 dwarf) is located at a distance
of 13pc in the foreground.


title: Gamma-ray emission expected from Kepler's SNR

abstract:
  Nonlinear kinetic theory of cosmic ray (CR) acceleration in supernova
remnants (SNRs) is used to investigate the properties of Kepler's SNR and, in
particular, to predict the gamma-ray spectrum expected from this SNR.
Observations of the nonthermal radio and X-ray emission spectra as well as
theoretical constraints for the total supernova (SN) explosion energy E_sn are
used to constrain the astronomical and particle acceleration parameters of the
system. Under the assumption that Kepler's SN is a type Ia SN we determine for
any given explosion energy E_sn and source distance d the mass density of the
ambient interstellar medium (ISM) from a fit to the observed SNR size and
expansion speed. This makes it possible to make predictions for the expected
gamma-ray flux. Exploring the expected distance range we find that for a
typical explosion energy E_sn=10^51 erg the expected energy flux of TeV
gamma-rays varies from 2x10^{-11} to 10^{-13} erg/(cm^2 s) when the distance
changes from d=3.4 kpc to 7 kpc. In all cases the gamma-ray emission is
dominated by \pi^0-decay gamma-rays due to nuclear CRs. Therefore Kepler's SNR
represents a very promising target for instruments like H.E.S.S., CANGAROO and
GLAST. A non-detection of gamma-rays would mean that the actual source distance
is larger than 7 kpc.


title:
The large-scale axisymmetric magnetic topology of avery-low-mass
  fully-convective star

abstract:
  Understanding how cool stars produce magnetic fields within their interiors
is crucial for predicting the impact of such fields, such as the activity cycle
of the Sun. In this respect, studying fully convective stars enables us to
investigate the role of convective zones in magnetic field generation. We
produced a magnetic map of a rapidly rotating, very-low-mass, fully convective
dwarf through tomographic imaging from time series of spectropolarimetric data.
Our results, which demonstrate that fully convective stars are able to trigger
axisymmetric large-scale poloidal fields without differential rotation,
challenge existing theoretical models of field generation in cool stars.


title: A dynamical model for the dusty ring in the Coalsack

abstract:
  Lada et al. recently presented a detailed near-infrared extinction map of
Globule G2 in the Coalsack molecular cloud complex, showing that this starless
core has a well-defined central extinction minimum. We propose a model for G2
in which a rapid increase in external pressure is driving an approximately
symmetric compression wave into the core. The rapid increase in external
pressure could arise because the core has recently been assimilated by the
Coalsack cloud complex, or because the Coalsack has recently been created by
two large-scale converging flows. The resulting compression wave has not yet
converged on the centre of the core, so there is a central rarefaction. The
compression wave has increased the density in the swept-up gas by about a
factor of ten, and accelerated it inwards to speeds of order $0.4 {\rm km} {\rm
s}^{-1}$. It is shown that even small levels of initial turbulence destroy the
ring seen in projection almost completely. In the scenario of strong external
compression that we are proposing this implies that the initial turbulent
energy in this globule is such that $E_{{\rm turb}} / E_{{\rm grav}} \le 2 %$.
Protostar formation should occur in about $40,000 {\rm years}$.