title: Disklike Structure in the Semiregular Pulsating Star X Her

abstract:
  The author presents the results of Berkeley-Illinois-Maryland (BIMA) array
interferometric observations in the CO J=1-0 line toward X Her and EP Aqr, the
semiregular pulsating stars with a composite CO line profile, and also reports
finding of a disklike structure in X Her. In the CO spectrum both of X Her and
EP Aqr, a composite profile including narrow and broad components is seen as
reported by the previous single-dish observations. The spatial structure of the
broad component region of X Her shows a bipolar shape, and that of the narrow
component shows an elliptical/spherical shape. The blue- and red-shifted parts
of the X Her narrow component show a systematic difference in the velocity
integrated intensity map. The spatio-kinetic properties of the X Her narrow
component are reminiscent of a Keplerian rotating disk with a central mass of
0.9 Msun. The spatial distributions of both the narrow and the broad components
of EP Aqr appear to be roughly round with the same peak positions; no
significant velocity gradient is seen. The spatio-kinetic properties of EP Aqr
are reminiscent of a multiple-shell structure model rather than of a bipolar
flow and disk model.


title: An Optical Emission Line Survey of Large Planetary Nebulae

abstract:
  Accurate emission line fluxes from planetary nebulae (PNe) provide important
constraints on the nature of the final phases of stellar evolution. Large,
evolved PNe may trace the latest stages of PN evolution, where material from
the AGB wind is returned to the interstellar medium. However, the low surface
brightness and spatially extended emission of large PNe have made accurate
measurements of line fluxes difficult with traditional long-slit spectroscopic
techniques. Furthermore, distinguishing these nebulae from HII regions,
supernova remnants, or interstellar gas ionized by a hot, evolved stellar core
can be challenging. Here, we report on an ongoing survey of large Galactic PNe
(r > 5') with the Wisconsin H-Alpha Mapper (WHAM), a Fabry-Perot spectrograph
designed to detect faint diffuse optical emission lines with high sensitivity
and spectral resolution. Our sample includes newly revealed H-alpha
enhancements from the AAO/UKST and WHAM H-alpha surveys of Parker et al. and
Haffner et al. We present accurate emission line fluxes of H-alpha, [NII], and
[OIII], and compare our data to other measurements. We use the emission line
ratios and kinematics of the ionized gas to assess, or in some cases reassess,
the identification of some nebulae.


title:
Neutron stars in globular clusters: formation and observational
  manifestations

abstract:
  Population synthesis is used to model the number of neutron stars in globular
clusters that are observed as LMXBs and millisecond PSRs. The dynamical
interaction between binary and single stars in a GC are assumed to take place
with a permanently replenished "background" of single stars whose density
distribution keeps track with the cluster evolution as a whole and evolution of
single stars. We use the hypothesis (Podsiadlowski et al) that NS forming in
binary systems from components with initial masses \sim 8-12 M_\odot during the
electron-capture collapse of the degenerate O-Ne-Mg core do not acquire a high
space velocities (kicks). The remaining NSs (i.e. from single stars with M>8
M_\odot or binary comonents with M>12 M_\odot) are assumed to be born with high
kicks, as found from obsrevations of single pulsars (Hobbs et al. 2005). Under
this assumption, a sizeable fraction of NSs remain in GCs (about 1000 NSs in a
GC with a mass of 5\times 10^5 M_\odot). The number of ms PSRs formed in the
cluster via accretion spin-up in binaries is then about 10, which is consistent
with observations. Our modelling reproduces the observed shape of the X-ray
luminosity function for accreting NSs in binaries with normal and degenerate
components and the distribution of spin periods of ms PSRs in GCs under the
assumption of accretion-driven magnetic field decay of NSs up to a bottom value
of 10^8 G. The number of LMXBs and ms PSRs dynamically expelling from GCs is
also calculated.


title:
Line formation in solar granulation VII. CO lines and the solar C and O
  isotopic abundances

abstract:
  CO spectral line formation in the Sun has long been a source of consternation
for solar physicists, as have the elemental abundances it seems to imply. We
modelled solar CO line formation using a realistic, ab initio, time-dependent
3D radiative-hydrodynamic model atmosphere. Results were compared with
observations from the space-based ATMOS experiment. We employed weak 12C16O,
13C16O and 12C18O lines from the fundamental and first overtone bands to
determine the solar carbon abundance, as well as the 12C/13C and 16O/18O
isotopic ratios. A weighted carbon abundance of log epsilonC = 8.39 +-0.05 was
found. We note with satisfaction that the derived abundance is identical to our
recent 3D determination based on CI, [C I], C2 and CH lines. Identical
calculations were carried out using 1D models, but only the 3D model was able
to produce abundance agreement between different CO lines and the other atomic
and molecular diagnostics. Solar 12C/13C and 16O/18O ratios were measured as
86.8+3.9-3.7 (delta13C = 30+46-44) and 479+29-28 (delta18O = 41+67-59),
respectively. These values may require current theories of solar system
formation to be revised. Excellent agreement was seen between observed and
predicted weak CO line shapes, without invoking micro- or macroturbulence.
Agreement breaks down for the strongest CO lines however, which are formed in
very high atmospheric layers. The simplest explanation is that temperatures are
overestimated in the highest layers of the 3D simulation. Thus, our analysis
supports the presence of a COmosphere above the traditional photospheric
temperature minimum, with an average temperature of less than 4000K. The
shortcoming of the model atmosphere is not surprising, given that it was never
intended to properly describe such high layers.


title: A Neutron Star in F-sharp

abstract:
  In this short introductory commentary on the paper (Hessels et al 2006,
Science, 311, 1901) reporting the discovery of the shortest spin period
millisecond pulsar (MSP) Ter5-ad in the globular cluster Terzan 5, I also point
out a new explanation for possible minimum spin periods, P, of MSPs without
requiring gravitational radiation (or other) slow-down torques. If the
accretion of matter required to spinup a MSP also reduces (buries) the neutron
star (NS) magnetic field, B, as commonly believed, an inverse correlation
between neutron star mass, M, and B is expected together with a positive
correlation between P and B. Both are suggested for the 4 MSPs with NS mass
measures reported (Latimer and Prakash 2004, Science, 304, 536) to have <~10%
uncertainties. The correlations imply the Ter5-ad NS has ~2.5 Msun, B ~5 x 10^7
G and thus Pdot ~3 x 10^-21 s/s -- which can be tested when a timing solution
is found. If confirmed, the highest spin frequency NSs do not pulse simply
because their B fields are too low.


title:
High-temperature phase transition in a plasma and the mechanism of
  powerful solar flares

abstract:
  It is shown that the high- temperature phase transition in a plasma gives the
mechanism of transition from the highly conductive state to the highly
resistive state of a plasma in the `electric circuit' model of solar flares
which was first introduced by H.Alfven and P.Carlqvist in 1967. With this
addendum, the modern version of the electric circuit model can explain both the
fast dissipation of energy and the acceleration of particles in a solar flare.


title:
Absolute motions of globular clusters. II. [HST astrometry and VLT
  radial velocities in NGC6397]

abstract:
  In this paper we present a new, accurate determination of the three
components of the absolute space velocity of the Galactic globular cluster
NGC6397 (l 338d, b -12d). We used three HST/WFPC2 fields with multi-epoch
observations to obtain astrometric measurements of objects in three different
fields in this cluster. The identification of 33 background galaxies with sharp
nuclei allowed us to determine an absolute reference point and measure the
absolute proper motion of the cluster. The third component has been obtained
from radial velocities measured on spectra from the multi-fiber spectrograph
FLAMES at UT2-VLT. We find [mu_alpha cos(delta), mu_delta](J2000.0) = [+3.39
+/- 0.15, -17.55 +/- 0.15] mas/yr, and V_rad = +18.36 +/- 0.09 (+/-0.10) km/s.
Assuming a Galactic potential, we calculate the cluster orbit for various
assumed distances, and briefly discuss the implications.


title:
Simulating the formation of molecular clouds. I. Slow formation by
  gravitational collapse from static initial conditions

abstract:
  We study the formation of H2 in the ISM, using a modified version of the
astrophysical magnetohydrodynamical code ZEUS-MP that includes a
non-equilibrium treatment of the formation and destruction of H2. We examine
two different approximations to treat the shielding of H2 against
photodissociation: a local approximation, which gives us a solid lower bound on
the amount of shielding, and a method based on ray-tracing that is considerably
more accurate in some circumstances but that produces results that are harder
to clearly interpret. Either approximation allows one to perform
three-dimensional high-resolution simulations of cloud formation with only
modest computational resources. We also include a detailed treatment of the
thermal behaviour of the gas.
  In this paper, we focus on the problem of molecular cloud formation in
gravitationally unstable, initially static gas. We show that in these
conditions, and for initial densities consistent with those observed in the
cold, neutral atomic phase of the interstellar medium, H2 formation occurs on a
timescale t > 10 Myr, comparable to or longer than the gravitational free-fall
timescale of the cloud. We also show that the collapsing gas very quickly
reaches thermal equilibrium and that the equation of state of the gas is
generally softer than isothermal.
  Finally, we demonstrate that although these results show little sensitivity
to variations in most of our simulation parameters, they are highly sensitive
to the assumed initial density n_i. Reducing n_i significantly increases the
cloud formation timescale and decreases the amount of hydrogen ultimately
converted to H2. (Abridged).


title:
Simulating the formation of molecular clouds. II. Rapid formation from
  turbulent initial conditions

abstract:
  (Abridged). In this paper, we present results from a large set of numerical
simulations that demonstrate that H2 formation occurs rapidly in turbulent gas.
Starting with purely atomic hydrogen, large quantities of molecular hydrogen
can be produced on timescales of 1 -- 2 Myr, given turbulent velocity
dispersions and magnetic field strengths consistent with observations.
Moreover, as our simulations underestimate the effectiveness of H2
self-shielding and dust absorption, we can be confident that the molecular
fractions that we compute are strong lower limits on the true values. The
formation of large quantities of H2 on the timescale required by rapid cloud
formation models therefore appears to be entirely plausible.
  We also investigate the density and temperature distributions of gas in our
model clouds. We show that the density probability distribution function is
approximately log-normal, with a dispersion that agrees well with the
prediction of Padoan, Nordlund & Jones (1997). The temperature distribution is
similar to that of a polytrope, with an effective polytropic index gamma_eff
\simeq 0.8, although at low gas densities, the scatter of the actual gas
temperature around this mean value is considerable, and the polytropic
approximation does not capture the full range of behaviour of the gas.


title: Detection of the ISW effect and corresponding dark energy constraints

abstract:
  Using a directional spherical wavelet analysis we detect the integrated
Sachs-Wolfe (ISW) effect, indicated by a positive correlation between the
Wilkinson Microwave Anisotropy Probe (WMAP) and NRAO VLA Sky Survey (NVSS)
data, at the 3.9 sigma level. In a flat universe the detection of the ISW
effect provides direct and independent evidence for dark energy. Moreover, we
use our detection to constrain the dark energy density Omega_Lambda. We obtain
estimates for Omega_Lambda consistent with other analysis techniques and data
sets and rule out a zero cosmological constant at greater than 99%
significance.


title:
The Abundance of Distant and Extremely Red Galaxies: The Role of AGN
  Feedback in Hierarchical Models

abstract:
  We investigate the effect of AGN feedback associated to the bright QSO phase
onto the color distribution of galaxies from z=0 up to z=4. To this aim, we
insert a blast-wave model of AGN feedback in our semi-analytic model of galaxy
formation, which includes the growth of supermassive black holes and the AGN
activity triggered by interactions of the host galaxies. The AGN feedback is
directly related to the impulsive, luminous quasar phase. We test our model by
checking the consistency of its results against i) the QSO luminosity functions
from z=0 to z=4; ii) the observed local relation between the black hole mass
m_{BH} and the mass of the host galaxy. At low redshift the inclusion of AGN
feedback enhances the number of red bright galaxies, so that the color
distribution of M_r<-22 objects is entirely dominated by red (u-r>1.5)
galaxies; at 0.5< z< 2 it yields rest-frame U-V color distribution in agreement
with existing observations. In the range z=1.5-2.5, we find that 31% of
galaxies contribute to the EROs population with m_K<20 (Vega system); at such a
magnitude, the model yields an EROs surface density of 6.3 10^3 /deg^2 matching
existing data; about 80 % of the above density is contributed by passive
galaxies with old stellar populations. Extending our analysis to z=4, the model
matches the observed surface density 1.5 10^3 /deg^2 of DRGs at m_K=20; such a
population is predicted to be dominated by galaxies with old stellar
populations for z>2.5.


title:
Self-consistent theory of turbulent transport in the solar tachocline.
  II. Tachocline confinement

abstract:
  We provide a consistent theory of the tachocline confinement (or anisotropic
momentum transport) within an hydrodynamical turbulence model. The goal is to
explain helioseismological data, which show that the solar tachocline thickness
is at most 5% of the solar radius, despite the fact that, due to radiative
spreading, this transition layer should have thickened to a much more
significant value during the sun's evolution. Starting from the first principle
with the physically plausible assumption that turbulence is driven externally
(e.g. by plumes penetrating from the convection zone), we derive turbulent
(eddy) viscosity in the radial (vertical) and azimuthal (horizontal) directions
by incorporating the crucial effects of shearing due to radial and latitudinal
differential rotations in the tachocline. We show that the simultaneous
presence of both shears induces effectively a much more efficient momentum
transport in the horizontal plane than in the radial direction. In particular,
in the case of strong radial turbulence (driven by overshooting plumes from the
convection zone), the ratio of the radial to horizontal eddy viscosity is
proportional to ${\cal A}^{-1/3}$, where ${\cal A}$ is the strength of the
shear due to radial differential rotation. In comparison, in the case of
horizontally driven turbulence, this ratio becomes of order $-\epsilon^2$, with
negative radial eddy viscosity. Here, $\epsilon$ ($\ll 1$) is the ratio of the
radial to latitudinal shear. The resulting anisotropy in momentum transport
could thus be sufficiently strong to operate as a mechanism for the tachocline
confinement against spreading.


title: Dissolution of Globular Clusters

abstract:
  Globular clusters are among the oldest objects in galaxies, and understanding
the details of their formation and evolution can bring valuable insight into
the early history of galaxies. This review summarises the current knowledge
about the dissolution of star clusters and discusses the implications of star
cluster dissolution for the evolution of the mass function of star cluster
systems in galaxies.


title: Deuterium enhancement in H3+ in prestellar cores

abstract:
  Deuterium enhancement of monodeuterated species has been recognized for more
than 30 years as a result of the chemical fractionation that results from the
difference in zero point energies of deuterated and hydrogenated molecules. The
key reaction is the deuteron exchange in the reaction between HD, the reservoir
of deuterium in dark interstellar clouds, and the H3+ molecular ion, leading to
the production of the H2D+ molecule, and the low temperature in dark
interstellar clouds favors this production. Furthermore, the presence of
multiply deuterated species have incited our group to proceed further and
consider the subsequent reaction of H2D+ with HD, leading to D2H+ (first
detected by Vastel et al. 2004), which can further react with HD to produce
D3+. In prestellar cores, where CO was found to be depleted (Bacmann et al.
2003), this production should be increased, as CO would normally destroy H3+.
The first model including D2H+ and D3+ (Roberts, Herbst & Millar 2003)
predicted that these molecules should be as abundant as H2D+ (see contribution
by H. Roberts). The first detection of the D2H+ was made possible by the recent
laboratory measurement by Hirao & Amano (2003) for the frequency of the
fundamental line of the para-D2H+ (see contribution by T. Amano). Here we
present observations of H2D+ and D2H+ towards a sample of dark clouds and
prestellar cores and show how the distribution of ortho-H2D+ (1_1,0-1_1,1) can
trace the deuterium factory in prestellar cores. We also present how future
instrumentation will improve our knowledge concerning the deuterium enhancement
of H3+.


title:
Dynamical evidence of the age--metallicity relation in the Milky Way
  disk

abstract:
  We studied the relationship between the average stellar abundance of several
elements and the orbital evolution of stars in the neighbourhood of the Sun,
using both observational data for 325 late-type dwarfs in a volume-complete
sample and simulations of the orbital diffusion. Metallicities, ages, and
initial position and velocities for the simulated stars are sampled from
empirical distributions of these quantities in the Milky Way. We found that
that there is a relationship between the average stellar abundance of Fe, Na,
Si, Ca, Ni, and Ba and the mean orbital radius of stars currently passing
through the solar neighbourhood. The greater the difference between the mean
orbital radius and the solar Galactocentric distance, the more deficient the
star is, on average, in these chemical species. The stars that take a longer
time to come from their birthplaces to arrive in the present solar
neighbourhood are more likely to be more metal-poor than those that were born
here. This result is a direct, independent indication that a tightly defined
Galactic age-metallicity relation exists.


title: APECS - The Atacama Pathfinder Experiment Control System

abstract:
  APECS is the distributed control system of the new Atacama Pathfinder
EXperiment (APEX) telescope located on the Llano de Chajnantor at an altitude
of 5107 m in the Atacama desert in northern Chile. APECS is based on Atacama
Large Millimeter Array (ALMA) software and employs a modern, object-oriented
design using the Common Object Request Broker Architecture (CORBA) as the
middleware. New generic device interfaces simplify adding instruments to the
control system. The Python based observer command scripting language allows
using many existing software libraries and facilitates creating more complex
observing modes. A new self-descriptive raw data format (Multi-Beam FITS or
MBFITS) has been defined to store the multi-beam, multi-frequency data. APECS
provides an online pipeline for initial calibration, observer feedback and a
quick-look display. APECS is being used for regular science observations in
local and remote mode since August 2005.


title:
Energy-dependent variability and the origin of the soft X-ray excess in
  AGN

abstract:
  The origin of the soft excess seen in many AGN below ~1 keV is still an
unsolved problem. It is unlikely to represent a true continuum component as its
characteristic 'temperature' shows a remarkable constancy over a wide range of
AGN luminosity and black hole mass. This instead favours an association with
atomic processes, in particular with the increase in opacity between 0.7-2 keV
associated with partially ionized O and Fe. The opacity jump can give rise to a
soft excess either through reflection or transmission, and both scenarios can
fit the spectra equally well as long as there is strong velocity shear to smear
out the characteristic narrow atomic features. Here we use orthogonal
constraints from the energy-dependent variability. The rms spectra seen in
XMM-Newton AGN data often show a broad peak between 0.7-2 keV. We show that the
absorption model can explain the data well if the ionization state of the
smeared absorption responds to luminosity changes in the continuum.


title: Variable iron-line emission near the black hole of Markarian 766

abstract:
  We investigate the link between ionised Fe X-ray line emission and continuum
emission in the bright nearby AGN, Mrk 766. A new long (433 ks) XMM-Newton
observation is analysed, together with archival data from 2000 and 2001. The
contribution from ionised line emission is measured and its time variations on
short (5-20 ks) timescales are correlated with the continuum emission. The
ionised line flux is found to be highly variable and to be strongly correlated
with the continuum flux, demonstrating an origin for the ionised line emission
that is co-located with the continuum emission. Most likely the emission is
ionised reflection from the accretion disc within a few A.U. of the central
black hole, and its detection marks the first time that such an origin has been
identified other than by fitting to spectral line profiles. Future observations
may be able to measure a time lag and hence achieve reverberation mapping of
AGN at X-ray energies.


title:
Galaxy pairs in cosmological simulations: effects of interactions on
  colours and chemical abundances

abstract:
  We perform an statistical analysis of galaxies in pairs in a Lambda-CDM
scenario by using the chemical GADGET-2 of Scannapieco et al. (2005) in order
to study the effects of galaxy interactions on colours and metallicities. We
find that galaxy-galaxy interactions can produce a bimodal colour distribution
with galaxies with significant recent star formation activity contributing
mainly to blue colours. In the simulations, the colours and the fractions of
recently formed stars of galaxies in pairs depend on environment more strongly
than those of galaxies without a close companion, suggesting that interactions
play an important role in galaxy evolution. If the metallicity of the stellar
populations is used as the chemical indicator, we find that the simulated
galaxies determine luminosity-metallicity and stellar mass-metallicity
relations which do not depend on the presence of a close companion. However, in
the case of the luminosity-metallicity relation, at a given level of
enrichment, we detect a systematic displacement of the relation to brighter
magnitudes for active star forming systems. Regardless of relative distance and
current level of star formation activity, galaxies in pairs have stellar
populations with higher level of enrichment than galaxies without a close
companion. In the case of the gas component, this is no longer valid for
galaxies in pairs with passive star formation which only show an excess of
metals for very close pair members, consequence of an important recent past
star formation activity. (Abridged).


title:
Resolved Massive Star Clusters in the Milky Way and its Satellites:
  Brightness Profiles and a Catalogue of Fundamental Parameters

abstract:
  [Abridged]: We present a database of structural and dynamical properties for
153 spatially resolved star clusters (50 "young massive clusters" and 103 old
globulars) in the Milky Way, the Large and Small Magellanic Clouds, and the
Fornax dwarf spheroidal. This database complements and extends others in the
literature, such as those of Harris, and Mackey & Gilmore. By fitting a number
of models to the clusters' density profiles, we derive various characteristic
surface brightnesses and radii; central potentials, velocity dispersions, and
escape velocities; total luminosities, masses, and binding energies;
phase-space densities and relaxation timescales; and ``kappa-space''
parameters. Population-synthesis models are used to predict intrinsic (B-V)
colors, reddenings, and V-band mass-to-light ratios for the same 153 clusters
plus another 63 globulars in the Milky Way, and we compare these predictions to
the observed quantities where available. These results are intended to serve as
the basis for future investigations of structural correlations and the
fundamental plane of massive star clusters, including especially comparisons
between the systemic properties of young and old clusters. We also address the
question of what structural model fits each cluster best, and argue that the
extended halos known to characterize many Magellanic Cloud clusters may be
examples of the generic envelope structure of self-gravitating star clusters,
not just transient features associated strictly with young age.


title: Compact X-ray Binaries in and out of Core Collapsed Globulars

abstract:
  We review new Chandra and HST observations of the core collapsed cluster NGC
6397 as a guide to understanding the compact binary (CB) populations in core
collapse globulars. New cataclysmic variables (CVs) and main sequence
chromospherically active binaries (ABs) have been identified, enabling a larger
sample for comparison of the Lx, Fx/Fv and X-ray vs. optical color
distributions. Comparison of the numbers of CBs with Lx >10^31 erg/s in 4 core
collapse vs. 12 King model clusters reveals that the specific frequency Sx
(number of CBs per unit cluster mass) is enhanced in core collapse clusters,
even when normalized for their stellar encounter rate. Although core collapse
is halted by the dynamical heating due to stellar (and binary) interaction with
CBs in the core, we conclude that production of the hardest CBs -- especially
CVs -- is enhanced during core collapse. NGC 6397 has its most luminous CVs
nearest the cluster center, with two newly discovered very low luminosity (old,
quiescent) CVs far from the core. The active binaries as well as neutron star
systems (MSP and qLMXB) surround the central core. The overall CB population
appears to be asymmetric about the cluster center, as in several other core
collapse clusters observed with Chandra, suggesting still poorly-understood
scattering processes.


title: An Extremely Curved Relativistic Jet in PKS 2136+141

abstract:
  We report the discovery of an extremely curved jet in the radio-loud quasar
PKS2136+141. Multi-frequency Very Long Baseline Array (VLBA) images show a
bending jet making a turn-around of 210 degrees in the plane of the sky, which
is, to our knowledge, the largest ever observed change in the position angle of
an astrophysical jet. Images taken at six different frequencies, from 2.3 to 43
GHz, reveal a spiral-like trajectory, which is likely a sign of an intrinsic
helical geometry. A space-VLBI image, taken with the HALCA satellite at 5 GHz
and having comparable resolution to our ground-based 15 GHz data, confirms that
the bend is a frequency-independent structure. VLBA monitoring data at 15 GHz,
covering eight years of observations, show knots in the jet clearly deviating
from ballistic motion, which suggests that the bending may be caused by a
growing helical Kelvin-Helmholtz normal mode. The jet appearance suggests a
helical wave at a frequency well below the "resonant" frequency of the jet,
which indicates that the wave is driven by a periodic perturbation at the base
of the jet. We fit the observed structure in the source with a helical twist,
and we find that a simple isothermal model with a constant wave speed and
wavelength gives a good fit. The measured apparent velocities indicate some
degree of acceleration along the jet, which together with an observed change in
the apparent half-opening angle of the jet allow us to estimate the changes in
the angle between the local jet direction and our line of sight. We suggest
that the jet in PKS2136+141 is distorted by a helical Kelvin-Helmholtz normal
mode externally driven into the jet (e.g. by precession), and that our line of
sight falls within the opening angle of the helix cone.


title:
The Uncorrelated Universe: Statistical Anisotropy and the Vanishing
  Angular Correlation Function in WMAP Years 1-3

abstract:
  The large-angle (low-ell) correlations of the Cosmic Microwave Background
(CMB) as reported by the Wilkinson Microwave Anisotropy Probe (WMAP) after
their first year of observations exhibited statistically significant anomalies
compared to the predictions of the standard inflationary big-bang model. We
suggested then that these implied the presence of a solar system foreground, a
systematic correlated with solar system geometry, or both. We re-examine these
anomalies for the data from the first three years of WMAP's operation. We show
that, despite the identification by the WMAP team of a systematic correlated
with the equinoxes and the ecliptic, the anomalies in the first-year Internal
Linear Combination (ILC) map persist in the three-year ILC map, in all-but-one
case at similar statistical significance. The three-year ILC quadrupole and
octopole therefore remain inconsistent with statistical isotropy -- they are
correlated with each other (99.6% C.L.), and there are statistically
significant correlations with local geometry, especially that of the solar
system. The angular two-point correlation function at scales >60 degrees in the
regions outside the (kp0) galactic cut, where it is most reliably determined,
is approximately zero in all wavebands and is even more discrepant with the
best fit LambdaCDM inflationary model than in the first-year data - 99.97% C.L.
for the new ILC map. The full-sky ILC map, on the other hand, has a
non-vanishing angular two-point correlation function, apparently driven by the
region inside the cut, but which does not agree better with LambdaCDM. The role
of the newly identified low-ell systematics is more puzzling than reassuring.


title:
The Search for other Earths: limits on the giant planet orbits that
  allow habitable terrestrial planets to form

abstract:
  Gas giant planets are far easier than terrestrial planets to detect around
other stars, and are thought to form much more quickly than terrestrial
planets. Thus, in systems with giant planets, the late stages of terrestrial
planet formation are strongly affected by the giant planets' dynamical
presence. Observations of giant planet orbits may therefore constrain the
systems that can harbor potentially habitable, Earth-like planets. We present
results of 460 N-body simulations of terrestrial accretion from a disk of Moon-
to Mars-sized planetary embryos. We systematically vary the orbital semimajor
axis of a Jupiter-mass giant planet between 1.6 and 6 AU, and eccentricity
between 0 and 0.4. We find that for Sun-like stars, giant planets inside
roughly 2.5 AU inhibit the growth of 0.3 Earth-mass planets in the habitable
zone. If planets accrete water from volatile-rich embryos past 2-2.5 AU, then
water-rich habitable planets can only form in systems with giant planets beyond
3.5 AU. Giant planets with significant orbital eccentricities inhibit both
accretion and water delivery. The majority of the current sample of extra-solar
giant planets appears unlikely to form habitable planets.


title: Nucleosynthesis: Stellar and Solar Abundances and Atomic Data

abstract:
  Abundance observations indicate the presence of often surprisingly large
amounts of neutron capture (i.e., s- and r-process) elements in old Galactic
halo and globular cluster stars. These observations provide insight into the
nature of the earliest generations of stars in the Galaxy -- the progenitors of
the halo stars -- responsible for neutron-capture synthesis. Comparisons of
abundance trends can be used to understand the chemical evolution of the Galaxy
and the nature of heavy element nucleosynthesis. In addition age
determinations, based upon long-lived radioactive nuclei abundances, can now be
obtained. These stellar abundance determinations depend critically upon atomic
data. Improved laboratory transition probabilities have been recently obtained
for a number of elements. These new gf values have been used to greatly refine
the abundances of neutron-capture elemental abundances in the solar photosphere
and in very metal-poor Galactic halo stars. The newly determined stellar
abundances are surprisingly consistent with a (relative) Solar System r-process
pattern, and are also consistent with abundance predictions expected from such
neutron-capture nucleosynthesis.


title: The effect of planetary migration on the corotation resonance

abstract:
  The migration of a planet through a gaseous disc causes the locations of
their resonant interactions to drift and can alter the torques exerted between
the planet and the disc. We analyse the time-dependent dynamics of a
non-coorbital corotation resonance under these circumstances. The ratio of the
resonant torque in a steady state to the value given by Goldreich & Tremaine
(1979) depends essentially on two dimensionless quantities: a dimensionless
turbulent diffusion time-scale and a dimensionless radial drift speed. When the
drift speed is comparable to the libration speed and the viscosity is small,
the torque can become much larger than the unsaturated value in the absence of
migration, but is still proportional to the large-scale vortensity gradient in
the disc. Fluid that is trapped in the resonance and drifts with it acquires a
vortensity anomaly relative to its surroundings. If the anomaly is limited by
viscous diffusion in a steady state, the resulting torque is inversely
proportional to the viscosity, although a long time may be required to achieve
this state. A further, viscosity-independent, contribution to the torque comes
from fluid that streams through the resonant region. In other cases, torque
oscillations occur before the steady value is achieved. We discuss the
significance of these results for the evolution of eccentricity in
protoplanetary systems. We also describe the possible application of these
findings to the coorbital region and the concept of runaway (or type III)
migration. [Abridged]


title: The Evolution of Outflow-Envelope Interactions in Low-Mass Protostars

abstract:
  We present multi-line and continuum observations of the circumstellar
environment within 10^4 AU of a sample of protostars to investigate how the
effects of outflows on their immediate environment changes over time. 12CO(1-0)
emission probes the high-velocity molecular outflows near the protostars and
demonstrate that the outflow opening angle widens as the nascent star evolves.
Maps of the 13CO(1-0) and HCO+(1-0) outflow emission show that protostellar
winds erode the circumstellar envelope through the entrainment of the outer
envelope gas. The spatial and velocity distribution of the dense circumstellar
envelope, as well as its mass, is traced by the C18O(1-0) emission and also
displays evolutionary changes. We show that outflows are largely responsible
for these changes, and propose an empirical model for the evolution of
outflow-envelope interactions. In addition, some of the outflows in our sample
appear to affect the chemical composition of the surrounding environment,
enhancing the HCO+ abundance. Overall, our results confirm that outflows play a
major role in the star formation process through their strong physical and
chemical impacts on the environments of the young protostars.


title: Ultraluminous X-ray Sources, High Redshift QSOs and Active Galaxies

abstract:
  It is shown that all of the 32 point X-ray sources which lie within about 10'
of the centre of nearby galaxies, and which have so far been optically
identified are high redshift objects - AGN or QSOs. Thus the surface density of
these QSOs p similar or equal to 0.1 per square arc minute. Some of them were
originally discovered as X-ray sources and classified as ultraluminous X-ray
sources (ULXs), nearly all of which lie near the centers of active galaxies. We
demonstrate that this concentration around galactic nuclei is of high
statistical significance: the probabiliy that p that they are accidental lies
in the range one in a thousand to one in ten thousand, and apparently this
excess cannot be accounted for by microlensing.


title:
On Iron Enrichment, Star Formation, and Type Ia Supernovae in Galaxy
  Clusters

abstract:
  The nature of star formation and Type Ia supernovae (SNIa) in galaxies in the
field and in rich galaxy clusters are contrasted by juxtaposing the build-up of
heavy metals in the universe inferred from observed star formation and
supernovae rate histories with data on the evolution of Fe abundances in the
intracluster medium (ICM). Models for the chemical evolution of Fe in these
environments are constructed, subject to observational constraints, for this
purpose. While models with a mean delay for SNIa of 3 Gyr and standard initial
mass function (IMF) are consistent with observations in the field, cluster Fe
enrichment immediately tracks a rapid, top-heavy phase of star formation --
although transport of Fe into the ICM may be more prolonged and star formation
likely continues to redshifts <1. The source of this prompt enrichment is Type
II supernovae (SNII) yielding at least 0.1 solar masses per explosion (if the
SNIa rate normalization is scaled down from its value in the field according to
the relative number of candidate progenitor stars in the 3-8 solar mass range)
and/or SNIa explosions with short delay times associated with the rapid star
formation mode. Star formation is >3 times more efficient in rich clusters than
in the field, mitigating the overcooling problem in numerical cluster
simulations. Both the fraction of baryons cycled through stars, and the
fraction of the total present-day stellar mass in the form of stellar remnants,
are substantially greater in clusters than in the field.


title: Global Modeling of Spur Formation in Spiral Galaxies

abstract:
  We investigate the formation of substructure in spiral galaxies using global
MHD simulations, including gas self-gravity. Our models extend previous local
models by Kim and Ostriker (2002) by including the full effects of curvilinear
coordinates, a realistic log-spiral perturbation, self-gravitational
contribution from 5 radial wavelengths of the spiral shock, and variation of
density and epicyclic frequency with radius. We show that with realistic Toomre
Q values, self-gravity and galactic differential rotation produce filamentary
gaseous structures with kpc-scale separations, regardless of the strength -- or
even presence -- of a stellar spiral potential. However, the growth of sheared
features distinctly associated with the spiral arms, described as spurs or
feathers in optical and IR observations of many spiral galaxies, requires a
sufficiently strong spiral potential in self gravitating models. Unlike
independently-growing ''background'' filaments, the orientation of arm spurs
depends on galactic location. Inside corotation, spurs emanate outward, on the
convex side of the arm; outside corotation, spurs grow inward, on the concave
side of the arm. Based on spacing, orientation, and the relation to arm clumps,
it is possible to distinguish ''true spurs'' that originate as instabilities in
the spiral arms from independently growing ''background'' filaments. Our models
also suggest that magnetic fields are important in preserving grand design
spiral structure when gas in the arms fragments via self-gravity into GMCs.


title:
Multiwavelength Observations of EXO 0748-676 - I. Reprocessing of X-ray
  Bursts

abstract:
  We present the first high time-resolution simultaneous X-ray, ultraviolet,
and optical observations of X-ray bursts in UY Vol, the optical counterpart of
the low mass X-ray binary EXO 0748-676, obtained with RXTE, HST, and Gemini-S.
Strong reprocessed signals are present in the ultraviolet (a factor of 4) and
optical (a factor of 2.5). These signals are lagged with respect to the X-rays
and appear significantly smeared as well. The addition of far-ultraviolet
coverage for one burst, together with the high quality of the dataset, allow
much tighter constraints upon the temperature and geometry of the reprocessing
region than previously possible. A single-zone black body reprocessing model
for this burst suggests a rise in temperatures during the burst from 18,000 to
35,000K and an emitting area comparable to that expected for the disk and/or
irradiated companion star. The lags, a mean of 4.0s and range of 2.5s, are
consistent with those expected within the binary. The single-zone black body
model cannot reproduce the ratio of optical to ultraviolet flux during the
burst, however. The discrepancy, corresponding to underpredicting the optical
by more than a factor of two, seems too large to explain with deviations from a
local black body spectrum and more likely indicates that a range of
reprocessing temperatures are required, as would be expected, with cooler
regions not contributing to the UV. Comparable results are derived from other
bursts, and in particular the lag and smearing both appear shorter when the
companion star is on the near side of the disk as predicted. The burst observed
by HST also yielded a spectrum of the reprocessed light. [Abridged]


title:
Properties of Hickson Compact Groups and of the Loose Groups within
  which they are Embedded

abstract:
  We use the Sloan Digital Sky Survey (SDSS) redshift catalogue to look for
galaxies with accordant redshifts in the nearby environment (up to ~2 Mpc) of
15 Hickson Compact Groups (HCG) and 7 more HCG+environment from the literature.
We find that: (a) HCG's tend to be aligned with the overall galaxy distribution
in their ~1 Mpc environment, (b) the well-established orientation effect by
which the group velocity dispersion correlates with group axial ratio, is
present also in the HCG+environment systems, (c) the radial velocity dispersion
of the HCG+environment systems and of ordinary poor groups only weakly depends
on the group richness, (d) the mean absolute K-band magnitude of E/S0 galaxies
in HCGs is similar to that in ordinary poor groups, and is brighter than that
of isolated E/S0's, indicating that they were formed by the merging of two
galaxies of similar luminosity, (e) the fraction of E/S0 galaxies in these HCGs
depends only weakly on the group richness and velocity dispersion, (f) the
fraction of AGNs is similar in the HCGs and their close environment, while that
of starbursts is significantly higher in the HCGs, (g) the fraction of AGNs and
starbursts is anti-correlated with the velocity dispersion of the
HCG+environment systems. Furthermore, the observed fractions of early-type and
active galaxies as well as their correlations with the group velocity
dispersion suggests a picture by which nuclear activity and galaxy
transformation by merging is instigated by effective gravitational interactions
in the low-velocity dispersion groups, which then dynamically evolve via
virialization processes to higher velocity dispersion groups, which thus have a
higher fraction of early-type galaxies.


title: Rocking the Lighthouse: Circumpulsar Asteroids and Radio Intermittency

abstract:
  We propose that neutral, circumpulsar debris entering the light cylinder can
account for many time-dependent pulsar phenomena that are otherwise difficult
to explain. Neutral material avoids propeller ejection and injects sufficient
charges -- after heating, evaporation, and ionization -- to alter current flows
and pair-production and thus trigger, detune, or extinguish coherent emission.
Relevant phenomena, with time scales from seconds to months, include nulls,
rotating radio transients (RRATs), rapid changes in pulse profile (``mode
changes''), variable subpulse drift rates, quasi-periodic bursts from B1931+24,
and torque variations. Over the 10 Myr lifetime of a canonical pulsar with
trillion-gauss surface magnetic field, less than a millionth of an Earth mass
of material is needed to modulate the Goldreich-Julian current by 100%.
Circumpulsar material originates from metal-rich, supernova fallback gas that
aggregates into asteroids. Debris disks can inject sufficient material on time
scales of interest, yet be too tenuous to form large planets detectable in
pulse timing data. Asteroid migration results from collisions and the
radiation-driven Yarkovsky and Poynting-Robertson effects. For B1931+24, an
asteroid in a $\sim 40$~day elliptical orbit pollutes the magnetosphere
stochastically through collisions with other debris. Injection is less likely
for hot, young and highly magnetized pulsars or millisecond pulsars that
pre-ionize any debris material well outside their small magnetospheres.
Injection effects will therefore be most prominent in long-period, cooler
pulsars, consistent with the distribution of relevant objects in perid and
period derivative. A pulsar's spin history and its radiation-beam orientation
may influence whether it displays nulling, RRATs and other effects.


title: The First Jet in the Universe: Protostellar Jets from the First Stars

abstract:
  The protostellar jets driven by the formation of the first stars are studied
by using MHD nested grid simulations. Starting from a slowly rotating spherical
cloud of 5.1 times 10^4 Msun permeated by a uniform magnetic field, we follow
the evolution from the central number density n = 10^3 cm^-3 to n simeq 10^23
cm^-3. We calculate four models that differ in initial magnetic field strengths
and angular velocities. In all models, protostars of simeq 10^-3 Msun are
formed at n simeq 10^22 cm^-3 in accordance with one-dimensional calculations.
By this epoch, the magnetic flux density is amplified by 10 orders of magnitude
from the initial value. Consequently, the formed protostar possesses the
magnetic field of \sim 10^6 G that is much larger than the flux density of the
present counterparts, reflecting the fact that the dissipation of a magnetic
field is ineffective in primordial gas clouds. If the initial magnetic field B
> 10^-9 (n/10^3 cm^-3)^2/3 G, the protostellar jet is launched and its
velocities reaches \sim 70 km s^-1 by the time the protostellar mass becomes
(4-6) times 10^-3 Msun, and a fraction (3-10%) of the accreting matter is blown
off from the central region. Owing to the interaction of these ejecta with
surrounding matter, expanding bow shocks are created at both heads of the jet.
If this jet continues to sweep out the surrounding gas that otherwise accretes
onto the central star or circumstellar disk, the final mass of the first star
can be substantially reduced. In addition, dense post-shock regions behind the
bow shocks are expected to promote the chemical reactions (formation of H_2 and
HD), and this provides possible environments for subsequent low-mass star
formation in the early universe.


title: Spectral diversity of Type Ia Supernovae

abstract:
  We use published spectroscopic and photometric data for 8 Type Ia supernovae
to construct a dispersion spectrum for this class of object, showing their
diversity over the wavelength range 3700A to 7100A. We find that the B and V
bands are the spectral regions with the least dispersion, while the U band
below 4100A is more diverse. Some spectral features such as the Si line at
6150A are also highly diverse. We then construct two objective measures of
'peculiarity' by (i) using the deviation of individual objects from the average
SN Ia spectrum compared to the typical dispersion and (ii) applying principle
component analysis. We demonstrate these methods on several SNe Ia that have
previously been classified as peculiar.


title: The Type Ia Supernova Rate at z ~0.5 from the Supernova Legacy Survey

abstract:
  We present a measurement of the distant Type Ia supernova rate derived from
the first two years of the Canada -- France -- Hawaii Telescope Supernova
Legacy Survey. We observed four one-square degree fields with a typical
temporal frequency of <Delta t> ~ 4 observer-frame days over time spans of from
158 to 211 days per season for each field, with breaks during full moon. We
used 8-10 meter-class telescopes for spectroscopic followup to confirm our
candidates and determine their redshifts. Our starting sample consists of 73
spectroscopically verified Type Ia supernovae in the redshift range 0.2 < z <
0.6. We derive a volumetric SN Ia rate of r_V(<z>=0.47) = 0.42^{+0.13}_{-0.09}
(systematic) +- 0.06 (statistical) X 10^-4 yr^-1 Mpc^3, assuming h = 0.7,
Omega_m = 0.3 and a flat cosmology. Using recently published galaxy luminosity
functions derived in our redshift range, we derive a SN Ia rate per unit
luminosity of r_L(<z>=0.47) = 0.154^{+0.048}_{-0.033} (systematic)
^{+0.039}_{-0.031} (statistical) SNu. Using our rate alone, we place an upper
limit on the component of SN Ia production that tracks the cosmic star
formation history of 1 SN Ia per 10^3 M_sun of stars formed. Our rate and other
rates from surveys using spectroscopic sample confirmation display only a
modest evolution out to z=0.55.


title: The non-constant slope of the CIV Baldwin effect in NGC 4151

abstract:
  The relationship between the emission-line equivalent width and the continuum
luminosity, so called the Baldwin effect, plays an important role in studying
the physics of the broad line region of AGNs. Using the archived ultraviolet
spectra obtained by IUE, HST, and HUT in 1978-2002, we investigated the
intrinsic CIV Baldwin effect of a well-studied Seyfert 1 galaxy NGC 4151. Both
its continuum flux and CIV emission-line flux varied about two orders of
magnitude in more than two decades, making it one of the best targets for
studying the slope variation of the Baldwin effect. We fitted the CIV line
profile of the 490 archived UV spectra of NGC 4151 with the same model
consisting of a few Gaussian components, and derived the slope in the log-log
plot for the total flux of CIV emission line against the UV continuum flux in
different observation epochs.We found that the slope is not constant for NGC
4151, as it varies from 0.58 in the highest flux epoch to 0.83 in the lowest
flux epoch. The slope evidently decreases as the continuum flux increases,
which reinforces the previous findings of the non-constant slope in the H_beta
Baldwin effect of NGC 5548 and the CIV Baldwin effect of Fairall 9. Our result
suggests that such a non-constant slope may not be unusual for AGNs. Its
physical origin is probably related to the different non-linear responses of
the emission line to the variable ionizing continuum caused by the different
accretion modes at different luminosity levels. We briefly discuss the effects
of various absorption components in the CIV line profile of NGC 4151 and argue
that the slope variation is not driven mainly by the absorption effect.
Intensive, long-term and high resolution spectral observations of strongly
variable AGNs are needed in the future to confirm our result.


title:
The UV spectrum of HS1700+6416 II. FUSE observations of the HeII Lyman
  alpha forest

abstract:
  We present the far-UV spectrum of the quasar HS1700+6416 taken with FUSE.
This QSO provides the second line of sight with the HeII absorption resolved
into a Ly alpha forest structure. Since HS1700+6416 is slightly less redshifted
(z=2.72) than HE2347-4342, we only probe the post-reionization phase of HeII,
seen in the evolution of the HeII opacity, which is consistent with a simple
power law. The HeII/HI ratio eta is estimated using a line profile-fitting
procedure and an apparent optical depth approach, respectively. The expected
metal line absorption in the far-UV is taken into account as well as molecular
absorption of galactic H_2. About 27% of the eta values are affected by metal
line absorption. In order to investigate the applicability of the analysis
methods, we create simple artificial spectra based on the statistical
properties of the HI Ly alpha forest. The analysis of the artificial data
demonstrates that the apparent optical depth method as well as the line
profile-fitting procedure lead to confident results for restricted data samples
only (12.0 < log N(HI) < 13.0). The reasons are saturation in the case of the
apparent optical depth and thermal line widths in the case of the profile fits.
Furthermore, applying the methods to the unrestricted data set may mimic a
correlation between eta and the strength of the HI absorption. For the
restricted data samples a scatter of 10 - 15% in eta would be expected even if
the underlying value is constant. The observed scatter is significantly larger
than expected, indicating that the intergalactic radiation background is indeed
fluctuating. In the redshift range 2.58 < z < 2.72, where the data quality is
best, we find eta ~ 100, suggesting a contribution of soft sources like
galaxies to the UV background.


title:
On the efficiency and reliability of cluster mass estimates based on
  member galaxies

abstract:
  We study the efficiency and reliability of cluster mass estimators that are
based on the projected phase-space distribution of galaxies in a cluster
region. To this aim, we analyse a data-set of 62 clusters extracted from a
concordance LCDM cosmological hydrodynamical simulation. Galaxies (or Dark
Matter particles) are first selected in cylinders of given radius (from 0.5 to
1.5 Mpc/h) and ~200 Mpc/h length. Cluster members are then identified by
applying a suitable interloper removal algorithm.
  Two cluster mass estimators are considered: the virial mass estimator (Mvir),
and a mass estimator (Msigma) based entirely on the cluster velocity dispersion
estimate. Mvir overestimates the true mass by ~10%, and Msigma underestimates
the true mass by ~15%, on average, for sample sizes of > 60 cluster members.
For smaller sample sizes, the bias of the virial mass estimator substantially
increases, while the Msigma estimator becomes essentially unbiased. The
dispersion of both mass estimates increases by a factor ~2 as the number of
cluster members decreases from ~400 to ~20. The bias in the Mvir estimates is
reduced in clusters without significant evidence for subclustering, and when
only early-type galaxies are selected.
  Radially-dependent incompleteness can drastically affect Mvir estimates, but
leaves the Msigma estimates almost unaffected. Other observational effects,
like centering and velocity errors, and different observational apertures, have
little effect on the mass estimates. (Abridged)


title: A new sample of bright galaxy pairs in UZC

abstract:
  We present a new sample of bright galaxy pairs extracted applying an
objective selection code to UZC catalog.The sample is volume limited to
M$_{zw}$ = -18.9 +5 log ${\it h}$ and contains 89 galaxy pairs.We analyze the
kinematical, morphological and photometrical properties of galaxies belonging
to this sample. We show that velocity separation, $| \Delta v_{r} |$, between
pair members is significantly lower in spiral type (S+S) pairs than in
early-type (E+E) and mixed (E+S) pairs.This indicates that truly isolated
galaxy pairs are more likely to be found among S+S pairs. We show that
ellipticals are rare and underluminous in B and that late spirals (T $\ge$ 4)
are overluminous. We confirm that the formation of bright ellipticals is a
phenomenon linked to group/cluster environment, while galaxy-galaxy interaction
may enhance blue luminosity of disk galaxies through SF phenomena. This last
statement is supported by the presence of strong FIR emission from early
spirals in this sample and by the high frequency of AGN/SB phenomenon, revealed
mainly in pairs of low relative radial velocity separation and showing signs of
interaction.


title:
Ionization structure in the winds of B[e] supergiants II. Influence of
  rotation on the formation of equatorial hydrogen neutral zones

abstract:
  Context: B[e] supergiants are known to have non-spherical winds, and the
existence of disks that are neutral in hydrogen close to their stellar surface
has been postulated. A suitable mechanism to produce non-spherical winds seems
to be rapid rotation, and at least for three B[e] supergiants in the Magellanic
Clouds rotation velocities at a substantial fraction of their critical velocity
have been found. Aims: We want to find suitable recombination distances in the
equatorial plane of rapidly rotating stars that explain the observed huge
amounts of neutral material in the vicinity of B[e] supergiants. Methods: We
perform ionization structure calculations in the equatorial plane around
rapidly rotating luminous supergiants. The restriction to the equatorial plane
allows us to treat the ionization balance equations 1-dimensionally, while the
stellar radiation field is calculated 2-dimensionally, taking into account the
latitudinal variation of the stellar surface parameters. The stellar parameters
used correspond to those known for B[e] supergiants. The assumptions made in
the computations all have in common that the total number of available ionizing
photons at any location within the equatorial plane is overestimated, resulting
in upper limits for the recombination distances. Results: We find that despite
the drop in equatorial surface density of rapidly rotating stars (neglecting
effects like bi-stability and/or wind compression), hydrogen and helium
recombine at or close to the stellar surface, for mass loss rates Mdot > 5d-5
M_sun/yr and rotation speeds in excess of v(rot,eq)/v(crit)=0.8.


title: Nature of giant pulses in radio pulsars

abstract:
  Formation of giant radio pulses is attributed to propagation effects in the
plasma of pulsar magnetosphere. Induced scattering of radio waves by the plasma
particles is found to lead to an efficient redistribution of the radio emission
in frequency. With the steep spectrum of pulsar radiation, intensity transfer
between the widely spaced frequencies may imply significant narrow-band
amplification of the radiation. This may give rise to giant pulses. It is
demonstrated that the statistics of giant pulse intensities observed can be
reproduced if one take into account pulse-to-pulse fluctuations of the plasma
number density and the original intensity. Polarization properties of the
strongly amplified pulses, their location in the average pulse window and the
origin of the nanostructure of giant pulses are discussed as well.


title: The influence of gas on the structure of merger remnants

abstract:
  We present a large set of merger simulations of early-type disc galaxies with
mass ratios of 1:1 and 3:1 and 10% of the total disc mass in gas. In contrast
to the collisionless case equal-mass mergers with gas do not result in very
boxy remnants which is caused by the suppression of box orbits and the change
of the projected shape of minor-axis tube orbits in the more axisymmetric
remnants. The isophotal shape of 3:1 remnants and the global kinematic
properties of 1:1 and 3:1 remnants are only weakly affected by the presence of
gas. 1:1 remnants are slowly rotating whereas 3:1 remnants are fast rotating
and discy. The shape of the stellar LOSVD is strongly influenced by gas. The
LOSVDs of collisionless remnants have broad leading wings while their gaseous
counterparts show steep leading wings, more consistent with observations of
elliptical galaxies. We show that this change is also caused by the suppressed
populating of box orbits and it is amplified by the formation of extended gas
discs in the merger remnants. If elliptical galaxies have formed from mergers
our results indicate that massive, slowly rotating boxy elliptical galaxies can
not have formed from dissipative mergers of discs. Pure stellar (dry) mergers
are the more likely candidates. On the other hand lower mass, fast rotating and
discy ellipticals can have formed from dissipative (wet) mergers of early-type
discs. So far, only unequal-mass disc mergers with gas can successfully explain
their observed substructure. This is consistent with the revised morphological
classification scheme of increasing importance of gas dissipation when moving
from boxy ellipticals to discy ellipticals and then to spiral galaxies,
proposed by Kormendy & Bender (abbreviated).


title:
The Real-Time Evolution of Sakurai's Star (V4334 Sgr) and other (V)LTP
  Objects

abstract:
  We report on the progress of our on-going campaign to monitor the evolution
of the VLTP objects V4334 Sgr and V605 Aql, as well as the suspected (V)LTP
object CK Vul. V4334 Sgr does not show signs of increased ionization compared
to our previous observations in 2004. We obtained the first radio detection of
V605 Aql, indicating a strong increase in radio flux since 1987. We also
present the first radio detection of CK Vul and discuss the expansion of the
material ejected during the 1670 event.


title: Black hole mass and accretion rate of Active Galactic Nuclei

abstract:
  The determination of the central black hole mass is crucial to the
understanding of AGN physics. In this paper we briefly review some methods that
are currently used to estimate the black hole mass of AGNs. Particularly we
demonstrate the importance of two correlations: one between the black hole mass
and the stellar velocity dispersion and another one between the broad line
region (BLR) size and the optical continuum luminosity. Besides applying these
relations in deriving black hole masses of various types of AGNs, we also
employed the fundamental plane of elliptical galaxies to estimate the central
velocity dispersions of AGN host galaxies, and then the black hole masses of
AGNs including BL Lac objects. In addition, we derived another empirical
relation between the BLR size and H_beta emission line luminosity from AGNs
with the BLR size measured by reverberation mapping studies, and argued that
more accurate black hole masses of extremely radio-loud AGNs could be obtained
with it than using the usual R-L_{5100\AA} relation because of the jet
contribution to the optical continuum. Finally we pointed out that black hole
mass estimation is very much helpful to determine the accretion rate and
understand the accretion process in AGNs.


title:
First evidence for molecular interfaces between outflows and ambient
  cloud in high-mass star forming regions?

abstract:
  We present new observations of the CepA-East region of massive star formation
and describe an extended and dynamically distinct feature not previously
recognised. This feature is present in emission from H2CS, OCS, CH3OH, and HDO
at -5.5 km/s, but is not traced by conventional tracers of star forming regions
H2S, SO2, SO, CS. The feature is extended up to at least 0.1 pc. We show that
the feature is neither a hot core nor a shocked outflow. However, the chemistry
of the feature is consistent with predictions of a model of an eroding
interface between a fast wind and a dense core; mixing between the two media
occurs in the interface on a timescale of 10-50 years. If these observations
are confirmed by detailed maps and by detections in species also predicted to
be abundant (e.g. HCO+, H2CO, and NH3) this feature would be the first
detection of such an interface in regions of massive star formation. An
important implication of the model is that a significant reservoir of sulfur in
grain mantles is required to be in the form of OCS.


title: A rule of thumb for cosmological backreaction

abstract:
  In the context of second order perturbation theory, cosmological backreaction
is seen to rescale both time and the scale factor. The issue of the homogeneous
limit of long-wavelength perturbations is addressed and backreaction is
quantified in terms of a gauge-invariant metric function that is the true
physical degree of freedom in the homogeneous limit. The time integral of this
metric function controls whether backreaction hastens or delays the expansion
of the universe. As an example, late-time acceleration of the universe is shown
to be inconsistent with a perturbative approach. Any tendency to accelerate the
expansion requires negative non-adiabatic pressure fluctuations.


title: Infrared Imaging of Planetary Nebulae from the Ground Up

abstract:
  New ground-based telescopes and instruments, the return of the NICMOS
instrument on the Hubble Space Telescope (HST), and the recent launch of the
Spitzer Space Telescope have provided new tools that are being utilized in the
study of planetary nebulae. Multiwavelength, high spatial resolution
ground-based and HST imaging have been used to probe the inner regions of young
PNe to determine their structure and evaluate formation mechanisms.
Spitzer/IRAC and MIPS have been used to image more evolved PNe to determine the
spatial distribution of molecular hydrogen, ionized gas, and dust in the
nebulae and halos.


title:
High spatial resolution mid-infrared spectroscopy of the starburst
  galaxies NGC 3256, IIZw40 and Henize 2-10

abstract:
  In order to show the importance of high spatial resolution observations of
extra-galactic sources when compared to observations obtained with larger
apertures such as ISO, we present N-band spectra (8-13 um) of some locations in
three starburst galaxies. In particular, the two galactic nuclei of the spiral
galaxy NGC3256, the compact IR supernebula in the dwarf galaxy IIZw40 and the
two brightest IR knots in the central starburst of the WR galaxy He2-10. The
spectra have been obtained with TIMMI2 on the ESO 3.6m telescope. An inventory
of the spectra in terms of atomic fine-structure lines and molecular bands is
presented. We show the great value of these high spatial resolution data at
constraining properties such as the extinction in the mid-IR, metallicity or
stellar content (age, IMF, etc.). Regarding this, we have constrained the
stellar content of the IR compact knot in IIZw40 by using the mid-IR
fine-structure lines and setting restrictions on the nebular geometry.
Considering the PAH bands, we have constructed a new mid-/far-IR diagnostic
diagram based on the 11.2 um PAH and continuum, accessible to ground-based
observations. Finally, we find a dependence between the presence or
non-presence of PAHs and the hardness of the radiation field as measured by the
[SIV]/[NeII] ratio. In particular, sources with PAH emission have in general a
[SIV]/[NeII] ratio < 0.35. We investigate possible origins for this relation
and conclude that it does not necessarily imply PAH destruction, but could also
be explained by the PAH-dust competition for FUV photons.


title: Globular Cluster System evolution in early type galaxies

abstract:
  Globular clusters (GCs) constitute a system which is evolving because of
various interactions with the galactic environment. Evolution may be the
explanation of many observed features of Globular Cluster Systems (GCSs); the
different radial distribution of the GCS and the stellar component of early
type galaxies is explained by dynamical friction and tidal effects, this latter
acting both on the large scale (that of the bulge-halo stars) and on the small
scale (that of the nucleus, often containing a central massive black hole).
Merging of quickly orbitally decayed massive GCs leads to formation of a Super
Star Cluster (SSC) which enriches the galactic nucleus and is a reservoire of
mass-energy for a centrally located black hole


title: Kinematics of Protostellar Objects in the $\rho$ Ophiuchus A Region

abstract:
  We present the detection of infall, rotation and outflow kinematic signatures
towards both a protostellar source, VLA 1623 and what was initially thought to
be a pre-protostellar core, SM1N, in the rho-Ophiuchus A region. The kinematic
signatures of early star formation were detected in the dense molecular gas
surrounding the embedded sources using high signal-to-noise millimeter and
submillimeter data. Centroid velocity maps made with HCO+ J=4->3 and J=1->0
line emission exhibit the blue bulge signature of infall, which is predicted to
be seen when infall motion dominates over rotational motion. Further evidence
for infalling gas is found in the HCO+ blue asymmetric line profiles and red
asymmetric opacity profiles. We also performed CO J=3->2 and J=1->0
observations to determine the direction, orientation, and extent of molecular
outflows, and report the discovery of a new bipolar outflow possibly driven by
SM1N.


title: Photometric study of selected cataclysmic variables

abstract:
  We present time-resolved photometry of five relatively poorly-studied
cataclysmic variables: V1193 Ori, LQ Peg, LD 317, V795 Her, and MCT 2347-3144.
The observations were made using four 1m-class telescopes for a total of more
than 250 h of observation and almost 16,000 data points. For LQ Peg WHT
spectroscopic data have been analysed as well.
  The light curves show a wide range of variability on different time scales
from minutes to months. We detect for the first time a brightness variation of
0.05 mag in amplitude in V1193 Ori on the same timescale as the orbital period,
which we interpret as the result of the irradiation of the secondary. A 20-min
quasi-periodic oscillation is also detected. The mean brightness of the system
has changed by 0.5 mag on a three-month interval, while the flickering was
halved. In LQ Peg a 0.05 mag modulation was revealed with a period of about 3
h. The flickering was much smaller, of the order of 0.025 mag. A possible
quasi-periodic oscillation could exist near 30 min. For this object, the WHT
spectra are single-peaked and do not show any radial-velocity variations. The
data of LD 317 show a decrease in the mean magnitude of the system. No periodic
signal was detected but this is certainly attributable to the very large
flickering observed: between 0.07 and 0.1 mag. For V795 Her, the 2.8-hour
modulation, thought to be a superhump arising from the precession of the disc,
is present. We show that this modulation is not stable in terms of periodicity,
amplitude, and phase. Finally, for MCT 2347-3144, a clear modulation is seen in
a first dataset obtained in October 2002. This modulation is absent in August
2003, when the system was brighter and showed much more flickering.


title: Bridging the Virtual Observatory and the GRID with the query element

abstract:
  The current generation of Grid infrastructures designed for production
activity is strongly computing oriented and tuned on the needs of applications
that requires intensive computations. Problems arise when trying to use such
Grids to satisfy the sharing of data-oriented and service-oriented resources as
happens in the IVOA community. We have designed, developed and implemented a
Grid query element to access data source from an existing production Grid
environment. We also enhanced the Grid middleware model (collective resources
and sites) to manage Data Sources extending the Grid semantic. The query
element and the modified grid Information System are able to connect the Grid
environment to Virtual Observatory resources. A specialized query element is
designed to work as Virtual Observatory resource in the Grid so than an
Astronomer can access Virtual Observatory data using the IVOA standards.


title: Theoretical Aspects of High Energy Neutrinos and GRB

abstract:
  Neutrinos at energies ranging from sub-TeV to EeV from astrophysical sources
can yield interesting physical information about fundamental interactions,
about cosmic rays and about the nature of the sources and their environment.
Gamma-ray bursts are a leading candidate source, and their expected neutrino
emission can address a number of current questions, which may be answered with
forthcoming experiments such as IceCube, Auger, ANITA and KM3NeT.


title:
Spitzer Observations of V838 Monocerotis: Detection of a Rare Infrared
  Light Echo

abstract:
  We present Spitzer observations of the unusual variable V838 Monocerotis.
Extended emission is detected around the object at 24, 70 and 160um. The
extended infrared emission is strongly correlated spatially with the HST
optical light echo images taken at a similar epoch. We attribute this diffuse
nebulosity to be from an infrared light echo caused by reprocessed thermal
emission from dust heated by the outward-propagating radiation from the 2002
eruption. The detection of an IR light echo provides an opportunity to estimate
the mass in dust of the echo material and hence constrain its origin. We
estimate the dust mass of the light echo to be on the order of a solar mass -
thereby implying the total gas plus dust mass to be considerably more - too
massive for the echo material to be the ejecta from previous
outburst/mass-losing events. This is therefore suggestive that a significant
fraction of the matter seen through the light echo is interstellar in origin.
Unresolved emission at 24 and 70um is also seen at the position of the central
star possibly indicating the presence of hot dust freshly condensed in the
outburst ejecta.


title:
The Far Ultraviolet Spectroscopic Explorer Survey of OVI Emission in the
  Milky Way

abstract:
  We present a survey of OVI 1032 emission in the Milky Way using data from the
Far Ultraviolet Spectroscopic Explorer (FUSE) satellite. The observations span
the period from launch in 1999 to July 2003. Our survey contains 112 sight
lines, 23 of which show measurable OVI 1032 emission. The OVI 1032 emission
feature was detected at all latitudes and exhibits intensities of 1900-8600
photons/s/cm^2/sr. Combined with values from the literature, these emission
measurements are consistent with the picture derived from recent OVI absorption
surveys: high-latitude sight lines probe OVI-emitting gas in a clumpy, thick
disk or halo, while low-latitude sight lines sample mixing layers and
interfaces in the thin disk of the Galaxy.


title: Generalized Galilei-Invariant Classical Mechanics

abstract:
  To describe the ``slow'' motions of n interacting mass points, we give the
most general 4-d non-instantaneous, non-particle symmetric Galilei-invariant
variational principle. It involves two-body invariants constructed from
particle 4-positions and 4-velocities of the proper orthochronous inhomogeneous
Galilei group. The resulting 4-d equations of motion and multiple-time
conserved quantities involve integrals over the world lines of the other n-1
interacting particles. For a particular time-asymmetric retarded (advanced)
interaction, we show the vanishing of all integrals over world-lines in the ten
standard 4-d multiple-time conserved quantities, thus yielding a Newtonian-like
initial value problem. This interaction gives 3-d non-instantaneous,
non-particle symmetric, coupled non-linear second-order delay-differential
equations of motion that involve only algebraic combinations of
non-simultaneous particle positions, velocities, and accelerations. The ten 3-d
non-instantaneous, non-particle symmetric conserved quantities involve only
algebraic combinations of non-simultaneous particle positions and velocities. A
two-body example with a generalized Newtonian gravity is provided. We suggest
that this formalism might be useful as an alternative slow-motion mechanics for
astrophysical applications.


title: The Metal-Poor Halo of the Andromeda Spiral Galaxy (M31)

abstract:
  We present spectroscopic observations of red giant branch (RGB) stars over a
large expanse in the halo of the Andromeda spiral galaxy (M31), acquired with
the DEIMOS instrument on the Keck II 10-m telescope. Using a combination of
five photometric/spectroscopic diagnostics -- (1) radial velocity, (2)
intermediate-width DDO51 photometry, (3) Na I equivalent width (surface gravity
sensitive), (4) position in the color-magnitude diagram, and (5) comparison
between photometric and spectroscopic [Fe/H] estimates -- we isolate over 250
bona fide M31 bulge and halo RGB stars located in twelve fields ranging from R
= 12-165kpc from the center of M31 (47 of these stars are halo members with R >
60 kpc). We derive the photometric and spectroscopic metallicity distribution
function of M31 RGB stars in each of these fields. The mean of the resulting
M31 spheroid (bulge and halo) metallicity distribution is found to be
systematically more metal-poor with increasing radius, shifting from <[Fe/H]> =
-0.47+/-0.03 (sigma = 0.39) at R < 20 kpc to <[Fe/H]> = -0.94+/-0.06 (sigma =
0.60) at R ~ 30 kpc to <[Fe/H]> = -1.26+/-0.10 (sigma = 0.72) at R > 60 kpc,
assuming [alpha/Fe] = 0.0. These results indicate the presence of a metal-poor
RGB population at large radial distances out to at least R = 160 kpc, thereby
supporting our recent discovery of a stellar halo in M31: its halo and bulge
(defined as the structural components with R^{-2} power law and de Vaucouleurs
R^{1/4} law surface brightness profiles, respectively) are shown to have
distinct metallicity distributions. If we assume an alpha-enhancement of
[alpha/Fe] = +0.3 for M31's halo, we derive <[Fe/H]> = -1.5+/-0.1 (sigma =
0.7). Therefore, the mean metallicity and metallicity spread of this newly
found remote M31 RGB population are similar to those of the Milky Way halo.


title:
A New Method for Isolating M31 Red Giant Stars: The Discovery of Stars
  out to a Radial Distance of 165 Kiloparsecs

abstract:
  We present a method for isolating a clean sample of red giant stars in the
outerregions of the Andromeda spiral galaxy (M31) from an ongoing spectroscopic
survey using the DEIMOS instrument on the Keck 10-m telescope. The survey aims
to study the kinematics, global structure, substructure, and metallicity of
M31's halo. Although most of our spectroscopic targets were photometrically
screened to reject foreground Milky Way dwarf star contaminants, the latter
class of objects still constitutes a substantial fraction of the observed
spectra in the sparse outer halo. Our likelihood-based method for isolating M31
red giants uses five criteria: (1) radial velocity, (2) photometry in the
intermediate-width DDO51 band to measure the strength of the MgH/Mgb absorption
features, (3) strength of the Na I 8190A absorption line doublet, (4) location
within an (I, V-I) color-magnitude diagram, and (5) comparison of photometric
(CMD-based) versus spectroscopic (Ca II 8500A triplet-based) metallicity
estimates. We also discuss K I and TiO diagnostics for giant/dwarf separation
that might be useful in future analyses. Training sets consisting of definite
M31 red giants and Galactic dwarf stars are used to derive empirical
probabilitydistribution functions for each diagnostic. These functions are used
to calculate the likelihood that a given star is a red giant in M31 versus a
Milky Way dwarf. By applying this diagnostic method to our spectroscopic data
set, we isolate 40 M31 red giants beyond a projected distance of R = 60 kpc
from the galaxy's center, including three out at R ~ 165 kpc. The ability to
identify individual M31 red giants gives us an unprecedented level of
sensitivity in studying the properties of the galaxy's outer halo.


title:
Discovery of an Extended Halo of Metal-poor Stars in the Andromeda
  Spiral Galaxy

abstract: This paper has been withdrawn. Please see astro-ph/0502366.


title: Why the cosmological constant is small and positive

abstract:
  Within conventional big bang cosmology, it has proven to be very difficult to
understand why today's cosmological constant is so small. In this paper, we
show that a cyclic model of the universe can naturally incorporate a dynamical
mechanism that automatically relaxes the value of the cosmological constant,
taking account of contributions to the vacuum density at all energy scales.
Because the relaxation time grows exponentially as the vacuum density
decreases, nearly every volume of space spends an overwhelming majority of the
time at the stage when the cosmological constant is small and positive, as
observed today.


title:
Silicate Emission Profiles from Low-Mass Protostellar Disks in the Orion
  Nebula: Evidence for Growth and Thermal Processing of Grains

abstract:
  We present 8--13 micron low resolution spectra (R~100) of 8 low-mass
protostellar objects ("proplyds") in the Orion Nebula using the Long Wavelength
Spectrometer (LWS) at the W. M. Keck Observatory. All but one of the sources in
our sample show strong circumstellar silicate emission, with profiles that are
qualitatively similar to those seen in some T Tauri and Herbig Ae/Be stars. The
silicate profile in all cases is significantly flattened compared to the
profile for typical interstellar dust, suggesting that the dominant emitting
grains are significantly larger than those found in the interstellar medium.
The 11.3-to-9.8 micron flux ratio--often used as an indicator of grain
growth--is in the 0.8 to 1.0 range for all of our targets, indicating that the
typical grain size is around a few microns in the surface layers of the
attendant circumstellar disk for each object. Furthermore, the silicate
profiles show some evidence of crystalline features, as seen in other young
stellar objects. The results of our analysis show that the grains in the
photoevaporating protostellar disks of Orion have undergone significant growth
and perhaps some annealing, suggesting that grain evolution for these objects
is not qualitatively different from other young stellar objects.


title: Coincidence of Universe age in $\Lambda$CDM and Milne cosmologies

abstract:
  The age of the Universe in the $\Lambda$CDM cosmology with
$\Omega_{matter}=0.26$ and $\Omega_{\Lambda}=0.74$ is the same as in the Milne
cosmology which correspods to an almost empty universe. In both cases it is a
reciprocal Hubble constant, $1/H_0$, that for now preferred value $H_0=71
km/s/Mpc$ is 13.7 billion years. The most curious coincidence is that at the
present time, in the $\Lambda$CDM model the decelerated expansion is exactly
compensated by the accelerated expansion, as if the Universe coast for 13.7
billion years.


title: Interested in observing TrES-Her0-07621?

abstract:
  TrES-Her0-07621 is a recently discovered detached M Dwarf eclipsing binary
system. We present some follow-up observations of this system including new
minima times and a refined orbital period. We have also obtained better
estimates of the stellar radii and inclination.


title:
Understanding the Relationship Between Observations and Stellar
  Parameters in an Eclipsing Binary System

abstract:
  We would like to investigate the information contained in our observations
and to what extent each of them contributes individually to constraining the
physical parameters of the system we are investigating. To do this, we present
a study involving the technique of Singular Value Decomposition using as a
simple example a detached eclipsing binary system. We intend to apply an
extension of this technique to asteroseismic measurements of Delta~Scuti stars
that are members of eclipsing binary systems.


title:
The Extragalactic Lens VLBI Imaging Survey (ELVIS). I. A Search for the
  Central Image in the Gravitational Lens PMN J1838-3427

abstract:
  The Extragalactic Lens VLBI Imaging Survey (ELVIS) searches for central
images of lensed radio quasars, in order to measure the central density
profiles of distant galaxies. Here we present sensitive multi-epoch Very Long
Baseline Array (VLBA) observations of PMN J1838-3427 at 8 GHz, with a 1 sigma
noise level of 38 microJy beam^(-1). Based on the absence of a central image of
the background source at this level, we explore the possibilities for the
central matter distribution in the lens galaxy. A power-law density profile,
rho ~ r^(-gamma), must have gamma > 1.93. Thus the density profile is close to
an isothermal profile (gamma = 2) or steeper. The upper limit on any
constant-density core in an otherwise isothermal profile is ~< 5 parsecs. We
also derive the constraints on models in which the density profile is
isothermal on kiloparsec scales, but is allowed to have a different power law
in the central ~100 parsecs. If the lens galaxy harbors a supermassive black
hole, the galaxy profile is allowed to be shallower, but for the expected black
hole mass the galaxy profile must still be close to isothermal or steeper.


title: Extragalactic Star Clusters in Merging Galaxies

abstract:
  The study of cluster populations as tracer of galaxy evolution is now quite
possible with 8 m class telescopes and modern instrumentation. The cluster
population can be used as a good tracer of the star forming episodes undergone
by the merging system. We present two young galaxies mergers NGC3256 and
NGC4038, and the studies about the young cluster population on those system. We
found that the clusters ages are agree with the mergers age and their
metallicities are consistent with them being the progenitors of the old metal
rich globulars in ellipticals.


title: Fe/Ni ratio in the Ant Nebula Mz 3

abstract:
  We have analyzed the [Fe II] and [Ni II] emission lines in the bipolar
planetary nebula Mz~3. We find that the [Fe II] and [Ni II] lines arise
exclusively from the central regions. Fluorescence excitation in the formation
process of these lines is negligible for this low-excitation nebula. From the
[Fe II]/[Ni II] ratio, we obtain a higher Fe/Ni abundance ratio with respect to
the solar value. The current result provides further supporting evidence for Mz
3 as a symbiotic Mira.


title: Abundances of s-process elements in planetary nebulae: Br, Kr & Xe

abstract:
  We identify emission lines of post-iron peak elements in very high
signal-to-noise spectra of a sample of planetary nebulae. Analysis of lines
from ions of Kr and Xe reveals enhancements in most of the PNe, in agreement
with the theories of s-process in AGB star. Surprisingly, we did not detect
lines from Br even though s-process calculations indicate that it should be
produced with Kr at detectable levels.


title:
Effects of dust scattering albedo and 2175 A bump on ultraviolet colours
  of normal disc galaxies

abstract:
  We discuss dust properties in the interstellar medium (ISM) of nearby normal
galaxies, by comparing observations in the ultraviolet (UV) with simulations by
a radiative transfer model. The observed UV colours of nearby galaxies show a
reddening relative to their expected intrinsic colours. Some authors argued
that the Milky Way dust cannot reproduce the reddening because of the prominent
2175 \AA absorption bump. Other authors proposed a reduction mechanism of the
bump strength in an {\it attenuation law} derived from the ratio of the
observed intensity to the intrinsic one through an age-selective attenuation
(i.e., young stars are more attenuated selectively). We newly find that the
wavelength dependence of the scattering albedo also has a strong effect on the
UV colour; an albedo decreasing toward shorter wavelengths (except for the
absorption bump range) produces a significant UV reddening. After comparing the
observed UV colours of nearby normal galaxies with those expected from
radiative transfer simulations assumed several dust models, we find two sorts
of dust suitable for these galaxies: (1) dust with a bump and a smaller albedo
for a shorter wavelength (except for the bump range), and (2) dust without any
bump but with an almost constant albedo. If very small carbonaceous grains
responsible for the common unidentified infrared emission band are also the
bump carrier, the former dust is favorable. Finally, we derive mean attenuation
laws of various dust models as a function of the UV attenuation, and derive
some relations between the UV attenuation and observable/theoretical
quantities.


title:
Competition between dust scattering albedo and 2175 A bump for
  ultraviolet colours of nearby disc galaxies

abstract:
  Observed ultraviolet (UV) colours of nearby disc galaxies show a reddening
relative to their expected intrinsic colours. Since the 2175 \AA bump found in
the Milky Way's dust extinction law blues the UV colours, it might suggest that
dust in nearby disc galaxies does not have the bump and that the Milky Way is
exceptional. However, this conclusion can be modified by the effect of
scatterings. If the scattering albedo decreases towards shorter wavelengths,
observable UV colours redden. An extensive comparison between observed UV
colours and those expected from radiative transfer simulations shows two types
of dust suitable for nearby disc galaxies: (1) dust with a bump and a smaller
albedo for a shorter wavelength (except for the bump range), and (2) dust
without any bump but with an almost constant albedo. If very small carbonaceous
grains responsible for the common unidentified infrared emission band are also
the bump carrier, the former dust is favorable.


title:
Observations and analysis of two type IIP supernovae: the intrinsically
  faint object SN 2005cs and the ambiguous object SN 2005ay

abstract:
  Aims: To derive observational properties and physical parameters of the
progenitor stars of type IIP supernovae SN 2005ay and SN 2005cs from their
U,B,V,R,I CCD photometry, and to define their velocity behaviour. Methods:
Light curves are analysed, and the velocities and spectral characteristics of
SN 2005cs are obtained using synthetic spectra modeling. Results: Both
supernovae are found to be fainter than the average
  SN IIP, with SN 2005cs being more subluminous and showing slight brightening
in the second half of plateau stage in the
  V,R,I bands and a low expansion velocity.
  The effects of two different plausible distance moduli on the derived
physical parameters of SN 2005ay are considered.
  Two approaches are used to recover the amounts of the ejected 56Ni,
indicating masses of the order of
  0.02 Msun, although late luminosities might indicate a higher amount for SN
2005ay, especially for the large distance case.
  Constraints on the progenitor properties are also presented, based on
empirical analytical models. Two approaches are used to estimate the expansion
velocities at the middle of the plateau phase. SN 2005cs represents an example
of where all 3 physical parameters, velocity, energy and 56Ni mass are lower
than average, a correlation not always observed in SNe IIP. SN 2005ay may
belong to the same class if the shorter distance possibility is adopted.
Furthermore, the estimated mass range for SN 2005cs is in agreement with limits
established by using pre-supernova imaging.


title: IR-source IRAS20508+2011: spectral variability of the central star

abstract:
  Over the five years of high-resolution spectroscopy of the cool star
identified with the IR source IRAS20508+2011, the photospheric radial velocity
variability Vr=15-30km/s is detected. In the same time, the Halpha profile
varied from an intense bell-shaped emission line with a small absorption to
2-peaked emission with a central absorption feature below the continuum level.
The NaD doublet lines shown a complex profile with broad (FWHM \approx 120km/s)
emission and photospheric absorption, as well as an interstellar component. We
used model atmospheres to determine the physical parameters and chemical
composition of the star's atmosphere: Te=4800K, log g=1.5, [Fe/H]=-0.36, [O/Fe]
=+1.79 (with the ratio [C/O]=-0.9). The totality of the parameters suggests
that the optical component of IRAS20508+2011 is an O-rich AGB star with
luminosity Mv


title:
Oscillator Strengths and Predissociation Rates for Rydberg Transitions
  in 12C16O, 13C16O, and 13C18O Involving the E 1Pi, B 1Sigma+, and W 1Pi
  States

abstract:
  One of the processes controlling the interstellar CO abundance and the ratio
of its isotopologues is photodissociation. Accurate oscillator strengths and
predissociation rates for Rydberg transitions are needed for modeling this
process. We present results on absorption from the E ^1Pi-X ^1Sigma^+ (1-0) and
B ^1Sigma^+-X ^1Sigma^+ (6-0) bands at 1051 and 1002 \AA, respectively, and the
vibrational progression W ^1Pi-X ^1Sigma^+ (v'-0) bands with v' = 0 to 3 at
972, 956, 941, and 925 \AA, respectively. The corresponding spectra were
acquired at the high resolution (R ~ 30,000) SU5 beam line at the Super ACO
Synchrotron in Orsay, France. Spectra were obtained for the ^12C^16O, ^13C^16O,
and ^13C^18O isotopologues. These represent the most complete set of
measurements available. Comparison is made with earlier results, both empirical
and theoretical. While earlier determinations of oscillator strengths based on
absorption from synchrotron radiation tend to be somewhat smaller than ours,
the suite of measurements from a variety of techniques agree for the most part
considering the mutual uncertainties. For the bands studied here, their
relative weakness, or their significant line widths arising from
predissociation, minimizes potential problems from large optical depths at line
center in absorption measurements. Predissociating line widths could generally
be extracted from the spectra thanks to the profile simulations used in the
analysis. In many cases, these simulations allowed us to consider e and f
parity levels separately and to determine the dependence of the width on
rotational quantum number, J. Our results are consistent with earlier
determinations, especially the widths inferred from laser experiments.


title:
A Spitzer/IRAC Search for Substellar Companions of the Debris Disk Star
  epsilon Eridani

abstract:
  We have used the InfraRed Array Camera (IRAC) onboard the Spitzer Space
telescope to search for low mass companions of the nearby debris disk star
epsilon Eridani. The star was observed in two epochs 39 days apart, with
different focal plane rotation to allow the subtraction of the instrumental
Point Spread Function, achieving a maximum sensitivity of 0.01 MJy/sr at 3.6
and 4.5 um, and 0.05 MJy/sr at 5.8 and 8.0 um. This sensitivity is not
sufficient to directly detect scattered or thermal radiation from the epsilon
Eridani debris disk. It is however sufficient to allow the detection of Jovian
planets with mass as low as 1 MJ in the IRAC 4.5 um band. In this band, we
detected over 460 sources within the 5.70 arcmin field of view of our images.
To test if any of these sources could be a low mass companion to epsilon
Eridani, we have compared their colors and magnitudes with models and
photometry of low mass objects. Of the sources detected in at least two IRAC
bands, none fall into the range of mid-IR color and luminosity expected for
cool, 1 Gyr substellar and planetary mass companions of epsilon Eridani, as
determined by both models and observations of field M, L and T dwarf. We
identify three new sources which have detections at 4.5 um only, the lower
limit placed on their [3.6]-[4.5] color consistent with models of planetary
mass objects. Their nature cannot be established with the currently available
data and a new observation at a later epoch will be needed to measure their
proper motion, in order to determine if they are physically associated to
epsilon Eridani.


title:
Unravelling the chemical inhomogeneity of PNe with VLT FLAMES
  integral-field unit spectroscopy

abstract:
  Recent weak emission-line long-slit surveys and modelling studies of PNe have
convincingly argued in favour of the existence of an unknown component in the
planetary nebula plasma consisting of cold, hydrogen-deficient gas, as an
explanation for the long-standing recombination-line versus forbidden-line
temperature and abundance discrepancy problems. Here we describe the rationale
and initial results from a detailed spectroscopic study of three Galactic PNe
undertaken with the VLT FLAMES integral-field unit spectrograph, which advances
our knowledge about the small-scale physical properties, chemical abundances
and velocity structure of these objects across a two-dimensional field of view,
and opens up for exploration an uncharted territory in the study and modelling
of PNe and photoionized nebulae in general.


title:
Structure and Kinematics of the Interstellar Medium in the Star-Forming
  Region in the BCD Galaxy VIIZw403 (UGC6456)

abstract:
  The structure and kinematics of ionized gas in the star-forming region in the
BCD galaxy VIIZw403 (UGC6456) are analyzed using observations with the SCORPIO
focal reducer on the 6-m Special Astrophysical Observatory telescope in three
modes: direct imaging (in the H-alpha, [OIII], and [SII] lines), long-slit
spectroscopy, and spectroscopy with a scanning Fabry-Perot interferometer. In
addition to the previously known bright HII regions and the faint giant ring
that surrounds the entire star-forming region, many new faint diffuse and arc
structures have been detected. Fine structure of the giant ring has been
revealed. We do not confirm the previously detected expansion of the bright
shells around young stellar associations with a velocity of 50-70 km/s. We have
estimated their expansion velocities to be no higher than 15-20 km/s; the
corresponding kinematic age, no younger than 3-4 Myr, agrees well with the age
of the compact OB associations related to them. We associate the faint extended
filamentary and diffuse regions of ionized gas identified in nearly the entire
central region of the galaxy and the giant HII ring with the older (10 Myr)
stellar population of the most recent starburst. Weak high-velocity [OIII] and
H-alpha line wings (up to 300 km/s from the line center) have been detected in
the brightest HII region. Such velocities have been observed in the galaxy for
the first time. The previously published H-alpha luminosity measurements for
the galaxy are refined.


title:
A Prominent Accretion Disk in the Low-Hard State of the Black Hole
  Candidate SWIFT J1753.5-0127

abstract:
  We report on simultaneous XMM-Newton and RXTE observations of the
stellar-mass black hole candidate SWIFT J1753.5-0127. The source was observed
in the low-hard state, during the decline of a hard outburst. The inner
accretion disk is commonly assumed to be radially truncated in the low-hard
state, and it has been suggested that this property may be tied the production
of steady, compact jets. Fits to the X-ray spectra of SWIFT J1753.5-0127 with a
number of simple models clearly reveal a cool (kT ~ 0.2 keV) accretion disk.
The disk component is required at more than the 8 sigma level of confidence.
Although estimates of inner disk radii based on continuum spectroscopy are
subject to considerable uncertainty, fits with a number of models suggest that
the disk is observed at or close to the innermost stable circular orbit.
Recently, an observation of GX 339-4 revealed a disk extending to the innermost
stable circular orbit at L_X/L_Edd ~ 0.05; our results from SWIFT J1753.5-0127
may extend this finding down to L_X/L_Edd ~ 0.003 (d/8.5 kpc)^2 (M/Msun). We
discuss our results within the context of low-luminosity accretion flow models
and disk-jet connections.