title: Testable anthropic predictions for dark energy

abstract:
  In the context of models where the dark energy density $\rD$ is a random
variable, anthropic selection effects may explain both the "old" cosmological
constant problem and the "time coincidence". We argue that this type of
solution to both cosmological constant problems entails a number of definite
predictions, which can be checked against upcoming observations. In particular,
in models where the dark energy density is a discrete variable, or where it is
a continuous variable due to the potential energy of a single scalar field, the
anthropic approach predicts that the dark energy equation of state is
$p_D=-\rho_D$ with a very high accuracy. It is also predicted that the dark
energy density is greater than the currently favored value $\Omega_D\approx
0.7$. Another prediction, which may be testable with an improved understanding
of galactic properties, is that the conditions for civilizations to emerge
arise mostly in galaxies completing their formation at low redshift, $z\approx
1$. Finally, there is a prediction which may not be easy to test
observationally: our part of the universe is going to recollapse eventually.
However, the simplest models predict that it will take more than a trillion
years of accelerated expansion before this happens.


title:
V463 Scuti (Nova Sct 2000): Rapidly Evolving Nova with a Prominent
  Premaximum Halt

abstract:
  We summarize photometric and spectroscopic observations of V463 Sct (Nova Sct
2000), which was originally thought to be a red variable. The spectrum taken on
2000 March 16.81 UT showed prominent emission lines with a FHWM of 990 km/s (H
alpha). The light curve shows a conspicuous premaximum halt lasting at least
for 24 d, and a late-phase flare-like maximum. The nova then started rapidly
fading at a rate corresponding to t2 = 15 +/- 3 d. Long premaximum halts have
been considered as a unique character of the "slowest" novae. The present
observation, however, suggests that the long premaximum halts are not a unique
character of the slowest novae, but a more general phenomenon spreading over a
wider range of nova speed classes than has been previously believed. A recent
interpretation of premaximum halts requires that the conditions of
thermonuclear runaway was only marginally satisfied. Since such conditions are
more difficult to meet in rapidly evolving novae, V463 Sct would provide an
unique opportunity in testing this interpretation. The early post-outburst
spectrum showed co-existence of Fe II lines and some forbidden lines, which
suggests that substantial amount of material may have been ejected before the
observed optical maximum. The impact of the modern global network (VSNET) on
confirmatory processes of transient objects is briefly discussed.


title: XMM-Newton observations of the nearby brown dwarf LP 944-20

abstract:
  The nearby (d=5.0 pc) brown dwarf LP944-20 was observed with the XMM-Newton
satellite on 07 January 2001. The target was detected with the Optical Monitor
(V=16.736$\pm$0.081), but it was not detected during the $\approx 48$ ks
observation with the X-ray telescopes. We determine a $3\sigma$ upper limit for
the X-ray emission from this object of $L_{X}<3.1 \times 10^{23}$ $ergs \cdot
s^{-1}$, equivalent to a luminosity ratio upper limit of $\log{(L_{X}/L_{bol})}
\le -6.28$. This measurement improves by a factor of 3 the previous
\emph{Chandra} limit on the quiescent X-ray flux. This is the most sensitive
limit ever obtained on the quiescent X-ray emission of a brown dwarf. Combining
the XMM data with previous \emph{ROSAT} and \emph{Chandra} data, we derive
flare duty cycles as a function of their luminosities. We find that very strong
flares [Log$(L_X/L_{bol})>-$2.5] are very rare (less than 0.7% of the time).
Flares like the one detected by Chandra [Log$(L_X/L_{bol})=-$4.1] have a duty
cycle of about 6%, which is lower than the radio flare duty cycle ($\sim$13%).
When compared with other M dwarfs, LP944-20 appears to be rather inactive in
X-rays despite of its relative youth, fast rotation and its moderately strong
activity at radio wavelengths.


title:
Extreme Slim Accretion Disks and Narrow Line Seyfert 1 Galaxies: the
  Nature of the soft X-ray Hump

abstract:
  We present a detailed model of an extreme slim disk (ESD) with a hot corona
around a massive black hole with dimensionless accretion rate $\dotm$ in the
range $2.5\ll \dotm\leq 100$. We assume that a fraction $f$ of the
gravitational energy is released in the hot corona and the rest is released in
the ESD. The energy equation of the ESD is dominated by advection and the
spectrum shows a broad ``hump'' caused by saturated Comptonization with
monochromatic luminosity given by $\nu L_{\nu}\propto \nu^0$. This relationship
enables us to estimate the black hole mass from the ESD luminosity. The
spectrum of the hot corona is sensitive to the parameter $f\dotM$ and the
viscosity and shows a Comptonized power-law with a high-energy cutoff. The
model is used to explain the spectral properties of narrow line Seyfert 1
galaxies (NLS1s). In particular, it can explain the spectrum of extreme NLS1s
like NLS1 RE J1034+396. Our spectral estimate of the black hole mass in this
source is in good agreement with the mass obtained by applying the
reververation mapping correlation. We also examine the Eddington ratios in a
large NLS1 sample and find that most objects show super-Eddington accretion
rates. We argue that soft X-ray humps in NLS1s are natural consequences of
super-Eddington accretion in such objects.


title: VLT spectroscopy of globular cluster in NGC 3115

abstract:
  We present results derived from VLT-FORS2 spectra of 17 globular clusters
associated with the nearby lenticular galaxy NGC3115. Comparing line-strength
indices to new stellar population models by Thomas et al. we determine ages,
metallicities and element abundance ratios. Our data are also compared with the
Lick/IDS observations of Milky Way and M31 globular clusters. Our best age
estimates show that the observed clusters which sample the bimodal colour
distribution of NGC3115 globular clusters are coeval within our observational
errors (2-3 Gyr). Our best calibrated age/metallicity diagnostic diagram (Hbeta
vs [MgFe]) indicates an absolute age of 11-12 Gyr consistent with the
luminosity weighted age for the central part of NGC3115. We confirm with our
accurate line-strength measurements that the (V-I) colour is a good metallicity
indicator within the probed metallicity range (-1.5 < [Fe/H] < 0.0). The
abundance ratios for globular clusters in NGC3115 give an inhomogeneous
picture. We find a range from solar to super-solar ratios for both blue and red
clusters. This is similar to the data for M31 while the Milky Way seems to
harbour clusters which are mainly consistent with [alpha/Fe] =~ 0.3.


title: Is KT Mon a Classical Nova?

abstract:
  KT Mon has been considered as a classical nova in 1942 based on its light
curve and spectroscopy. However, we noticed a unusual feature for a nova soon
after its maximum: the early presence of high excitation emission lines such as
He II and N III. We propose previously overlooked interpretations that KT Mon
can be either a WZ Sge-type dwarf nova and an X-ray transient, although the
possibility of an unusual or a recurrent nova is not completely excluded. If KT
Mon is a WZ Sge-type dwarf nova, the system is expected to have a brown dwarf
secondary. If KT Mon is an X-ray transient, the system is a good candidate for
the nearest black-hole binary. Within our knowledge, the observed features seem
to more strongly support the latter possibility. In all possibilities, we can
expect a recurrent outburst in meaningfully near future.


title: CN abundance variations on the main sequence of 47 Tuc

abstract:
  We report on a deep spectroscopic survey for star-to-star CN variations along
the main sequence (MS) of the globular cluster 47 Tuc with ESO's VLT. We find a
significant bimodal distribution in the S(3839) index for main-sequence stars
in the mass range of ~0.85 to 0.65 M_sun, or from the main-sequence turn-off
down to ~2.5 mag below the main sequence turn-off. An anti-correlation of CN
and CH is evident on the MS. The result is discussed in the context of the
ability of faint MS stars to alter their surface composition through internal
evolutionary effects. We argue against internal stellar evolution as the only
origin for the abundance spread in 47 Tuc; an external origin such as pollution
seems to be more likely.


title:
Cosmic Inversion II --An iterative method for reproducing the primordial
  spectrum from the CMB data--

abstract:
  Pursuing the original idea proposed in our previous paper (Paper I), we
improve the method to determine the shape of the initial curvature perturbation
spectrum $P(k)$ from the CMB data. The thickness of the last scattering surface
(LSS) and the integrated Sachs-Wolfe (ISW) effect, which we neglect in Paper I,
are taken into account and an iterative method is newly developed. The new
method can reproduce the primordial power spectra with a high accuracy, given
the correct values of the cosmological parameters. Conversely, there appear
spurious peaks and dips in the reconstructed power spectrum if we use the
cosmological parameters slightly different from the true values, while there
appear regions of negative $P(k)$ in some cases if we use substantially
different values. In other words, the tacit assumption that the cosmological
parameters can be determined for an assumed initial spectrum is verified by our
reconstruction method. In addition, it could be a new tool to constrain the
cosmological parameters without recourse to models of the primordial power
spectra.


title: Mg, Ba and Eu abundances in thick disk and halo stars

abstract:
  Our sample of cool dwarf stars from previous papers is extended in this study
including 15 moderately metal-deficient stars. The samples of halo and thick
disk stars have overlapping metallicities with [Fe/H] in the region from -0.9
to -1.5, and we first compare chemical properties of these two kinematically
different stellar populations independent on their metallicity. We present
barium, europium and magnesium abundances for the new sample of stars. The
results are based on NLTE line formation obtained in differential model
atmosphere analyses of high resolution spectra observed mainly using the UVES
spectrogragh at the VLT of ESO. We confirm the overabundance of Eu relative to
Mg in the halo stars. Eight halo stars show the [Eu/Mg] ratios between 0.23 and
0.41, whereas stars in the thick and thin disk display a solar Eu to Mg ratio.
The [Eu/Ba] values found in the thick disk stars to lie between 0.35 and 0.57
suggest that during the thick disk formation evolved low-mass stars started to
enrich the interstellar gas by s-nuclei of Ba, and the s-process contribution
to Ba varies from 30% to 50%. Based on these results, and using the chemical
evolution calculations by Travaglio et al. (1999), we estimate that the thick
disk stellar population formed on a timescale from 1.1 to 1.6 Gyr from the
beginning of the protogalactic collapse. In the halo stars the [Eu/Ba] ratios
are found mostly between 0.40 and 0.67, which suggests a duration of the halo
formation of about 1.5 Gyr. For the whole sample of stars we present the
even-to-odd Ba isotope ratios as determined from hyperfine structure seen in
the Ba II resonance line lambda4554. Based on these data we deduce for the
thick disk stars the ratio of the s/r-process contribution to barium as 30 : 70
(+- 30%), in agreement with the results obtained from the [Eu/Ba] ratios.


title:
The Optical Gravitational Lensing Experiment. Is Interstellar Extinction
  Toward the Galactic Center Anomalous?

abstract:
  Photometry of the Galactic bulge, collected during the OGLE-II microlensing
search, indicates high and non-uniform interstellar extinction toward the
observed fields. We use the mean I-band magnitude and V-I color of red clump
stars as a tracer of interstellar extinction toward four small regions of the
Galactic bulge with highly variable reddening. Similar test is performed for
the most reddened region observed in the LMC.
  We find that the slope of the location of red clump stars in the
color-magnitude diagrams (CMDs) in the Galactic bulge is significantly smaller
than the slope of the reddening line following the standard extinction law
(R_V=3.1) for approximations of the extinction curve by both Cardelli, Clayton
and Mathis (1989, CCM89) and Fitzpatrick (1999, F99). The differences are much
larger for the CCM89 approximation which, on the other hand, indicates the same
slopes for the control field in the LMC, contrary to the F99 approximation. We
discuss possible systematic effects that could cause the observed discrepancy.
Anomalous extinction toward the Galactic bulge seems to be the most natural
explanation. Our data indicate that, generally, the ratio of the total to
selective absorption, R_VI, is much smaller toward the Galactic bulge than the
value corresponding to the standard extinction curve (R_V=3.1). However, R_VI
varies from one line-of-sight to another.
  Our results explain why the red clump and RR Lyr stars in the Baade's window
dereddened with standard value of R_VI are redder compared to those of the
local population.


title: The Slow Merger of Massive Stars

abstract:
  We study the complete merger of two massive stars inside a common envelope
and the subsequent evolution of the merger product, a rapidly rotating massive
supergiant. Three qualitatively different types of mergers have been identified
and investigated in detail, and the post-merger evolution has been followed to
the immediate presupernova stage. The ``quiet merger'' case does not lead to
significant changes in composition, and the star remains a red supergiant. In
the case of a ``moderate merger'', the star may become a blue supergiant and
end its evolution as a blue supergiant, depending on the core to total mass
ratio (as may be appropriate for the progenitor of SN 1987A). In the case of
the most effective ``explosive merger'', the merger product stays a red giant.
In last two cases, the He abundance in the envelope is increased drastically,
but significant s-processing is mainly expected in the ``explosive merger''
case.


title:
1ES 1927+654: Persistent and rapid X-ray variability in an AGN with low
  intrinsic neutral X-ray absorption and narrow optical emission lines

abstract:
  We present X-ray and optical observations of the X-ray bright AGN 1ES
1927+654. The X-ray observations obtained with ROSAT and Chandra reveal
persistent, rapid and large scale variations, as well as steep 0.1-2.4 keV
(Gamma = 2.6 +/- 0.3) and 0.3-7.0 keV (Gamma = 2.7 +/- 0.2) spectra. The
measured intrinsic neutral X-ray column density is approximately 7e20cm^-2. The
X-ray timing properties indicate that the strong variations originate from a
region, a few hundred light seconds from the central black hole, typical for
type 1 AGN. High quality optical spectroscopy reveals a typical Seyfert 2
spectrum with some host galaxy contamination and no evidence of Fe II
multiplets or broad hydrogen Balmer wings. The intrinsic optical extinction
derived from the BLR and NLR are A_V >= 3.7 and A_V=1.7, respectively. The
X-ray observations give an A_V value of less than 0.58, in contrast to the
optical extinction values. We discuss several ideas to explain this apparent
difference in classification including partial covering, an underluminous BLR
or a high dust to gas ratio.


title: Acceleration and Parallax Effects in Gravitational Microlensing

abstract:
  To generate the standard microlensing light curve one assumes that the
relative motion of the source, the lens, and the observer is linear. In
reality, the relative motion is likely to be more complicated due to
accelerations of the observer, the lens and the source. The simplest
approximation beyond the linear-motion assumption is to add a constant
acceleration. Microlensing light curves due to accelerations can be symmetric
or asymmetric depending on the angle between the acceleration and the velocity.
We show that it is possible that some of the previously reported shorter
marginal parallax events can be reproduced with constant-acceleration models,
while the longer, multi-year parallax events are ill-fitted by such models. We
find that there is a generic degeneracy inherent in constant-acceleration
microlensing models. We also find that there is an equivalent degeneracy in
parallax models, which manifests itself in short-duration events. The
importance of this new parallax degeneracy is illustrated with an example,
using one of these marginal parallax events. Our new analysis suggests that
another of these previously suspected parallax candidate events may be
exhibiting some weak binary-source signatures. If this turns out to be true,
spectroscopic observations of the source could determine some parameters in the
model and may also constrain or even determine the lens mass. We also point out
that symmetric light curves with constant accelerations can mimic blended light
curves, producing misleading Einstein-radius crossing time-scales when fitted
by the standard `blended' microlensing model; this may have some effect on the
estimation of optical depth.


title: Formation and Evolution of Disk Galaxies

abstract:
  I review several of the current issues in the theory of disk galaxy
formation. There is sti ll much to be done, observationally and theoretically,
before we can expect to approach an understanding of disk galaxies that is
reliable enough to make robust predictions about the high redshift universe.


title:
4C +12.50: A Superluminal Precessing Jet in the Recent Merger System
  IRAS 13451+1232

abstract:
  We present the results of a multi-epoch VLBA study of the powerful radio
source 4C +12.50 (PKS 1345+125) at a wavelength of 2 cm. This compact radio
source is associated with a hidden quasar whose host galaxy shows signs of a
recent merger. It has been classified as a compact symmetric source (CSO) due
to its small overall size (~220 pc) and twin-jet morphology, although it also
has faint extended emission that may be a relic of previous activity. We report
the detection of exceedingly high linear fractional polarization in isolated
features of the southern jet (up to 60%), which is highly unusual for a CSO.
Given the large amount of gas present in the host galaxy, we would expect
significant Faraday depolarization across the whole source, unless the
depolarizing gas is fairly clumpy. The southern jet also contains two features
that are moving outward from the core at apparent speeds of v/c = 1.0 +/- 0.3
and 1.2 +/- 0.3. These represent the first positive detections of superluminal
motion in a CSO, and taken together with the jet to counter-jet flux ratio,
suggest an intrinsic flow speed of v/c = 0.84 +/- 0.12. The apparent ridgeline
of the jet and counter-jet are consistent with a conical helix of wavelength
280 pc that is the result of Kelvin-Helmholtz instabilities driven by a slow
precession of the jet nozzle. A fit to the data implies that the nozzle is
precessing around a cone with half-angle 23 degrees, whose axis lies at an
angle of 82 degrees to the line of sight. We suggest that the "S"-shaped jet
morphologies commonly seen in recent AGN outflows such as 4C +12.50 may simply
reflect the fact that their black hole spin axes are still precessing, and have
not had sufficient time to align with their accretion disks.


title: Identification of 13 Cepheids and 333 Other Variables in M31

abstract:
  We present Cousins $R$ and $I$ band photometry of variable stars in a
$\sim13'\times 13'$ region in the disk of M31 galaxy, obtained during 141
nights. Of the 26 Cepheid variables present in the region, two are newly
discovered, 11 are classified as Cepheids for the first time and 13 are
confirmed as Cepheids. The extensive photometry of these Cepheids enabled us to
determine precise phase and amplitude of pulsation which ranges from 0.11 to
0.48 mag in $R$ band. The period of variability ranges from $\sim$7.5 to 56
days. The period-luminosity diagram is used to derive a distance modulus of
24.49$\pm$0.11 mag for M31 galaxy. We also report variability in 333 other
stars, of them, 115 stars appear to be long period variables, 2 suspected
eclipsing binaries and remaining 216 are irregular variables.


title: Modelling Quintessential Inflation with Branes

abstract:
  I discuss why quintessential inflation model-building is more natural in the
context of brane cosmology and study the dynamics of a particular model as an
example.


title:
Generalized Chaplygin gas as a scheme for Unification of Dark Energy and
  Dark Matter

abstract:
  We study the cosmological scenario arising from the dynamics of a generalized
Chaplygin gas. The equation of state of the system is given in terms of the
energy density, $\rho$, and pressure, $p$, by the relationship $p = -
A/\rho^{\alpha}$, where $A$ is a positive constant and $0 < \alpha \le 1$. The
conditions under which homogeneity arises are discussed and it is shown that
this equation of state describes a universe evolving from a phase dominated by
non-relativistic matter to a phase dominated by a cosmological constant via an
intermediate period where the effective equation of state is $p = \alpha \rho$.


title:
Discovery of a Near-Infrared Jet-Like Feature in the Z Canis Majoris
  System

abstract:
  We present near-infrared high resolution observations of the young binary
system Z Canis Majoris using the adaptive optics system at the Keck-II
telescope. Both components are unresolved at 1.25 and 1.65 microns, although
high dynamic range images reveal a previously unknown jet-like feature in the
circumstellar environment. We argue that this feature probably arises from
light scattered off the walls of a jet-blown cavity, and proper motion studies
of this feature can probe the dynamics of the bipolar outflow. Potentially, the
morphology of the dust-laden cavity walls offers a new probe of the momentum
profile and collimation of bipolar winds from young stellar objects. We also
derive high precision binary parameters, which when combined with historical
data have allowed the first detection of orbital motion. Lastly, our
observations confirm the high degree of flux variability in the system; the
North-West binary component is dominant at H-band, in contrast to all previous
observations.


title: Dwarf Galaxies: Important Clues to Galaxy Formation

abstract:
  The smallest dwarf galaxies are the most straight forward objects in which to
study star formation processes on a galactic scale. They are typically single
cell star forming entities, and as small potentials in orbit around a much
larger one they are unlikely to accrete much (if any) extraneous matter during
their lifetime (either intergalactic gas, or galaxies) because they will
typically lose the competition with the much larger galaxy. We can utilise
observations of stars of a range of ages to measure star formation and
enrichment histories back to the earliest epochs. The most ancient objects we
have ever observed in the Universe are stars found in and around our Galaxy.
Their proximity allows us to extract from their properties detailed information
about the time in the early Universe into which they were born. A currently
fashionable conjecture is that the earliest star formation in the Universe
occurred in the smallest dwarf galaxy sized objects.
  Here I will review some recent observational highlights in the study of dwarf
galaxies in the Local Group and the implications for understanding galaxy
formation and evolution.


title: The impact of mass loss on star cluster formation. I. Analytic results

abstract:
  We study analytically the disruptive effect of instantaneous gas removal from
a cluster containing O stars.
  We setup an iterative calculation based on the stellar velocity distribution
function to compute the fraction of stars that remain bound once the cluster
has ejected the gas and is out of equilibrium. We show that the stellar bound
fraction is a function of the initial cluster distribution function as well as
the star formation efficiency, $\epsilon$, taken constant throughout the
cluster.
  The case of the Plummer sphere is dealt with in greater details. We find for
this case that up to ~ 50% of the stars may remain bound when $\epsilon$
assumes values < 1/2, contrary to expectations derived from the virial theorem.
The fraction of bound stars is expressed algebraically for polytropic
distribution functions.


title:
Difficulties with Recovering The Masses of Supermassive Black Holes from
  Stellar Kinematical Data

abstract:
  We investigate the ability of three-integral, axisymmetric, orbit-based
modeling algorithms to recover the parameters defining the gravitational
potential (M/L ratio and black hole mass Mh) in spheroidal stellar systems
using stellar kinematical data. We show that the potential estimation problem
is generically under-determined when applied to long-slit kinematical data of
the kind used in most black hole mass determinations to date. A range of
parameters (M/L, Mh) can provide equally good fits to the data, making it
impossible to assign best-fit values. We illustrate the indeterminacy using a
variety of data sets derived from realistic models as well as published
observations of the galaxy M32. In the case of M32, our reanalysis demonstrates
that data published prior to 2000 are equally consistent with Mh in the range
1.5x10^6-5x10^6 solar masses, with no preferred value in that range. While the
HST/STIS data for this galaxy may overcome the degeneracy in Mh, HST data for
most galaxies do not resolve the black hole's sphere of influence and in these
galaxies the degree of degeneracy allowed by the data may be substantial. We
investigate the effect on the degeneracy of enforcing smoothness
(regularization) constraints. However we find no indication that the true
potential can be recovered simply by enforcing smoothness. For a given
smoothing level, all solutions in the minimum-chisquare valley exhibit similar
levels of noise. These experiments affirm that the indeterminacy is real and
not an artifact associated with non-smooth solutions. (Abridged)


title: The intriguing case of Sk-69 194

abstract:
  In this paper we report the discovery of eclipses in the early-type
Magellanic binary Sk-69 194. We derive an ephemeris for this system, and
present a CCD V light curve together with CCD spectroscopic observations. We
also briefly discuss the nature of the binary components.


title:
Measurements of streaming motions of the Galactic bar with Red Clump
  Giants

abstract:
  We report a measurement of the streaming motion of the stars in the Galactic
bar with the Red Clump Giants (RCGs) using the data of the Optical
Gravitational Lensing Experiment II (OGLE-II). We measure the proper motion of
46,961 stars and divide RCGs into bright and faint sub-samples which on average
will be closer to the near and far side of the bar, respectively. We find that
the far-side RCGs (4,979 stars) have a proper motion of \Delta <\mu> ~ 1.5 +-
0.11 mas yr^{-1} toward the negative l relative to the near-side RCGs (3,610
stars). This result can be explained by stars in the bar rotating around the
Galactic center in the same direction as the Sun with v_b ~ 100 km s^{-1}. In
the Disc Star (DS) and Red Giant (RG) samples, we do not find significant
difference between bright and faint sub-samples. For those samples \Delta <\mu>
\~ 0.3 +- 0.14 mas yr^{-1} and ~ 0.03 +- 0.14 mas yr^{-1}, respectively. It is
likely that the average proper motion of RG stars is the same as that of the
Galactic center. The proper motion of DSs with respect to RGs is ~ 3.3 mas
yr^{-1} toward positive l. This value is consistent with the expectations for a
flat rotation curve and Solar motion with respect to local standard of rest.
RGs have proper motion approzimately equal to the average of bright and faint
RCGs, which implies that they are on average near the center of the bar. This
pilot project demonstrates that OGLE-II data may be used to study streaming
motions of stars in the Galactic bar. We intend to extend this work to all 49
OGLE-II fields in the Galactic bulge region.


title: High energy neutrinos from magnetars

abstract:
  Magnetars can accelerate cosmic rays to high energies through the unipolar
effect, and are also copious soft photon emitters. We show that young,
fast-rotating magnetars whose spin and magnetic moment point in opposite
directions emit high energy neutrinos from their polar caps through photomeson
interactions. We identify a neutrino cut-off band in the magnetar
period-magnetic field strength phase diagram, corresponding to the photomeson
interaction threshold. Within uncertainties, we point out four possible
neutrino emission candidates among the currently known magnetars, the brightest
of which may be detectable for a chance on-beam alignment. Young magnetars in
the universe would also contribute to a weak diffuse neutrino background, whose
detectability is marginal, depending on the typical neutrino energy.


title:
A new infrared band in the Interstellar and Circumstellar Clouds: C_4 or
  C_4H?

abstract:
  We report on the detection with the Infrared Space Observatory (ISO) of a
molecular band at 57.5 microns (174 cm^{-1}) in carbon-rich evolved stars and
in Sgr B2. Taking into account the chemistry of these objects the most
likelihood carrier is a carbon chain. We tentatively assign the band to the
nu_5 bending mode of C_4 for which a wavenumber of 170-172.4 cm^{-1} has been
derived in matrix experiments (Withey et al. 1991). An alternate carrier might
be C_4H, although the frequency of its lowest energy vibrational bending mode,
nu_7, is poorly known (130-226 cm^{-1}). If the carrier is C_4, the derived
maximum abundance is nearly similar to that found for C_3 in the interstellar
and circumstellar media by Cernicharo, Goicoechea & Caux (2000). Hence,
tetra-atomic carbon could be one of the most abundant carbon chain molecules in
these media.


title:
Discovery of 15-second oscillations in Hubble Space Telescope
  observations of WZ Sagittae following the 2001 outburst

abstract:
  We report the discovery of 15-s oscillations in ultraviolet observations of
WZ Sge obtained with the Hubble Space Telescope approximately one month after
the peak of the 2001 outburst. This is the earliest detection of oscillations
in WZ Sge following an outburst and the first time that a signal near 15 s has
been seen to be dominant. The oscillations are quite strong (amplitude about
5%), but not particularly coherent. In one instance, the oscillation period
changed by 0.7 s between successive observations separated by less than 1 hour.
We have also found evidence for weaker signals with periods near 6.5 s in some
of our data. We discuss the implications of our results for the models that
have been proposed to account for the 28-s oscillations seen in quiescence. If
the periods of the 15-s oscillations can be identified with the periods of
revolution of material rotating about the white dwarf, the mass of the white
dwarf must satisfy M_WD > 0.71 M_sun. The corresponding limit for the 6.5-s
signals is M_WD > 1.03 M_sun.


title:
The bends in the slopes of radial abundance gradients in the disks of
  spiral galaxies -- do they exist?

abstract:
  Spiral galaxies with a reported bend in the slope of gradient in the oxygen
abundances (O/H)_R23, derived with traditionally used R23 - method, were
examined. It is shown that the artificial origin of the reported bends can be
naturally explained. Two reasons that result in a false bend in the slope of
(O/H)_R23 gradient are indicated. It is concluded that at the present time
there is no example of a galaxy with an undisputable established bend in the
slope of the oxygen abundance gradient.


title: The Mass to Light ratio and the Initial Mass Function in galactic discs

abstract:
  A low mass-to-light ratio for the baryonic component of spiral galaxies is
advocated by a number of dynamical studies and by cosmological simulations of
galaxy formation. We discuss the possibility of obtaining low mass-to-light
ratios for the stellar component in discs, by changing the Initial Mass
Function and the Star Formation History.


title:
Recent Astrophysics Results from ORELA and Possible Future Experiments
  at ORELA and SNS

abstract:
  I present some recent results from experiments at the Oak Ridge Electron
Linear Accelerator (ORELA) and discuss their impact in nuclear astrophysics. I
then describe some possible future nuclear astrophysics experiments at ORELA
and at the Spallation Neutron Source (SNS) being built in Oak Ridge. The SNS
and ORELA are complementary, world-class facilities and both will be needed for
important future experiments in nuclear astrophysics.


title:
An explanation for the curious mass loss history of massive stars: from
  OB stars, through Luminous Blue Variables to Wolf-Rayet stars

abstract:
  The stellar winds of massive stars show large changes in mass-loss rates and
terminal velocities during their evolution from O-star through the Luminous
Blue Variable phase to the Wolf-Rayet phase. The luminosity remains
approximately unchanged during these phases. These large changes in wind
properties are explained in the context of the radiation driven wind theory, of
which we consider four different models. They are due to the evolutionary
changes in radius, gravity and surface composition and to the change from
optically thin (in continuum) line driven winds to optically thick radiation
driven winds.


title:
Constraints on the $^{22}Ne(\alpha,n)^{25}$Mg s-process neutron source
  from analysis of $^{nat}Mg+n$ total and $^{25}Mg(n,\gamma)$ cross sections

abstract:
  I have analyzed previously reported $^{\text{nat}}$Mg+\textit{n%} total and
$^{25}$Mg(\textit{n},$\gamma $) cross sections to obtain a much improved set of
resonance parameters for states in $^{26}$Mg between threshold and the lowest
observed $^{22}$Ne($\alpha $,\textit{n})$^{25}$Mg resonance, and an improved
estimate of the uncertainty in the $^{22}$Ne($% \alpha $,\textit{n})$^{25}$Mg
reaction rate. For example, definitely two, and very likely at least four, of
the states in this region have natural parity and hence can contribute to the
$^{22}$Ne($\alpha $,\textit{n})$^{25}$% Mg reaction, but two others definitely
have non-natural parity and so can be eliminated from consideration. As a
result, a recent evaluation in which it was assumed that only one of these
states has natural parity has underestimated the reaction rate uncertainty by
at least a factor of ten, whereas evaluations that assumed all these states
could contribute probably have overestimated the uncertainty.


title: X-ray luminous galaxies I. Chandra observations of IRAS00317-2142

abstract:
  We present Chandra observations of the enigmatic galaxy IRAS00317-2142, which
is classified as a star-forming galaxy on the basis of the ionization level of
its emission lines. However, a weak broad H\alpha wing and a high
  X-ray luminosity give away the presence of an active nucleus. The Chandra
image reveals a nuclear point source (L_(2-10 keV) 6x10^{41} erg s-1),
contributing over 80% of the galaxy X-ray counts in the 0.3-8 keV band.
  This is surrounded by some fainter nebulosity extending up to 6 kpc.
  The nucleus does not show evidence for short-term variability. However, we
detect long term variations between the ROSAT, ASCA and Chandra epoch.
  Indeed,the source has decreased its flux by over a factor of 25 in a period
of about 10 years. The nuclear X-ray spectrum is well represented by a
power-law with a photon index of 1.91^{+0.17}_{-0.15} while the extended
emission by a Raymond-Smith component with a temperature of 0.6 keV.
  We find no evidence for the presence of an Fe line. The nucleus is absorbed
by an intrinsic column density of N_H ~ 8x10^{20} cm-2. Thus the Chandra
observations suggest that at least the X-ray emission is dominated by a type-1
  AGN. Then the observed optical spectrum can be explained due to the masking
of the nucleus by the powerful star-forming component. These together with
previous X-ray observations of galaxies with no clear signs of AGN activity in
the optical, (eg NGC6240) cast doubt on the optical classification scheme and
have implications for the nature of the 'normal' galaxies detected in deep
  Chandra X-ray surveys.


title: Emission and Absorption in the M87 LINER

abstract:
  The nucleus of M87 displays a LINER spectrum at optical wavelengths, with a
nuclear disk of nebulosity that is resolved by the Hubble Space Telescope. We
present new results from optical and ultraviolet spectra of the central ~40pc
as measured by HST. In contrast with previous results for the extended disk,
the emission-line spectrum of the central region is best reproduced by a
multi-component photoionization scenario, rather than shock heating. The
nebular properties as well as energetic considerations suggest a transition on
scales of several tens of parsecs, from predominantly photoionization by a
central accretion source, to shock ionization within the disk. If this source
is at all representative, it suggests that many LINERs may be composite in
terms of the energetic processes that give rise to the emission spectrum. We
also report measurements of resonance-line absorption for the nucleus. The
absorption spectrum, like the emission lines, is characterized by low
ionization. The absorption line measurements coupled with independent
constraints suggests a total hydrogen column density of 10^19 - 10^20 cm^-2,
outflowing from the galaxy center with a velocity of ~126 km/s. The kinematic
signature of an outflow, along with evidence that the absorber covers the
power-law continuum source but not the emission-line clouds, suggests that the
absorbing matter is related to accretion phenomena in the nucleus. The presence
of such an outflow resembles similar behaviour in luminous AGN, although the
low ionization that characterizes LINERs is probably indicative of a different
mode of accretion in these sources.


title: Comparison of Hadronic Interaction Models at Auger Energies

abstract:
  The three hadronic interaction models DPMJET 2.55, QGSJET 01, and SIBYLL 2.1,
implemented in the air shower simulation program CORSIKA, are compared in the
energy range of interest for the Pierre Auger experiment. The model dependence
of relevant quantities in individual hadronic interactions and air showers is
investigated.


title:
Tidal Dwarf Candidates in a Sample of Interacting Galaxies. II.
  Properties and Kinematics of the Ionized Gas

abstract:
  We present low-resolution spectroscopy of the ionized gas in a sample of
optical knots located along the tidal features of 14 interacting galaxies and
previously selected as candidates of Tidal Dwarf Galaxies (TDGs). From redshift
measurements, we are able to confirm their physical association with the
interacting system in almost all cases. For most knots, the oxygen abundance
does not depend on the blue luminosity. The average, 12+log(O/H)=8.34+-0.20, is
typical of TDGs and comparable to that measured in the outer stellar disk of
spirals from which they were formed. A few knots showing low metallicities are
probably pre-existing low-mass companions. The estimated Ha luminosity of the
TDG candidates is higher than the one of typical individual HII regions in
spiral disks and comparable to the global Ha luminosity of dwarf galaxies. We
find several instances of velocity gradients with amplitudes apparently larger
than 100 km/s in the ionized gas in the tidal knots and discuss various
possible origins for the large velocity amplitudes. While we can exclude tidal
streaming motions and outflows, we cannot rule out projection effects with the
current resolution. The velocity gradients could be indicative of the internal
kinematics characteristic of self-gravitating objects. Higher resolution
spectra are required to confirm whether the tidal knots in our sample have
already acquired their dynamical independence and are therefore genuine Tidal
Dwarf Galaxies.


title: The K correction

abstract:
  The K correction "corrects" for the fact that sources observed at different
redshifts are, in general, compared with standards or each other at different
rest-frame wavelengths. It is part of the relation between the emitted- or
rest-frame absolute magnitude of a source in one broad photometric bandpass to
the observed-frame apparent magnitude of the same source in another broad
bandpass. This short pedagogical paper provides definitions of and equations
for the K correction.


title:
Time-resolved spectroscopy and spectrophotometry of the pulsating sdB
  star PG 1605+072

abstract:
  We present the latest results from our analysis of time resolved spectroscopy
of PG 1605+072, a high amplitude pulsating sdB star. The star is believed to
have evolved off the extreme horizontal branch, and it is uncertain whether it
pulsates in p- or g-modes. Previous studies of PG 1605+072 have found amplitude
variation and/or very closely spaced frequencies. We compare our velocity
measurements with new simultaneous spectrophotometric measurements and analyse
phase differences for the 8 frequencies found in velocity. Phase differences
between velocity, spectrophotometry and equivalent width are discussed.


title: SS 433: Radio/X-ray anti-correlation and fast-time variability

abstract:
  We briefly review the Galactic microquasar SS 433/W50 and present a new RXTE
spectral and timing study. We show that the X-ray flux decreases during radio
flares, a behavior seen in other microquasars. We also find short time-scale
variability unveiling emission regions from within the binary system.


title:
X-Ray and Optical Observations of XTE J0052-723 a Transient Be/X-Ray
  Pulsar in the Small Magellanic Cloud

abstract:
  On December 27th 2000 during our regular SMC monitoring program with Rossi
X-ray Timing Explorer, strong pulsations were detected with a period of 4.78
seconds. Subsequent slew observations performed on Jan 9th and 13th across the
field of view allowed localisation of the pulsar's position to RA: 0 52 17,
Dec: 72 19 51 (J2000). The outburst continued until Jan 24th, 7 PCA
observations were obtained during this period, yielding a maximum X-ray
luminosity ~10^38 ergs/s. Following calculation of the pulsar position, optical
observations of the RXTE error box were made on Jan 16th 2001 with the 1m
telescope of the South African Astronomical Observatory (SAAO) while the source
was still in X-ray outburst. Candidate Be stars identified from their
photometric colours were subsequently observed with the SAAO 1.9m on Nov 7th
2001 to obtain spectra. Only one of the photometrically identified stars
[MA93]537 showed prominent H$\alpha$ emission, with a double peaked
line-profile (EW= -43.3+/-0.7 A, separation velocity= 200+/-15 km/s) confirming
the presence of a substantial circumstellar disk.


title:
Accretion and Outflow in Interacting Binary Systems: FUSE Observations
  of the Novalike Cataclysmic Variable, UX Ursae Majoris

abstract:
  We present far-ultraviolet (905 -- 1182 A), time-series spectroscopy of the
eclipsing, novalike cataclysmic variable, UX UMa, acquired with FUSE. The
time-averaged spectrum is complex and is dominated by overlapping spectral
features. The most prominent features are emission lines of CIII, NIII}, NIV,
and OVI. They are broad (FWHM >= 1800 km/s) and double-peaked with a central
absorption at zero velocity. During eclipse, the spectrum is simpler: the
emission lines remain bright, but the absorption components of the lines and
the weaker features between the emission lines disappear entirely, leaving a
flat continuum. This behavior is also evident in GHRS (1149 -- 1660 A) spectra
that we retrieved from the HST archive. The FUV spectra show flickering on time
scales of several minutes. The flickering is seen primarily in the continuum
and/or the weaker lines rather than in the prominent emission lines. The
orbital light curve has a dip in the FUV flux between orbital phases 0.45 --
0.65, similar to a pre-eclipse dip detected in HST observations. The EWs of the
line absorption features decrease during the dip. We have detected a systematic
wavelength shift of spectral features on the orbital period, but with a phase
lag of ~ 20 degrees, a phenomenon that has been reported at optical
wavelengths. We discuss the implications of our results in the context of
models of an accretion disk with a chromosphere between the disk and the
extended wind. Finally, we note that the observed FUV flux is too low to be
consistent with the temperature and radius of the WD derived by Baptista et al.
(1995), suggesting that their remaining binary parameters, including a mass
ratio of 1, ought to be viewed with skepticism.


title:
X-Ray Jet Emission from the Black Hole X-Ray Binary XTE J1550-564 with
  Chandra in 2000

abstract:
  We have discovered an X-ray jet due to material ejected from the black hole
X-ray transient XTE J1550-564. The discovery was first reported by Corbel et
al. (Science, 298, 196 and astro-ph/0210224), and here, we present an analysis
of the three Chandra observations made between 2000 June and 2000 September.
For these observations, a source is present that moves in an eastward direction
away from the point source associated with the compact object. The separation
between the new source and the compact object changes from 21.3 arcseconds in
June to 23.4 arcseconds in September, implying a proper motion of 21.2 +/- 7.2
mas/day, a projected separation of 0.31-0.85 pc and an apparent jet velocity
between 0.34 +/- 0.12 and 0.93 +/- 0.32 times the speed of light for a source
distance range of d = 2.8-7.6 kpc. These observations represent the first time
that an X-ray jet proper motion measurement has been obtained for any accretion
powered Galactic or extra-galactic source. While this work deals with the jet
to the east of the compact object, the western jet has also been detected in
the X-ray and radio bands. The most likely scenario is that the eastern jet is
the approaching jet and that the jet material was ejected from the black hole
in 1998. Along with a 1998 VLBI proper motion measurement, the Chandra proper
motion indicates that the eastern jet decelerated between 1998 and 2000. We
present results on the morphology and energy spectrum of the jet. We cannot
definitively determine the X-ray emission mechanism, but a synchrotron origin
is viable and may provide the simplest explanation for the observations.


title:
Around the Clock Observations of the Q0957+561 A,B Gravitationally
  Lensed Quasar II: Results for the second observing season

abstract:
  We report on an observing campaign in March 2001 to monitor the brightness of
the later arriving Q0957+561 B image in order to compare with the previously
published brightness observations of the (first arriving) A image. The 12
participating observatories provided 3543 image frames which we have analyzed
for brightness fluctuations. From our classical methods for time delay
determination, we find a 417.09 +/- 0.07 day time delay which should be free of
effects due to incomplete sampling. During the campaign period, the quasar
brightness was relatively constant and only small fluctuations were found; we
compare the structure function for the new data with structure function
estimates for the 1995--6 epoch, and show that the structure function is
statistically non-stationary. We also examine the data for any evidence of
correlated fluctuations at zero lag. We discuss the limits to our ability to
measure the cosmological time delay if the quasar's emitting surface is time
resolved, as seems likely.


title: X-Ray Emission from the Jets of XTE J1550-564

abstract:
  We report on X-ray observations of the the large-scale jets recently
discovered in the radio and detected in X-rays from the black hole candidate
X-ray transient and microquasar XTE J1550-564. On 11 March 2002, X-ray emission
was detected 23 arcsec to the West of the black hole candidate and was extended
along the jet axis with a full width at half maximum of 1.2 arcsec and a full
width at 10% of maximum intensity of 5 arcsec. The morphology of the X-ray
emission matched well to that of the radio emission at the same epoch. The jet
moved by 0.52 +/- 0.13 arcsec between 11 March and 19 June 2002. The apparent
speed during that interval was 5.2 +/- 1.3 mas/day. This is significantly less
than the average apparent speed of 18.1 +/- 0.4 mas/day from 1998 to 2002,
assuming that the jet was ejected in September 1998, and indicates that the jet
has decelerated. The X-ray spectrum is adequately described by a powerlaw with
a photon index near 1.8 subject to interstellar absorption. The unabsorbed
X-ray flux was 3.4 x 10^-13 erg cm^-2 s^-1 in the 0.3-8 keV band in March 2002,
and decreased to 2.9 x 10^-13 erg cm^-2 s^-1 in June. We also detect X-rays
from the eastern jet in March 2002 and show that it has decelerated and dimmed
since the previous detections in 2000.


title:
Detectability of Space-Time Fluctuations in Ultra High Energy Cosmic Ray
  Experiments

abstract:
  It is generally expected that quantum gravity affects the structure of
space-time by introducing stochastic fluctuations in the geometry, and,
ultimately, in the measurements of four-distances and four-momenta.These
fluctuations may induce observable consequences on the propagation of ultra
high energy particles, mainly in the range of energies of interest for cosmic
ray physics, over large distances, leading to their detection or constraining
the underlying quantum gravitational structure. We argue that the detectable
effects of fluctuations may extend to energies much lower than the threshold
for proton photopion production (the so-called GZK cut-off), so that lower
energy observations may provide strong constraints on the role of a fluctuating
space-time structure.


title: The Spectroscopic Variability of GRB 021004

abstract:
  We present spectra of the optical transient (OT) associated with GRB 021004.
The spectra show a blue continuum with superposed absorption features and one
emission line. We confirm two intervening metal-line systems at z = 1.380 and z
= 1.602 and one very strong absorption system at a redshift of z = 2.323.
Ly_alpha emission is also seen at this redshift. While the spectrum of the OT
overall cannot be simply described with a power law, the spectral index over
the range 5500-8850 A is steep, F_nu ~ nu^(-0.96 +/- 0.03). Comparison of
spectra from multiple epochs shows a distinct color evolution with the OT
becoming redder with time over the first three days. This is the first clear
example of color change in an OT detected spectroscopically.


title: Topic maps for custom viewing of data

abstract:
  A Topic Map is a structured network of hyperlinks that points into an
information pool. Topic Maps have an existence independent of the information
pool and hence different Topic Maps can form different layers above the same
information pool and provide us with different views of it. We explore the use
of Topic Maps with the Unified Column Descriptor (UCD) scheme developed in the
frame of the ESO-CDS data mining project. UCD, with its multi-tier hierarchical
structure, categorizes parameters reported in tables and catalogs. By using
Topic Maps we show how columns from different catalogs with similar but not
identical descriptions could be combined. A direct application for the Virtual
Observatory community is that of merging catalogs in order to generate
customized views of data.


title:
Spectroscopic Study of Blue Compact Galaxies II. Spectral Analysis and
  Correlations

abstract:
  This is the second paper in a series studying the star formation rates,
stellar components, metallicities, and star formation histories and evolution
of a sample of blue compact galaxies. We analyzed spectral properties of 97
blue compact galaxies, obtained with the Beijing Astronomical Observatory
(China) 2.16 m telescope, with spectral range 3580\AA -- 7400\AA. We classify
the spectra according to their emission lines: 13 of the total 97 BCGs sample
are non-emission line galaxies (non-ELGs); 10 have AGN-like emission (AGNs),
and 74 of them are star-forming galaxies (SFGs). Emission line fluxes and
equivalent widths, continuum fluxes, the 4000 \AA Balmer break index and
equivalent widths of absorption lines are measured from the spectra.
  We investigate the emission line trends in the integrated spectra of the
star-forming galaxies in our sample, and find that: 1) The equivalent widths of
emission lines are correlated with the galaxy absolute blue magnitude $M_B$;
lower luminosity systems tend to have larger equivalent widths. 2) The
equivalent width ratio [NII]6583/H$\alpha$ is anti-correlated with equivalent
width H$\alpha$; a relationship is given that can be used to remove the [NII]
contribution from blended H$\alpha$ + [NII]6548, 6583. 3) The [OII], H$\beta$,
H$\gamma$ and H$\alpha$ fluxes are correlated; those can be used as star
formation tracers in the blue. 4) The metallicity indices show trends with
galaxy absolute magnitude and attenuation by dust; faint, low-mass BCGs have
lower metallicity and color excess.


title: Empirical Population Synthesis for 74 Blue Compact Galaxies

abstract:
  We have observed the largest optical spectra sample of 74 blue compact
galaxies. Stellar population properties of them were derived by comparing the
equivalent widths of strong absorption features and continuum colors, using a
method of empirical population synthesis based on star cluster sample. The
results indicate that blue compact galaxies are typically age-composite stellar
system, the continuum flux fractions at 5870\AA due to old stellar components
and young stellar components are both important for most of the galaxies. The
stellar populations of blue compact galaxies present a variety of
characteristics, and the contribution from different age and metallicity
components is different. The star formation episodes are usually short, some
galaxies maybe undergoing their first global episode of star formation, while
for the most sample galaxies, older stars contribute to at most half the
optical emission. Our results suggest that BCGs are old galaxies, in which star
formation occurs in short intense burst separated by long quiescent phases.


title: Automated object classification with ClassX

abstract:
  ClassX is a project aimed at creating an automated system to classify X-ray
sources and is envisaged as a prototype of the Virtual Observatory. As a
system, ClassX integrates into a pipeline a network of classifiers and an
engine that searches and retrieves for a given target multi-wavelength
counterparts from the worldwide data storage media. It applies machine learning
methods to `train' different classifiers using different `training' data sets.
In ClassX, each classifier can make its own class (object type) assignment and
is optimized for handling different tasks and/or different object types. A user
would generally select a certain classifier to make, for instance, a most
complete list of candidate QSOs, but a different classifier would be used to
make a most reliable list of candidate QSOs. Still different classifiers would
be selected to make similar lists for other object types. Along with the class
name assignment, a network classifier outputs the probability for a source to
belong to the assigned class as well as probabilities that the source belongs
in fact to other classes. We illustrate the current capabilities of ClassX and
the concept of a classifiers network with the results obtained with classifiers
trained using ROSAT data. ~


title:
The Discovery of a Spatially-Resolved Supernova Remnant in M31 with
  Chandra

abstract:
  Chandra observations of M31 allow the first spatially resolved X-ray image of
a supernova remnant (SNR) in an external spiral galaxy. CXOM31 J004327.7+411829
is a slightly elongated ring-shaped object with a diameter of ~11'' (42 pc). In
addition, the X-ray image hints that the chemical composition of the SNR is
spatial dependent. The X-ray spectrum of the SNR can be well fitted with a
Raymond-Smith model or a non-equilibrium ionization model. Depending on the
spectral model, the 0.3-7 keV luminosity is between 3.2x10^36 erg/s and
4.5x10^37 erg/s. The age of the SNR is estimated to be 3210-22300 years and the
number density of ambient gas is ~0.003-0.3 cm^-3. This suggests that the local
interstellar medium around the SNR is low.


title: Formation of bulges in very late-type galaxies from SSCs

abstract:
  The dynamical evolution of super star clusters (SSCs) moving in the
background of a dark matter halo has been investigated as a possible event
responsible for the formation of bulges in late-type spirals. The underlying
physical processes include sinking of SSCs due to the dynamical friction and
stripping of SSCs on their way to the center. Our model calculations show that
only sinking of circumnuclear SSCs contributes to the formation of galactic
bulges at the early stage. Based on the assumption of a universal density
profile for the dark matter halo, and an isothermal model for the SSCs, our
simulations have yielded bulges that are similar in many aspects to the
observational ones. In particular, the derived surface density profiles can be
well fitted by anexponential structure with nuclear cusps, which is consistent
with HST observations.


title: Cooling flows and the entropy of the intragroup medium

abstract:
  We study steady, homogeneous and subsonic cooling flows in poor clusters of
galaxies in light of the recent proposal that radiative cooling of the
intracluster gas can explain the observations of the `entropy floor' and other
related X-ray observations. We study a family of cooling flow solutions
parameterized by the mass flux rate, and then determine the resulting entropy
and the X-ray luminosity. We find that cooling flows with mass flux rates in
excess of 1000 M_{solar} per yr are required to explain the observations of
entropy and X-ray luminosity. In view of the observed lack of such large flows
in rich clusters, our calculations suggest that heating sources are needed, in
addition to the effect of radiative cooling, to explain the observations.


title:
Understanding the radio emission geometry of multi-component radio
  pulsars from retardation and aberration effects

abstract:
  We have conducted a detailed analysis of the emission geometry of a handful
of radio pulsars that have prominent, multiple-component profiles at meter
wavelengths. From careful determination of the total number of emission
components and their locations in pulse longitude, we find that all of the six
pulsars show clear evidence for retardation and aberration effects in the conal
emission beams. Using this information, coupled with a dipolar field geometry,
we obtain estimates of the height and transverse location in the magnetosphere,
for each of the emitting cones in these pulsars. These results support our
earlier conclusions for PSR B0329+54 in that we find successive outer cones (in
cases of multi-cone pulsars) being emitted at higher altitudes in the
magnetosphere. The range of inferred heights is from ~200 to ~2200 km. The set
of ``active'' field lines from which the conal emissions originate are located
in the region from ~0.22 to ~0.74 of the polar cap radius. At the neutron star
surface, these conal rings map to radii of a few to several tens of meters and
the separation between successive rings is about 10 to 20 meters. We discuss
the implications of these findings for the understanding of the pulsar emission
geometry and for current theories and models of the emission mechanism.


title:
Oscillatory mean-field dynamos with spherically symmetric, isotropic
  alpha

abstract:
  Until recently, the existence of oscillatory mean-field dynamos of the
alpha^2-type with spherically symmetric and isotropic alpha was an open
question. We find such dynamos by means of an evolutionary strategy, and we
illustrate the spectral properties of the corresponding dynamo operators.


title: Limits on the infrared photometric monitoring of brown dwarfs

abstract:
  Recent monitoring programs of ultra cool field M and L dwarfs (low mass stars
or brown dwarfs) have uncovered low amplitude photometric I-band variations
which may be associated with an inhomogeneous distribution of photospheric
condensates. Further evidence hints that this distribution may evolve on very
short timescales, specifically of order a rotation period or less. In an
attempt to study this behaviour in more detail, we have carried out a pilot
program to monitor three L dwarfs in the near infrared where these objects are
significantly brighter than at shorter wavelengths. We present a robust data
analysis method for improving the precision and reliability of infrared
photometry. No significant variability was detected in either the J or Km bands
in 2M1439 and SDSS1203 above a peak-to-peak amplitude of 0.04 mag (0.08 mag for
2M1112). The main limiting factor in achieving lower detection limits is
suspected to be second order extinction effects in the Earth's atmosphere, on
account of the very different colours of the target and reference stars.
Suggestions are given for overcoming such effects which should improve the
sensitivity and reliability of infrared variability searches.


title: Galaxy Flow in the Canes Venatici I Cloud

abstract:
  We present an analysis of Hubble Space Telescope/WFPC2 images of eighteen
galaxies in the Canes Venatici I cloud.
  We derive their distances from the luminosity of the tip of the red giant
branch stars with a typical accuracy of ~12 %. The resulting distances are 3.9
Mpc (UGC 6541), 4.9 Mpc (NGC 3738), 3.0 Mpc (NGC 3741), 4.5 Mpc (KK 109), >6.3
Mpc (NGC 4150), 4.2 Mpc (UGC 7298), 4.5 Mpc (NGC 4244), 4.6 Mpc (NGC 4395), 4.9
Mpc (UGC 7559), 4.2 Mpc (NGC 4449), 4.4 Mpc (UGC 7605), 4.6 Mpc (IC 3687), 4.7
Mpc (KK 166), 4.7 Mpc (NGC 4736), 4.2 Mpc (UGC 8308), 4.3 Mpc (UGC 8320), 4.6
Mpc (NGC 5204), and 3.2 Mpc (UGC 8833). The CVn I cloud has a mean radial
velocity of 286 +- 9 km/s, a mean distance of 4.1 +- 0.2 Mpc, a radial velocity
dispersion of 50 km/s, a mean projected radius of 760 kpc, and a total blue
luminosity of 2.2 * 10^{10} L_{\sun}. Assuming virial or closed orbital motions
for the galaxies, we estimated their virial and their orbital
mass-to-luminosity ratio to be 176 and 88 M_{\sun}/L_{\sun}, respectively.
However, the CVn I cloud is characterized by a crossing time of 15 Gyr, and is
thus far from a state of dynamical equilibrium. The large crossing time for the
cloud, its low content of dSph galaxies ($ < 6$ %), and the almost
``primordial'' shape of its luminosity function show that the CVn I complex is
in a transient dynamical state, driven rather by the free Hubble expansion than
by galaxy interactions.


title: BL Lacertae: the multiwavelength campaign of 2000

abstract:
  We present two BeppoSAX observations of BL Lacertae as part of a
multiwavelength radio-to-TeV campaign. During the first observation we observe
a faint Compton spectrum, while during the second, we detect a synchrotron
spectrum with the highest [2-10] keV flux ever measured; above 10 keV an
inverse Compton component begin to dominate. The synchrotron flux is very
variable with time scales of 1 hr. We describe four different SED shifting the
synchrotron peak both in frequency and flux intensity and we sketch a scenario
in which a blob moves along a jet and can be located in or outside the BLR.
This implies different radiative mechanism at work, SSC or external Compton,
producing different high energy spectra.


title: The Faint Sky Variability Survey I: Goals and data reduction process

abstract:
  The Faint Sky Variability Survey is aimed at finding photometric and/or
astrometric variable objects in the brightness range between 16<V<24 on
timescales between tens of minutes and years with photometric precisions
ranging from 3 millimagnitudes for the brightest to 0.2 magnitudes for the
faintest objects. An area of ~23 square degrees, located at mid and high
Galactic latitudes, has been covered using the Wide Field Camera on the 2.5m
Isaac Newton Telescope on La Palma. Here we describe the main goals of the
Faint Sky Variability Survey and the data reduction process.


title:
A simple derivation and interpretation of the third integral in Stellar
  Dynamics

abstract:
  Starting from the problem of two fixed centres we find a simple derivation of
its third integral in terms of the scalar product of the angular momenta about
the two fixed centres. This is then generalised to find the general form of the
potential in which an exact third integral exists.


title: Relative Ages of Globular Clusters

abstract:
  Ages of extragalactic globular clusters can provide valuable insights into
the formation and evolution of galaxies. In this contribution the photometric
methods of age dating old globular cluster systems are summarised. The
spectroscopic approach is reviewed with an emphasis of the right choice of age
diagnostics. We present a new method of quantifying the relatively best
age-sensitive spectroscopic index given the quality of a data set and a certain
theoretical stellar synthesis model. The relatively best diagnostic plot is
constructed from the set of Lick indices and used to age date globular clusters
in several early-type galaxies which are part of a large spectroscopic survey
of extragalactic globular cluster systems. We find that, independently of host
galaxy, metal-poor ([Fe/H] < -0.8) globular clusters appear to be old (t > 8
Gyr) and coeval. Metal-rich clusters show a wide range of ages from ~15 down to
a few Gyr.


title: The Chemistry of Extragalactic Globular Clusters

abstract:
  We present preliminary results of VLT/FORS spectroscopy of globular clusters
in nearby early-type galaxies. Our project aims at studying the chemistry and
determine the ages of globular cluster (sub-)populations. First results
indicate that the different galaxies host from little to significant
intermediate-age populations, and that the latter have alpha-element over iron
ratios closer to solar than the old population that show an alpha-element
enhancement similar to the diffuse stellar light.


title: Extragalactic Globular Clusters in the Near-Infrared

abstract:
  Visual and near-infrared colours are used to identify intermediate-age
globular cluster in early-type galaxies. In NGC5846 and NGC4365 colour-colour
diagrams (V-I vs. V-K) reveal a sub-population in the globular cluster systems
with an age much younger than the expected old populations (13-15 Gyr). A
comparison with SSP models dates the formation of this younger population 2-7
Gyr back. Further evidence for multiple star formation events is given by the
age distribution in both systems and the comparison to models. Our photometric
age determination was confirmed by spectroscopy for a small sample of the
clusters in NGC4365.


title:
Self-gravitating discs: what can we learn from the dynamics of maser
  spots ?

abstract:
  For a few nearby active nuclei, the disc orbiting the black hole is traced by
water maser emission. By combining a simple model together with observed
velocity profiles, we show that it is possible to put constraints on the black
hole mass and on the distribution of matter (shape, density, size) in the outer
disc. We then report possible parameters for the non-keplerian disc and for the
black hole in NGC 1068, and mention an uncertainty of at least 25% on the
central mass in NGC 4258.


title:
Self-similar condensation of rotating magnetized self-gravitating
  isothermal filaments

abstract:
  Ordinary differential equations describing the self-similar collapse of a
rotating, magnetized, self-gravitating and isothermal filament are derived.
Explicit homologous solutions are studied with special emphasis on the
bifurcation that occurs at the magnetosonic critical point. It is shown that
there is a critical value for the toroidal magnetic field slope at the origin
above which no bifurcation occurs, the solution remains homologous, and below
which the density and the poloidal magnetic field tend to zero at large radius
(envelope) whereas the toroidal magnetic field and azimuthal velocity relax
towards a constant value. A series of spatial profiles of density, velocity and
magnetic field, potentially useful for comparison with numerical or
observational studies, is obtained numerically and discussed.


title: The W-function applied to the age of Globular Clusters

abstract:
  We present a statistical approach for estimating the age of Globular Clusters
by measurement of the likelihood between the observed cluster sequences in the
Colour--Magnitude Diagram and the synthetic cluster sequences computed from
stellar evolutionary models. In the conventional isochrone fitting procedure,
the age is estimated in a subjective way. Here, we calculate the degree of
likelihood by applying a modern statistical estimator, the Saha estimator {\it
W}, and the interval of confidence from $\chi^{2}$ statistics. We apply this
approach to sets of three different evolutionary models. Each of these sets
consists of different chemical abundances, ages, input physics, etc. Based on
our approach, we estimate the age of NGC 6397, M92 and M3. With a confidence
level of 99%, we find that the best estimate of the age is 14.0 Gyr within the
range of 13.8 to 14.4 Gyr for NGC 6397, 14.75 Gyr within the range of 14.50 to
15.40 Gyr for M92, and 16.0 Gyr within the range of 15.9 to 16.3 Gyr for M3.


title: Discovery of a Population of HI Clouds in the Galactic Halo

abstract:
  A population of discrete HI clouds in the halo of the inner Galaxy has been
discovered in 21cm observations made with the Green Bank Telescope. The halo
clouds are seen up to 1.5 kpc from the Galactic plane at many longitudes. Their
velocities follow Galactic rotation. A group of clouds chosen for detailed
study are found to have, in the median, a peak NHI of 2x10^19, a diameter of a
few tens of pc, a density of a few tenths cm^-3, and a mass in HI of 50 solar
masses. Some halo clouds have narrow lines implying that their temperature must
be <1000 K; some have a core-halo spectral structure. As much as half of the
mass of the neutral halo may reside in these discrete clouds. They may have
been formed in a Galactic fountain and are now returning to the disk.


title: A "Spiffy" Trigger for Gamma-Ray Bursts

abstract:
  The traditional design of trigger algorithms for GRB experiments requires the
specification of the background and burst samples in terms of acquisition times
that are of fixed duration and of fixed elapsed time from each other. One such
set of acquisition times is required for each characteristic timescale of GRB
variation that one desires to detect. One then slides each set through the
trigger data searching for samples that maximize the signal-to-noise of the
background-subtracted burst sample.
  Here we describe a new triggering approach in which the times at which the
background and burst samples are acquired are allowed to vary dynamically. Two
background samples bracket a burst sample. The background and burst durations
and elapsed time between them are allowed to be free parameters, which are
maximized using the downhill simplex method. This produces great flexibility in
the timescales that are available for detecting GRBs.


title:
Closest Star Seen Orbiting the Supermassive Black Hole at the Centre of
  the Milky Way

abstract:
  Measurements of stellar velocities and variable X-ray emission near the
centre of the Milky Way have provided the strongest evidence so far that the
dark mass concentrations seen in many galactic nuclei are likely supermassive
black holes, but have not yet excluded several alternative configurations. Here
we report ten years of high resolution astrometric imaging that allow us to
trace two thirds of the orbit of the star currently closest to the compact
radio source and massive black hole candidate SgrA*. In particular, we have
observed both peri- and apocentre passages. Our observations show that the star
is on a bound, highly elliptical Keplerian orbit around SgrA*, with an orbital
period of 15.2 years and a peri-centre distance of only 17 light hours. The
orbital elements require an enclosed point mass of 3.7+-1.5x10^6 solar masses.
The data exclude with high confidence that the central dark mass consists of a
cluster of astrophysical objects or massive, degenerate fermions, and strongly
constrain the central density structure.


title:
Astrometric Calibration and Estimate of the Systematic Error in WXM
  Localizations Obtained by the Chicago Bayesian Method

abstract:
  WXM gives GRB localizations in instrument coordinates. WXM localizations must
be converted to celestial coordinates using spacecraft aspect information
obtained by the optical cameras on HETE. We must therefore accurately determine
the alignment of the WXM boresight with respect to that of the optical cameras,
in order to accurately determine the celestial coordinates of WXM burst
locations. We use a seven-parameter model that treats as free parameters the
three Euler angles of a pure rotation, two horizontal shifts of the
coded-aperture masks with respect to the detectors, and the heights of the
masks above the two detectors. We determine the alignment by fitting the model
to a set of 252 WXM localizations of Sco X-1 obtained between 23 April and 28
June 2001. We estimate the systematic error in WXM GRB locations by comparing
the actual and the calculated locations of Sco X-1. We find that the systematic
error corresponding to a 68.3% confidence region is 1.7$'$, and the systematic
error corresponding to a 90% confidence region is 2.4$'$. We find that this
astrometric solution also provides a satisfactory fit to an independent sample
of SGR and XRB events. These results are consistent with the astrometric
calibration and the systematic error in WXM localizations derived independently
using the RIKEN localization method.


title: Star Clusters in Interacting Galaxies: The Case of M51

abstract:
  We present the results of an analysis of stellar clusters in the interacting
galaxy, M51, using HST-WFPC2 observations. The observations were made in five
broad band filters; f336w (U), f439w (B), f555w (V), f675w (R), f814w (I). By
comparing the spectral energy distribution (SED) of each source with those
those of evolutionary spectral synthesis models, we have derived an age, mass,
and extinction for each source. The comparison was done using the 3DEF method,
that is based on a least $\chi^{2}$ test. We find 533 sources that are resolved
and well fit with cluster models. Using this sample we study the cluster
formation history, the cluster initial mass function (cIMF), and search for
evidence of cluster disruption. We find that the cIMF is well represented by a
power law with index of -2.05. In addition, we confirm the cluster disruption
results by Boutloukos and Lamers (2002).


title: Localization of GRBs by Bayesian Analysis of Data from the HETE WXM

abstract:
  We describe a new method of transient point source localization for
coded-aperture X-ray detectors that we have applied to data from the HETE
Wide-Field X-Ray Monitor (WXM). The method is based upon the calculation of the
likelihood function and its interpretation as a probability density for the
transient source location by an application of Bayes' Theorem. The method gives
a point estimate of the source location by finding the maximum of this
probability density, and credible regions for the source location by choosing
suitable contours of constant probability density. We describe the application
of this method to data from the WXM, and give examples of GRB localizations
which illustrate the results that can be obtained using this method.


title:
Nonlinear Magnetic Diffusion and Magnetic Helicity Transport in Galactic
  Dynamos

abstract:
  We have extended our previous mean-field galactic dynamo model which included
algebraic and dynamic alpha nonlinearities (Kleeorin et al., A&A, v. 387, 453,
2002), to include also a quenching of turbulent diffusivity. We readily obtain
equilibrium states for the large-scale magnetic field in the local disc dynamo
model, and these fields have strengths that are comparable to the equipartition
field strength. We find that the algebraic nonlinearity alone (i.e. quenching
of both the alpha effect and turbulent magnetic diffusion) cannot saturate the
growth of the mean magnetic field; only the combined effect of algebraic and
dynamic nonlinearities can limit the growth of the mean magnetic field.
However, in contrast to our earlier work without quenching of the turbulent
diffusivity, we cannot now find satisfactory solutions in the no-z
approximation to the axisymmetric galactic dynamo problem.


title: AGN Feedback on the Intracluster Medium

abstract:
  Galaxy groups are quite underluminous in X-rays compared to clusters, so the
intracluster medium has to be considerably underdense in the former. We
consider this to be due to substantial energy fed back into the ICM when the
baryons in the member galaxies condense into stars ending up in SNe, or accrete
on to central supermassive black holes energizing AGNs. We compute the outflow
and the blowout effects driven by the AGNs and the resulting, steep
luminosity-temperature correlation L_X-T. We compare this with the SN
contribution and with the X-ray data; the latter require the AGN energy to be
coupled to the surrounding ICM at fractional levels around 5 10^{-2}. We link
the L_X-T behavior with the parallel effects of the AGN feedback on the gas in
the host galaxy; we find that these yield a correlation steep up to
M_{\bullet}\propto \sigma^5 between the galactic velocity dispersions and the
central BH masses.


title: Discovery of Two New Faint Cataclysmic Variables

abstract:
  We report on the discovery of two new faint cataclysmic variables. The
objects were selected as candidates from two different imaging surveys aimed at
the discovery of such faint systems. One survey used color and variability
while the other used color and H$_\alpha$ emission as selection criteria. We
present our spectra of the two new variables and discuss their properties. A
discussion of the implication of these discoveries on the space density of
faint cataclysmic variables is presented.


title: The Role of Dust in GRB Afterglows

abstract:
  We show that the clumpy structure of star-forming regions can naturally
explain the fact that 50-70% of GRB afterglows are optically ``dark.'' We also
show that dust echos from the GRB and its afterglow, produced by the clumpy
structure of the star-forming region in which the GRB occurs, can lead to
temporal variability and peaks in the NIR, optical, and UV lightcurves of GRB
afterglows. We note that the detection of GRB ``orphan'' afterglows would
provide strong evidence that the star-forming regions in which GRBs occur are
clumpy.


title: Gamma-Ray Bursts as a Probe of Cosmology

abstract:
  We show that, if the long GRBs are produced by the collapse of massive stars,
GRBs and their afterglows may provide a powerful probe of cosmology and the
early universe.


title: Determining the Gamma-Ray Burst Rate as a Function of Redshift

abstract:
  We exploit the 14 gamma-ray bursts (GRBs) with known redshifts $z$ and the 7
GRBs for which there are constraints on $z$ to determine the GRB rate $R_{\rm
GRB}(z)$, using a method based on Bayesian inference. We find that, despite the
qualitative differences between the observed GRB rate and estimates of the SFR
in the universe, current data are consistent with $R_{\rm GRB}(z)$ being
proportional to the SFR.


title:
Determining the GRB (Redshift, Luminosity)-Distribution Using Burst
  Variability

abstract:
  We use the possible Cepheid-like luminosity estimator for the long-duration
gamma-ray bursts (GRBs) developed by Reichart et al. (2000) to estimate the
intrinsic luminosity, and thus the redshift, of 907 long-duration GRBs from the
BATSE 4B catalog. We describe a method based on Bayesian inference which allows
us to infer the intrinsic GRB burst rate as a function of redshift for bursts
with estimated intrinsic luminosities and redshifts. We apply this method to
the above sample of long-duration GRBs, and present some preliminary results.


title:
Excitation of Orbital Eccentricities by Repeated Resonance Crossings:
  Requirements

abstract:
  Divergent migration of planets within a viscous circumstellar disk can
engender resonance crossings and dramatic excitation of orbital eccentricities.
We provide quantitative criteria for the viability of this mechanism. For the
orbits of two bodies to diverge, a ring of viscous material must be shepherded
between them. As the ring diffuses in radius by virtue of its intrinsic
viscosity, the two planets are wedged further apart. The ring mass must be
smaller than the planetary masses so that the crossing of an individual
resonance lasts longer than the resonant libration period. At the same time,
the crossing cannot be of such long duration that the disk's direct influence
on the bodies' eccentricities interferes with the resonant interaction between
the two planets. This last criterion is robustly satisfied because resonant
widths are typically tiny fractions of the orbital radius. We evaluate our
criteria not only for giant planets within gaseous protoplanetary disks, but
also for shepherd moons that bracket narrow planetary rings in the solar
system. A shepherded ring of gas orbiting at a distance of 1 AU from a
solar-type star and having a surface density of less than 500 g/cm^2, a
dimensionless alpha viscosity of 0.1, and a height-to-radius aspect ratio of
0.05 can drive two Jovian-mass planets through the 2:1 and higher-order
resonances so that their eccentricities amplify to values of several tenths.
Because of the requirement that the disk mass in the vicinity of the planets be
smaller than the planet masses, divergent resonance crossings may figure
significantly into the orbital evolution of planets during the later stages of
disk evolution, including the debris disk phase.


title: Upsilon Andromedae: A Rosetta Stone in Planetary Dynamics

abstract:
  We review the orbital dynamics exhibited by the first extra-solar planetary
system discovered, Upsilon Andromedae. This system is unique in combining all
of the surprising architectural features displayed individually by extrasolar
planetary systems found today: (1) a hot Jupiter, (2) two planets on highly
eccentric orbits, and (3) a stellar companion. We discuss the system's
stability properties and its possible origin. Planet-disk interactions seem
critical to the emerging story.


title: Exploring the Role of Jets in the Radio/X-ray Correlations of GX339-4

abstract:
  The Galactic black hole candidate X-ray binary GX339-4 spends most of its
time in the low/hard state, making it an ideal candidate for modeling the
assumedly low accretion phase. The radio emission correlates very tightly with
the X-rays over more than two orders of magnitude in X-ray flux density,
suggesting that the jet plasma also plays a role at higher frequencies. We
compare the predictions of our jet model, with and without acceleration, to
thirteen broadband simultaneous or quasi-simultaneous spectra over this
changing flux history. In addition, we consider a simple standard thin disk
which transitions to an optically thin accretion flow, in order to account for
the assumedly thermal optical data seen in some observations. A solution
without acceleration cannot describe the data without unrealistic energy
requirements. But because of the low disk luminosity, and possibly the assumed
disk geometry, acceleration in the jet is limited only by synchrotron cooling
and can extend easily into the X-rays. We present a model which can account for
all the broadband spectra included here, by changing only two parameters in the
jet model: the input power and the location of the first acceleration zone.
However, the model is most sensitive to changes in the jet power, the varying
of which can also account for the slope of the observed radio/X-ray correlation
analytically. At the highest low/hard state luminosities, the synchrotron
self-Compton emission from the jet could be detectable with missions such as
{\em GLAST}, providing a way to test the extent of the synchrotron
contribution. We conclude that jet synchrotron is a possible way to explain the
broadband features and this correlation, and discuss ways of incorporating this
component into the ``standard'' corona picture.


title: On the Plutinos and Twotinos of the Kuiper Belt

abstract:
  We illuminate dynamical properties of Kuiper Belt Objects (KBOs) in the 3:2
(``Plutino'') and 2:1 (``Twotino'') Neptunian resonances within the model of
resonant capture and migration. We analyze a series of numerical integrations,
each involving the 4 migratory giant planets and 400 test particles distributed
throughout trans-Neptunian space, to measure efficiencies of capture as
functions of migration speed. Snapshots of the spatial distribution of resonant
KBOs reveal that Twotinos cluster +/- 75 degrees away from Neptune's longitude,
while Plutinos cluster +/- 90 degrees away. Longitudinal clustering persists
even for surveys that are not volume-limited in their ability to detect
resonant KBOs. Remarkably, between -90 degrees and -60 degrees of Neptune's
longitude, we find the sky density of Twotinos to nearly equal that of
Plutinos, despite the greater average distance of Twotinos. We couple our
findings to observations to crudely estimate that the intrinsic Twotino
population is within a factor of 3 of the Plutino population. Most strikingly,
the migration model predicts that more Twotinos may lie at longitudes behind
that of Neptune than ahead of it. The magnitude of the asymmetry amplifies
dramatically with faster rates of migration and can be as large as 300%. A
differential measurement of the sky density of 2:1 resonant objects behind of
and in front of Neptune's longitude would powerfully constrain the migration
history of that planet.


title: Searching for dark matter halos in the Suprime-Cam 2 sq deg field

abstract:
  We report the first result of weak gravitational lensing survey on a 2.1 sq
deg Rc-band image taken with a wide field camera (Suprime-Cam) on the prime
focus of 8.2 m Subaru Telescope. The weak lensing mass reconstruction is
applied to the data to search for dark matter halos of cluster scale; M >=
10^14 solar mass. The reconstructed convergence field is divided by 1-sigma
noise to obtain the signal-to-noise ratio map (S/N-map) of the detection. Local
maxima and minima are searched on the S/N-map and the probability distribution
function (PDF) of the peaks are created to compare with model predictions. We
found excess over noise PDF created from the randomized realization on both
positive and negative sides. Negative peaks imply the presence of voids in the
dark matter distribution and this is the first report of the detection.
Positive peaks, on the other hand, represent the dark matter halos and the
number count of the halos on the 2.1 sq deg image is 4.9 +- 2.3 for S/N > 5
where the Gaussian smoothing radius of the convergence map is 1'. The result is
consistent with the prediction assuming the Press-Schechter mass function and
the NFW halo profile under the cluster normalized CDM cosmology. Although the
present statistics is not enough due to the limited field of view, this work
demonstrates that dark matter halo count via weak lensing is a promising way to
test the paradigm of structure formation and cosmological model.


title: Of Variability, or its Absence, in HgMn Stars

abstract:
  Current models and observations of variability in HgMn stars disagree. We
present here the models that argue for pulsating HgMn stars with properties
similar to those of Slowly Pulsating B Stars. The lack of observed variable
HgMn stars suggests that some physical process is missing from the models. Some
possibilities are discussed.


title: Searching for Line Profile Variability in HgMn Stars

abstract:
  Spectra of four non-magnetic chemically peculiar late B type stars (HgMn)
stars are analysed to detect periodic spectral line variations (LPVs). A
procedure developed to study LPVs in Slowly Pulsating B stars has been adopted
as pulsational properties of HgMn stars should be expected to be similar. In
the preliminary results discussed here no conclusive evidence for periodic LPVs
was uncovered. A more sensitive re-analysis of the data is under way.


title:
Possible cosmological implications in electrodynamics due to variations
  of the fine structure constant

abstract:
  Astronomical observations are suggesting that the fine structure constant
varies cosmologically. We present an analysis on the consequences that these
variations might induce on the electromagnetic field as a whole. We show that
under these circumstances the electrodynamics in vacuum could be described by
two fields, the ``standard'' Maxwell's field and a new scalar field. We provide
a generalised Lorentz force which can be used to test our results
experimentally.


title: Scalar fields and cosmological attractor solutions

abstract:
  Results of a general study on the dynamics of cosmological scalar fields with
arbitrary potentials are presented. Exact and approximate attractor solutions
are found, with applications to quintessence, moduli stabilization and
inflation.


title: A Simple Dynamical Model for Omega Cen

abstract:
  We construct a simple dynamical model of the massive globular cluster Omega
Cen. The model includes simple treatments of dynamical evolution in a galactic
tide, and evolution of single stars. Binary stars and rotation are neglected.
The model approximately fits observational data on the surface brightness
profile, the profile of radial velocity dispersion, and the main sequence mass
function at two radii.


title: Possible pulsations of the M giant in MWC560

abstract:
  MWC 560 and other peculiar symbiotic binary, CH Cyg, have been classified as
the prototypes of the new subclass of symbiotic systems - propellers, with
accretion onto a magnetic white dwarf being the source of activity. The
companion of the hot component in this model should demonstrate stellar wind
with relatively high mass-loss. It can be expected rather a late AGB, Mira or
semiregular variable (SR) than any normal red giant.Our analysis performed for
the I band shows that the M giant probably belongs to such kind of stars and
pulsates with a period of about 5 months.


title: HP Lyr - possibly the hottest RV Tau type object

abstract:
  We report Johnson's UBVRI photometric and optical spectroscopic observations
of a long period variable HP Lyr which up to now has been considered an
eclipsing binary with a period of 140 days. The spectral type changes
continually from A2-3 at maxima to A7-F2 at minima. We propose that the
brightness changes are caused by the pulsation of the star with two periods:
P1=69.35, and P2=2xP1=138.7 days. These periods decreased by more than 1%
between 1960 and 1980. The spectral luminosity class determination gives an A
type supergiant Iab. HP Lyr is also the optical counterpart of the infrared
source IRAS 19199+3950. Relatively high galactic latitude (b=+11.7 degr) and
high radial velocity (-113 km/s) indicate that HP Lyr is an evolved, most
likely post-AGB star. All presented features argue that this star is an RV Tau
type object.


title:
Spatially Resolved Millimeter Interferometry of SMMJ02399-0136: a Very
  Massive Galaxy at z=2.8

abstract:
  We report high-resolution millimeter mapping with the IRAM Plateau de Bure
interferometer of rest-frame 335 micron continuum and CO(3-2) line emission
from the z=2.8 submillimeter galaxy SMMJ02399-0136. The continuum emission
comes from a ~3" diameter structure whose elongation is approximately east-west
and whose centroid is coincident within the astrometric errors with the
brightest X-ray and rest-UV peak (L1). The line data show that this structure
is most likely a rapidly rotating disk. Its rotation velocity of >420 km/s
implies a total dynamical mass of >3x10^11 solar masses within an intrinsic
radius of 8 kpc, most of which is plausibly in the form of stars and gas.
SMMJ02399-0136 is thus a very massive system, whose formation at z~3 is not
easy to understand in current CDM hierarchical merger cosmogonies.


title:
Cosmic shear statistics in the Suprime-Cam 2.1 sq deg field: Constraints
  on Omega_m and sigma_8

abstract:
  We present measurements of the cosmic shear correlation in the shapes of
galaxies in the Suprime-Cam 2.1 deg^2 R_c-band imaging data. As an estimator of
the shear correlation originated from the gravitational lensing, we adopt the
aperture mass variance. We detect a non-zero E mode variance on scales between
2 and 40arcmin. We also detect a small but non-zero B mode variance on scales
larger than 5arcmin. We compare the measured E mode variance to the model
predictions in CDM cosmologies using maximum likelihood analysis. A
four-dimensional space is explored, which examines sigma_8, Omega_m, Gamma and
zs (a mean redshift of galaxies). We include three possible sources of error:
statistical noise, the cosmic variance estimated using numerical experiments,
and a residual systematic effect estimated from the B mode variance. We derive
joint constraints on two parameters by marginalizing over the two remaining
parameters. We obtain an upper limit of Gamma<0.5 for zs>0.9 (68% confidence).
For a prior Gamma\in[0.1,0.4] and zs\in[0.6,1.4], we find
sigma_8=(0.50_{-0.16}^{+0.35})Omega_m^{-0.37} for flat cosmologies and
sigma_8=(0.51_{-0.16}^{+0.29})Omega_m^{-0.34}$ for open cosmologies (95%
confidence). If we take the currently popular LCDM model, we obtain a
one-dimensional confidence interval on sigma_8 for the 95.4% level,
0.62<\sigma_8<1.32 for zs\in[0.6,1.4]. Information on the redshift distribution
of galaxies is key to obtaining a correct cosmological constraint. An
independent constraint on Gamma from other observations is useful to tighten
the constraint.


title:
Long-term X-ray variability of quasars in the Lockman Hole field
  observed with ROSAT

abstract:
  An improved method is utilized to estimate the X-ray power spectral densities
(PSD) and the variation time scales of three quasars in the Lockman Hole field.
Five archival ROSAT PSPC data covering two year range are analyzed. To estimate
PSD from sparse and unevenly-sampled lightcurves, a forward-method approach
with extensive Monte-Carlo simulations is adopted. A broken power-law type PSD
with a constant Poisson noise component is assumed with a break frequency
$f_{\rm b}$. Then, assuming the PSD slope $\alpha$ as $-2<\alpha<-1$, $1/
f_{\rm b}$ is constrained as $\gtrsim$ 25 days for one object, while the
constraints on the other two objects are very weak. The long time scale of the
one object is consistent with the view that luminous AGNs host massive black
holes.


title:
Formation of Large-Scale Semi-Organized Structures in Turbulent
  Convection

abstract:
  A new mean-field theory of turbulent convection is developed. This theory
predicts the convective wind instability in a shear-free turbulent convection
which causes formation of large-scale semi-organized fluid motions in the form
of cells or rolls. Spatial characteristics of these motions, such as the
minimum size of the growing perturbations and the size of perturbations with
the maximum growth rate, are determined. This study predicts also the existence
of the convective shear instability in a sheared turbulent convection which
results in generation of convective shear waves with a nonzero hydrodynamic
helicity. Increase of shear promotes excitation of the convective shear
instability. Applications of the obtained results to the atmospheric turbulent
convection and the laboratory experiments on turbulent convection are
discussed. This theory can be applied also for the describing a mesogranular
turbulent convection in astrophysics.


title: On the knee in the energy spectrum of cosmic rays

abstract:
  The knee in the all-particle energy spectrum is scrutinized with a
phenomenological model, named poly-gonato model, linking results from direct
and indirect measurements. For this purpose, recent results from direct and
indirect measurements of cosmic rays in the energy range from 10 GeV up to 1
EeV are examined. The energy spectra of individual elements, as obtained by
direct observations, are extrapolated to high energies using power laws and
compared to all-particle spectra from air shower measurements. A cut-off for
each element proportional to its charge Z is assumed. The model describes the
knee in the all-particle energy spectrum as a result of subsequent cut-offs for
individual elements, starting with the proton component at 4.5 PeV, and the
second change of the spectral index around 0.4 EeV as due to the end of stable
elements (Z=92). The mass composition, extrapolated from direct measurements to
high energies, using the poly-gonato model, is compatible with results from air
shower experiments measuring the electromagnetic, muonic, and hadronic
components. But it disagrees with the mass composition derived from X_max
measurements using Cerenkov and fluorescence light detectors.


title: Feedback and the fudamental line of low-luminosity LSB/dwarf galaxies

abstract:
  We study in simple terms the role of feedback in establishing the scaling
relations of low-surface-brightness and dwarf galaxies with stellar masses in
the range 6x10^5 <M*< 3x10^10 Msun. These galaxies, as measured from SDSS and
in the Local Group, show tight correlations of internal velocity, metallicity
and surface brightness (or radius) with M*. They define a fundamental line
distinguishing them from the brighter galaxies of high surface brightness and
metallicity. The idealized model assumes spherical collapse of CDM haloes to
virial equilibrium and angular-momentum conservation. The relations for bright
galaxies are reproduced by assuming that M* is a constant fraction of the halo
mass M. The upper bound to the low-luminosity LSBs coincides with the virial
velocity of haloes in which supernova feedback could significantly suppress
star formation, V<100km/s (Dekel & Silk 1986). We argue that the energy fed to
the gas obeys E_sn \prop M* despite the radiative losses, and equate it with
the binding energy of the gas to obtain M*/M \prop V^2. This idealized model
provides surprisingly good fits to the scaling relations of low-luminosity LSBs
and dwarfs, which indicates that supernova feedback had a primary role in
determining the fundamental line. The apparent lower bound for galaxies at
V~10km/s may be due to the cooling barrier at T~10^4 K. Some fraction of the
dark haloes may show no stars due to complete gas removal either by supernova
winds from neighboring galaxies or by radiative feedback after cosmological
reionization at z_ion. Radiative feedback may also explain the distinction
between dwarf spheroidals (dE) and irregulars (dI), where the dEs of V<30km/s
form stars before z_ion and are then cleaned out of gas, while the dIs with
V>30km/s retain gas-rich discs with feedback-regulated star formation.