title:
Photometry Results for the Globular Clusters M10 and M12: Extinction
  Maps, Color-Magnitude Diagrams, and Variable Star Candidates

abstract:
  We report on photometry results of the equatorial globular clusters (GCs) M10
and M12. These two clusters are part of our sample of GCs which we are probing
for the existence of photometrically varying eclipsing binary stars. During the
search for binaries in M10 and M12, we discovered the signature of differential
reddening across the fields of the clusters. The effect is stronger for M10
than for M12. Using our previously described dereddening technique, we create
differential extinction maps for the clusters which dramatically improve the
appearance of the color-magnitude diagrams (CMDs). Comparison of our maps with
the dust emissivity maps of Schlegel, Finkbeiner, & Davis (SFD) shows good
agreement in terms of spatial extinction features. Several methods of adding an
E_{V-I} zero point to our differential maps are presented of which isochrone
fitting proved to be the most successful. Our E_{V-I} values fall within the
range of widely varying literature values. More specifically, our reddening
zero point estimate for M12 agrees well with the SFD estimate, whereas the one
for M10 falls below the SFD value. Our search for variable stars in the
clusters produced a total of five variables: three in M10 and two in M12. The
M10 variables include a binary system of the W Ursa Majoris (W UMa) type, a
background RR Lyrae star, and an SX Phoenicis pulsator, none of which is
physically associated with M10. M12's variables are two W UMa binaries, one of
which is most likely a member of the cluster. We present the phased photometry
lightcurves for the variable stars, estimate their distances, and show their
locations in the fields and the CMDs of the GCs.


title: A Massive Jet-Ejection from SS433

abstract:
  The detection of a massive jet-ejection event from SS433 with RXTE is
reported. SS433 in its high state has been monitored with RXTE from 2001/11/09
(MJD = 52222) to 2001/11/25 (MJD = 52238), following a radio flare on
2001/11/02 (MJD = 52215). An irregular temporal variation with time scales of
100-1000 s appears in the light curve, and the amplitude increases day by day.
This is the first detection of such a fast variation from the source. In
addition to the fast variations, the daily light curve scatters with a time
scale of ~day from 2001/11/17 (MJD = 52230). Following the scatter, another
radio flare has been detected on 2001/11/22 (MJD = 52235), which has been
obviously formed during the X-ray scatter. This is a preliminary report on a
massive jet-ejection event witnessed in X-ray band for the first time.


title:
The REFLEX Galaxy Cluster Survey VII: Omega_m and sigma_8 from cluster
  abundance and large-scale clustering

abstract:
  For the first time the large-scale clustering and the mean abundance of
galaxy clusters are analysed simultaneously to get precise constraints on the
normalized cosmic matter density $\Omega_m$ and the linear theory RMS
fluctuations in mass $\sigma_8$. A self-consistent likelihood analysis is
described which combines, in a natural and optimal manner, a battery of
sensitive cosmological tests where observational data are represented by the
(Karhunen-Lo\'{e}ve) eigenvectors of the sample correlation matrix. This method
breaks the degeneracy between $\Omega_m$ and $\sigma_8$. The cosmological tests
are performed with the ROSAT ESO Flux-Limited X-ray (REFLEX) cluster sample.
The computations assume cosmologically flat geometries and a non-evolving
cluster population mainly over the redshift range $0<z<0.3$. The REFLEX sample
gives the cosmological constraints and their $1\sigma$ random errors of
$\Omega_m = 0.341 ^{+0.031}_{-0.029}$ and $\sigma_8 = 0.711
^{+0.039}_{-0.031}$. Possible systematic errors are evaluated by estimating the
effects of uncertainties in the value of the Hubble constant, the baryon
density, the spectral slope of the initial scalar fluctuations, the mass/X-ray
luminosity relation and its intrinsic scatter, the biasing scheme, and the
cluster mass density profile. All these contributions sum up to total
systematic errors of $\sigma_{\Omega_m}=^{+0.087}_{-0.071}$ and
$\sigma_{\sigma_8}=^{+0.120}_{-0.162}$.


title: Galaxy Formation Now and Then

abstract:
  I review the current state of our understanding of the galaxy formation and
evolution process from the modeler's perspective. With the advent of the cold
dark matter model and the support of fast computers and advanced simulation
techniques, there has been considerable progress in explaining the growth of
structure on the largest scales and in reproducing some of the basic properties
of galaxies and their evolution with redshift. However, many properties of
galaxies are still only poorly understood or appear to be in conflict with the
prediction of the cold dark matter model. I discuss in what direction the next
generation of galaxy formation models may go and why a large space-based
optical-UV telescope could be critical for the calibration and testing of these
advanced models.


title: M giants in Macho, DENIS and Isogal

abstract:
  A complete sample of 174 M giants classified by Blanco (1986) and later than
subtype M0 in the NGC6522 Baade's Window clear field has been investigated to
establish some general properties of cool Bulge stars. Photometric information
has been obtained from the MACHO database to search for variability and, where
possible, to determine periods. Near- and mid-IR magnitudes have been extracted
from DENIS and ISOGAL. 46 semi-regular variables and 2 irregulars were found a
mongst the 174. Many M5 and all stars M6 or later show variation, whereas
earlier subtypes do not. The DENIS I-J and J-K_S colours and the luminosities
of the M stars increase with M sub-class. K tends to increase with log P among
M-type SR variables. Almost all the variables were detected at 7 microns during
the ISOGAL programme. Excess radiation at 15 microns, indicative of heavy mass
loss, is associated with very high luminosity and late spectral type. The limit
of sensitivity of the ISOGAL survey was such that the non-variables were not
detected. Four probable M stars not listed by Blanco (1986), two of which are
semi-regular variables, were detected by ISOGAL. In the case of doubly-periodic
SR variables, the longer periods have K mags which place them close to the D
line of Wood (2000) in a K,log P diagram. The unusual MACHO light curve of one
particular star, Blanco 26, shows the commencement of a long-period variation
with an anomalously short and sharp event and appears to rule out a pulsational
model for this phenomenon.


title: The peculiar cooling flow cluster RX J0820.9+0752

abstract:
  (Abridged) We present observations of the cluster of galaxies associated with
the X-ray source RX J0820.9+0752 and its dramatic central cluster galaxy (CCG)
in the optical and X-ray wavebands.Unlike other cooling flow CCGs studied in
detail, this system does not contain a powerful radio source at its core, and
so provides us with an important example where we expect to see only the
processes directly due to the cooling flow itself. Chandra observations show
that the hot intracluster gas is cooling, dropping below 1.8 keV in the core.
Optical images (AAT and HST) show that the central galaxy is embedded in a
luminous line-emitting nebula that coincides spatially with an excess of X-ray
emission, and separate, off-nucleus clumps of blue continuum that form part of
a patchy structure arcing away from the main galaxy. The X-ray/H-Alpha feature
is reminiscent of a filament observed in A 1795 which is suggested to be a
cooling wake, produced by the motion of the CCG through the ICM. We present
optical spectra of the CCG and its surroundings, and find that the continuum
blobs show poperties clearly distinct from those of the surrounding nebula.
Accounting for the strong intrinsic reddening and its significant variation
over the extent of the line emitting region, we have fit the continuum spectra
of the blobs and the nucleus using stellar spectra. We found that continuum
emission from early main sequence stars can account for the blue excess light
in the blobs. Kinematical properties associate the gas in the system with a
nearby galaxy, suggesting some kind of tidal interaction between the two. We
suggest that the secondary galaxy has moved through the cooling wake produced
by the CCG, dragging some of the gas out of the wake and triggering the
starbursts found in the blobs.


title:
Unified Cloudy Models of L and T Dwarfs - Physical Basis of the Spectral
  Classification in the Substellar Regime

abstract:
  Based on a simple thermodynamical argument, we proposed a unified cloudy
model (UCM) with a warm dust cloud deep in the photosphere. We showed, for the
first time, that a single grid of model photospheres (Teff between 800 and
2600K) offers a natural explanation not only for the division of dwarfs cooler
than M into the two distinct types L and T but also for the changes of the
spectra and colors along the L -- T spectral sequence. Based on our model
analysis of the observed IR colors, we propose an effective temperature scale
and compare it with the empirical one. For detailed analyses of the spectra,
the chemical composition is an important basic stellar parameter besides Teff,
and the observed infrared spectrum of the L dwarf prototype GD165B can finally
be fitted with the predicted one based on our UCM being updated with the use of
the new solar carbon and oxygen abundances. We confirm that our UCMs provide
consistent interpretation of the spectra and colors of L and T dwarfs, and thus
will provide the physical basis for the spectral classification of the dwarfs
cooler than M extending to the substellar regime.


title:
Suppressing the contribution of intrinsic galaxy alignments to the shear
  two-point correlation function

abstract:
  Cosmological weak lensing gives rise to correlations in the ellipticities of
faint galaxies. This cosmic shear signal depends upon the matter power
spectrum, thus providing a means to constrain cosmological parameters. It has
recently been proposed that intrinsic alignments arising at the epoch of galaxy
formation can also contribute significantly to the observed correlations, the
amplitude increasing with decreasing survey depth. Here we consider the
two-point shear correlation function, and demonstrate that photometric redshift
information can be used to suppress the intrinsic signal; at the same time
Poisson noise is increased, due to a decrease in the effective number of galaxy
pairs. The choice to apply such a redshift-depending weighting will depend on
the characteristics of the survey in question. In surveys with a mean z of
about 1, although the lensing signal dominates, the measurement error bars may
soon become smaller than the intrinsic alignment signal; hence, in order not to
be dominated by systematics, redshift information in cosmic shear statistics
will become a necessity. We discuss various aspects of this.


title: Galaxy Voids in Cold Dark Matter Universes

abstract:
  We present predictions for numerous statistics related to the presence of
voids in the distribution of galaxies in a cold dark matter model of structure
formation using a semi-analytic model of galaxy formation. Our study is able to
probe galaxies with masses as low as 10^9Msun/h corresponding to absolute
magnitudes of M_bJ-5log(h)=-18.1 and M_r-5log(h)=-18.7. We quantify the void
and underdense probability functions, distributions of nearest neighbour
distances and void sizes and compute the density profiles of voids. These
results are contrasted with the expectations for dark matter (and the
difference examined in terms of the galaxy/dark matter biasing relation) and
are compared to analytic predictions and observational data where available.
The predicted void probability functions are consistent with those measured
from the Center for Astrophysics redshift surveys given the rather large
uncertainties in this relatively small (for studies of voids) observational
sample. The size of the observational sample is too small to probe the bias
between galaxies and dark matter that we predict. We also examine the predicted
properties of galaxies living within voids and contrast these with the general
galaxy population. Our predictions are aimed at forthcoming large galaxy
redshift surveys which should for the first time provide statistically accurate
measures of the void population.


title: Discovery of Newly Formed Broad Absorption Lines in a Radio-Loud Quasar

abstract:
  We report a serendipitous discovery of broad absorption lines that were newly
formed in the spectrum of the high-redshift, luminous radio-loud quasar TEX
1726 + 344, in a time interval of only 12 years. This is the first quasar
showing a transition from narrow absorption lines to broad absorption lines. It
also becomes one of the few radio-loud broad absorption line quasars. The gas
cloud responsible for these broad absorption lines is derived to have
parameters coinciding with those of the remnant of a tidally disrupted star.


title:
On Radiation Pressure and the Poynting-Robertson Effect for Fluffy Dust
  Particles

abstract:
  Equation of motion for real dust particle under the action of electromagnetic
radiation is more general than equation of motion corresponding to standardly
used Poynting-Robertson effect (P-R effect). As a consequence, orbital
evolution of particles may significantly differ from that corresponding to the
P-R effect. The paper discusses recently published (Icarus, June 2002)
derivation of equation of motion, which is in contradiction with known
relativistically covariant formulation. The ``new'' derivation does not respect
fundamental physical laws (law of conservation of energy, law of conservation
of momentum) which must hold in any frame of reference. Application of the
derived ``general'' equation of motion to the special case treated by Einstein
in 1905 yields result which is not consistent with Einstein's result. Correct
solution is presented.


title:
SDSS Survey for Resolved Milky Way Satellite Galaxies II: High-Velocity
  Clouds in the Early Data Release

abstract:
  In this paper, we limit the stellar content of 13 high-velocity clouds (HVCs;
including 1 compact HVC) using the detection limits of a new survey for
resolved Milky Way satellite galaxies in the Sloan Digital Sky Survey Early
Data Release (EDR). Our analysis is sensitive to stellar associations within
the virial radius of the Milky Way that are up to 50 times fainter than the
faintest known Milky Way satellites. Statistically, we find no stellar
overdensity associated with any of the clouds. These non-detections suggest
lower limits of M_{HI}/L_V that range between ~ 0.2 and 250, assuming cloud
distances of 50 and 300 kpc and using fiducial optical scale lengths of 3' and
7'. We explore the implication of these non-detections on the origin of the
HVCs.


title:
Photometric Light Curve for the Kuiper Belt Object 2000 EB173 on 78
  Nights

abstract:
  Kuiper Belt Objects (KBOs) are generally very faint and cannot in practice be
monitored with a well-sampled long-term light curve; so our discovery of the
bright KBO 2000 EB173 offers an excellent opportunity for synoptic studies. We
present a well-sampled photometric time series (77 R magnitudes and 29 V
magnitudes on 78 nights) over a 225-day time span centered on the 2001
opposition. The light curve (corrected to the year 2001 opposition distance)
varies from 19.11 to 19.39 mag with a single peak that is smooth, time
symmetric, and coincident with opposition. All variations in the light curve
are consistent with a linear opposition surge (Ropp = 19.083 + 0.125Xalpha,
where alpha is the solar phase angle), while any rotational modulation must
have a peak-to-peak amplitude of less than 0.097 mag. This is the first
measured opposition surge for any KBO (other than Pluto). The V-R color is
0.63+-0.02, with no apparent variation with phase at the few percent level.
With R=19.11 at opposition, 2000 EB173 remains the brightest known KBO and a
prime target for future photometric and spectroscopic studies.


title: Balmer and He I absorption in the nuclear spectrum of NGC 4151

abstract:
  Spectra taken with the Space Telescope Imaging Spectrograph (STIS) allow
accurate location and extraction of the nuclear spectrum of NGC 4151, with
minimal contamination by extended line emission and circumnuclear starlight.
Spectra since 1997 show that the P Cygni Balmer and He I absorption seen
previously in low nuclear states, is present in higher states, with outflow
velocity that changes with the nuclear flux. The phenomenon is discussed in
terms of some of the absorbers seen in the UV resonance lines, and outflows
from the central source and surrounding torus.


title:
On the Indirect Detection of Sodium in the Atmosphere of the Planetary
  Companion to HD 209458

abstract:
  Using a self-consistent atmosphere code, we construct a new model of the
atmosphere of the transiting extrasolar giant planet HD 209458b to investigate
the disparity between the observed strength of the sodium absorption feature at
589 nm and the predictions of previous models. For the atmospheric
temperature-pressure profile we derive, silicate and iron clouds reside at a
pressure of several mbar in the planet's atmosphere. These clouds have
significant vertical extent and optical depth due to our slant viewing geometry
and lead to increased absorption in bands directly adjacent to the sodium line
core. Using a non-LTE sodium ionization model that includes photoionization by
stellar UV flux, collisional processes with H_2, and radiative recombination,
we show that the ionization depth in the planet's atmosphere reaches ~1/2 mbar
at the day/night terminator. Ionization leads to a slight weakening of the
sodium feature. We present our baseline model, including ionization and clouds,
which falls near the observational error bars. The sensitivity of our
conclusions to the derived atmospheric temperature-pressure profile is
discussed.


title: Spectroscopy of Brown Dwarf Candidates in the NGC 1333 Molecular Cloud

abstract:
  We present an analysis of low-resolution infrared spectra for 25 brown dwarf
candidates in the NGC 1333 molecular cloud. Candidates were chosen on the basis
of their association with the high column density cloud core, and near-infrared
fluxes and colors. We compare the depths of water vapor absorption bands in our
candidate objects with a grid of dwarf, subgiant, and giant standards to
determine spectral types which are independent of reddening. These data are
used to derive effective temperatures and bolometric luminosities which, when
combined with theoretical tracks and isochrones for pre-main sequence objects,
enable us to estimate masses and ages. Depending on the models considered, a
total of 9 to 20 brown dwarfs are identified with a median of age of < 1 Myr.


title: Saha Ionization Formula and the Voids

abstract:
  The ultra-low density limit of Saha ionization formula suggests that, in this
limit, matter would prefer to remain ionized.This has a very important
implication for cosmic structures known as Voids.These are ultra-low density
(much less than average density of matter in the Universe) regions in the
galactic clusters and superclusters.The ionization formula implies that matter
trapped in the Voids should be ionized.Therefore, we expect a very faint
radiation glow from the Voids resulting from the motion of the charged
particles.


title: Spectroscopy of the neighboring massive clusters Abell 222 and Abell 223

abstract:
  We present a spectroscopic catalog of the neighboring massive clusters Abell
222 and Abell 223. The catalog contains the positions, redshifts, R magnitudes,
V-R color, as well as the equivalent widths for a number of lines for 183
galaxies, 153 of them belonging to the A 222 and A 223 system. We determine the
heliocentric redshifts to be z=0.2126+/-0.0008 for A 222 and z=0.2079+/-0.0008
for A 223. The velocity dispersions of both clusters in the cluster restframe
are about the same: sigma = 1014^{+90}_{-71} km/s and sigma = 1032^{+99}_{-76}
km/s for A 222 and A 223, respectively. While we find evidence for substructure
in the spatial distribution of A 223, no kinematic substructure can be
detected. From the red cluster sequence identified in a
color--magnitude--diagram we determine the luminosity of both clusters and
derive mass--to--light ratios in the R--band of (M/L)_A222 = (202+/-43) h_70
M_{su}n/L_{sun} and (M/L)_A223 = (149+/-33) h_70 M_{sun}/L_{sun}. Additionally
we identify a group of background galaxies at z ~ 0.242.


title:
Uniformly rotating axisymmetric fluid configurations bifurcating from
  highly flattened Maclaurin spheroids

abstract:
  We give a thorough investigation of sequences of uniformly rotating,
homogeneous axisymmetric Newtonian equilibrium configurations that bifurcate
from highly flattened Maclaurin spheroids. Each one of these sequences
possesses a mass-shedding limit. Starting at this point, the sequences proceed
towards the Maclaurin sequence and beyond. The first sequence leads to the well
known Dyson rings, whereas the end points of the higher sequences are
characterized by the formation of a two-body system, either a core-ring system
(for the second, the fourth etc. sequence) or a two-ring system (for the third,
the fifth etc. sequence). Although the general qualitative picture drawn by
Eriguchi and Hachisu in the eighties has been confirmed, slight differences
turned out in the interpretation of the origin of the first two-ring sequence
and in the general appearance of fluid bodies belonging to higher sequences.


title: The Fundamental Plane of Ellipticals: I. The Dark Matter Connection

abstract:
  We show that the small scatter around the Fundamental Plane (FP) of massive
elliptical galaxies can be used to derive important properties of their dark
and luminous matter. The central velocity dispersion sigma_0, appearing in
(e.g.) the Fundamental Plane, is linked to photometric, dynamical and
geometrical properties of (luminous and dark) matter. We find that, inside the
effective radius R_e, the matter traced by the light must largely dominate over
the dark matter (DM), in order to keep the ellipticals close enough to the FP.
This recalls analogous findings for spiral galaxies.
  In particular we also find that cuspy DM distributions, as predicted by
numerical simulations in Lambda CDM cosmology, are unable to explain the very
existence of the FP; in fact, according to this theory, the structural
properties of dark and luminous matter are so interwoven that a curved surface
is predicted in the log-space (sigma_0, R_e, L), rather than a plane. In order
to agree with the FP, CDM halos must have concentrations parameters in the
range of 5-9 (i.e. values significantly lower than the current predictions).
  Assuming a more heuristic approach and allowing for cored DM halos, we find
that the small intrinsic scatter of the FP yields to i) an average value for
the dark-to-light-traced mass ratio inside the length-scale of light R_e of
about 0.3, ii) a mass-to-light ratio of the matter traced by the light
increasing with spheroid luminosity as L^(0.2) in Gunn-r band, with a value of
5.3 at L = 2.7 x 10^{10} L_{sol}.


title:
Temperature and gravity of the pulsating extreme helium star LSS 3184
  (BX Cir) through its pulsation cycle

abstract:
  We report the analysis of optical spectra of the extreme helium star LSS 3184
(BX Cir) to determine its effective temperature and gravity throughout its
pulsation cycle. The spectra were also used to measure its chemical abundances.
  We report rest gravity, log g = 3.38 +/- 0.02, and a chemical abundance
mixture consistent with those reported earlier in a study using an optical
spectrum with lower spectral resolution and a lower signal to noise ratio. Our
analysis decreases the upper limit for the H abundance to H < 6.0 (mass
fraction < 7.1 x 10^-7). Our gravity corresponds to stellar mass M = 0.47 +/-
0.03 M_sun.
  We find that the effective log g varies through the pulsation cycle with an
amplitude of 0.28 dex. The effective gravity is smaller than the rest gravity
except when the star is very near its minimum radius. The change in effective
gravity is primarily caused by acceleration of the stellar surface.
  Based on the optical spectra, we find the temperature varies with an
amplitude of 3450 K. We find a time averaged mean temperature, 23390 +/- 90 K,
consistent with that found in the earlier optical spectrum study. The mean
temperature is 1750 K hotter than that found using combined ultraviolet spectra
and V and R photometry and the variation amplitude is larger. This discrepancy
is similar to that found for the extreme helium star V652 Her.


title: PX Andromedae: Superhumps and variable eclipse depth

abstract:
  Results of a photometric study of the SW Sex novalike PX And are presented.
The periodogram analysis of the observations obtained in October 2000 reveals
the presence of three signals with periods of 0.142, 4.8 and 0.207 days. The
first two periods are recognized as "negative superhumps" and the corresponding
retrograde precession period of the accretion disk. The origin of the third
periodic signal remains unknown. The observations in September-October 2001
point only to the presence of "negative superhumps" and possibly to the
precession period. The origin of the "negative superhumps" is discussed and two
possible mechanisms are suggested. All light curves show strong flickering
activity and power spectra with a typical red noise shape. PX And shows
eclipses with highly variable shape and depth. The analysis suggests that the
eclipse depth is modulated with the precession period and two possible
explanations of this phenomenon are discussed. An improved orbital ephemeris is
also determined: T_min[HJD]=49238.83662(14)+0.146352739(11)E.


title: Structure of pulsar beams: conal versus patchy

abstract:
  Structure of mean pulsar radiation patterns is discussed within the
nested-cones and patchy beam models. Observational predictions of both these
models are analyzed and compared with available data on pulsar waveforms. It is
argued that observational properties of pulsar waveforms are highly consistent
with the nested-cone model and, in general, inconsistent with the patchy beam
model.


title:
The Kelvin-Helmholtz Instability in an Expanding Universe and its Effect
  on Dark Matter

abstract:
  We extend the Kelvin-Helmholtz instability to an expanding background. We
study the evolution of a non-viscous irrotational fluid and find that for
wavelengths much smaller than the Hubble scale small perturbations of the fluid
are unstable for wavenumbers larger than a critical value. We then apply this
result in the early universe, treating cold dark matter as a classical fluid
with vanishing background pressure.


title: The Duty Cycle of GRS 1915+105

abstract:
  We propose a scenario for a periodic filling and emptying of the accretion
disc of GRS 1915+105, by computing the mass transfer rate from the donor and
comparing it with the observed accretion rate. The binary parameters found by
Greiner et al. (2001) predict evolutionary expansion of the donor along the
giant branch with a conservative mass transfer rate (1 - 2)E-8 solar masses per
year. This reservoir can support the present accretion with a duty cycle 0.05 -
0.1 (the active time as a fraction of the total life time). The viscosity time
scale at the circularization radius (15 solar radii from the primary 14 solar
mass black hole) is identified as the recurrent quiescent time during which a
new disc is formed once consumed by the BH. For small viscosity (alpha = 0.001)
it equals to 300 - 400 years. The microquasar phase, with the duty cycle, will
last around 10 million years ending with a long period black hole + white dwarf
system.


title:
A photometric monitoring of bright high-amplitude delta Scuti stars. I.
  The double-mode pulsation of V567 Ophiuchi

abstract:
  We present the first results of an observational project, which addresses the
period changing behaviour of a sample of high-amplitude delta Scuti stars. In
this paper we discuss the double-mode nature of V567 Ophiuchi. It was observed
on 15 nights in two consecutive years in order to resolve the long-standing
ambiguity related to its secondary period. A frequency analysis of almost 5000
individual single-filtered CCD V measurements resulted in two independent
frequencies (f_1=6.6879 c/d and f_2=11.8266 c/d) with a ratio of f_1/f_2=0.565.
Earlier data taken from the literature were used to refine the dominant period,
and the re-analysis supports the existence of the secondary period. Possible
asteroseismological implications are briefly discussed.


title:
Change of primary cosmic radiation nuclear composition in the energy
  range 10^{15} - 10^{17} eV

abstract:
  The dependence E_h (N_e) of Extensive Air Shower (EAS) hadronic component
energy flux on the number N_e of particles in EAS is investigated in the
primary energy range of the order of 10^{15} - 10^{17} eV. The work was aimed
at checking the existence of irregularities of E_h (N_e)/N_e behavior at these
energies in several independent experiments. The investigation is carried out
using large statistical material obtained at different configurations of
experimental apparatus and under different triggering conditions. The existence
of irregularities of E_h (N_e)/N_e behavior in the region Ne > 2*10^6 is
confirmed. These irregularities have the character of sharp deeps and are
located near the same values of N_e regardless of the experimental material and
selection conditions used. So, at recent stage of research the existence of
these irregularities of E_h (N_e)/N_e behavior in the range of N_e > 2*10^6 may
be regarded as reliably established. This fact supports our earlier conclusion
on the existence of primary cosmic radiation (PCR) nuclei spectra cutoff effect
in the primary energy region 10^{15} - 10^{17} eV.


title:
Exploring Halo Substructure with Giant Stars III: First Results from the
  Grid Giant Star Survey and Discovery of a Possible Nearby Sagittarius Tidal
  Structure in Virgo

abstract:
  We describe first results of a spectroscopic probe of selected fields from
the Grid Giant Star Survey. Multifiber spectroscopy of several hundred stars in
a strip of eleven fields along delta approximately -17^{circ}, in the range 12
<~ alpha <~ 17 hours, reveals a group of 8 giants that have kinematical
characteristics differing from the main field population, but that as a group
maintain coherent, smoothly varying distances and radial velocities with
position across the fields. Moreover, these stars have roughly the same
abundance, according to their MgH+Mgb absorption line strengths. Photometric
parallaxes place these stars in a semi-loop structure, arcing in a contiguous
distribution between 5.7 and 7.9 kpc from the Galactic center. The spatial,
kinematical, and abundance coherence of these stars suggests that they are part
of a diffuse stream of tidal debris, and one roughly consistent with a wrapped,
leading tidal arm of the Sagittarius dwarf spheroidal galaxy.


title:
The precession of the giant HH34 outflow: a possible jet deceleration
  mechanism

abstract:
  The giant jets represent a fundamental trace of the historical evolution of
the outflow activity over timescales which are comparable to the accretion time
of the outflow sources in their main protostellar phase. The study of such huge
jets provides the possibility of retrieving important elements related to the
life of the outflow sources. In this paper, we study the role of precession
(combined with jet velocity-variability and the resulting enhanced interaction
with the surrounding environment) as a deceleration mechanism for giant jets
using a numerical approach. We obtain predictions of H alpha intensity maps and
position-velocity diagrams from 3D simulations of the giant HH 34 jet
(including an appropriate ejection velocity time-variability and a precession
of the outflow axis), and we compare them with previously published
observations of this object. Our simulations represent a step forward from
previous numerical studies of HH objects, in that the use of a 7-level, binary
adaptive grid has allowed us to compute models which appropiately cover all
relevant scales of a giant jet, from the ~ 100 AU jet radius close to the
source to the ~ 1 pc length of the outflow. A good qualitative and quantitative
agreement is found between the model predictions and the observations.
Moreover, we show that a critical parameter for obtaining a better or worse
agreement with the observations is the ratio rho_j/rho_a between the jet and
the environmental densities. The implications of this result in the context of
the current star formation models are discussed (ABRIDGED).


title:
The Influence of Supershells and Galactic Outflows on the Escape of
  Ionizing Radiation from Dwarf Starburst Galaxies

abstract:
  We study the escape of Lyman continuum radiation from the disks of dwarf
starburst galaxies, with and without supershells, by solving the radiation
transfer problem of stellar radiation through them. We model disks with
Md=10^8-10Msun, with exponential surface density profiles as a function of
redshift, and model the of repeated supernova explosions driving supershells
out of the disks, using the hydrodynamic simulation code, ZEUS-3D. The amount
of star formation is assumed proportional to mass above some density threshold.
We vary the threshold to explore the range of star formation efficiencies,
f*=0.006, 0.06, and 0.6. We find that the interstellar gas swept up in dense
supershells can effectively trap the ionizing photons, before the supershells
blow out of the disks. The blow-outs then create galactic outflows, chimneys
which allow the photons to escape directly to the intergalactic medium. Our
results are consistent with escape fractions of less than 0.1 measured in local
dwarf starburst galaxies, because they are likely observed while the starbursts
are young, before blow-out. We suggest that high-redshift dwarf starburst
galaxies may make a substantial contribution to the UV background radiation
with total escape fractions >0.2, as expected if star formation efficiencies
>0.06.


title:
Structure in the Epislon Eridani dusty disk caused by mean motion
  resonances with a 0.3 eccentricity planet at periastron

abstract:
  The morphology of the epsilon Eridani dust ring is reproduced by a numerical
simulation of dust particles captured into the 5:3 and 3:2 exterior mean-motion
resonances with a 0.3 eccentricity 10^-4 solar mass planet at periastron at a
semi-major axis of 40 AU. The morphology will differ when the planet is at
aphelion, in about 140 years. Moderate eccentricity planets in outer
extra-solar systems will cause observable variations in the morphology of
associated dusty rings.


title:
Chandra Study of a Complete Sample of Millisecond Pulsars in 47Tuc and
  NGC6397

abstract:
  We report Chandra observations of the complete sample of millisecond pulsars
(MSPs) with precise radio positions in the globular clusters 47Tuc (NGC104) and
NGC6397. The 47Tuc MSPs are predominantly soft sources suggestive of thermal
emission from small (r_x < 0.6km) polar caps on the neutron star rather than
magnetospheric emission and are a relatively homogeneous sample, with most
x-ray luminosities in a surprisingly narrow range (Lx ~1-4 X 10^30 erg/s). We
use previously derived intrinsic Pdot values and find a new relation between Lx
and spindown luminosity, Edot: Lx ~ Edot^beta, with beta ~0.5 vs. ~1.0 for both
pulsars and MSPs in the field. This Lx-Edot relation and also the Lx/Edot vs.
spindown age are each similar to that found by Harding & Muslimov (2002) for
thermal emission from polar cap heating although the cluster MSPs are
relatively longer-lived (in thermal x-rays) than either the models or field
MSPs. We suggest the cluster MSPs may have altered surface magnetic field
topology (e.g.multipole) or their neutron stars are more massive from repeated
accretion episodes due to encounters and repeated exchange interactions. MSP
binary companions on or just off the main sequence are likely to have been
re-exchanged and might show anomalous Pdot and Edot values due to relaxation of
misaligned core-crust spins. The radial distribution of 40 soft Chandra sources
in 47Tuc is consistent with a 1.4Msun component. The implied total MSP
population in 47Tuc with Lx >10^30 erg/s is ~35-90, and can constrain the
relative beaming in radio vs. soft x-rays. NGC6397 is relatively deficient in
MSPs; its single detected example may have been re-exchanged out of the cluster
core. (abridged)


title:
Probing the Masses of the PSR J0621+1002 Binary System Through
  Relativistic Apsidal Motion

abstract:
  Orbital, spin and astrometric parameters of the millisecond pulsar PSR
J0621+1002 have been determined through six years of timing observations at
three radio telescopes. The chief result is a measurement of the rate of
periastron advance, omega_dot = 0.0116 +/- 0.0008 deg/yr. Interpreted as a
general relativistic effect, this implies the sum of the pulsar mass, m_1, and
the companion mass, m_2, to be M = m_1 + m_2 = 2.81 +/- 0.30 msun. The
Keplerian parameters rule out certain combinations of m_1 and m_2, as does the
non-detection of Shapiro delay in the pulse arrival times. These constraints,
together with the assumption that the companion is a white dwarf, lead to the
68% confidence maximum likelihood values of m_1 = 1.70(+0.32 -0.29) msun and
m_2 =0.97(+0.27 - 0.15) msun and to the 95% confidence maximum likelihood
values of m_1 = 1.70(+0.59 -0.63) msun and m_2 = 0.97(+0.43 -0.24) msun. The
other major finding is that the pulsar experiences dramatic variability in its
dispersion measure (DM), with gradients as steep as 0.013 pc cm^{-3} / yr. A
structure function analysis of the DM variations uncovers spatial fluctuations
in the interstellar electron density that cannot be fit to a single power law,
unlike the Kolmogorov turbulent spectrum that has been seen in the direction of
other pulsars. Other results from the timing analysis include the first
measurements of the pulsar's proper motion, mu = 3.5 +/- 0.3 mas / yr, and of
its spin-down rate, dP/dt = 4.7 x 10^{-20}, which, when corrected for kinematic
biases and combined with the pulse period, P = 28.8 ms, gives a characteristic
age of 1.1 x 10^{10} yr and a surface magnetic field strength of 1.2 x 10^{9}
G.


title: A primer on the ekpyrotic scenario

abstract:
  This is an introduction to the ekpyrotic scenario, with an emphasis on the
two contexts of brane cosmology and primordial universe scenarios. A
self-contained introduction to brane cosmology and a qualitative overview and
comparison of the inflationary, pre-big bang and ekpyrotic scenarios are given
as background. The ekpyrotic scenario is then presented in more detail,
stressing various problems.


title:
Water Masers as Tracers of Protostellar Disks and Outflows in the
  Intermediate Mass Star Forming Region NGC 2071

abstract:
  We have mapped the water maser emission associated with the infrared centers
IRS1 and IRS3 of the NGC 2071IR star forming region at four epochs over ~4
months with the Very Long Baseline Array (VLBA). We detected 269 maser features
with ~1 km/sec linewidths and measured 30 proper motions. In each infrared
center, the water maser emission appears to trace parts of a protostellar disk
and collimated outflow. The disk components are ~9 and ~17 AU long, in IRS3 and
IRS1 respectively, and ~2 AU wide. They are identified as disks by their
compact size, elongation parallel to the direction of known IR polarization,
central location in the maser maps, small internal proper motions, and
proximity to 1.3 cm continuum emission. The outflows have axes perpendicular to
the disks and exhibit proper motions of up to ~42 km/sec. They are outlined by
maser emission up to ~260 AU from the protostars. The IRS3 outflow appears to
be conical on one side, while the IRS1 outflow comprises a narrowly collimated
bipolar flow surrounded by outward-facing, funnel-shaped cavities. The
detection of water maser emission tracing such compact disk components and
specifically conical or funnel-shaped structures is unusual. The fact that the
distributions are similar in IRS3 and IRS1 may indicate the two infrared
centers are roughly coeval. NGC 2071IR provides a rare opportunity to resolve
the structures and dynamics of disks and outflows together, and to do so for
two protostars that are only ~2000 AU apart (in projection) in a deeply
embedded star forming region of intermediate luminosity.


title:
The Beginning of the End: Hubble Space Telescope Images of Seyfert's
  Sextet

abstract:
  Hubble Space Telescope Wide Field Planetary Camera 2 images of Hickson
Compact Group 79, Seyfert's Sextet, are presented. Both point sources and
extended sources detected on the three WF chips were photometered in four
filters: F336W, F439W, F555W, and F814W. Unlike other HCGs that have been
imaged with HST, there do not appear to be any candidate young star clusters
among the detected point sources. The majority of the point sources that may be
star clusters associated with the Sextet have red colors consistent with
stellar populations older than 1 Gyr. A similar conclusion is drawn with regard
to the extended sources. The majority of these appear to be background
galaxies, but a few candidate dwarf galaxies are identified as potentially
associated with Seyfert's Sextet. However, no blue, star forming objects
similar to the tidal dwarf galaxy candidates identified in other HCGs are found
among the extended objects identified in this study. A redshift for one dwarf
galaxy candidate was measured from a spectrum obtained with the Hobby-Eberly
Telescope, and this object was found to have a redshift similar to NGC6027e,
the discordant spiral formerly identified as a member of this compact group.
The HST observations presented here and previous radio observations of the
neutral gas content of this group suggest that the interactions that have taken
place in the Sextet only redistributed the stars from the member galaxies
within the group. We speculate that future interactions may be strong enough to
strip the gas from NGC6027d and trigger star cluster formation.


title:
The percentage of stellar light re-radiated by dust in late-type Virgo
  Cluster galaxies

abstract:
  We show that the mean percentage of stellar light re-radiated by dust is ~30
percent for the Virgo Cluster late-spirals measured with ISOPHOT by Tuffs et
al. (2002). A strong dependence of this ratio with morphological type was
found, ranging from typical values of ~15 percent for early spirals to up to
~50 percent for some late spirals. The extreme BCDs can have even higher
percentages of their bolometric output re-radiated in the thermal infrared.
Luminosity correction factors for the cold dust component are given for general
use in converting far-infrared (FIR) luminosities derived from IRAS.


title:
Exponential Stellar Disks in Low Surface Brightness Galaxies: A Critical
  Test of Viscous Evolution

abstract:
  Viscous redistribution of mass in Milky Way-type galactic disks is an
appealing way of generating an exponential stellar profile over many scale
lengths, almost independent of initial conditions, requiring only that the
viscous timescale and star formation timescale are approximately equal.
However, galaxies with solid-body rotation curves cannot undergo viscous
evolution. Low surface brightness (LSB) galaxies have exponential surface
brightness profiles, yet have slowly rising, nearly solid-body, rotation
curves. Because of this, viscous evolution may be inefficient in LSB galaxies:
the exponential profiles, instead would give important insight into initial
conditions for galaxy disk formation.
  Using star formation laws from the literature, and tuning the efficiency of
viscous processes to reproduce an exponential stellar profile in Milky Way-type
galaxies, I test the role of viscous evolution in LSB galaxies. Under the
conservative and not unreasonable condition that LSB galaxies are
gravitationally unstable for at least a part of their lives, I find that it is
impossible to rule out a significant role for viscous evolution. This type of
model still offers an attractive way of producing exponential disks, even in
LSB galaxies with slowly-rising rotation curves.


title:
Discovery and quantitative spectral analysis of an Ofpe/WN9 (WN11) star
  in the Sculptor spiral galaxy NGC 300

abstract:
  We have discovered an Ofpe/WN9 (WN11 following Smith et al.) star in the
Sculptor spiral galaxy NGC 300, the first object of this class found outside
the Local Group, during a recent spectroscopic survey of blue supergiant stars
obtained at the ESO VLT. The light curve over a five-month period in late 1999
displays a variability at the 0.1 mag level. The intermediate resolution
spectra (3800-7200 A) show a very close resemblance to the Galactic LBV AG Car
during minimum. We have performed a detailed non-LTE analysis of the stellar
spectrum, and have derived a chemical abundance pattern which includes H, He,
C, N, O, Al, Si and Fe, in addition to the stellar and wind parameters. The
derived stellar properties and the He and N surface enrichments are consistent
with those of other Local Group WN11 stars in the literature, suggesting a
similar quiescent or post-LBV evolutionary status.


title:
Viscous Effects on the Interaction between the Coplanar Decretion Disc
  and the Neutron Star in Be/X-Ray Binaries

abstract:
  We study the viscous effects on the interaction between the coplanar Be-star
disc and the neutron star in Be/X-ray binaries, using a three-dimensional,
smoothed particle hydrodynamics code. For simplicity, we assume the Be disc to
be isothermal at the temperature of half the stellar effective temperature. In
order to mimic the gas ejection process from the Be star, we inject particles
with the Keplerian rotation velocity at a radius just outside the star. Both Be
star and neutron star are treated as point masses. We find that the Be-star
disc is effectively truncated if the Shakura-Sunyaev viscosity parameter
alpha_SS >> 1, which confirms the previous semi-analytical result. In the
truncated disc, the material decreted from the Be star accumulates, so that the
disc becomes denser more rapidly than if around an isolated Be star. The
resonant truncation of the Be disc results in a significant reduction of the
amount of gas captured by the neutron star and a strong dependence of the mass
capture rate on the orbital phase. We also find that an eccentric mode is
excited in the Be disc through direct driving due to a one-armed bar potential
of the binary. The strength of the mode becomes greater in the case of a
smaller viscosity. In a high-resolution simulation with alpha_SS=0.1, the
eccentric mode is found to precess in a prograde sense. The mass capture rate
by the neutron star modulates as the mode precesses.


title:
An X-ray investigation of the NGC346 field in the SMC (1) : the LBV
  HD5980 and the NGC346 cluster

abstract:
  We present results from a Chandra observation of the NGC346 cluster. This
cluster contains numerous massive stars and is responsible for the ionization
of N66, the most luminous HII region and the largest star formation region in
the SMC. In this first paper, we will focus on the characteristics of the main
objects of the field. The NGC346 cluster itself shows only relatively faint
X-ray emission (with L_X^{unabs} ~ 1.5 times 10^{34} erg s^{-1}), tightly
correlated with the core of the cluster. In the field also lies HD5980, a LBV
star in a binary (or possibly a triple system) that is detected for the first
time at X-ray energies. The star is X-ray bright, with an unabsorbed luminosity
of L_X^{unabs} ~ 1.7 times 10^{34} erg s^{-1}, but needs to be monitored
further to investigate its X-ray variability over a complete 19d orbital cycle.
The high X-ray luminosity may be associated either with colliding winds in the
binary system or with the 1994 eruption. HD5980 is surrounded by a region of
diffuse X-ray emission, which is a supernova remnant. While it may be only a
chance alignment with HD5980, such a spatial coincidence may indicate that the
remnant is indeed related to this peculiar massive star.


title:
O and Ne K absorption edge structures and interstellar abundance towards
  Cyg X-2

abstract:
  We have studied the O and Ne absorption features in the X-ray spectrum of Cyg
X-2 observed with the Chandra LETG. The O absorption edge is represented by the
sum of three absorption-edge components within the limit of the energy
resolution and the photon counting statistics. Two of them are due to the
atomic O; their energies correspond to two distinct spin states of
photo-ionized O atoms. The remaining edge component is considered to represent
compound forms of oxide dust grains. Since Cyg X-2 is about 1.4 kpc above the
galactic disk, the H column densities can be determined by radio (21 cm and CO
emission line) and H alpha observations with relatively small uncertainties.
Thus the O abundance relative to H can be determined from the absorption edges.
We found that the dust scattering can affect the apparent depth of the edge of
the compound forms. We determined the amplitude of the effect, which we
consider is the largest possible correction factor. The ratio of column
densities of O in atomic to compound forms and the O total abundance were
respectively determined to be in the range 1.7^{+3.0}_{-0.9} to
2.8^{+5.1}_{-1.5} (ratio), and 0.63 +/- 0.12 solar to 0.74 +/- 0.14 solar
(total), taking into account the uncertainties in the dust-scattering
correction and in the ionized H column density. We also determined the Ne
abundance from the absorption edge to be 0.75 +/- 0.20 solar. These abundance
values are smaller than the widely-used solar values but consistent with the
latest estimates of solar abundance.


title: Model atmosphere analyses of post-common envelope stars

abstract:
  Understanding post-common-envelope evolution is important in the studies of
close-binary systems. The majority of all interacting binaries with a compact
object in their system (e.g. cataclysmic variables, X-ray binaries) are thought
to have passed through a common-envelope (CE) phase. Current models of
interacting binaries all assume, as a starting point, that there is no
significant modification of the secondary star compared with a normal star of
similar spectral type. The extent to which the CE significantly alters the
composition of the secondary star has yet to be determined.
  We are studying the M-type secondary in the pre-CV system EG UMa, in order to
determine its atmospheric parameters by comparison with synthetic spectra
generated using PHOENIX. Absorption lines due to several elements have been
used in investigating the stellar parameters of effective temperature, gravity
and over elemental abundance. In addition, we are searching for anomalies due
to s-process elements (such as Ba, Sr, Rb, Y), which may have been deposited in
the atmosphere during the CE stage, and prove that CE evolution has occurred.
  EG UMa displays strong YO absorption bands, which are normally associated
with giants and S stars. These bands may have been formed as a result of an
Y-abundance enhancement introduced by the CE, which would be consistent with
the observed possible Rb and Sr enrichment.


title: Seismic Inference using Genetic Algorithms

abstract:
  A flood of reliable seismic data will soon arrive. The migration to larger
telescopes on the ground may free up 4-m class instruments for multi-site
campaigns, and several forthcoming satellite missions promise to yield nearly
uninterrupted long-term coverage of many pulsating stars. We will then face the
challenge of determining the fundamental properties of these stars from the
data, by trying to match them with the output of our computer models. The
traditional approach to this task is to make informed guesses for each of the
model parameters, and then adjust them iteratively until an adequate match is
found. The trouble is: how do we know that our solution is unique, or that some
other combination of parameters will not do even better? Computers are now
sufficiently powerful and inexpensive that we can produce large grids of models
and simply compare_all_ of them to the observations. The question then becomes:
what range of parameters do we want to consider, and how many models do we want
to calculate? This can minimize the subjective nature of the process, but it
may not be the most efficient approach and it may give us a false sense of
security that the final result is_correct_, when it is really just_optimal_. I
discuss these issues in the context of recent advances in the
asteroseismological analysis of white dwarf stars.


title:
Hydrodynamical simulations of the decay of high-speed molecular
  turbulence. I. Dense molecular regions

abstract:
  We present the results from three dimensional hydrodynamical simulations of
decaying high-speed turbulence in dense molecular clouds. We compare our
results, which include a detailed cooling function, molecular hydrogen
chemistry and a limited C and O chemistry, to those previously obtained for
decaying isothermal turbulence.
  After an initial phase of shock formation, power-law decay regimes are
uncovered, as in the isothermal case. We find that the turbulence decays faster
than in the isothermal case because the average Mach number remains higher, due
to the radiative cooling. The total thermal energy, initially raised by the
introduction of turbulence, decays only a little slower than the kinetic
energy.
  We discover that molecule reformation, as the fast turbulence decays, is
several times faster than that predicted for a non-turbulent medium. This is
caused by moderate speed shocks which sweep through a large fraction of the
volume, compressing the gas and dust. Through reformation, the molecular
density and molecular column appear as complex patterns of filaments, clumps
and some diffuse structure. In contrast, the molecular fraction has a wider
distribution of highly distorted clumps and copious diffuse structure, so that
density and molecular density are almost identically distributed during the
reformation phase. We conclude that molecules form in swept-up clumps but
effectively mix throughout via subsequent expansions and compressions.


title: NLTE Radiative Transfer and Model Atmospheres of Hot Stars

abstract:
  We describe our method to construct line blanketed NLTE model atmospheres for
hot stars. We employ the Accelerated Lambda Iteration and use statistical
methods to deal with metal line blanketing.


title: Statistical Cosmology with Quadratic Density Fields

abstract:
  Primordial fluctuations in the cosmic density are usually assumed to take the
form of a Gaussian random field that evolves under the action of gravitational
instability. In the early stages, while they have low amplitude, the
fluctuations grow linearly. During this phase the Gaussian character of the
fluctuations is preserved. Later on, when the fluctuations have amplitude of
order the mean density or larger, non-linear effects cause departures from
Gaussianity. In Fourier space, non-linearity is responsible for coupling
Fourier modes and altering the initially random distribution of phases that
characterizes Gaussian initial conditions. In this paper we investigate some of
the effects of quadratic non-linearity on basic statistical properties of
cosmological fluctuations. We demonstrate how this form of non-linearity can
affect asymptotic properties of density fields such as homogeneity, ergodicity,
and behaviour under smoothing. We also show how quadratic density fluctuations
give rise to a particular relationship between the phases of different Fourier
modes which, in turn, leads to the generation of a non-vanishing bispectrum. We
thus elucidate the relationship between higher-order power spectra and phase
distributions.


title: Chandra imaging spectroscopy of 1E 1740.7 - 2942

abstract:
  We have observed the black hole candidate 1E 1740.7 - 2942, the brightest
persistent hard X-ray source within a few degrees of the Galactic centre, for
10 ksec with Chandra (ACIS-I) on August 2000. Attempting to compensate for
pile-up effects we found the spectra were well-fit by an absorbed power law,
with photon indices Gamma = 1.54 ^{+0.42}_{-0.37} (readout streak) and Gamma =
1.42^{+0.14}_{-0.14} (annulus), consistent with a black hole low/hard state. We
have analysed a public observation performed by Chandra which utilised short
frames in order to avoid severe pile-up effects: subtracting the core point
spread function from the whole image, we did not find evidence for any
elongated feature perpendicular to the radio jet axis, as reported in a recent
analysis of the same data. Moreover, comparing the radial profiles with those
of an unscattered X-ray point source, we found indication of an extended,
previously undetected, X-ray scattering halo. The measured halo fractional
intensity at 3 keV is between 30 and 40 percent within 40 arcsec but drops
below detectable levels at 5 keV. Finally, by placing a limit on the X-ray flux
from the radio emitting lobe which has been identified as the hot spot at the
end of the northern jet of 1E 1740.7 - 2942, we are able to constrain the
magnetic energy density in that region.


title: Moriond Conference Summary: The Cosmological Model(s)

abstract:
  The XXXVIIth Rencontres de Moriond on "The Cosmological Model" is briefly
summarized. Almost none of the current observations argues against the popular
Cold Dark Matter + Lambda concordance model. However, it remains to be tested
how astrophysical uncertainties involved in the interpretation of the different
data sets affect the derived cosmological parameters. Independent tests are
still required to establish if the Cold Dark Matter and Dark Energy components
are `real', or just `epicycles' that happen to fit the current data sets well.


title: Abundances of Molecular Species in Barnard 68

abstract:
  Abundances for 5 molecules (C18O, CS, NH3, H2CO, and C3H2) and 1 molecular
ion (N2H+) and upper limits for the abundances of 1 molecule (13CO) and 1
molecular ion (HCO+) are derived for gas within the Bok globule Barnard 68
(B68). The abundances were determined using our own BIMA millimeter
interferometer data and single-dish data gathered from the literature, in
conjunction with a Monte Carlo radiative transfer model. Since B68 is the only
starless core to have its density structure strongly constrained via extinction
mapping, a major uncertainty has been removed from these determinations. All
abundances for B68 are lower than those derived for translucent and cold dense
clouds, but perhaps only significantly for N2H+, NH3, and C3H2. Depletion of CS
toward the extinction peak of B68 is hinted at by the large offset between the
extinction peak and the position of maximum CS line brightness. Abundances
derived here for C18O and N2H+ are consistent with other, recently determined
values at positions observed in common.


title:
Primordial black holes in braneworld cosmologies: Accretion after
  formation

abstract:
  We recently studied the formation and evaporation of primordial black holes
in a simple braneworld cosmology, namely Randall-Sundrum Type II. Here we study
the effect of accretion from the cosmological background onto the black holes
after formation. While it is generally believed that in the standard cosmology
such accretion is of negligible importance, we find that during the high-energy
regime of braneworld cosmology accretion can be the dominant effect and lead to
a mass increase of potentially orders of magnitude. However, unfortunately the
growth is exponentially sensitive to the accretion efficiency, which cannot be
determined accurately. Since accretion becomes unimportant once the high-energy
regime is over, it does not affect any constraints expressed at the time of
black hole evaporation, but it can change the interpretation of those
constraints in terms of early Universe formation rates.


title:
Beyond the Cosmic Veil: Star and Planet Formation Research after SIRTF
  and NGST

abstract:
  How do planets form from circumstellar disks of gas and dust? What physical
processes are responsible for determining the final masses of forming stars and
ultimately the initial mass function (IMF)? The Hubble Space Telescope has made
major contributions in helping to address these fundamental questions. In the
next decade, the Space Infrared Telescope Facility (SIRTF) and the Next
Generation Space Telescope (NGST) will build on this heritage in the near- to
far-infrared. However several crucial questions will remain. We review recent
progress made in star and planet formation with HST, summarize key science
objectives for SIRTF and NGST, and suggest problems that would be uniquely
suited to a large aperture UV/optical space-based telescope. We focus on
studies that take advantage of high spatial resolution and the unique
wavelength range not accessible from the ground such as: 1) circumstellar disk
structure and composition (resolved images of dust and UV spectroscopy of gas);
and 2) extreme populations of young stars in the local group (UV imaging and
spectroscopy of massive star-forming regions). An 8m UV/O space telescope
operating from 1100-6000 Angstroms over fields of view 4-10' and with
spectroscopic capabilities from R = 3,000-10,000 down to < 1000 Angstroms would
be a powerful tool for star and planet formation research.


title:
Monocular Measurement of the Spectrum of UHE Cosmic Rays by the FADC
  Detector of the HiRes Experiment

abstract:
  We have measured the spectrum of UHE cosmic rays using the Flash ADC (FADC)
detector (called HiRes-II) of the High Resolution Fly's Eye experiment running
in monocular mode. We describe in detail the data analysis, development of the
Monte Carlo simulation program, and results. We also describe the results of
the HiRes-I detector. We present our measured spectra and compare them with a
model incorporating galactic and extragalactic cosmic rays. Our combined
spectra provide strong evidence for the existence of the spectral feature known
as the ``ankle.''


title:
The X-Ray Scattering Halo Around Nova Cygni 1992: Testing a Model for
  Interstellar Dust

abstract:
  We use published ROSAT observations of the X-ray Nova V1974 Cygni 1992 to
test a model for interstellar dust, consisting of a mixture of carbonaceous
grains and silicate grains. The time-dependent X-ray emission from the nova is
modelled, and X-ray scattering is calculated for a dust mixture with a
realistic size distribution. Model results are compared with the scattered
X-ray halos measured by ROSAT at 9 epochs. The observed X-ray halos are
consistent with the halos calculated for the size distribution of Weingartner &
Draine which reproduces the Milky Way extinction with R_V=3.1, provided that
the reddening E(B-V) approx 0.20, consistent with E(B-V) = 0.19 inferred from
the late-time Balmer decrement. The time delay of the scattered halo relative
to the direct flux from the nova is clearly detected.
  Models with smoothly-distributed dust give good overall agreement with the
observed scattering halo, but tend to produce somewhat more scattering than
observed at 200-300", and insufficient scattering at 50-100". While an
additional population of large grains can increase the scattered intensity at
50-100", this could also be achieved by having ~30% of the dust in a cloud at a
distance from us equal to ~95% of the distance to the nova. Such a model also
improves agreement with the data at larger angles, and illustrates the
sensitivity of X-ray scattering halos to the location of the dust. The
observations therefore do not require a population of micron-sized dust grains.


title:
A Model of Short Gamma-Ray Bursts: Heated Neutron Stars in Close Binary
  Systems

abstract:
  In this paper we present a model for the short (< 1 second) population of
gamma-ray bursts. In this model heated neutron stars in a close binary system
near its last stable orbit emit a large amount of neutrinos (~10^53 ergs). A
fraction of these neutrinos will annihilate to form an e+e- pair plasma wind
which will, in turn, expand and recombine to photons which make the gamma-ray
burst. We study neutrino annihilation and show that a substantial fraction
(~1/2) of energy deposited into e+e- pairs comes from inter-star neutrinos,
where each member of the neutrino pair originates from each neutron star. Thus,
in addition to the annihilation of neutrinos blowing off of a single star,
there is a new source of baryon-free plasma that is deposited between the
stars. To model the e+e- pair plasma wind between stars, we do
three-dimensional relativistic numerical hydrodynamic calculations. We find
that the time scale for these bursts, deriving from the baryon-free plasma, is
less than one second and they will have a hot spectrum ~5 MeV. The energy in
bursts is the order of 10^52 ergs.


title:
On the Theory of Gamma Ray Bursts and Hypernovae: The Black Hole Soft
  X-ray Transient Sources

abstract:
  We show that a common evolutionary history can produce the black hole
binaries in the Galaxy in which the black holes have masses of ~ 5-10 M_sun. In
with low-mass, <~ 2.5 M_sun, ZAMS (zero age main sequence) companions, the
latter remain in main sequence during the active stage of soft X-ray transients
(SXTs), most of them being of K or M classification. In two intermediate cases,
IL Lupi and Nova Scorpii with ZAMS ~ 2.5 M_sun companions the orbits are
greatly widened because of large mass loss in the explosion forming the black
hole, and whereas these companions are in late main sequence evolution, they
are close to evolving. Binaries with companion ZAMS masses >~ 3 M_sun are
initially "silent" until the companion begins evolving across the Herzsprung
gap. We provide evidence that the narrower, shorter period binaries, with
companions now in main sequence, are fossil remnants of gamma ray bursters
(GRBs). We also show that the GRB is generally accompanied by a hypernova
explosion (a very energetic supernova explosion). We further show that the
binaries with evolved companions are good models for some of the ultraluminous
X-ray sources (ULXs) recently seen by Chandra in other galaxies. The great
regularity in our evolutionary history, especially the fact that most of the
companions of ZAMS mass <~ 2.5 M_sun remain in main sequences as K or M stars
can be explained by the mass loss in common envelope evolution to be Case C;
i.g., to occur only after core He burning has finished. Since our argument for
Case C mass transfer is not generally understood in the community, we add an
appendix, showing that with certain assumptions which we outline we can
reproduce the regularities in the evolution of black hole binaries by Case C
mass transfer.


title:
Survey for Transiting Extrasolar Planets in Stellar Systems (STEPSS):
  The Frequency of Planets in NGC 1245

abstract:
  We present first results from the Survey for Transiting Extrasolar Planets in
Stellar Systems (STEPSS). Our goal is to assess the frequency of close-in
extrasolar planets around main-sequence stars in several open clusters. By
concentrating on main-sequence stars in clusters of known (and varied) age,
metallicity, and stellar density, we will gain insight into how these various
properties affect planet formation, migration, and survival. We show
preliminary results from our 19 night photometric campaign of the old, solar
metallicity cluster NGC 1245. Taking into account the photometric precision,
observational window function, transit probability, and total number of stars
monitored, we estimate that we should be able to probe planetary companion
fractions of <1% for separations of a<0.03 AU. If 1% of the stars in the
cluster have Jupiter-sized companions evenly distributed in log(a) between 0.03
and 0.3 AU, we expect to find ~2 transits. A preliminary search of our light
curve data has revealed a transit with a depth ~4%. Based on its shape, it is
likely to be a grazing binary eclipse rather than a planetary transit,
emphasizing the need for high temporal resolution in transit surveys.


title: Alternatives to Hibernation

abstract:
  I outline the evidence pertinent to the connection between the nova explosion
and mass transfer rates in CVs. I conclude that there is still insufficient
evidence to decide whether or not such a connection exists.


title:
Interstellar Scintillation of the Polarized Flux Density in Quasar, PKS
  0405-385

abstract:
  The remarkable rapid variations in radio flux density and polarization of the
quasar PKS 0405-385 observed in 1996 are subject to a correlation analysis,
from which characteristic time scales and amplitudes are derived. The
variations are interpreted as interstellar scintillations. The cm wavelength
observations are in the weak scintillation regime for which models for the
various auto- and cross-correlations of the Stokes parameters are derived and
fitted to the observations. These are well modelled by interstellar
scintillation (ISS) of a 30 by 22 micro-as source, with about 180 degree
rotation of the polarization angle along its long dimension. This success in
explaining the remarkable intra-day variations (IDV)in polarization confirms
that ISS gives rise to the IDV in this quasar. However, the fit requires the
scintillations to be occurring much closer to the Earth than expected according
to the standard model for the ionized interstellar medium (IISM). Scattering at
distances in the range 3-30 parsec are required to explain the observations.
The associated source model has a peak brightness temperature near 2.0
10^{13}K, which is about twenty-five times smaller than previously derived for
this source. This reduces the implied Doppler factor in the relativistic jet,
presumed responsible to 10-20, high but just compatible with cm wavelength VLBI
estimates for the Doppler factors in Active Galactic Nuclei (AGNs).


title:
Effect of Internal Flows on Sunyaev-Zeldovich Measurements of Cluster
  Peculiar Velocities

abstract:
  Galaxy clusters are potentially powerful probes of the large-scale velocity
field in the Universe because their peculiar velocity can be estimated directly
via the kinematic Sunyaev-Zeldovich effect (kSZ). Using high-resolution
cosmological simulations of an evolving cluster of galaxies, we evaluate how
well the average velocity obtained via a kSZ measurement reflects the actual
cluster peculiar velocity. We find that the internal velocities in the
intracluster gas are comparable to the overall cluster peculiar velocity, 20 to
30% of the sound speed even when a cluster is relatively relaxed. Nevertheless,
the velocity averaged over the kSZ map inside a circular aperture matched to
the cluster virial region provides an unbiased estimate of a cluster's radial
peculiar velocity with a dispersion of 50 to 100 km/s, depending on the line of
sight and dynamical state of the cluster. This dispersion puts a lower limit on
the accuracy with which cluster peculiar velocity can be measured. Although the
dispersion of the average is relatively small, the velocity distribution is
broad; regions of low signal must be treated with care to avoid bias. We
discuss the extent to which systematic errors might be modelled, and the
resulting limitations on using galaxy clusters as cosmological velocity
tracers.


title: The Gaiasphere and the limits of knowledge

abstract:
  At the heart of a successful theory of galaxy formation must be a detailed
physical understanding of the dissipational processes which form spiral
galaxies. To what extent can we unravel the events that produced the Galaxy as
we see it today? Could some of the residual inhomogeneities from prehistory
have escaped the dissipative process at an early stage? To make a comprehensive
inventory of surviving inhomogeneities would require a vast catalog of stellar
properties that is presently out of reach. The Gaia space astrometry mission,
set to launch at the end of the decade, will acquire detailed phase space
coordinates for about one billion stars, within a sphere of diameter 20 kpc --
the Gaiasphere. Here we look forward to a time when all stars within the
Gaiasphere have complete chemical abundance measurements (including alpha, s
and r process elements). Even with such a vast increase in information, there
may exist fundamental -- but unproven -- limits to unravelling the observed
complexity.


title: The Search for Brown Dwarfs around White Dwarfs

abstract:
  The infrared search for substellar companions to nearby white dwarfs has been
going for a little more than a decade. The most recent phase has been a wide
field proper motion search carried out primarily at Steward Observatory, where
we are complete down to J=18. Earlier phases included near field searches at
the IRTF and Keck Observatory. In the last year we have discovered ten
previously unrecognized faint proper motion companions. Of the recent
discoveries, most are white dwarfs and a few M dwarfs. GD165B, discovered in
1988 as part of our program, is still the only known companion to a white dwarf
with spectral type later than M.


title:
Log-Normal Distributions in Cygnus X-1: Possible Physical Link with
  Gamma-Ray Bursts and Blazars

abstract:
  Prompted by recent discoveries of log-normal distributions in gamma-ray/X-ray
temporal variabilities of gamma-ray bursts (GRBs) and blazars, we re-examine
the X-ray variability of Cygnus X-1 in the hard/low state using Ginga data in
1990. It was previously reported that the distributions of the time intervals
between X-ray shots (flares) deviated from the Poisson distributions at short
time intervals: the occurrence of shots tended to be suppressed for several
seconds before and/or after a shot event. Detailed analyses show that this
deviation is larger for shots with larger peaks, and that the time-interval
distributions for large shots approach log-normal distributions with a peak at
the interval of 7--8 s. Furthermore, we also show that the peak-intensity
distribution for the shots is consistent with the log-normal distribution,
though no typical peak intensity can be seen. This might indicate the presence
of a physical link connecting the physics of black hole accretion flow and that
of jet/GRB formation.


title: The influence of Hall drift on the magnetic fields of neutron stars

abstract:
  We consider the evolution of magnetic fields under the influence of Hall
drift and Ohmic decay. The governing equation is solved numerically, in a
spherical shell with r_i/r_o = 0.75. Starting with simple free decay modes as
initial conditions, we then consider the subsequent evolution. The Hall effect
induces so-called helicoidal oscillations, in which energy is redistributed
among the different modes. We find that the amplitude of these oscillations can
be quite substantial, with some of the higher harmonics becoming comparable to
the original field. Nevertheless, this transfer of energy to the higher
harmonics is not sufficient to significantly accelerate the decay of the
original field, at least not at the R_B = O(100) parameter values accessible to
us, where this Hall parameter R_B measures the ratio of the Ohmic timescale to
the Hall timescale. We do find clear evidence though of increasingly fine
structures developing for increasingly large R_B, suggesting that perhaps this
Hall-induced cascade to ever shorter lengthscales is eventually sufficiently
vigorous to enhance the decay of the original field. Finally, the implications
for the evolution of neutron star magnetic fields are discussed.


title:
Optical Recombination Lines of Heavy-elements in Giant Extragalactic HII
  Regions

abstract:
  We present high resolution observations of the giant extragalactic H II
regions NGC 604, NGC 2363, NGC 5461 and NGC 5471, based on observations taken
with the ISIS spectrograph on the William Herschel Telescope. We have detected
-by the first time- C II and O II recombination lines in these objects. We find
that recombination lines give larger C^{++} and O^{++} abundances than
collisionallly excited lines, suggesting that temperature variations can be
present in the objects. We detect [Fe IV] lines in NGC 2363 and NGC 5471, the
most confident detection of optical lines of this kind in H II regions.
Considering the temperature structure we derive their H, He, C, N, O, Ne, S,
Ar, and Fe abundances. From the recombination lines of NGC 5461 and NGC 5471 we
determine the presence of C/H and O/H gradients in M101. We calculate the Delta
Y/Delta O and Delta Y/Delta Z values considering the presence of temperature
variations and under the assumption of constant temperature. We obtain a better
agreement with models of galactic chemical evolution by considering the
presence of temperature variations than by assuming that the temperature is
constant in these nebulae.


title:
Enhancement of the helium resonance lines in the solar atmosphere by
  suprathermal electron excitation I: non-thermal transport of helium ions

abstract:
  Models of the solar transition region made from lines other than those of
helium cannot account for the strength of the helium lines. However, the
collisional excitation rates of the helium resonance lines are unusually
sensitive to the energy of the exciting electrons. Non-thermal motions in the
transition region could drive slowly-ionizing helium ions rapidly through the
steep temperature gradient, exposing them to excitation by electrons
characteristic of higher temperatures than those describing their ionization
state. We present the results of calculations which use a more physical
representation of the lifetimes of the ground states of He I and He II than was
adopted in earlier work on this process. New emission measure distributions are
used to calculate the temperature variation with height. The results show that
non-thermal motions can lead to enhancements of the He I and He II resonance
line intensities by factors that are comparable with those required. Excitation
by non-Maxwellian electron distributions would reduce the effects of
non-thermal transport. The effects of non-thermal motions are more consistent
with the observed spatial distribution of helium emission than are those of
excitation by non-Maxwellian electron distributions alone. In particular, they
account better for the observed line intensity ratio I(537.0 A)/I(584.3 A), and
its variation with location.


title:
Stellar Structure Modeling using a Parallel Genetic Algorithm for
  Objective Global Optimization

abstract:
  Genetic algorithms are a class of heuristic search techniques that apply
basic evolutionary operators in a computational setting. We have designed a
fully parallel and distributed hardware/software implementation of the
generalized optimization subroutine PIKAIA, which utilizes a genetic algorithm
to provide an objective determination of the globally optimal parameters for a
given model against an observational data set. We have used this modeling tool
in the context of white dwarf asteroseismology, i.e., the art and science of
extracting physical and structural information about these stars from
observations of their oscillation frequencies. The efficient, parallel
exploration of parameter-space made possible by genetic-algorithm-based
numerical optimization led us to a number of interesting physical results: (1)
resolution of a hitherto puzzling discrepancy between stellar evolution models
and prior asteroseismic inferences of the surface helium layer mass for a DBV
white dwarf; (2) precise determination of the central oxygen mass fraction in a
white dwarf star; and (3) a preliminary estimate of the astrophysically
important but experimentally uncertain rate for the ^12C(alpha,gamma)^16O
nuclear reaction. These successes suggest that a broad class of
computationally-intensive modeling applications could also benefit from this
approach.


title: UBVRI photometric sequences for symbiotic stars

abstract:
  Deep, wide-range and accurate UBVRI photometric sequences have been
established around more than 80 symbiotic stars, to assist current photometry
as well as measurement of old photographic plates. Sequences for 40 symbiotic
stars have already been published; the observations for the others have already
been secured.


title: Astrometry of circumstellar masers

abstract:
  The circumstellar masers around evolved stars offer an interesting
possibility to measure stellar parameters through VLBI astrometry. In this
paper the application of this technique is discussed, including the accuracy
and the uncertainties of the method. The different maser species (OH, H_2O,
SiO) have slightly different characteristics and applications. This paper does
not concern astrometry of maser spots to study the kinematics of the envelope,
but concentrates on attempting to measure the motion of the underlying star.


title:
High resolution spectral survey of symbiotic stars in the near-IR over
  the GAIA wavelength range

abstract:
  High resolution (R~20,000), high signal-to-noise (S/N~100) spectra were
collected for ~40 symbiotic stars with the Asiago echelle spectrograph over the
same 8480-8740 Ang wavelength range covered by the ESA Cornerstone mission
GAIA, centered on the near-IR CaII triplet and the head of the Paschen series.
A large number (~140) of cool MKK giant and supergiant templates were observed
with the same instrumentation to serve as a reference and classification grid.
The spectra offer bright prospects in classifying and addressing the nature of
the cool component of symbiotic stars (deriving T(eff), log g, [Fe/H],
[alpha/Fe], V(rot)sin i both via MDM-like methods and syntetic atmosphere
modeling) and mapping the physical condition and kinematics of the gas regions
responsible for the emission lines.


title:
Criteria for spectral classification of cool stars in the near-IR GAIA
  wavelength region

abstract:
  The far-red portion of the spectrum offers bright prospects for an accurate
classification of cool stars, like the giant components of symbiotic stars. The
8480--8740 Ang region, free from telluric absorptions and where the GAIA
Cornerstone mission by ESA will record spectra for 3x10^8 stars, is
investigated on the base of available observed and synthetic spectral atlases.
We have identified and calibrated diagnostic line ratios useful to derive the
effective temperature (spectral type) and gravity (luminosity class) for cool
stars observed at spectral resolutions 10,000 <= lambda/delta-lambda <= 20,000,
bracketing that eventually chosen for GAIA. A few are presented here.


title:
Evidence that an Intrinsic Redshift Component that is a Harmonic of z =
  0.062 May be Present in Every Quasar Redshift

abstract:
  After estimating and removing all ejection-related Doppler components from
the redshifts of the QSOs near NGC 1068, the remaining redshift is assumed to
be intrinsic. This well-studied case is the first example in which it has
finally been possible to separate the intrinsic redshift component from the
cosmological and other Doppler components. It is shown that this leads to
intrinsic redshift components that occur at exact multiples of z = 0.062 and
are defined by the relation zi = 0.062[10N - M] where N and M can have only
certain discrete values. It is also shown that the intrinsic redshifts given by
this relation and others obtained for different N and M-values, agree closely
with the redshifts found to be preferred in analyses of quasar emission-line
redshifts. It is now apparent that the peaks in the distribution of quasar
emission line redshifts also occur at pure harmonics of z = 0.062. Although
these peaks have previously been fitted by a log(1+z) relation, the above
explanation now seems more appropriate. These results indicate that the
Delta(z) = 0.062 redshift interval, long known to be present in QSO
emission-line redshifts below z = 0.6, is also present in an intrinsic
component of QSO redshifts up to z ~ 2. This appears to imply that the Delta(z)
= 0.062 redshift interval represents a fundamental redshift spacing that arises
from the very nature of the intrinsic redshifts.


title: Mass Function of the Arches Cluster from Gemini Adaptive Optics Data

abstract:
  We have analysed high resolution adaptive optics (AO) science demonstration
data of the young, massive stellar cluster Arches near the Galactic Center,
obtained with the Gemini North telescope in combination with the University of
Hawai'i AO system Hokupa'a. The AO H and K' photometry is calibrated using
HST/NICMOS observations in the equivalent filters F160W and F205W obtained by
Figer et al. (1999). ... After a thorough technical comparison, the Gemini and
HST data are used in combination to study the spatial distribution of stellar
masses in the Arches cluster. ... A strong colour gradient is observed over the
cluster field. The visual extinction increases by Delta A_V ~ 10 mag over a
distance of 15 arcsec from the cluster core. Extinction maps reveal a
low-extinction cavity in the densest parts of Arches (R < 5 arcsec), indicating
the depletion of dust due to stellar winds or photo-evaporation. We correct for
the change in extinction over the field and show that the slope of the mass
function is strongly influenced by the effects of differential extinction. We
obtain present-day mass function slopes of Gamma=-0.8 +- 0.2 in the mass range
6 < M < 65 Msun from both data sets. The spatial analysis reveals a steepening
of the mass function slope from close to zero in the cluster center to about
-1.7 +- 0.7 at R > 10 arcsec, in accordance with a Salpeter slope, Gamma=-1.35.
The bias in the mass function towards high-mass stars in the Arches center is a
strong indication for mass segregation. The dynamical and relaxation timescales
for Arches are estimated, and possible mass segregation effects are discussed
with respect to cluster formation models.


title: A dynamical study of the circumstellar gas in UX Orionis

abstract:
  We present the results of a high spectral resolution study of the
circumstellar (CS) gas around the intermediate mass, pre-main sequence star UX
Ori. The results are based on a set of 10 echelle spectra, monitoring the star
on time scales of months, days and hours. A large number of transient
blueshifted and redshifted absorption features are detected in the Balmer and
in many metallic lines. A multigaussian fit is applied to determine for each
transient absorption the velocity, v, dispersion velocity, Delta v, and the
parameter R, which provides a measure of the absorption strength of the CS gas.
The time evolution of those parameters is presented and discussed. A comparison
of intensity ratios among the transient absorptions suggests a solar-like
composition of the CS gas. This confirms previous results and excludes a very
metal-rich environment as the cause of the transient features in UX Ori. The
features can be grouped by their similar velocities into 24 groups, of which 17
are redshifted and 7 blueshifted. An analysis of the velocity of the groups
allows us to identify them as signatures of the dynamical evolution of 7 clumps
of gas, of which 4 represent accretion events and 3 outflow events. Most of the
events decelerate at a rate of tenths of ms-2, while 2 events accelerate at
approximately the same rate; one event is seen experiencing both an
acceleration and a deceleration phase and lasts for a period of few days. This
time scale seems to be the typical duration of outflowing and infalling events
in UX Ori. The dispersion velocity and the relative aborption strength of the
features do not show drastic changes during the lifetime of the events, which
suggests they are gaseous blobs preserving their geometrical and physical
identity.


title:
The Dynamical Evolution of the Circumstellar Gas around Low- and
  Intermediate-Mass stars.II. The Planetary Nebula formation

abstract:
  We have studied the effect of the mass of the central star (CS) on the gas
evolution during the planetary nebula (PN) phase. We have performed numerical
simulations of PN formation using CS tracks for six stellar core masses
corresponding to initial masses from 1 to 5 Msun. The gas structure resulting
from the previous asymptotic giant branch (AGB) evolution is used as the
starting configuration. The formation of multiple shells is discussed in the
light of our models, and the density, velocity and halpha emission brightness
profiles are shown for each stellar mass considered. We have computed the
evolution of the different shells in terms of radius, expansion velocity, and
halpha peak emissivity. We find that the evolution of the main shell is
controlled by the ionization front rather than by the thermal pressure provided
by the hot bubble during the early PN stages. This effect explains why the
kinematical ages overestimate the age in young CSs. At later stages in the
evolution and for low mass progenitors the kinematical ages severely
underestimate the CS age. Large (up to 2.3 pc), low surface brightness shells
(less than 2000 times the brightness of the main shell) are formed in all of
our models (with the exception of the 5 Msun model). These PN halos contain
most of the ionized mass in PNe, which we find is greatly underestimated by the
observations because of the low surface brightness of the halos.


title:
The Molecular Counterpart of the Galactic Center Arched Filament HII
  Complex: OVRO Observations of the CS(2-1) Line

abstract:
  The Owens Valley Radio Observatory (OVRO) millimeter array was used to make
observations of the CS(2-1) line (at 97.981 GHz) arising from the G0.07+0.04
region of the ``-30 km/s'' molecular cloud near the Galactic center with a
spatial resolution of ~8". The ionized edges of this cloud forms the Arched
Filament HII regions which are ionized by the adjacent Arches stellar cluster.
The OVRO data were combined with single-dish data obtained at the 30-m IRAM
telescope by Serabyn & Guesten (1987). A comparison of this CS(2-1) data and
the H92alpha recombination line data of Lang, Goss & Morris (2001) reveals that
the ionized and molecular gas are physically related, but that their velocities
in this region differ by up to 35 km/s. This difference in velocity can be
understood if the gas that gave rise to the G0.07+0.04 HII region has been
fully ionized. An overall comparison of the molecular and ionized gas across
the entire -30 km/s cloud based on the single dish CS(2-1) data and the
H92alpha line data illustrates that such differences in velocity between the
ionized and molecular gas are common and that the geometrical arrangement of
these components is complicated. Much of the ionized gas resides on the near
side (to the observer) of the molecular cloud; however, in several regions,
some molecular material must lie in front of the HII region. The Arches stellar
cluster therefore appears to be located in the midst of the molecular clouds
such that some of the near-side cloud surfaces along our line of sight have not
been exposed to the ionizing radiation.


title:
Weak Lensing of the CMB: Cumulants of the Probability Distribution
  Function

abstract:
  We discuss the real-space moments of temperature anisotropies in the cosmic
microwave background (CMB) due to weak gravitational lensing by intervening
large-scale structure. We show that if the probability distribution function of
primordial temperature anisotropies is Gaussian, then it remains unchanged
after gravitational lensing. With finite resolution, however, non-zero
higher-order cumulants are generated both by lensing autocorrelations and by
cross-correlations between the lensing potential and secondary anisotropies in
the CMB such as the Sunayev-Zel'dovich (SZ) effect. Skewness is produced by
these lensing-SZ correlations, while kurtosis receives contributions from both
lensing alone and lensing-SZ correlations. We show that if the projected
lensing potential is Gaussian, all cumulants of higher-order than the kurtosis
vanish. While recent results raise the possibility of detection of the skewness
in upcoming data, the kurtosis will likely remain undetected.


title: Expected Performance of CryoArray

abstract:
  WIMP-nucleon cross sections below 10^(-9) pb may be probed by ton-scale
experiments with low thresholds and background rates ~20 events per year. An
array of cryogenic detectors ("CryoArray") could perform well enough to reach
this goal. Sufficient discrimination and background suppression of photons has
already been demonstrated. Reduction of neutron backgrounds may be achieved by
siting the experiment deep enough. Removal of the surface-electron backgrounds
alone has not yet been demonstrated, but the reductions required even for this
troublesome background are quite modest and appear achieveable.


title: N-Body Simulations of Small Galaxy Groups

abstract:
  A series of N-body simulations aimed to study the dynamics of small groups of
galaxies are presented. The properties of small galaxy groups are very well
reproduced, and those of Hickson's compact groups are well reproduced by the
most advanced stage of collapsing groups. We find no overmerging problem in our
simulations. An important fraction of groups (~40%) initially in virial
equilibrium can last for ~10 Gyr without complete merging. These results
provide an alternative solution to the overmerging expected in Hicksons's
compact groups.


title: High Dynamic Range and the Search for Planets

abstract:
  General arguments for optimized coronagraphy in the search for planets are
presented. First, off-axis telescopes provide the best telescopic platforms for
use with coronagraphy, and telescope fabrication technology now allows the
fabrication of such telescopes with diameters of up to 6.5 m. We show that in
certain circumstances a smaller telescope with an off-axis primary has a
signal-to-noise advantage compared with larger Cassegrain telescopes. Second,
to fully exploit the advantages of the coronagraph for suppressing stray light,
it is necessary to use a high Strehl ratio adaptive optics system. This can be
best achieved initially with modest aperture telescopes of 3--4 m in diameter.
Third, application of simultaneous differential imaging and simultaneous
polarimetric techniques are required to reach the photon-limit of coronagraphic
imaging. These three developments, if pursued together, will yield significant
improvements in the search for planets.


title: Modeling the Radio to X-ray SED of Galaxies

abstract:
  Our multi-wavelength model GRASIL for the SED of galaxies is described, in
particular the recent extension to the radio and X-ray range. With our model we
can study different aspects of galaxy evolution by exploiting all available
spectral observations, where different emission components dominate.


title: Joint Formation of QSOs and Spheroids

abstract:
  In view of the extensive evidence of tight inter-relationships between
spheroidal galaxies (and galactic bulges) with massive black holes hosted at
their centers, a consistent model must deal jointly with the evolution of the
two components. We describe one such model, which successfully accounts for the
local luminosity function of spheroidal galaxies, for their photometric and
chemical properties, for deep galaxy counts in different wavebands, including
those in the (sub)-mm region which proved to be critical for current
semi-analytic models stemming from the standard hierarchical clustering
picture, for clustering properties of SCUBA galaxies, of EROs, and of LBGs, as
well as for the local mass function of massive black holes and for quasar
evolution. Predictions that can be tested by surveys carried out by SIRTF are
presented.


title: NGC 3576 IRS 1 in the Mid Infrared

abstract:
  We present the results of high-resolution mid-infrared observations of the
source NGC 3576 IRS 1. Near diffraction-limited images were taken at the Gemini
South Observatory through OSCIR's filters N, 7.9, 9.8, 12.5 and IHW18. The
source IRS 1 was resolved into 3 sources for the first time at mid-infrared
wavelengths. For each source we constructed the SED from 1.25 to 18 microns, as
well the color temperature and the spatial distribution of the dust in the
region. The optical depth of the silicate absorption feature at 9.8 microns is
presented also.


title: Phase diagram for rotating compact stars with two high density phases

abstract:
  For the classification of rotating compact stars with two high density phases
a phase diagram in the angular velocity (Omega) - baryon number (N) plane is
investigated. The dividing line N_crit(Omega) between configurations with one
and two phases is correlated to a local maximum of the moment of inertia and
can thus be subject to experimental verification by observation of the
rotational behavior of accreting compact stars. Another characteristic line,
which also can be measured is the transition line to black holes that of the
maximum mass configurations. The positions and the shape of these lines are
sensitive to changes in the equation of state (EoS) of stellar matter. A
comparison of the regional structure of phase diagrams is performed for
polytropic and relativistic mean field type EoS and correlations between the
topology of the transition lines and the properties of two-phase EoS are
obtained. Different scenarios of compact star evolution are discussed as
trajectories in the phase diagram. It is shown that a population gap in the
Omega - N plane for accreting compact stars would signal a high density phase
transition and could be observed in the distribution of so called Z sources of
quasi periodic oscillations in low-mass X-ray binaries.


title: How Black Are Black Hole Candidates?

abstract:
  In previous work we found that many of the spectral properties of x-ray
binaries, including both galactic black hole candiates (GBHC) and neutron
stars, were consistent with the existence of intrinsically magnetized central
objects. Here we review and extend the observational evidence for the existence
of intrinsically magnetized GBHC and show that their existence is consistent
with a new class of solutions of the Einstein field equations of General
Relativity. These solutions are based on a strict adherence to the Principle of
Equivalence, which prevents the time-like geodesics of physical matter from
becoming null on trapped surfaces of infinite red shift. The new solutions
emerge from the fact that the structure and radiation transfer properties of
the energy-momentum tensor on the right hand side of the Einstein field
equations must have a form that is consistent with this Principle of
Equivalence requirement. In this context, we show that the Einstein field
equations allow the existence of highly red shifted, magnetospheric, eternally
collapsing objects (MECO) which do not have trapped surfaces which lead to
event horizons. Since MECO lifetimes are many orders of magnitude greater than
a Hubble time, they provide an elegant and unified framework for understanding
the broad range of observations associated with GBHC and active galactic
nuclei.