237 research outputs found
The Stanley Foundation Bipolar Network: Results of the naturalistic follow-up study after 2.5 years of follow-up in the German centres
The Stanley Foundation Bipolar Network (SFBN) is an international, multisite network investigating the characteristics and course of bipolar disorder. Methods (history, ratings and longitudinal follow-up) are standardized and equally applied in all 7 centres. This article describes demographics and illness characteristics of the first 152 German patients enrolled in them SFBN as well as the results of 2.5 years of follow-up. Patients in Germany were usually enrolled after hospitalisation. More than 72% of the study population suffered from bipolar I disorder and 25% from bipolar 11 disorder. The mean +/- SD age of the study participants was 42.08 +/- 13.5 years, and the mean SD age of onset 24.44 +/- 10.9 years. More than 40% of the sample reported a rapid-cycling course in history, and even more a cycle acceleration overtime. 37% attempted suicide at least once. 36% had an additional Axis I disorder, with alcohol abuse being the most common one, followed by anxiety disorders. During the follow-up period, only 27% remained stable, 56% had a recurrence, 12.8% perceived subsyndromal symptoms despite treatment and regular visits. 27% suffered from a rapid-cycling course during the follow-up period. Recurrences were significantly associated with bipolar I disorder, an additional comorbid Axis I disorder, rapid cycling in history, a higher number of mood stabilizers and the long-term use of typical antipsychotics. Rapid cycling during follow-up was only associated with a rapidcycling course in history, a higher number of mood stabilizers and at least one suicide attempt in history. Copyright (c) 2003 S. Karger AG, Basel
KMOS LENsing Survey (KLENS) : morpho-kinematic analysis of star-forming galaxies at
We present results from the KMOS lensing survey-KLENS which is exploiting
gravitational lensing to study the kinematics of 24 star forming galaxies at
with a median mass of and median
star formation rate (SFR) of . We find that 25% of
these low-mass/low-SFR galaxies are rotation dominated, while the majority of
our sample shows no velocity gradient. When combining our data with other
surveys, we find that the fraction of rotation dominated galaxies increases
with the stellar mass, and decreases for galaxies with a positive offset from
the main sequence. We also investigate the evolution of the intrinsic velocity
dispersion, , as a function of the redshift, , and stellar mass,
, assuming galaxies in quasi-equilibrium (Toomre Q parameter equal
to 1). From the relation, we find that the redshift evolution of
the velocity dispersion is mostly expected for massive galaxies (). We derive a relation, using
the Tully-Fisher relation, which highlights that a different evolution of the
velocity dispersion is expected depending on the stellar mass, with lower
velocity dispersions for lower masses, and an increase for higher masses,
stronger at higher redshift. The observed velocity dispersions from this work
and from comparison samples spanning appear to follow this relation,
except at higher redshift (), where we observe higher velocity dispersions
for low masses () and lower velocity
dispersions for high masses () than
expected. This discrepancy could, for instance, suggest that galaxies at
high- do not satisfy the stability criterion, or that the adopted
parametrisation of the specific star formation rate and molecular properties
fail at high redshift.Comment: Accepted for publication in A&A, 21 pages, 10 figure
The formation of the first galaxies and the transition to low-mass star formation
The formation of the first galaxies at redshifts z ~ 10-15 signaled the
transition from the simple initial state of the universe to one of ever
increasing complexity. We here review recent progress in understanding their
assembly process with numerical simulations, starting with cosmological initial
conditions and modelling the detailed physics of star formation. In this
context we emphasize the importance and influence of selecting appropriate
initial conditions for the star formation process. We revisit the notion of a
critical metallicity resulting in the transition from primordial to present-day
initial mass functions and highlight its dependence on additional cooling
mechanisms and the exact initial conditions. We also review recent work on the
ability of dust cooling to provide the transition to present-day low-mass star
formation. In particular, we highlight the extreme conditions under which this
transition mechanism occurs, with violent fragmentation in dense gas resulting
in tightly packed clusters.Comment: 16 pages, 7 figures, appeared in the conference proceedings for IAU
Symposium 255: Low-Metallicity Star Formation: From the First Stars to Dwarf
Galaxies, a high resolution version (highly recommended) can be found at
http://www.ita.uni-heidelberg.de/~tgreif/files/greif08.pd
High-Resolution Imaging of Molecular Gas and Dust in the Antennae (NGC 4038/39): Super Giant Molecular Complexes
We present new aperture synthesis CO maps of the Antennae (NGC 4038/39)
obtained with the Caltech Millimeter Array. These sensitive images show
molecular emission associated with the two nuclei and a partial ring of star
formation to the west of NGC 4038, as well as revealing the large extent of the
extra-nuclear region of star formation (the ``overlap region''), which
dominates the CO emission from this system. The largest molecular complexes
have masses of 3-6x10^8 M_sun, typically an order of magnitude larger than the
largest structures seen to date in more quiescent galaxy disks. The extremely
red luminous star clusters identified previously with HST are well-correlated
with the CO emission, which supports the conclusion that they are highly
embedded young objects rather than old globular clusters. There is an excellent
correlation between the CO emission and the 15 micron emission seen with ISO,
particularly for the brightest regions. The most massive complexes in the
overlap region have similar [NeIII]/[NeII] ratios, which implies that all these
regions are forming many massive stars. However, only the brightest
mid-infrared peak shows strong, rising continuum emission longward of 10
microns, indicative of very small dust grains heated to high temperatures by
their proximity to nearby luminous stars. Since these grains are expected to be
removed rapidly from the immediate environment of the massive stars, it is
possible that this region contains very young (< 1 Myr) sites of star
formation. Alternatively, fresh dust grains could be driven into the sphere of
influence of the massive stars, perhaps by the bulk motions of two giant
molecular complexes. The kinematics and morphology of the CO emission in this
region provide some support for this second scenario.Comment: Accepted for publication in The Astrophysical Journal, 13 pages, 5
figures, higher quality color images available at
http://www.astro.cornell.edu/staff/vassilis/papers/ngc4038_co.ps.g
Discovery and quantitative spectral analysis of an Ofpe/WN9 (WN11) star in the Sculptor spiral galaxy NGC 300
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.Comment: 9 pages, 4 figures, 2 tables. Accepted for publication in the
Astrophysical Journal Letter
Discovery of a rich proto-cluster at z=2.9 and associated diffuse cold gas in the VIMOS Ultra-Deep Survey (VUDS)
[Abridged] We characterise a massive proto-cluster at z=2.895 that we found
in the COSMOS field using the spectroscopic sample of the VIMOS Ultra-Deep
Survey (VUDS). This is one of the rare structures at z~3 not identified around
AGNs or radio galaxies, so it is an ideal laboratory to study galaxy formation
in dense environments. The structure comprises 12 galaxies with secure
spectroscopic redshift in an area of 7'x8', in a z bin of Dz=0.016. The
measured galaxy number overdensity is delta_g=12+/-2. This overdensity has
total mass of M~8.1x10^(14)M_sun in a volume of 13x15x17 Mpc^3. Simulations
indicate that such an overdensity at z~2.9 is a proto-cluster that will
collapse in a cluster of total mass M~2.5x10^(15)M_sun at z=0. We compare the
properties of the galaxies within the overdensity with a control sample at the
same z but outside the overdensity. We did not find any statistically
significant difference between the properties (stellar mass, SFR, sSFR, NUV-r,
r-K) of the galaxies inside and outside the overdensity. The stacked spectrum
of galaxies in the overdensity background shows a significant absorption
feature at the wavelength of Lya redshifted at z=2.895 (lambda=4736 A), with a
rest frame EW = 4+/- 1.4 A. Stacking only background galaxies without
intervening sources at z~2.9 along their line of sight, we find that this
absorption feature has a rest frame EW of 10.8+/-3.7 A, with a detection S/N of
~4. These EW values imply a high column density (N(HI)~3-20x10^(19)cm^(-2)),
consistent with a scenario where such absorption is due to intervening cold gas
streams, falling into the halo potential wells of the proto-cluster galaxies.
However, we cannot exclude the hypothesis that this absorption is due to the
diffuse gas within the overdensity.Comment: 15 pages, 9 figures, accepted for publication in A&A (revised version
after referee's comments and language editing
Discovering extremely compact and metal-poor, star-forming dwarf galaxies out to z ~ 0.9 in the VIMOS Ultra-Deep Survey
We report the discovery of 31 low-luminosity (-14.5 > M_{AB}(B) > -18.8),
extreme emission line galaxies (EELGs) at 0.2 < z < 0.9 identified by their
unusually high rest-frame equivalent widths (100 < EW[OIII] < 1700 A) as part
of the VIMOS Ultra Deep Survey (VUDS). VIMOS optical spectra of unprecedented
sensitivity ( ~ 25 mag) along with multiwavelength photometry and HST
imaging are used to investigate spectrophotometric properties of this unique
sample and explore, for the first time, the very low stellar mass end (M* <
10^8 M) of the luminosity-metallicity (LZR) and mass-metallicity
(MZR) relations at z < 1. Characterized by their extreme compactness (R50 < 1
kpc), low stellar mass and enhanced specific star formation rates (SFR/M* ~
10^{-9} - 10^{-7} yr^{-1}), the VUDS EELGs are blue dwarf galaxies likely
experiencing the first stages of a vigorous galaxy-wide starburst. Using
T_e-sensitive direct and strong-line methods, we find that VUDS EELGs are
low-metallicity (7.5 < 12+log(O/H) < 8.3) galaxies with high ionization
conditions, including at least three EELGs showing HeII 4686A emission and four
EELGs of extremely metal-poor (<10% solar) galaxies. The LZR and MZR followed
by EELGs show relatively large scatter, being broadly consistent with the
extrapolation toward low luminosity and mass from previous studies at similar
redshift. However, we find evidences that galaxies with younger and more
vigorous star formation -- as characterized by their larger EWs, ionization and
sSFR -- tend to be more metal-poor at a given stellar mass.Comment: Letter in A&A 568, L8 (2014). This replacement matches the published
versio
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