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Galaxy evolution in groups and clusters: star formation rates, red sequence fractions, and the persistent bimodality
methods: statistical-galaxies: groups: general-galaxies: clusters:general-galaxies: haloes-galaxies: evolution-galaxies: star formation
2011/10/17
Using galaxy group/cluster catalogs created from the Sloan Digital Sky Survey Data Release 7, we examine in detail the specific star formation rate (SSFR) distribution of satellite galaxies and its de...
Pairwise Velocities of Dark Matter Halos: a Test for the Lambda Cold Dark Matter Model using the Bullet Cluster
method : N-body simulations — galaxies : evolution — galaxies : for-mation — galaxies: clusters — cosmology : theory — cosmology : dark matter
2011/10/13
The existence of a bullet cluster (such as 1E0657-56) poses a challenge to the concordance Lambda cold dark matter model. Here we investigate the velocity distribution of dark matter halo pairs in lar...
A Southern Sky and Galactic Plane Survey for Bright Kuiper Belt Objects
Southern Sky Galactic Plane Survey Bright Kuiper Objects
2011/10/17
About 2500 square degrees of sky south of declination -25 degrees and/or near the galactic plane were surveyed for bright outer solar system objects. This survey is one of the first large scale southe...
Swift J2058.4+0516: Discovery of a Possible Second Relativistic Tidal Disruption Flare
Swift Possible Second Relativistic idal Disruption Flare
2011/10/17
We report the discovery by the Swift hard X-ray monitor of the transient source Swift J2058.4+0516 (Sw J2058+05). Our multi-wavelength follow-up campaign uncovered a long-lived (duration >~ months), l...
AMBER high-spectral resolution interferometry of Be stars: More than just stars and disks?
high-spectral resolution interferometry stars disks
2011/10/17
High spectral-resolution Br-gamma VLTI/AMBER observations of classical Be stars reveal complex visibility, phase, and closure phase profiles, which were not seen in previous lower-resolution data. The...
2MASS wide field extinction maps: IV. The Orion, Mon R2, Rosette, and Canis Major star forming regions
clouds dust extinction structure individual objects Orion molecular complex
2011/10/21
We present a near-infrared extinction map of a large region (approximately 2200 deg^2) covering the Orion, the Monoceros R2, the Rosette, and the Canis Major molecular clouds. We used robust and optim...
The beaming of external Compton emission
galaxies active radiation mechanisms nonthermal gamma rays theory
2011/10/21
We consider a relativistically moving blob consisting of an isotropic electron distribution that Compton-scatters photons from an external isotropic radiation field. We compute the resulting beaming p...
Two O2 If*/WN6 stars possibly ejected from the massive young Galactic cluster Westerlund 2
Stars: individual:WR20aa - Stars: individual:WR20c - Stars:Wolf-Rayet (Galaxy): open clusters and associations: individual:Westerlund 2
2011/10/19
In this paper we report the identification of two new Galactic O2 If*/WN6 stars (WR20aa and WR20c), in the outskirt of the massive young stellar cluster Westerlund 2. The morphological similarity betw...
On the redundancy of operators and the bispectrum in the most general second-order scalar-tensor theory
redundancy operators bispectrum general second-order scalar-tensor theory
2011/10/19
In this short note we explain how to use the linear equation of motions to simplify the third-order action for the cosmological fluctuations. No field redefinition is needed in this exact procedure wh...
Another Look at the EBS: A Stellar Debris Stream and a Possible Progenitor
Another Look Stellar Debris Stream Possible Progenitor
2011/10/19
Using the Sloan Digital Sky Survey Data Release 7, we reexamine the Eastern Banded Structure (EBS), a stellar debris stream first discovered in Data Release 5 and more recently detected in velocity sp...
Too small to succeed? Lighting up massive dark matter subhaloes of the Milky Way
methods: numerical - N-body simulations – galaxies: formation - haloes - Local Group
2011/10/19
Using Constrained Local UniversE Simulations (CLUES) of the formation of the Local Group in a cosmological context we investigate the recently highlighted problem that the majority of the most massive...
Dust driven mass loss from carbon stars as function of stellar parameters - II. Effects of grain size on wind properties
AGB and post-AGB – Stars: atmospheres – Stars: carbon – Stars: circumstellar matter – Stars: evolution – Stars: mass loss –2 Hydrodynamics – Radiative transfer
2011/9/30
In this paper we explore grain size effects on wind properties of carbon stars, using a generalized description of radiative cross sections valid for particles of arbitrary sizes. The purpose of the s...
Discovery of a stripped red giant core in a bright eclipsing binary system
binaries: spectroscopic – binaries: individual: KOI-81 – stars: individual 1SWASP J024743.37− 251549.2
2011/10/19
We have identified a star in the WASP archive photometry with an unusual lightcurve due to the total eclipse of a small, hot star by an apparently normal A-type star and with an orbital period of only...
Stellar Evolution Constraints on the Triple-Alpha Reaction Rate
Stellar Evolution Constraints Triple-Alpha Reaction Rate
2011/10/19
We investigate the quantitative constraint on the triple-alpha reaction rate based on stellar evolution theory, motivated by the recent significant revision of the rate proposed by nuclear physics cal...
Deriving the radial-velocity variations induced by stellar activity from high-precision photometry - Test on HD189733 with simultaneous MOST/SOPHIE data
late-type – stars: activity – stars: rotation – techniques: radial velocity – planetary systems – stars: individual
2011/10/19
Stellar activity induces apparent radial velocity (RV) variations in late-type main-sequence stars that may hamper the detection of low-mass planets and the measurement of their mass. We use simultane...