December 2011
6 posts
Whiting 1: A New Halo Young Globular Cluster →
The Astrophysical Journal Letters (01 March 2005), L61. We report on BVI CCD photometry of a field centered in the region of the Galactic star cluster Whiting 1 down to V = 23.0. This cluster has…
Is the massive young cluster Westerlund I bound? →
(19 Dec 2011) Context. Westerlund I is the richest young cluster currently known in our Galaxy, making it one of the most massive clusters for which we can resolve the individual stars even in the…
Simulations of the Hyades →
Astronomy & Astrophysics, Vol. 536, A64. A Ernst, A Just, P Berczik, C Olczak
Relaxation-limited evaporation of globular... →
(9 Dec 2011) Evaporative evolution of stellar clusters is shown to be relaxation limited when the number of stars satisfies $N»N_c$, where $N_c∼eq 1600$. For a Maxwell velocity distribution that…
The first confirmed microlens in a globular... →
(2 Dec 2011) In July/August 2000 a microlensing event occurred at a distance of 2.33 arcmin from the center of the globular cluster M22 (NGC6656), observed against the dense stellar field of the…
Search for and Characterization of Galactic Open... →
(30 Nov 2011) We have developed a star-counting algorithm and tested it on the 2MASS star catalog to search for density enhancements significantly above the field in Galactic latitude…
November 2011
4 posts
Millihertz quasi-periodic oscillations and... →
(16 Nov 2011) We present a comprehensive study of the thermonuclear bursts and millihertz quasi-periodic oscillations (mHz QPOs) from the neutron star (NS) transient and 11 Hz X-ray pulsar IGR…
2MASS photometry and age estimate of globular... →
(11 Nov 2011) We present the first photometric results in J, H, and K_s from 2MASS imaging of 10 classical globular clusters in the far outer regions of M31. Combined with the V and I photometric…
Age and structure parameters of a remote M31... →
(10 Nov 2011) B514 is a remote M31 globular cluster which locating at a projected distance of R_p~55 kpc. Deep observations with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope…
Evolution and Nucleosynthesis of AGB stars in... →
(7 Nov 2011) We present stellar evolutionary sequences for asymptotic giant branch (AGB) stars in the Magellanic Cloud clusters NGC,1978, NGC,1846 and NGC,419. The new stellar models for the…
October 2011
7 posts
Two views of globular cluster stars in the... →
(21 Oct 2011) In Martell & Grebel (2010) we reported the discovery in the Sloan Digital Sky Survey-II/SEGUE spectroscopic database of a small subset of halo red giants, 2.5%, with CN and CH band…
Relativistic Binaries in Globular Clusters →
(20 Oct 2011) Galactic globular clusters are old, dense star systems typically containing 10\super4—10\super7 stars. As an old population of stars, globular clusters contain many collapsed and…
The initial mass spectrum of old globular clusters... →
(18 Oct 2011) We test whether the masses of old globular clusters (GCs) in dwarf galaxies are consistent with the same initial mass spectrum as young massive clusters (YMCs) in nearby star-forming…
On a new theoretical calibration of the Stroemgren... →
(19 Oct 2011) We present a new theoretical calibration of the Stroemgren metallicity index hk by using alpha-enhanced evolutionary models transformed into the observational plane by using…
Wide-Field Precision Kinematics of the M87... →
(12 Oct 2011) We present the most extensive combined photometric and spectroscopic study to date of the enormous globular cluster (GC) system around M87, the central giant elliptical galaxy in the…
The detection of globular clusters in galaxies as... →
(10 Oct 2011) We present an application of self-adaptive supervised learning classifiers derived from the Machine Learning paradigm, to the identification of candidate Globular Clusters in deep,…
Wide-field imaging of NGC 4365's globular cluster... →
(6 Oct 2011) Analysis of the globular cluster (GC) system of the giant elliptical (E3) galaxy NGC 4365, from eight Hubble Space Telescope/Advanced Camera for Surveys (ACS) pointings and a…
September 2011
4 posts
The globular cluster system of the Milky Way:... →
(20 Sep 2011) We examine the significance of a planar arrangement in the spatial distribution of the Milky Way’s globular clusters (GCs). We find that, when separated on the basis of horizontal…
VOGCLUSTERS: an example of DAME web application →
(19 Sep 2011) We present the alpha release of the VOGCLUSTERS web application, specialized for data and text mining on globular clusters. It is one of the web2.0 technology based services of Data…
The Chemical Evolution of Globular Clusters - II.... →
(9 Sep 2011) In the first paper in this series, we proposed a new framework in which to model the chemical evolution of globular clusters. This model, is predicated upon the assumption that…
Formation of Compact Stellar Clusters by... →
(7 Sep 2011) The early universe hosted a large population of low-mass virialized “minihalos,” that were not massive enough to form stars on their own. While most minihalos were photoevaporated by…
August 2011
2 posts
Photometric search for variable stars in young... →
(4 Aug 2011) We present time-series photometry of stars located in the extremely young open cluster Berkeley 59. Using the 1.04 m telescope at ARIES, Nainital, we have identified 42 variables in a…
A UBVI and uvbyCaHbeta Analysis of the... →
(2 Aug 2011) NGC 5822 is a richly populated, moderately nearby, intermediate-age open cluster covering an area larger than the full moon on the sky. A CCD survey of the cluster on the UBVI and…
July 2011
2 posts
CCD time-series photometry of the globular cluster... →
Monthly Notices of the Royal Astronomical Society, Vol. 413, No. 2. (2011), pp. 1275-1294. ABSTRACT We present the results from 10 nights of observations of the globular cluster NGC 6981 (M72) in…
Formation of Multiple Populations in Globular... →
(29 Jun 2011) While chemical composition spreads are now believed to be a universal characteristic of globular clusters (GCs), not all of them present multiple populations in their color-magnitude…
June 2011
4 posts
SMBH Formation via Gas Accretion in Nuclear... →
(29 Jun 2011) Black holes exceeding a billion solar masses have been detected at redshifts greater than six. The rapid formation of these objects may suggest a massive early seed or a period of…
Dynamical evolution of stellar clusters →
(23 Jun 2011) The evolution of star clusters is determined by several internal and external processes. Here we focus on two dominant internal effects, namely energy exchange between stars through…
Finding short GRB remnants in globular clusters:... →
(22 Jun 2011) Globular cluster are believed to boost the rate of compact binary mergers which may launch a certain type of cosmological gamma-ray bursts (GRBs). Therefore globular clusters appear…
Photometric study of the star cluster NGC 2155 in... →
(6 Jun 2011) We present results of new photometry for the globular star cluster NGC 2155 in the Large Magellanic Cloud (LMC). Our I- and V-band observations were obtained with the 6.5-meter…
May 2011
9 posts
Multi-wavelength environment of the Galactic... →
(27 May 2011) Terzan 5 is a Galactic globular cluster exhibiting prominent X-ray and gamma-ray emission. Following the discovery of extended X- ray emission in this object, we explore here archival…
Chemical composition of evolved stars in the open... →
(20 May 2011) In this study we present abundances of 12^C, 13^C, N, O and up to 26 other chemical elements in two first ascent giants and two core-helium-burning ‘clump’ stars of the open cluster…
Testing stellar population synthesis models with... →
(17 May 2011) Accurate stellar population synthesis models are vital in understanding the properties and formation histories of galaxies. In order to calibrate and test the reliability of these…
Astrophysical parameters of ten new discovered... →
(13 May 2011) We present here the fundamental parameters of ten open star clusters, nominated from Kronberger et al. (2006) who presented some new discovered stellar groups on the basis of 2MASS…
s-Processing in the Galactic Disk. I. Super-Solar... →
(11 May 2011) In a recent study, based on homogeneous barium abundance measurements in open clusters, a trend of increasing [Ba/Fe] ratios for decreasing cluster age was reported. We present here…
Dynamics of massive stellar black holes in young... →
(3 May 2011) In low-metallicity environments, massive stars might avoid supernova explosion and directly collapse, forming massive (~25-80 solar masses) stellar black holes (MSBHs), at the end of…
Two Distinct Red Giant Branches in the Globular... →
(3 May 2011) We report the presence of two distinct red giant branches (RGBs) in the globular cluster NGC 288 from the narrow-band calcium and Strömgren b & y photometry obtained at the CTIO 4m…
RR Lyrae Variables in NGC 2808 →
(29 Apr 2011) NGC 2808 is a unique globular cluster with not only a bimodal-horizontal branch (HB) but also with gaps on the blue horizontal branch. Adequate interpretation of the nature of the…
The oxygen vs. sodium (anti)correlation(s) in... →
(2 May 2011) Recent exam of large samples of omega Cen giants shows that it shares with mono-metallic globular clusters the presence of the sodium versus oxygen anticorrelation, within each subset…
April 2011
9 posts
Spitzer spectra of evolved stars in omega Centauri... →
(27 Apr 2011) Dust production is explored around 14 metal-poor ([Fe/H] = -1.91 to -0.98) giant stars in the Galactic globular cluster omega Centauri using new Spitzer IRS spectra. This sample…
A New Look at the Old Star Cluster NGC 6791 →
(28 Apr 2011) We present comprehensive cluster membership and g’r’ photometry of the prototypical old, metal-rich Galactic star cluster NGC 6791. The proper-motion catalog contains 58,901 objects…
Near-infrared photometry of four metal-rich bulge... →
Monthly Notices of the Royal Astronomical Society, Vol. 361, No. 1. (July 2005), pp. 272-282. ABSTRACT We present high-quality near-infrared (near-IR) photometry of four bulge metal-rich globular…
Discovery of a candidate quiescent low-mass X-ray... →
(19 Apr 2011) This paper reports the search for quiescent low-mass X-ray binaries (qLMXBs) in the globular cluster (GC) NGC 6553 using an XMM-Newton observation designed specifically for that…
External Mass Accumulation onto Core Potentials:... →
(15 Apr 2011) Accretion studies have been focused on the flow around bodies with point mass gravitational potentials, but few general results are available for non-point mass distributions. Here,…
AAOmega spectroscopy of 29 351 stars in fields... →
(13 Apr 2011) Galactic globular clusters have been pivotal in our understanding of many astrophysical phenomena. Here we publish the extracted stellar parameters from a recent large spectroscopic…
Chemical abundance anticorrelations in globular... →
(8 Apr 2011) It is widely accepted that individual Galactic globular clusters harbor two coeval generations of stars, the first one born with the `standard’ $α$-enhanced metal mixture observed in…
Four new black hole candidates identified in M31... →
(5 Apr 2011) We have identified four new black hole candidates in M31 globular clusters using 123 Chandra, and 4 XMM-Newton observations of the M31 central region. The X-ray source associated with…
Star cluster formation and evolution in Mrk 930:... →
(29 Mar 2011) We present a HST multiband analysis of the large population of star clusters in the blue compact galaxy (BCG) Mrk 930. We have reconstructed the spectral energy distributions of the…
March 2011
11 posts
On the reliability of proxies for globular cluster... →
(30 Mar 2011) (Abridged) Proxies for the stellar collision rates in globular clusters are often used. We present comparisons between these proxies and the full integrated collision rate for King…
Long period variables and mass loss in the... →
(28 Mar 2011) The pulsation periods of long period variables (LPVs) depend on their mass and helium abundance as well as on their luminosity and metal abundance. Comparison of the observed periods…
A dwarf nova in the globular cluster M13 →
(23 Mar 2011) Dwarf novae in globular clusters seem to be rare with only 12 detections in the 157 known Galactic globular clusters. We report the identification of a new dwarf nova in M13, the 13th…