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A new X-ray selected and X-ray flux-limited galaxy cluster sample is presented. Based on the ROSAT All-Sky Survey the 63 brightest clusters with galactic latitude |bII| >= 20 deg and flux fx(0.1-2.4 keV) >= 2 * 10^{-11} ergs/s/cm^2 have…

Astrophysics · Physics 2011-02-11 Thomas H. Reiprich , Hans Boehringer

A growing fraction of Simple Stellar Population (SSP) models, in an aim to create more realistic simulations capable of including stochastic variation in their outputs, begin their simulations with a distribution of discrete stars following…

Astrophysics of Galaxies · Physics 2015-06-18 Bogdan Popescu , M. M. Hanson

We study the early dynamical evolution of young, dense star clusters using Monte Carlo simulations for systems with up to N~10^7 stars. Rapid mass segregation of massive main-sequence stars and the development of the Spitzer instability can…

Astrophysics · Physics 2010-04-06 M. Atakan Gürkan , Marc Freitag , Frederic A. Rasio

The stellar initial mass function (IMF) is critical to our understanding of star formation and the effects of young stars on their environment. On large scales, it enables us to use tracers such as UV or Halpha emission to estimate the star…

The stellar initial mass function (IMF) describes the mass distribution of stars at the time of their formation and is of fundamental importance for many areas of astrophysics. The IMF is reasonably well constrained in the disk of the Milky…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Pieter van Dokkum , Charlie Conroy

We study the stellar cluster population in two adjacent fields in the nearby, face-on spiral galaxy, M83, using WFC3/HST imaging. The clusters are selected through visual inspection to be centrally concentrated, symmetric, and resolved on…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 N. Bastian , A. Adamo , M. Gieles , E. Silva Villa , H. J. G. L. M Lamers , S. S. Larsen , L. J. Smith , I. S. Konstantopoulos , E. Zackrisson

We show that we can obtain a good fit to the present day stellar mass functions (MFs) of a large sample of young and old Galactic clusters in the range 0.1 - 10 Msolar with a tapered power law distribution function with an exponential…

Astrophysics of Galaxies · Physics 2015-05-19 Guido De Marchi , Francesco Paresce , Simon Portegies Zwart

We present an observational mass function ranging from galaxies to massive galaxy clusters, derived from direct dynamical mass estimates. Our mass function shows, in the low-mass range of galaxies and groups, a behaviour in agreement with…

Astrophysics · Physics 2007-05-23 G. Giuricin , F. Mardirossian , M. Mezzetti , M. Persic , P. Salucci

The initial mass function (IMF) succinctly characterizes a stellar population, provides a statistical measure of the end result of the star-formation process, and informs our under- standing of the structure and dynamical evolution of…

Solar and Stellar Astrophysics · Physics 2011-07-25 Kevin R. Covey , Nate Bastian , Michael R. Meyer

We show the results of deep V and I HST photometry of 6 rich star clusters in the Large Magellanic Cloud with different ages and metallicities. The number of stars with measured magnitudes in each cluster varies from about 3000 to 10000. We…

Astrophysics · Physics 2009-11-06 B. Santiago , S. Beaulieu , R. Johnson , G. Gilmore

We study mass functions of globular clusters derived from HST/ACS images of the early-type merger remnant galaxy NGC 1316 which hosts a significant population of metal-rich globular clusters of intermediate age (~3 Gyr). For the old,…

Cosmology and Nongalactic Astrophysics · Physics 2012-04-27 Paul Goudfrooij

We used archival Hubble Space Telescope WFC3 images to obtain the Luminosity Function of the remote globular cluster NGC2419 from two magnitudes above the Horizontal Branch level down to \sim3.0 magnitudes below the Turn Off point (to…

Astrophysics of Galaxies · Physics 2015-06-04 M. Bellazzini , E. Dalessandro , A. Sollima , R. Ibata

We present velocity dispersion measurements of 20 Local Group stellar clusters (7 < log(age [yrs]) < 10.2) from integrated light spectra and examine the evolution of the stellar mass-to-light ratio, Upsilon_*. We find that the clusters…

Astrophysics of Galaxies · Physics 2015-06-11 Dennis Zaritsky , Janet E. Colucci , Peter M. Pessev , Rebecca A. Bernstein , Rupali Chandar

We report on the discovery of a surprising observed correlation between the slope of the low-mass stellar global mass function (GMF) of globular clusters (GCs) and their central concentration parameter c=log(r_t/r_c), i.e. the logarithmic…

Astrophysics · Physics 2009-11-13 Guido De Marchi , Francesco Paresce , Luigi Pulone

The stellar initial mass function (IMF), which is often assumed to be universal across unresolved stellar populations, has recently been suggested to be "bottom-heavy" for massive ellipticals. In these galaxies, the prevalence of…

The log-normal shape of the mass function for metal-poor halo globular clusters is proposed to result from an initial M^{-2} power law modified rapidly by evaporation, collisions with clouds, and mutual cluster interactions in the dense…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Bruce G. Elmegreen

A number of recent studies have proposed that the stellar initial mass function (IMF) of early type galaxies varies systematically as a function of galaxy mass, with higher mass galaxies having bottom heavy IMFs. These bottom heavy IMFs…

We test claims that the power-law mass functions of young star clusters (ages $\lesssim\mbox{few}\times10^8$~yr) have physical upper cutoffs at $M_*\sim10^5~M_{\odot}$. Specifically, we perform maximum-likelihood fits of the Schechter…

Astrophysics of Galaxies · Physics 2019-02-20 Angus Mok , Rupali Chandar , S. Michael Fall

The properties of young star clusters formed within a galaxy are thought to vary in different interstellar medium (ISM) conditions, but the details of this mapping from galactic to cluster scales are poorly understood due to the large…

We investigated the stellar mass function and the binary fraction of 114 nearby open clusters (OCs) using the high-precision photometric data from Gaia Data Release 3 (Gaia DR3). We estimated the mass of member stars by using a ridge line…

Solar and Stellar Astrophysics · Physics 2024-05-22 Yueyue Jiang , Jing Zhong , Songmei Qin , Tong Tang , Li Chen , Jinliang Hou