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Binary fraction and orbital characteristics provide indications on the conditions of star formation, as they shed light on the environment they were born in. Multiple systems are more common in low density environments rather than in higher…

Solar and Stellar Astrophysics · Physics 2015-11-18 S. Lucatello , A. Sollima , R. Gratton , E. Vesperini , V. D'Orazi , E. Carretta , A. Bragaglia

Radial velocity measurements can be used to constrain the dynamical state of a stellar cluster. However, for clusters with velocity dispersions smaller than a few km/s the observed radial velocity distribution tends to be dominated by the…

Solar and Stellar Astrophysics · Physics 2015-06-11 Michiel Cottaar , Michael R. Meyer , Richard J. Parker

We report an analysis of the dynamical structure of clusters of galaxies from a survey of photometric and spectroscopic observations in the fields of southern Abell Clusters. We analyze the galaxy velocity field in extended regions up to 7…

Astrophysics · Physics 2009-11-07 Hernan Muriel , Hernan Quintana , Leopoldo Infante , Diego G. Lambas , Michael J. Way

Detailed studies of resolved young massive star clusters are necessary to determine their dynamical state and evaluate the importance of gas expulsion and early cluster evolution. In an effort to gain insight into the dynamical state of the…

The initial velocity dispersion of newborn stars is a major unconstrained aspect of star formation theory. Using near-infrared spectra obtained with the APOGEE spectrograph, we show that the velocity dispersion of young (1-2 Myr) stars in…

We present internal velocity dispersion determinations from high-resolution spectroscopic observations of a sample of nine globular clusters in M31. Comprehensive numerical simulations are used to show that the typical uncertainty of our…

Astrophysics · Physics 2007-05-23 P. Dubath , C. J. Grillmair

A significant proportion of Milky Way stars are born in stellar clusters, which dissolve over time so that the members become part of the disc and halo populations of the Galaxy. In the present work we will assume that these young stellar…

Astrophysics of Galaxies · Physics 2013-07-08 G. R. I. Moyano Loyola , J. R. Hurley

Certain types of globular clusters have the very important property that the predictions for their kinematics in the Newtonian and modified Newtonian dynamics (MOND) contexts are divergent. Here, we caution the recent claim that the stellar…

Astrophysics of Galaxies · Physics 2015-05-14 Gianfranco Gentile , Benoit Famaey , Garry W. Angus , Pavel Kroupa

Velocity dispersion measurements of recently discovered Milky Way satellites with $M_V\gtrsim-7$ imply they posses high mass-to-light ratios. The expected velocity dispersions due to their baryonic mass are $\sim0.2$\,km\,s$^{-1}$, but…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Alan W. McConnachie , Patrick Cote

Small number statistics may heavily affect the structure of the broadening function in integrated spectra of galactic globular cluster centers. As a consequence, it is a priori unknown how closely line broadening measure- ments gauge the…

Astrophysics · Physics 2007-05-23 Simone R. Zaggia , Massimo Capaccioli , Giampaolo Piotto

The standard method of measuring the galaxy pairwise velocity dispersion on small scales is heavily weighted by the densest regions in a way that is difficult to calibrate. We propose a new statistic which measures the small-scale velocity…

Astrophysics · Physics 2009-10-30 Michael A. Strauss , Jeremiah P. Ostriker , Renyue Cen

We present a suite of direct N-body simulations of low mass ($<10^4~M_{\odot}$) globular cluster streams initialized with observationally-motivated binary demographics in order to understand the effect of in-cluster dynamical processing on…

Astrophysics of Galaxies · Physics 2026-03-10 Anya Phillips , Charlie Conroy , Jacob Nibauer , Long Wang , Vedant Chandra , Ana Bonaca , Jay Strader , Morgan MacLeod

Recent spectroscopic and photometric surveys are providing a comprehensive view of the MW bulge stellar population properties with unprecedented accuracy. This in turn allows us to explore the correlation between kinematics and stellar…

We quantify the structure of a very large number of Galactic open clusters and look for evidence of mass segregation for the most massive stars in the clusters. We characterise the structure and mass segregation ratios of 1276 clusters in…

Astrophysics of Galaxies · Physics 2017-10-30 Sami Dib , Stefan Schmeja , Richard J. Parker

We report on the radial velocity measurements of 18 globular clusters and one dE galaxy in the field of the giant elliptical galaxy NGC 1399, the dominant galaxy of the Fornax cluster. We present also the radial velocity measurements of…

Astrophysics · Physics 2009-10-30 Dante Minniti , Markus Kissler-Patig , Paul Goudfrooij , Georges Meylan

What is the role of clusters of galaxies in probing the large-scale velocity field of the universe? We investigate the distribution of peculiar velocities of clusters of galaxies in the popular low-density ($\Omega=0.3$) flat…

Astrophysics · Physics 2009-10-22 Neta A. Bahcall , Renyue Cen , Mirt Gramann

Upon their formation, dynamically cool (collapsing) star clusters will, within only a few million years, achieve stellar mass segregation for stars down to a few solar masses, simply because of gravitational two-body encounters. Since…

Solar and Stellar Astrophysics · Physics 2015-06-12 Richard de Grijs , Chengyuan Li , Yong Zheng , Licai Deng , Yi Hu , M. B. N. Kouwenhoven , James E. Wicker

Observations and theory both suggest that star clusters form sub-virial (cool) with highly sub-structured distributions. We perform a large ensemble of N-body simulations of moderate-sized (N=1000) cool, fractal clusters to investigate…

Astrophysics of Galaxies · Physics 2015-05-18 Richard J. Allison , Simon P. Goodwin , Richard J. Parker , Simon F. Portegies Zwart , Richard de Grijs

We study the dynamical evolution of disk and halo globular clusters in the Milky Way using a series of Fokker-Planck calculations combined with parametric statistical models. Our sample of 113 clusters with velocity data is predicted to…

Astrophysics · Physics 2007-05-23 Chigurupati Murali , Martin D. Weinberg

We report the discovery of a probable CH star in the core of the Galactic globular cluster M14, identified from an integrated-light spectrum of the cluster obtained with the MOS spectrograph on the CFHT. From a high- resolution echelle…