Proper Motions and Structural Parameters of the Galactic Globular Cluster M71*

Abstract

Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Abstract By exploiting two ACS/HST data sets separated by a temporal baseline of ∼7 years, we have determined the relative stellar proper motions (PMs; providing membership) and the absolute PM of the Galactic globular cluster M71. The absolute PM has been used to reconstruct the cluster orbit within a Galactic, three-component, axisymmetric potential. M71 turns out to be in a low-latitude disk-like orbit inside the Galactic disk, further supporting the scenario in which it lost a significant fraction of its initial mass. Since large differential reddening is known to affect this system, we took advantage of near-infrared, ground-based observations to re-determine the cluster center and density profile from direct star counts. The new structural parameters turn out to be significantly different from the ones quoted in the literature. In particular, M71 has a core and a half-mass radii almost 50% larger than previously thought. Finally, we estimate that the initial mass of M71 was likely one order of magnitude larger than its current value, thus helping to solve the discrepancy with the observed number of X-ray sources.

The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XV. The Dynamical Clock: Reading Cluster Dynamical Evolution from the Segregation Level of Blue Straggler Stars

“…Table 1: Structural/dynamical parameters and values of A + rh for the 27 program clusters: concentration parameter (column 2), core and half-mass radii in arcseconds (columns 3 and 4, respectively), logarithm of the central relaxation time in Gyr (column 5), derived value of A + rh and its error (columns 6 and 7). The structural parameters are from Miocchi et al (2013), L16, Cadelano et al (2017), and Harris (1996) if not available in the previous studies, but for NGC 6717 and NGC 6535 and NGC 6496 for which we performed new determinations (Ferraro et al 2018, in preparation). Clusters are ordered in terms of increasing value of A + rh .…”

The Peculiar Radial Distribution of Multiple Populations in the Massive Globular Cluster M80

“…C grav was determined by using an iterative procedure that averages the positions α and δ of stars in a defined magnitude range and lying within a given distance from a first guess center. At each iteration star distances are re-calculated respect to the center obtained in the previous iteration until convergence is reached (see for example Dalessandro et al 2013;Cadelano et al 2017, for more details). We used as starting guess center the one found by Goldsbury et al (2010).…”

Star-density Profiles of Six Old Star Clusters in the Large Magellanic Cloud

“…However, starting from studies dedicated to specific objects or very small sets of clusters (e.g. Ferraro et al 1999Ferraro et al , 2003Dalessandro et al 2008Dalessandro et al , 2013Dalessandro et al , 2015Salinas et al 2012;Saracino et al 2015;Cadelano et al 2017), the systematic determination of gravitational centers and surface density profiles from resolved stars counts is increasingly adopted (see, e.g., the study of a sample of 26 Galactic GCs discussed in Miocchi et al 2013).…”