The central blue straggler population in four outer-halo globular clusters

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DOIResolve DOI: http://doi.org/10.1088/0004-637X/754/2/108
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TypeArticle
Journal titleThe Astrophysical Journal
ISSN0004-637X
Volume754
Issue2
Article number108
AbstractUsing Hubble Space Telescope/Wide Field Planetary Camera 2 data, we have performed a comparative study of the Blue Straggler Star (BSS) populations in the central regions of the globular clusters (GCs) AM 1, Eridanus, Palomar 3, and Palomar 4. Located at distances R GC > 50kpc from the Galactic center, these are (together with Palomar 14 and NGC2419) the most distant clusters in the halo. We determine their color-magnitude diagrams and centers of gravity. The four clusters turn out to have similar ages (10.5-11Gyr), significantly smaller than those of the inner-halo globulars, and similar metallicities. By exploiting wide-field ground-based data, we build the most extended radial density profiles from resolved star counts ever published for these systems. These are well reproduced by isotropic King models of relatively low concentration. BSSs appear to be significantly more centrally segregated than red giants in all GCs, in agreement with the estimated core and half-mass relaxation times which are smaller than the cluster ages. Assuming that this is a signature of mass segregation, we conclude that AM 1 and Eridanus are slightly dynamically more evolved than Pal 3 and Pal 4. © 2012. The American Astronomical Society. All rights reserved.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada (NRC-CNRC); NRC Herzberg Institute of Astrophysics (HIA-IHA)
Peer reviewedYes
NPARC number21269520
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Record identifier7ab5aeb4-c922-4c0c-8868-662358f2c606
Record created2013-12-12
Record modified2016-07-18
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