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Tracing the dynamical history of the globular cluster 47 Tucanae

Monkman, Eric and Sills, Alison and Howell, Justin and Guhathakurta, Puragra and de Angeli, Francesca and Beccari, Giacomo (2006) Tracing the dynamical history of the globular cluster 47 Tucanae. Astrophysical Journal, 650 (1). pp. 195-202. ISSN 0004-637X.

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We use two stellar populations in the globular cluster 47 Tucanae to trace its dynamical history: blue stragglers and low-mass main-sequence stars. We assumed that the blue stragglers were formed through stellar collisions in all regions of the cluster. We find that in the core of the cluster, models of collisional blue stragglers agree well with the observations as long as blue stragglers are still continuing to form and the mass function in the cluster is extremely biased toward massive stars (x = -8, where a Salpeter mass function has x = +1.35). We show that such an extreme mass function is supported by direct measurements of the luminosity function of main-sequence stars in the center of the cluster. In the middle region of our data set (25–130 from the cluster center), blue straggler formation seems to have stopped about half a billion years ago. In the outskirts of the cluster, our models are least successful at reproducing the blue straggler data. Taken at face value, they indicate that blue straggler formation has been insignificant over the past billion years and that a Salpeter mass function applies. However, it is more likely that the dominant formation mechanism in this part of the cluster is not the collisional one and that our models are not appropriate for this region of the cluster. We conclude that blue stragglers can be used as tracers of dynamics in globular clusters, despite our incomplete understanding of how and where they were formed.

Item Type:Article
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URLURL TypeDescription
Sills, Alison0000-0003-3551-5090
Guhathakurta, Puragra0000-0001-8867-4234
Additional Information:© 2006 The American Astronomical Society. Received 2006 May 19; accepted 2006 June 28. E.M. thanks Alison Sills for her guidance and assistance throughout this project. A.S. is supported by NSERC. E.M. was supported in part by Human Resources and Development Canada.
Subject Keywords:blue stragglers; globular clusters;47 Tucanae; luminosity function; mass function
Issue or Number:1
Record Number:CaltechAUTHORS:MONapj06c
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:6004
Deposited By: Lindsay Cleary
Deposited On:13 Nov 2006
Last Modified:09 Mar 2020 13:19

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