The VMC Survey. XVIII. Radial Dependence of the Low-mass, 0.55--0.82 M Stellar Mass Function in the Galactic Globular Cluster 47 Tucanae
Journal
Date Issued
2015
Author(s)
Zhang, Chaoli
•
Li, Chengyuan
•
de Grijs, Richard
•
Bekki, Kenji
•
Deng, Licai
•
•
•
Piatti, Andrés E.
•
Cioni, Maria-Rosa L.
•
Emerson, Jim
•
For, Bi-Qing
•
•
•
Ivanov, Valentin D.
•
Chen, Li
Description
The analysis in this article is based on observations made with the VISTA telescope at the European Southern Observatory under program ID 179.B-2003. We thank the team responsible for the UK's VISTA Data Flow System for providing calibrated data products, supported by the UK's Science and Technology Facilities Council. We also would like to thank the Globular Cluster Treasury program team (PI: A. Sarajedini) for their guidance on the HST completeness table. C.Z. is grateful to the Kavli Institute for Astronomy and Astrophysics for their hospitality and dedicated assistance during the period of this work, and special thanks are due to Yang Huang for his insightful discussions on data reduction. C.Z., C.L., and R.d.G. acknowledge funding support from the National Natural Science Foundation of China (grant 11373010). C.Z., L.C., and C.L. acknowledge financial support from “973 Program” 2014 CB845702 and the Strategic Priority Research Program “The Emergence of Cosmological Structures” of the Chinese Academy of Sciences (CAS; grants XDB09010100 and XDB09000000).
Abstract
We use near-infrared observations obtained as part of the Visible and Infrared Survey Telescope for Astronomy (VISTA) Survey of the Magellanic Clouds (VMC), as well as two complementary Hubble Space Telescope (HST) data sets, to study the luminosity and mass functions (MFs) as a function of clustercentric radius of the main-sequence stars in the Galactic globular cluster 47 Tucanae. The HST observations indicate a relative deficit in the numbers of faint stars in the central region of the cluster compared with its periphery, for 18.75 ≤ mF606W ≤ 20.9 mag (corresponding to a stellar mass range of 0.55 < m*/M☉ < 0.73). The stellar number counts at 6.′7 from the cluster core show a deficit for 17.62 ≤ mF606W ≤ 19.7 mag (i.e., 0.65 < m*/M☉ < 0.82), which is consistent with expectations from mass segregation. The VMC-based stellar MFs exhibit power-law shapes for masses in the range 0.55 < m*/M☉ < 0.82. These power laws are characterized by an almost constant slope, α. The radial distribution of the power-law slopes α thus shows evidence of the importance of both mass segregation and tidal stripping, for both the first- and second-generation stars in 47 Tuc.
Volume
815
Issue
2
Start page
95
Issn Identifier
0004-637X
Ads BibCode
2015ApJ...815...95Z
Rights
open.access
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