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On the luminosity function, lifetimes, and origin of blue stragglers in globular clustersWe compute theoretical evolutionary tracks of blue stragglers created by mergers. Two formation scenarios are considered: mergers of primordial binaries, and stellar collisions. These two scenarios predict strikingly different luminosity functions, which are potentially distinguishable observationally. Tabulated theoretical luminosity functions and lifetimes are presented for blue stragglers formed under a variety of input conditions. We compare our results with observations of the blue straggler sequences in 47 Tucanae and M3. In the case of 47 Tuc, the luminosity function and the formation rate are compatible with the hypothesis that the blue stragglers formed through the collision of single stars. Mergers of primordial binaries are only marginally cosistent with the data, and a significant enhancement of the collision cross section by binary-single-star encounters appears to be ruled out. In the case of M3, we find that the innermost blue stragglers have a luminosity function significantly different from that of the outer stragglers, thus confirming earlier suggestions that there are two distinct populations of blue stragglers in this cluster. The inner stragglers are preferentially brighter and bluer, as would be expected if they were made by collisions, but there are so many of them that the collision rate would need to be enhanced by interactions involving wide binaries. The luminosity function of the outer stragglers is almost identical to the predictions of mergers from primordial binaries and is inconsistent with the collision hypothesis.
Document ID
19950044710
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Bailyn, Charles D.
(Yale Univ. New Haven, CT, United States)
Pinsonneault, Marc H.
(Ohio State Univ. Columbus, OH, United States)
Date Acquired
August 16, 2013
Publication Date
February 1, 1995
Publication Information
Publication: The Astrophysical Journal, Part 1
Volume: 439
Issue: 2
ISSN: 0004-637X
Subject Category
Astrophysics
Funding Number(s)
CONTRACT_GRANT: NAGW-2469
Distribution Limits
Public
Copyright
Other
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