The Ages of the Thin Disk, Thick Disk, and the Halo from Nearby White Dwarfs
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Author
Kilic, MukreminMunn, Jeffrey A.
Harris, Hugh C.
Hippel, Ted von
Liebert, James W.
Williams, Kurtis A.
Jeffery, Elizabeth
DeGennaro, Steven
Affiliation
Univ Arizona, Steward ObservIssue Date
2017-03-15
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IOP PUBLISHING LTDCitation
The Ages of the Thin Disk, Thick Disk, and the Halo from Nearby White Dwarfs 2017, 837 (2):162 The Astrophysical JournalJournal
The Astrophysical JournalRights
© 2017. The American Astronomical Society. All rights reserved.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
We present a detailed analysis of the white dwarf luminosity functions derived from the local 40 pc sample and the deep proper motion catalog of Munn et al. Many previous studies have ignored the contribution of thick disk white dwarfs to the Galactic disk luminosity function, which results in an erroneous age measurement. We demonstrate that the ratio of thick/thin disk white dwarfs is roughly 20% in the local sample. Simultaneously fitting for both disk components, we derive ages of 6.8-7.0 Gyr for the thin disk and 8.7 +/- 0.1 Gyr for the thick disk from the local 40 pc sample. Similarly, we derive ages of 7.4-8.2 Gyr for the thin disk and 9.5-9.9 Gyr for the thick disk from the deep proper motion catalog, which shows no evidence of a deviation from a constant star formation rate in the past 2.5 Gyr. We constrain the time difference between the onset of star formation in the thin disk and the thick disk to be 1.6(-0.4)(+0.3) Gyr. The faint end of the luminosity function for the halo white dwarfs is less constrained, resulting in an age estimate of 12.5(-3.4)(+1.4) Gyr for the Galactic inner halo. This is the first time that ages for all three major components of the Galaxy have been obtained from a sample of field white dwarfs that is large enough to contain significant numbers of disk and halo objects. The resultant ages agree reasonably well with the age estimates for the oldest open and globular clusters.ISSN
1538-4357Version
Final published versionSponsors
NSF; NASA [AST-0607480, AST-0602288, AST1312678, NNX14AF65G]Additional Links
http://stacks.iop.org/0004-637X/837/i=2/a=162?key=crossref.6a70e8a5990404bfd2490172e55178a7ae974a485f413a2113503eed53cd6c53
10.3847/1538-4357/aa62a5