期刊
ASTRONOMICAL JOURNAL
卷 145, 期 5, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/0004-6256/145/5/134
关键词
open clusters and associations: general; open clusters and associations: individual (Ruprecht 147)
资金
- Pennsylvania State University
- Eberly College of Science
- Pennsylvania Space Grant Consortium
- National Science Foundation [DGE1255832, AST-1211785]
- Stephen B. Brumbach graduate fellowship
- Zaccheus Daniel travel grant program
- NOAO [PA-10A-0378]
- NSF
- NASA
- W. M. Keck Foundation
- NASA's Earth Science Technology Office, Computation Technologies Project [NCC5-626]
- Direct For Mathematical & Physical Scien
- Division Of Astronomical Sciences [1211785] Funding Source: National Science Foundation
Ruprecht 147 is a hitherto unappreciated open cluster that holds great promise as a standard in fundamental stellar astrophysics. We have conducted a radial velocity survey of astrometric candidates with Lick, Palomar, and MMT observatories and have identified over 100 members, including 5 blue stragglers, 11 red giants, and 5 double-lined spectroscopic binaries (SB2s). We estimate the cluster metallicity from spectroscopic analysis, using Spectroscopy Made Easy (SME), and find it to be [M/H] = +0.07 +/- 0.03. We have obtained deep CFHT/MegaCam g'r'i'z' photometry and fit Padova isochrones to the (g' - i') and Two Micron All Sky Survey (J - K-S) color-magnitude diagrams, using the tau(2) maximum-likelihood procedure of Naylor, and an alternative method using two-dimensional cross-correlations developed in this work. We find best fits for Padova isochrones at age t = 2.5 +/- 0.25 Gyr, m - M = 7.35 +/- 0.1, and A(V) = 0.25 +/- 0.05, with additional uncertainty from the unresolved binary population and possibility of differential extinction across this large cluster. The inferred age is heavily dependent on our choice of stellar evolution model: fitting Dartmouth and PARSEC models yield age parameters of 3 Gyr and 3.25 Gyr, respectively. At similar to 300 pc and similar to 3 Gyr, Ruprecht 147 is by far the oldest nearby star cluster.
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