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The distances to open clusters from main-sequence fitting. III. Improved accuracy with empirically calibrated isochrones

Deokkeun, An and Terndrup, Donald M. and Pinsonneault, Marc H. and Paulson, Diane B. and Hanson, Robert B. and Stauffer, John R. (2007) The distances to open clusters from main-sequence fitting. III. Improved accuracy with empirically calibrated isochrones. Astrophysical Journal, 655 (1). pp. 233-260. ISSN 0004-637X.

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We continue our series of papers on open cluster distances with a critical assessment of the accuracy of main-sequence fitting using isochrones that employ empirical corrections to the color-temperature relations. We use four nearby open clusters with multicolor photometry and accurate metallicities and present a new metallicity for Praesepe ([Fe/H]=+0.11±0.03) from high-resolution spectra. The internal precision of distance estimates is about a factor of 5 better than the case without the color calibrations. After taking into account all major systematic errors, we obtain distances accurate to about 2%–3% when there exists a good metallicity estimate. Metallicities accurate to better than 0.1 dex may be obtained from BVICKs photometry alone. We also derive a helium abundance for the Pleiades of Y=0.279±0.015, which is equal within the errors to the Sun's initial helium abundance and that of the Hyades. Our best estimates of distances are (m-M)0=6.33±0.04,8.03±0.04, and 9.61±0.03 to Praesepe, NGC 2516, and M67, respectively. Our Pleiades distance at the spectroscopic metallicity,(m-M)0=5.66±0.01(internal)±0.05(systematic), is in excellent agreement with several geometric distance measurements. We have made calibrated isochrones for -0.3≤[Fe/H]≤+0.2 available online.

Item Type:Article
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URLURL TypeDescription
Pinsonneault, Marc H.0000-0002-7549-7766
Stauffer, John R.0000-0003-3595-7382
Additional Information:© 2007. The American Astronomical Society. Received 2006 July 20; accepted 2006 September 21. We are greatly indebted to Jennifer Johnson for her detailed and thoughtful reading of the first draft of this paper. Many suggestions by Constantine Deliyannis are gratefully acknowledged. We also thank Andrew Gould for useful discussions on the proper motion of cluster members and Hwankyung Sung for detailed description on his photometry. The work reported here was partially supported by grants AST 02-06008 and AST 02-05789 from the National Science Foundation to the Ohio State Research Foundation and with funds provided by the Ohio State University Department of Astronomy. D. B. P. acknowledges support from the NASA Postdoctoral Program, which is administered by the Oak Ridge Associated Universities. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
NSFAST 02-06008
NSFAST 02-05789
Ohio State UniversityUNSPECIFIED
Subject Keywords:Hertzsprung-Russell diagram—open clusters and associations: individual (M67, NGC 2516, Pleiades, Praesepe)—stars: abundances—stars: activity—stars: distances—stars: evolution
Issue or Number:1
Record Number:CaltechAUTHORS:ANDapj07
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:12489
Deposited By: Marie Noren
Deposited On:18 Dec 2008 05:11
Last Modified:03 Oct 2019 00:29

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