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    A UvbyCa Hβ ANALYSIS OF THE OLD OPEN CLUSTER, NGC 6819

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    Twarog_CaH_analysis2014.pdf (1.156Mb)
    Issue Date
    2014-09
    Author
    Anthony-Twarog, Barbara
    Deliyannis, Constantine P.
    Twarog, Bruce A.
    Publisher
    American Astronomical Society
    Type
    Article
    Article Version
    Scholarly/refereed, publisher version
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    Abstract
    NGC 6819 is a richly populated, older open cluster situated within the Kepler field. A CCD survey of the cluster on the uvbyCaHβ system, coupled with proper-motion membership, has been used to isolate 382 highly probable, single-star unevolved main-sequence members over a 20' field centered on the cluster. From 278 F dwarfs with high precision photometry in all indices, a mean reddening of E(b – y) = 0.117 ± 0.005 or E(B – V) = 0.160 ± 0.007 is derived, where the standard errors of the mean include both internal errors and the photometric zero-point uncertainty. With the reddening fixed, the metallicity derived from the same 278 stars is [Fe/H] = –0.116 ± 0.101 from m 1 and –0.055 ± 0.033 from hk, for a weighted average of [Fe/H] = –0.06 ± 0.04, where the quoted standard errors of the mean include the internal errors from the photometric scatter plus the uncertainty in the photometric zero points. If metallicity is derived using individual reddening values for each star to account for potential reddening variation across the face of the cluster, the analogous result is unchanged. The cluster members at the turnoff of the color-magnitude diagram are used to test and confirm the recently discovered variation in reddening across the face of the cluster, with a probable range in the variation of ΔE(B – V) = 0.045 ± 0.015. With the slightly higher reddening and lower [Fe/H] compared to commonly adopted values, isochrone fitting leads to an age of 2.3 ± 0.2 Gyr for an apparent modulus of (m – M) = 12.40 ± 0.12.
    Description
    This is the published version. Copyright © 2014. The American Astronomical Society. All rights reserved.
    URI
    http://hdl.handle.net/1808/19285
    DOI
    https://doi.org/10.1088/0004-6256/148/3/51
    Collections
    • Physics & Astronomy Scholarly Works [1713]
    Citation
    Anthony-Twarog, Barbara J., Constantine P. Deliyannis, and Bruce A. Twarog. "A UvbyCa Hβ ANALYSIS OF THE OLD OPEN CLUSTER, NGC 6819." The Astronomical Journal 148.3 (2014): 51. http://dx.doi.org/10.1088/0004-6256/148/3/51

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    KU Libraries
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    785-864-8983

    KU Libraries
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    Lawrence, KS 66045
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    Contact KU ScholarWorks
    785-864-8983
    KU Libraries
    1425 Jayhawk Blvd
    Lawrence, KS 66045
    785-864-8983

    KU Libraries
    1425 Jayhawk Blvd
    Lawrence, KS 66045
    Image Credits
     

     

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