期刊
ASTRONOMICAL JOURNAL
卷 132, 期 2, 页码 902-918出版社
IOP PUBLISHING LTD
DOI: 10.1086/505687
关键词
Cepheids; Galaxy : abundances; Galaxy : evolution; stars : abundances
This paper reports on the spectroscopic investigation of 54 Cepheids, deriving parameters and abundances. These Cepheids extend previous samples by about 35% in number and increase the amount of the Galactic disk coverage, especially in the direction of l approximate to 120 degrees. We find that there exists in the Galactic disk at that longitude and at a solar distance of about 3-4 kpc a region that has enhanced abundances, < Fe/H]> approximate to +0.2, with respect to the local region. A simple linear fit to all Cepheid data now extant yields a gradient d[Fe/H]/dR(G) = -0.068 +/- 0.003 dex kpc(-1). After consideration of the spatial abundance inhomogeneities in the sample, we conclude that the best current estimate of the overall gradient is d[Fe/H]/dRG = -0.06 dex kpc(-1).
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