Faint High-Latitude Carbon Stars Discovered by the Sloan Digital Sky Survey: An Initial Catalog
Faint High-Latitude Carbon Stars Discovered by the Sloan Digital Sky Survey: An Initial Catalog
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DOI：
10.1086/383211
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发表时间：
2004-02
期刊：
影响因子：
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通讯作者：
R. Downes;B. Margon;S. Anderson;H. Harris;G. Knapp;Joshua Schroeder;D. Schneider;D. York;J. Pier;J. Brinkmann
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文献类型：
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作者：
R. Downes;B. Margon;S. Anderson;H. Harris;G. Knapp;Joshua Schroeder;D. Schneider;D. York;J. Pier;J. Brinkmann
斯隆数字巡天对超过3000度2的高纬度天空进行了搜索，发现了251颗微弱的高纬度碳星（FHLCs），其中大部分以前未被编目。我们提出了均匀的光谱学，光度学和天体测量的样品。这些天体位于15.6 < r < 20.8的范围内，表现出各种各样的表观光球温度，从M附近的光谱类型到早于F的光谱类型。对222个天体的自行测量表明，这些天体中至少有50%，很可能超过60%实际上是低光度的矮碳（dC）星，这与最近各种更有限的调查一致，这些调查表明，这些天体是光谱中C2的星星的主要类型。SDSS的这颗110颗dC恒星的均匀样本现在占所有已知碳矮星的90%，并将在调查完成时再增加2-3倍。由于dC星和暗晕巨星C星的光谱非常相似（至少在光谱分辨率为103时），尽管光度相差10等，但必须开发简单的光度判别式而不是自行。我们使用我们的放大样本的FHLCs检查各种可能的光度标准，包括许多以前提出的，并发现，与某些重要的警告，JHK测光可能分离的矮星和巨星。
A search of more than 3000 deg2 of high-latitude sky by the Sloan Digital Sky Survey has yielded 251 faint high-latitude carbon stars (FHLCs), the large majority previously uncataloged. We present homogeneous spectroscopy, photometry, and astrometry for the sample. The objects lie in the 15.6 < r < 20.8 range and exhibit a wide variety of apparent photospheric temperatures, ranging from spectral types near M to as early as F. Proper-motion measurements for 222 of the objects show that at least 50%, and quite probably more than 60%, of these objects are actually low-luminosity dwarf carbon (dC) stars, in agreement with a variety of recent, more limited investigations that show that such objects are the numerically dominant type of star with C2 in the spectrum. This SDSS homogeneous sample of ∼110 dC stars now constitutes 90% of all known carbon dwarfs and will grow by another factor of 2–3 by the completion of the survey. As the spectra of the dC and the faint halo giant C stars are very similar (at least at spectral resolution of 103), despite a difference of 10 mag in luminosity, it is imperative that simple luminosity discriminants other than proper motion be developed. We use our enlarged sample of FHLCs to examine a variety of possible luminosity criteria, including many previously suggested, and find that, with certain important caveats, JHK photometry may segregate dwarfs and giants.