0.3-2.5微米的恒星SED：追踪恒星轨迹并在SDSS和2 MASS中搜索颜色异常值
Stellar SEDs from 0.3-2.5 Microns: Tracing the Stellar Locus and Searching for Color Outliers in SDSS and 2MASS
摘要：
斯隆数字巡天（SDSS）和2微米全天巡天（2 MASS）是研究恒星天体物理和银河系结构与形成历史的丰富资源。由于新的调查和仪器采用类似的过滤器集，它是越来越重要的了解ugrizJHKs恒星轨迹的属性，既告知研究的“正常”的主序星，以及强大的搜索点源不寻常的颜色。使用SDSS和2 MASS检测到的约600，000个点源样本，我们将ugrizJHKs恒星轨迹的位置和宽度作为g-i颜色的函数列表，并提供准确的多项式拟合。我们映射的摩根-基南光谱类型序列的中位数恒星轨迹，通过使用合成测光的光谱标准，并通过分析3000 SDSS恒星光谱与自定义光谱分型管道。我们开发了一种算法来计算一个点源的最小间距从恒星轨迹在一个七维的颜色空间，并使用它来鲁棒地识别对象与不寻常的颜色，以及虚假的SDSS/2 MASS匹配。对2117个颜色异常值的最终目录的分析确定了370个白矮星/M矮星（WDMD）对，93个类星体和90个M巨星/碳星候选者，并表明WDMD对和类星体可以根据它们的J-Ks和r-z颜色来区分。我们还确定了一组对象与相关的偏移量在u-g与g-r和g-r与r-i颜色-颜色空间，但随后的后续工作是必要的，以揭示这些对象的性质。该算法的未来应用程序相匹配的SDSS-UKIDSS目录可以很好地识别其他类别的物体与不寻常的颜色探测新的领域的颜色幅度空间。
英文摘要：
The Sloan Digital Sky Survey (SDSS) and Two Micron All Sky Survey (2MASS) are rich resources for studying stellar astrophysics and the structure and formation history of the Galaxy. As new surveys and instruments adopt similar filter sets, it is increasingly important to understand the properties of the ugrizJHKs stellar locus, both to inform studies of `normal' main sequence stars as well as for robust searches for point sources with unusual colors. Using a sample of ~600,000 point sources detected by SDSS and 2MASS, we tabulate the position and width of the ugrizJHKs stellar locus as a function of g-i color, and provide accurate polynomial fits. We map the Morgan-Keenan spectral type sequence to the median stellar locus by using synthetic photometry of spectral standards and by analyzing 3000 SDSS stellar spectra with a custom spectral typing pipeline. We develop an algorithm to calculate a point source's minimum separation from the stellar locus in a seven-dimensional color space, and use it to robustly identify objects with unusual colors, as well as spurious SDSS/2MASS matches. Analysis of a final catalog of 2117 color outliers identifies 370 white-dwarf/M dwarf (WDMD) pairs, 93 QSOs, and 90 M giant/carbon star candidates, and demonstrates that WDMD pairs and QSOs can be distinguished on the basis of their J-Ks and r-z colors. We also identify a group of objects with correlated offsets in the u-g vs. g-r and g-r vs. r-i color-color spaces, but subsequent follow-up is required to reveal the nature of these objects. Future applications of this algorithm to a matched SDSS-UKIDSS catalog may well identify additional classes of objects with unusual colors by probing new areas of color-magnitude space.
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