arXiv 1409.47752014-09-16astro-ph.SRastro-ph.GA

最好的和明亮的贫金属星

The Best and Brightest Metal-Poor Stars

Kevin C. Schlaufman, Andrew R. Casey

备注：: 28 pages, 6 figures, and 4 tables in emulateapj format; accepted for publication in ApJ
DOI：: 10.1088/0004-637X/797/1/13

摘要：

大样本的极贫金属（EMP）恒星的化学丰度可以用来研究无金属的恒星星族，超新星和核合成，以及银河系及其祖先晕的形成和星系化学演化。然而，目前EMP星的研究进展受到其微弱视星等的限制。获取微弱EMP星的高信噪比光谱需要大量的望远镜时间承诺，使得建造EMP星丰度的大样本成本过高。我们已经开发出一种新的，有效的选择，只使用公共的，全天空的APASS光学，2MASS近红外和WISE中红外测光，通过它们在4.6微米附近缺乏分子吸收来识别明亮的贫金属恒星候选者。我们已经用我们的选择识别了11，916颗V <14的贫金属恒星候选者，在这个星等范围内，公众可获得的候选者数量增加了五倍以上。它们明亮的视星等极大地简化了高分辨率的后续观测，这些观测已经确定了7颗[Fe/H]<~-3.0的未知恒星。我们的后续活动显示3.8 ^{+1.3}-1.1}%的候选人[Fe/H]<~-3.0，32.5 ^{+3.0}-2.9}%的候选人[Fe/H]<~-2.0。隆起是任何现有的银河系第三星族恒星最有可能的位置，我们选择的一个只有红外线的变体非常适合于识别隆起中的贫金属恒星。事实上，我们确认的两颗贫金属恒星[Fe/H]<~-2.7，距离银河系中心约2千秒差距。它们是已知的核球中最贫金属的恒星之一。

英文摘要：

The chemical abundances of large samples of extremely metal-poor (EMP) stars can be used to investigate metal-free stellar populations, supernovae, and nucleosynthesis as well as the formation and galactic chemical evolution of the Milky Way and its progenitor halos. However, current progress on the study of EMP stars is being limited by their faint apparent magnitudes. The acquisition of high signal-to-noise spectra for faint EMP stars requires a major telescope time commitment, making the construction of large samples of EMP star abundances prohibitively expensive. We have developed a new, efficient selection that uses only public, all-sky APASS optical, 2MASS near-infrared, and WISE mid-infrared photometry to identify bright metal-poor star candidates through their lack of molecular absorption near 4.6 microns. We have used our selection to identify 11,916 metal-poor star candidates with V < 14, increasing the number of publicly-available candidates by more than a factor of five in this magnitude range. Their bright apparent magnitudes have greatly eased high-resolution follow-up observations that have identified seven previously unknown stars with [Fe/H] <~ -3.0. Our follow-up campaign has revealed that 3.8^{+1.3}_{-1.1}% of our candidates have [Fe/H] <~ -3.0 and 32.5^{+3.0}_{-2.9}% have -3.0 <~ [Fe/H] <~ -2.0. The bulge is the most likely location of any existing Galactic Population III stars, and an infrared-only variant of our selection is well suited to the identification of metal-poor stars in the bulge. Indeed, two of our confirmed metal-poor stars with [Fe/H] <~ -2.7 are within about 2 kpc of the Galactic Center. They are among the most metal-poor stars known in the bulge.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

摘要：

英文摘要：

相关论文