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arXiv 1601.05413astro-ph.GAastro-ph.SR
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化学标记可以工作:纯粹通过化学丰度相似性识别恒星相空间结构

Chemical tagging can work: Identification of stellar phase-space structures purely by chemical-abundance similarity

David W. Hogg, Andrew R. Casey, Melissa Ness, Hans-Walter Rix, Daniel Foreman-Mackey, Sten Hasselquist, Anna Y. Q. Ho, Jon A. Holtzman, Steven R. Majewski, Sara… 展开作者

David W. Hogg, Andrew R. Casey, Melissa Ness, Hans-Walter Rix, Daniel Foreman-Mackey, Sten Hasselquist, Anna Y. Q. Ho, Jon A. Holtzman, Steven R. Majewski, Sarah L. Martell, Szabolcs Meszaros, David L. NIdever, Matthew Shetrone

摘要:

化学标记有望使用详细的丰度测量来识别空间分离的恒星,这些恒星实际上是很久以前一起诞生的(在同一分子云中)。这个想法并没有取得太大的实际成功,大概是因为化学丰度测量中的噪音和不完整性。我们已经成功地大大改善了光谱测量与大炮,它现在已经提供了15个单独的丰度约100,000恒星观察作为APOGEE光谱调查的一部分,精度约0.04 dex。我们测试的化学标记的假设,通过在丰度空间中的集群,并确认它们聚集在相空间。我们确定(通过k-means算法)的15维化学丰度空间的大炮交付的恒星的超密度,并绘制相空间中的相关恒星。我们只使用丰度空间信息(没有位置信息)来识别恒星群。我们发现丰度空间中的团簇确实是相空间中的团簇。我们恢复一些已知的相空间集群,并发现其他有趣的结构。这是有史以来第一个通过纯粹在丰度空间中进行盲搜索来确定测量规模的相空间结构的项目;它验证了大炮提供的丰度测量的精度;未来数据集的前景非常好。

英文摘要:

Chemical tagging promises to use detailed abundance measurements to identify spatially separated stars that were in fact born together (in the same molecular cloud), long ago. This idea has not yielded much practical success, presumably because of the noise and incompleteness in chemical-abundance measurements. We have succeeded in substantially improving spectroscopic measurements with The Cannon, which has now delivered 15 individual abundances for ~100,000 stars observed as part of the APOGEE spectroscopic survey, with precisions around 0.04 dex. We test the chemical-tagging hypothesis by looking at clusters in abundance space and confirming that they are clustered in phase space. We identify (by the k-means algorithm) overdensities of stars in the 15-dimensional chemical-abundance space delivered by The Cannon, and plot the associated stars in phase space. We use only abundance-space information (no positional information) to identify stellar groups. We find that clusters in abundance space are indeed clusters in phase space. We recover some known phase-space clusters and find other interesting structures. This is the first-ever project to identify phase-space structures at survey-scale by blind search purely in abundance space; it verifies the precision of the abundance measurements delivered by The Cannon; the prospects for future data sets appear very good.

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