Wide binaries from the H3 survey: the thick disc and halo have similar wide binary fractions
Wide binaries from the H3 survey: the thick disc and halo have similar wide binary fractions
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H3 巡天的宽双星：厚盘和光环具有相似的宽双星分数
DOI：
10.1093/mnras/stac650
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发表时间：
2022
影响因子：
4.8
通讯作者：
Speagle, Joshua S.
中科院分区：
文献类型：
--
作者：
Hwang, Hsiang-Chih;Ting, Yuan-Sen;Conroy, Charlie;Zakamska, Nadia L.;El-Badry, Kareem;Cargile, Phillip;Zaritsky, Dennis;Chandra, Vedant;Han, Jiwon Jesse;Speagle, Joshua S.
由于银河系盘状物和晕状物所处的环境不同，比较盘状物和晕状物中的宽双星是理解宽双星形成和演化的关键。通过使用∼早期发布的数据3，我们在H3调查中搜索可分辨的宽双星伴星，H3调查是一项光谱调查，到目前为止已经汇编了厚盘和晕星的GAI150 000光谱。我们确定了800个高置信度(污染率为4% %)宽的双星和两个可分辨的三元组，双星的分离大多在103Au和105Au之间，最低的[Fe/H]为−2.7.根据它们的银河系运动学，其中33个是晕宽的双星，其中大多数与被吸积的Gaia-香肠-Enceladus星系有关。厚盘中的宽二元组分向低金属度端减少，这与先前对薄盘的发现一致。我们的关键发现是，在固定的[Fe/H]下，晕宽的双星分数与厚盘恒星一致。广泛的二进制分数与α捕获的丰度没有显著的依赖关系。因此，广泛的二元组分主要是由铁的丰度决定的，而不是它们的圆盘或晕的来源，也不是α捕获的丰度。我们的结果表明，形成环境对宽双星分数起主要作用，而不是只适用于盘星的径向迁移等其他过程。
Due to the different environments in the Milky Way’s disc and halo, comparing wide binaries in the disc and halo is key to understanding wide binary formation and evolution. By usingGaiaEarly Data Release 3, we search for resolved wide binary companions in the H3 survey, a spectroscopic survey that has compiled ∼150 000 spectra for thick-disc and halo stars to date. We identify 800 high-confidence (a contamination rate of 4 per cent) wide binaries and two resolved triples, with binary separations mostly between 103and 105au and a lowest [Fe/H] of −2.7. Based on their Galactic kinematics, 33 of them are halo wide binaries, and most of those are associated with the accretedGaia-Sausage-Enceladus galaxy. The wide binary fraction in the thick disc decreases toward the low metallicity end, consistent with the previous findings for the thin disc. Our key finding is that the halo wide binary fraction is consistent with the thick-disc stars at a fixed [Fe/H]. There is no significant dependence of the wide binary fraction on the α-captured abundance. Therefore, the wide binary fraction is mainly determined by the iron abundance, not their disc or halo origin nor the α-captured abundance. Our results suggest that the formation environments play a major role for the wide binary fraction, instead of other processes like radial migration that only apply to disc stars.