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arXiv 1602.07582astro-ph.SRastro-ph.EP
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在过渡盘天体中寻找光谱双星

Searching for spectroscopic binaries within transition disk objects

Saul A. Kohn, Evgenya L. Shkolnik, Alycia J. Weinberger, Joleen K. Carlberg, Joe Llama

摘要:

过渡盘(TD)是中间阶段的拱星盘,其特征在于盘结构内的内部间隙。为了测试这些间隙是否可能是由近距离轨道运行的、以前未被发现的恒星伴星形成的,我们收集了31个TD天体的高分辨率光谱,以寻找光谱双星(SB)。其中24个天体位于蛇夫座,7个位于冕座、南冕座和变色龙I恒星形成区。我们测量了多个时期的径向速度,获得了400 ms $^{-1}$的中位精度。我们在蛇夫座发现了双线SB SSTc 2d J163154.7-250324,我们确定它由一颗K7($\pm$ 0.5)和一颗K9($\pm$ 0.5)恒星组成,轨道极限为$a<$ 0.6 AU和$P<$ 150天。这导致蛇夫座的SB分数为0.04 $^{+0.12}_{-0.03}$,这与该地区其他非TD天体的光谱调查一致。这种相似性表明,TDs并不是由密近双星的存在而优先塑造的,并且密近双星周围的行星形成可能发生在与单星周围相似的时间尺度上。

英文摘要:

Transition disks (TDs) are intermediate stage circumstellar disks characterized by an inner gap within the disk structure. To test whether these gaps may have been formed by closely orbiting, previously undetected stellar companions, we collected high-resolution optical spectra of 31 TD objects to search for spectroscopic binaries (SBs). Twenty-four of these objects are in Ophiuchus and seven are within the Coronet, Corona Australis, and Chameleon I star-forming regions. We measured radial velocities for multiple epochs, obtaining a median precision of 400 ms$^{-1}$. We identified double-lined SB SSTc2d J163154.7-250324 in Ophiuchus, which we determined to be composed of a K7($\pm$0.5) and a K9($\pm$0.5) star, with orbital limits of $a<$0.6 AU and $P<$150 days. This results in an SB fraction of 0.04$^{+0.12}_{-0.03}$ in Ophiuchus, which is consistent with other spectroscopic surveys of non-TD objects in the region. This similarity suggests that TDs are not preferentially sculpted by the presence of close binaries and that planet formation around close binaries may take place over similar timescales to that around single stars.

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