揭开Sco-Cen中K型恒星的宽轨道伴星与Gaia EDR3
Unveiling wide-orbit companions to K-type stars in Sco-Cen with Gaia EDR3
摘要：
缩写。我们的目标是使用盖亚太空任务提供的天体测量和补充VLT/SPHERE数据来识别年轻恒星的新的低质量同伴。我们确定伴侣候选人的样本K型，前主序星在天蝎座半人马座协会使用的早期版本的第三次数据发布的盖亚空间任务。基于所提供的位置，自行，和幅度，我们确定在一个预定义的半径，其微分自行与引力约束系统一致的所有对象。我们通过与进化轨迹的比较得出了伴随质量。对于七个确定的伴星候选者，我们使用VLT/SPHERE和VLT/NACO收集的额外数据来评估仅基于盖亚测光的伴星属性的准确性。我们确定了110个共动的同伴，有一个陪伴的可能性超过$95\,\%$。我们确定了十个特别有趣的同伴，在褐矮星制度的质量下降到$20\,M_\mathrm{Jup}$。我们的高对比度成像数据证实了仅来自盖亚的天体测量和光度测量质量。我们发现了一个新的褐矮星伴星TYC 8252-533-1 B，与它的类太阳主星的投影距离大约为$570\,\mathrm{au}$。SED建模提供了$52^{+17}_{-11}\,M_\mathrm{Jup}$的伴随质量。我们表明，盖亚数据库可以识别低质量的同伴在广泛的分离，从他们的主恒星。对于K型天蝎座-半人马座成员，盖亚可以探测到投影距离大于$300\,\mathrm{au}$的亚恒星物体，并且灵敏度限制在$1,000\,\mathrm{au}$之外，质量下限低至$20\,M_\mathrm{Jup}$。对其他恒星形成区进行类似的分析可以大大扩大这类天体的样本量，并检验行星系的形成和演化理论。
英文摘要：
Abbreviated. We aim to identify new low-mass companions to young stars using the astrometric measurements provided by the Gaia space mission and complementary VLT/SPHERE data. We identify companion candidates from a sample of K-type, pre-main sequence stars in the Scorpius Centaurus association using the early version of the third data release of the Gaia space mission. Based on the provided positions, proper motions, and magnitudes, we identify all objects within a predefined radius whose differential proper motions are consistent with a gravitationally bound system. We derive companion masses through comparison with evolutionary tracks. For seven identified companion candidates we use additional data collected with VLT/SPHERE and VLT/NACO to assess the accuracy of the properties of the companions based on Gaia photometry alone. We identify 110 comoving companions that have a companionship likelihood of more than $95\,\%$. We identify ten especially intriguing companions that have masses in the brown dwarf regime down to $20\,M_\mathrm{Jup}$. Our high-contrast imaging data confirm both astrometry and photometric masses derived from Gaia alone. We discover a new brown dwarf companion, TYC 8252-533-1 B, with a projected separation of approximately $570\,\mathrm{au}$ from its Sun-like primary. SED modeling provides a companion mass of $52^{+17}_{-11}\,M_\mathrm{Jup}$. We show that the Gaia database can identify low-mass companions at wide separations from their host stars. For K-type Sco-Cen members Gaia can detect sub-stellar objects at projected separations larger than $300\,\mathrm{au}$ and is sensitivity limited beyond $1,000\,\mathrm{au}$ with a lower mass limit down to $20\,M_\mathrm{Jup}$. A similar analysis of other star-forming regions could significantly enlarge the sample size of such objects and test formation and evolution theories of planetary systems.
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