ESPRESSO mass determination of TOI-263b: an extreme inhabitant of the brown dwarf desert
ESPRESSO mass determination of TOI-263b: an extreme inhabitant of the brown dwarf desert
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DOI：
10.1051/0004-6361/202039937
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发表时间：
2021-03
影响因子：
6.5
通讯作者：
E. Pallé;R. Luque;M. Z. Osorio;H. Parviainen;M. Ikoma;H. Tabernero;M. Zechmeister;A. Mustill
中科院分区：
文献类型：
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作者：
E. Pallé;R. Luque;M. Z. Osorio;H. Parviainen;M. Ikoma;H. Tabernero;M. Zechmeister;A. Mustill
TESS任务报告了围绕明亮和附近恒星的大量新的行星系统，可以详细描述行星的性质和大气层。然而，并不是所有有趣的TESS行星都围绕明亮的主恒星运行。TOI-263b是一个被证实的超短周期亚恒星天体，围绕一颗微弱的(V=18.97)M3.5矮星运行0.56天的轨道。用多色光度法研究了TOI-263b的星下性质：确定了TOI-263b的真实半径为0.87±0.21RJ，确定了TOI-263b‘S的性质介于膨胀的海王星和棕矮星之间。TOI-263b占据的轨道周期-半径参数空间是非常独特的，这促使人们进一步描述它的真实性质。我们用三个VLT装置测量了TOI-263的径向速度，并用意式浓缩光谱仪恢复了TOI-263b的质量。我们发现TOI-263b是一颗质量为61.6±4.0MJup的棕矮星。此外，棕矮星的轨道周期与主星的自转周期是同步的，系统相对活跃，可能揭示了恒星与棕矮星的相互作用。所有这些发现表明，该系统的形成历史可能是通过磁盘碎片和后来向近距离轨道的迁移来解释的。如果该系统被发现是不稳定的，TOI-263将是在棕矮星被其母星“吞噬”之前测试迁移机制的一个极好的靶子。
The TESS mission has reported a wealth of new planetary systems around bright and nearby stars amenable for detailed characterizations of planet properties and atmospheres. However, not all interesting TESS planets orbit around bright host stars. TOI-263 b is a validated ultra-short-period substellar object in a 0.56-day orbit around a faint (V = 18.97) M 3.5 dwarf star. The substellar nature of TOI-263 b was explored using multicolor photometry: a true radius of 0.87 ± 0.21 RJ was determined, establishing TOI-263 b ’s nature as somewhere between an inflated Neptune and a brown dwarf. The orbital period-radius parameter space occupied by TOI-263 b is quite unique, which prompted a further characterization of its true nature. Here, we report radial velocity measurements of TOI-263 obtained with three VLT units and the ESPRESSO spectrograph to retrieve the mass of TOI-263 b. We find that TOI-263 b is a brown dwarf with a mass of 61.6 ± 4.0 MJup. Additionally, the orbital period of the brown dwarf is found to be synchronized with the rotation period of the host star, and the system is found to be relatively active, possibly revealing a star–brown dwarf interaction. All these findings suggest that the system’s formation history might be explained via disk fragmentation and a later migration to close-in orbits. If the system is found to be unstable, TOI-263 will be an excellent target to test the migration mechanisms before the brown dwarf becomes “engulfed” by its parent star.