Planetesimals around stars with TESS (PAST) – II. An M dwarf ‘dipper’ star with a long-lived disc in the TESS continuous viewing zone
Planetesimals around stars with TESS (PAST) – II. An M dwarf ‘dipper’ star with a long-lived disc in the TESS continuous viewing zone
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围绕恒星运行的微行星与 TESS (PAST) — II。
DOI：
10.1093/mnras/stac1433
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发表时间：
2022
影响因子：
4.8
通讯作者：
LaCourse, Daryll
中科院分区：
文献类型：
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作者：
Gaidos, Eric;Mann, Andrew W;Rojas-Ayala, Bárbara;Feiden, Gregory A;Wood, Mackenna L;Narayanan, Suchitra;Ansdell, Megan;Jacobs, Tom;LaCourse, Daryll
对金牛座T盘的研究为行星形成理论提供了信息；对星周尘埃掩星引起的变化的观测是对未解之谜的有用探测，形成行星的内盘，特别是在暗淡的M矮星周围。我们报告了对m0632的观测，它是船底座年轻移动群的一个M矮星成员，是由凌日系外行星测量卫星在两个1年的间隔中观测到的。合并后的光曲线包含了bb300个变暗事件，每个变暗事件持续数小时，深度达40%（0.55等）。这些随机事件与一个独特的、稳定的1.86 d周期信号相关，这个信号可能是恒星旋转。同时，基于地面的多波段光度测量显示与星际介质状尘埃一致的变红。这颗恒星的红外辐射以及光学和红外光谱的发射线显示，它周围有一个类似金牛座T的吸积盘。通过对星系空间运动和位置的贝叶斯分析，我们确认了2M0632属于船底座星系群。我们结合了恒星演化模型，结合了对亮度、亮度和光球层中可探测到的锂的限制，将该团和2M0632的年龄限制在40-60 Myr之间，与先前的估计一致。2M0632加入了少数几个长寿命星盘的行列，它们挑战了星盘寿命小于10myr的标准。所有已知的例子都围绕着M矮星，这表明这些恒星较低的x射线/紫外线照射和较慢的光蒸发可以显著地影响盘的演化。由长寿命盘片产生的多行星系统可能经历了显著的轨道阻尼和向近距离共振轨道的迁移，可能以TRAPPIST-1系统为代表。
Studies of T Tauri discs inform planet formation theory; observations of variability due to occultation by circumstellar dust are a useful probe of unresolved, planet-forming inner discs, especially around faint M dwarf stars. We report observations of 2M0632, an M dwarf member of the Carina young moving group that was observed byTransiting Exoplanet Survey Satelliteover two 1-yr intervals. The combined light curve contains >300 dimming events, each lasting a few hours, and as deep as 40 per cent (0.55 magnitudes). These stochastic events are correlated with a distinct, stable 1.86-d periodic signal that could be stellar rotation. Concurrent ground-based, multiband photometry show reddening consistent with interstellar medium-like dust. The star’s excess emission in the infrared and emission lines in optical and infrared spectra reveal a T Tauri-like accretion disc around the star. We confirm membership of 2M0632 in the Carina group by a Bayesian analysis of its Galactic space motion and position. We combine stellar evolution models withGaiaphotometry and constraints onTeff, luminosity, and the absence of detectable lithium in the photosphere to constrain the age of the group and 2M0632 to 40–60 Myr, consistent with earlier estimates. 2M0632 joins a handful of long-lived discs which challenge the canon that disc lifetimes are ≲10 Myr. All known examples surround M dwarfs, suggesting that lower X-ray/ultraviolet irradiation and slower photoevaporation by these stars can dramatically affect disc evolution. The multiplanet systems spawned by long-lived discs probably experienced significant orbital damping and migration into close-in, resonant orbits, and perhaps represented by the TRAPPIST-1 system.