NGTS-7Ab: an ultrashort-period brown dwarf transiting a tidally locked and active M dwarf
NGTS-7Ab: an ultrashort-period brown dwarf transiting a tidally locked and active M dwarf
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DOI：
10.1093/mnras/stz2496
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发表时间：
2019-06
影响因子：
4.8
通讯作者：
J. Jackman;P. Wheatley;D. Bayliss;S. Gill;S. Hodgkin;M. Burleigh;I. Braker;M. Günther;T. Louden;O. Turner;D. Anderson;C. Belardi;F. Bouchy;J. Briegal;E. Bryant;J. Cabrera;S. Casewell;A. Chaushev;J. Costes;S. Csizmadia;P. Eigmüller;A. Erikson;B. Gänsicke;E. Gillen;M. Goad;J. Jenkins;J. McCormac;M. Moyano;L. Nielsen;D. Pollacco;K. Poppenhaeger;D. Queloz;H. Rauer;L. Raynard;Alexis M. S. Smith;S. Udry;J. Vines;C. Watson;R. West
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文献类型：
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作者：
J. Jackman;P. Wheatley;D. Bayliss;S. Gill;S. Hodgkin;M. Burleigh;I. Braker;M. Günther;T. Louden;O. Turner;D. Anderson;C. Belardi;F. Bouchy;J. Briegal;E. Bryant;J. Cabrera;S. Casewell;A. Chaushev;J. Costes;S. Csizmadia;P. Eigmüller;A. Erikson;B. Gänsicke;E. Gillen;M. Goad;J. Jenkins;J. McCormac;M. Moyano;L. Nielsen;D. Pollacco;K. Poppenhaeger;D. Queloz;H. Rauer;L. Raynard;Alexis M. S. Smith;S. Udry;J. Vines;C. Watson;R. West
我们提出了NGTS-7Ab的发现，一个高质量的棕矮星过境的M矮星，周期为16.2小时，发现作为下一代过境调查（NGTS）的一部分。这是迄今为止褐矮星围绕主序星或前主序星星星运行的最短周期。M星星宿主（NGTS-7A）的年龄大约为5500万年，处于自旋轨道同步状态，我们将其归因于与褐矮星的潮汐相互作用，使星星旋转。宿主星星是磁活动的，在NGTS和后续光变曲线上显示出多个耀斑，我们利用这些耀斑来探测耀斑-星星-黑子的相位关系。主星星星也有一颗M星星伴星，距离为1.13角秒，具有非常相似的自行和系统速度，这表明NGTS-7系统是一个等级三元组。潮汐同步和磁制动的结合预计将推动褐矮星轨道的持续衰变，其剩余寿命仅为5-10百万年。
We present the discovery of NGTS-7Ab, a high-mass brown dwarf transiting an M dwarf with a period of 16.2 h, discovered as part of the Next Generation Transit Survey (NGTS). This is the shortest period transiting brown dwarf around a main or pre-main sequence star to date. The M star host (NGTS-7A) has an age of roughly 55 Myr and is in a state of spin–orbit synchronization, which we attribute to tidal interaction with the brown dwarf acting to spin-up the star. The host star is magnetically active and shows multiple flares across the NGTS and follow-up light curves, which we use to probe the flare–star-spot phase relation. The host star also has an M star companion at a separation of 1.13 arcsec with very similar proper motion and systemic velocity, suggesting that the NGTS-7 system is a hierarchical triple. The combination of tidal synchronisation and magnetic braking is expected to drive on-going decay of the brown dwarf orbit, with a remaining lifetime of only 5–10 Myr.