NGTS-19b: a high-mass transiting brown dwarf in a 17-d eccentric orbit
NGTS-19b: a high-mass transiting brown dwarf in a 17-d eccentric orbit
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DOI：
10.1093/mnras/stab1459
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发表时间：
2021-05
影响因子：
4.8
通讯作者：
J. Acton;M. Goad;M. Burleigh;S. Casewell;H. Breytenbach;L. Nielsen;Gareth D. Smith;D. Anderson-D.-Anderso
中科院分区：
文献类型：
--
作者：
J. Acton;M. Goad;M. Burleigh;S. Casewell;H. Breytenbach;L. Nielsen;Gareth D. Smith;D. Anderson-D.-Anderso
NGTS-19 b是下一代凌日巡天发现的一颗大质量的凌日褐矮星。我们使用南非天文台的后续测光以及第11部门过境系外行星调查卫星数据，结合CORALIE光谱仪的径向速度测量来精确描述系统。我们发现NGTS-19 b是一颗K星的褐矮星伴星，质量为69.5 ^{+5.7}-5.4}$ MJup，半径为1.034 ^{+0.055}-0.053}$RJup.该系统具有较长的周期（17.84 d）和较高的偏心率（0.3767 ^{+0.0061}_{-0.0061}$）。根据质量和半径推断其年龄为0.46 ^{+0.26}-{-0.15}$ Gyr，但这与由主星星光谱能量分布确定的年龄不一致，表明褐矮星可能是膨胀的。这是不寻常的，因为它的大质量和相对较低的辐射水平将使它更难膨胀。NGTS-19 b增加了小，但越来越多的褐矮星过境主序星，是一个有价值的补充，因为我们开始人口所谓的褐矮星沙漠。
We present the discovery of NGTS-19b, a high-mass transiting brown dwarf discovered by the Next Generation Transit Survey. We investigate the system using follow-up photometry from the South African Astronomical Observatory, as well as sector 11 Transiting Exoplanet Survey Satellite data, in combination with radial velocity measurements from the CORALIE spectrograph to precisely characterize the system. We find that NGTS-19b is a brown dwarf companion to a K-star, with a mass of $69.5 ^{+5.7}_{-5.4}$ MJup and radius of $1.034 ^{+0.055}_{-0.053}$RJup. The system has a reasonably long period of 17.84 d, and a high degree of eccentricity of $0.3767 ^{+0.0061}_{-0.0061}$. The mass and radius of the brown dwarf imply an age of $0.46 ^{+0.26}_{-0.15}$ Gyr, however, this is inconsistent with the age determined from the host star spectral energy distribution, suggesting that the brown dwarf may be inflated. This is unusual given that its large mass and relatively low levels of irradiation would make it much harder to inflate. NGTS-19b adds to the small, but growing number of brown dwarfs transiting main-sequence stars, and is a valuable addition as we begin to populate the so-called brown dwarf desert.