TOI-1728b: The Habitable-zone Planet Finder Confirms a Warm Super-Neptune Orbiting an M-dwarf Host
TOI-1728b: The Habitable-zone Planet Finder Confirms a Warm Super-Neptune Orbiting an M-dwarf Host
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DOI：
10.3847/1538-4357/aba0a2
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发表时间：
2020-06
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通讯作者：
S. Kanodia;C. Cañas;G. Stefansson;J. Ninan;L. Hebb;Andrea S. J. Lin;Helen Baran;M. Maney
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作者：
S. Kanodia;C. Cañas;G. Stefansson;J. Ninan;L. Hebb;Andrea S. J. Lin;Helen Baran;M. Maney
我们使用地面测光、近红外多普勒测速和宜居带行星探测器的光谱学相结合的方法，确认了TOI-1728b的行星性质。TOI-1728是一颗古老的、不活跃的M0星，其TEff=K，它拥有一颗凌日的超海王星，其轨道周期为∼3.49天。径向速度、TESS和地面凌日的联合拟合得到行星半径R⊕、质量M⊕和偏心率。我们估计了恒星的性质，并搜索了这颗行星在凌日期间的10830á吸收，以90%的置信度声称探测到了零，上限为1.1%。在类似的气态行星GJ 3470b的行星大气中检测到了更深层次的He 10830ä吸收。TOI-1728b是在M矮星附近发现的最大的超海王星--海王星和质量更大的气态巨行星之间的中间行星类。由于其相对较大的质量和半径，TOI-1728在M矮星系外行星质量-半径图中是一个有价值的数据点，弥合了较轻的海王星大小的行星和已知围绕M矮星运行的较重的木星之间的差距。TOI-1728b的体积密度很低，为g cm−3，围绕着一颗明亮的主星(J∼9.6，V∼12.4)运行，也是从地面和太空传输光谱的一个很有前途的候选者，可以用来约束行星的形成和演化模型。
We confirm the planetary nature of TOI-1728b using a combination of ground-based photometry, near-infrared Doppler velocimetry and spectroscopy with the Habitable-zone Planet Finder. TOI-1728 is an old, inactive M0 star with Teff = K, which hosts a transiting super-Neptune at an orbital period of ∼3.49 days. Joint fitting of the radial velocities and TESS and ground-based transits yields a planetary radius of R⊕, mass M⊕, and eccentricity . We estimate the stellar properties, and perform a search for He 10830 Å absorption during the transit of this planet and claim a null detection with an upper limit of 1.1% with 90% confidence. A deeper level of He 10830 Å absorption has been detected in the planet atmosphere of GJ 3470b, a comparable gaseous planet. TOI-1728b is the largest super-Neptune—the intermediate subclass of planets between Neptune and the more massive gas-giant planets—discovered around an M dwarf. With its relatively large mass and radius, TOI-1728 represents a valuable data point in the M-dwarf exoplanet mass–radius diagram, bridging the gap between the lighter Neptune-sized planets and the heavier Jovian planets known to orbit M dwarfs. With a low bulk density of g cm−3, and orbiting a bright host star (J ∼ 9.6, V ∼ 12.4), TOI-1728b is also a promising candidate for transmission spectroscopy both from the ground and from space, which can be used to constrain planet formation and evolutionary models.