The CARMENES search for exoplanets around M dwarfs

IF 6.5 2区物理与天体物理

Astronomy & Astrophysics Pub Date : 2020-03-01 DOI:10.1051/0004-6361/202037867

G. Nowak, R. Luque, H. Parviainen, E. Pallé, K. Molaverdikhani, V. Béjar, J. Lillo-Box, C. Rodríguez-López, J. A. Caballero, M. Zechmeister, V. Passegger, C. Cifuentes, A. Schweitzer, N. Narita, B. Cale, N. Espinoza, F. Murgas, D. Hidalgo, M. R. Z. Osorio, F. Pozuelos, F. Aceituno, P. Amado, K. Barkaoui, D. Barrado, F. Bauer, Z. Benkhaldoun, D. Caldwell, N. C. Barris, P. Chaturvedi, Guo-qing Chen, K. Collins, K. Collins, M. Cortés-Contreras, I. Crossfield, J. D. Leon, E. D. Alonso, S. Dreizler, M. E. Mufti, E. Esparza-Borges, Z. Essack, A. Fukui, E. Gaidos, M. Gillon, E. Gonzales, P. Guerra, A. Hatzes, T. Henning, E. Herrero, K. Hesse, T. Hirano, S. Howell, S. Jeffers, E. Jehin, J. Jenkins, A. Kaminski, J. Kemmer, J. Kielkopf, D. Kossakowski, T. Kotani, M. Kürster, M. Lafarga, D. Latham, Nicholas Law, Jack J. Lissauer, N. Lodieu, A. Madrigal-Aguado, A. Mann, B. Massey, R. Matson, E. Matthews, P. Montañés-Rodríguez, D. Montes, J. C. Morales, M. Mori, E. Nagel, M. Oshagh, S. Pedraz, P. Plavchan, D. Pollacco

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引用次数: 10

Abstract

We present the discovery and characterisation of two transiting planets observed by the Transiting Exoplanet Survey Satellite (TESS) orbiting the nearby (d⋆ ≈ 22 pc), bright (J ≈ 9 mag) M3.5 dwarf LTT 3780 (TOI–732). We confirm both planets and their association with LTT 3780 via ground-based photometry and determine their masses using precise radial velocities measured with the CARMENES spectrograph. Precise stellar parameters determined from CARMENES high-resolution spectra confirm that LTT 3780 is a mid-M dwarf with an effective temperature of Teff = 3360 ± 51 K, a surface gravity of log g⋆ = 4.81 ± 0.04 (cgs), and an iron abundance of [Fe/H] = 0.09 ± 0.16 dex, with an inferred mass of M⋆ = 0.379 ± 0.016M⊙ and a radius of R⋆ = 0.382 ± 0.012R⊙. The ultra-short-period planet LTT 3780 b (Pb = 0.77 d) with a radius of 1.35−0.06+0.06 R⊕, a mass of 2.34−0.23+0.24 M⊕, and a bulk density of 5.24−0.81+0.94 g cm−3 joins the population of Earth-size planets with rocky, terrestrial composition. The outer planet, LTT 3780 c, with an orbital period of 12.25 d, radius of 2.42−0.10+0.10 R⊕, mass of 6.29−0.61+0.63 M⊕, and mean density of 2.45−0.37+0.44 g cm−3 belongs to the population of dense sub-Neptunes. With the two planets located on opposite sides of the radius gap, this planetary system is anexcellent target for testing planetary formation, evolution, and atmospheric models. In particular, LTT 3780 c is an ideal object for atmospheric studies with the James Webb Space Telescope (JWST).

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CARMENES 搜寻 M 矮星周围的系外行星

我们介绍了由凌日系外行星巡天卫星（TESS）观测到的两颗凌日行星的发现和特征，它们围绕着附近（d⋆ ≈ 22 pc）明亮（J ≈ 9 mag）的M3.5矮星LTT 3780（TOI-732）运行。我们通过地面光度测量确认了这两颗行星及其与 LTT 3780 的联系，并利用 CARMENES 光谱仪测量的精确径向速度确定了它们的质量。通过 CARMENES 高分辨率光谱测定的精确恒星参数证实，LTT 3780 是一颗中 M 矮星，有效温度为 Teff = 3360 ± 51 K，表面引力为 log g⋆ = 4.81 ± 0.04 (cgs)，铁丰度为 [Fe/H] = 0.09 ± 0.16 dex，推断质量为 M⋆ = 0.379 ± 0.016M⊙，半径为 R⋆ = 0.382 ± 0.012R⊙。超短周期行星LTT 3780 b (Pb = 0.77 d)的半径为1.35-0.06+0.06 R⊕，质量为2.34-0.23+0.24 M⊕，体积密度为5.24-0.81+0.94 g cm-3，加入了地球大小行星的行列。外行星 LTT 3780 c 的轨道周期为 12.25 d，半径为 2.42-0.10+0.10 R⊕，质量为 6.29-0.61+0.63 M⊕，平均密度为 2.45-0.37+0.44 g cm-3，属于高密度亚海王星。由于两颗行星位于半径差距的两侧，这个行星系统是测试行星形成、演化和大气模型的一个极好目标。特别是，LTT 3780 c 是利用詹姆斯-韦伯太空望远镜（JWST）进行大气研究的理想天体。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Astronomy & Astrophysics ASTRONOMY & ASTROPHYSICS-

自引率

27.70%

发文量

期刊介绍： Astronomy & Astrophysics is an international Journal that publishes papers on all aspects of astronomy and astrophysics (theoretical, observational, and instrumental) independently of the techniques used to obtain the results.