卡门犬在M矮人周围寻找系外行星。半径间隙的两个行星在附近的M矮人LTT 3780

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卡门犬在M矮人周围寻找系外行星。半径间隙的两个行星在附近的M矮人LTT 3780

The CARMENES search for exoplanets around M dwarfs. Two planets on the opposite sides of the radius gap transiting the nearby M dwarf LTT 3780

论文作者

Nowak, G., Luque, R., Parviainen, H., Pallé, E., Molaverdikhani, K., Béjar, V. J. S., Lillo-Box, J., Rodríguez-López, C., Caballero, J. A., Zechmeister, M., Passegger, V. M., Cifuentes, C., Schweitzer, A., Narita, N., Cale, B., Espinoza, N., Murgas, F., Hidalgo, D., Osorio, M. R. Zapatero, Pozuelos, F. J., Aceituno, F. J., Amado, P. J., Barkaoui, K., Barrado, D., Bauer, F. F., Benkhaldoun, Z., Caldwell, D. A., Barris, N. Casasayas, Chaturvedi, P., Chen, G., Collins, K. A., Collins, K. I., Cortés-Contreras, M., Crossfield, I. J. M., de León, J. P., Alonso, E. Díez, Dreizler, S., Mufti, M. El, Esparza-Borges, E., Essack, Z., Fukui, A., Gaidos, E., Gillon, M., Gonzales, E. J., Guerra, P., Hatzes, A., Henning, T., Herrero, E., Hesse, K., Hirano, T., Howell, S. B., Jeffers, S. V., Jehin, E., Jenkins, J. M., Kaminski, A., Kemmer, J., Kielkopf, J. F., Kossakowski, D., Kotani, T., Kürster, M., Lafarga, M., Latham, D. W., Law, N., Lissauer, J. J., Lodieu, N., Madrigal-Aguado, A., Mann, A. W., Massey, B., Matson, R. A., Matthews, E., Montanés-Rodríguez, P., Montes, D., Morales, J. C., Mori, M., Nagel, E., Oshagh, M., Pedraz, S., Plavchan, P., Pollacco, D., Quirrenbach, A., Reffert, S., Reiners, A., Ribas, I., Ricker, G. R., Rose, M. E., Schlecker, M., Schlieder, J. E., Seager, S., Stangret, M., Stock, S., Tamura, M., Tanner, A., Teske, J., Trifonov, T., Twicken, J. D., Vanderspek, R., Watanabe, D., Wittrock, J., Ziegler, C., Zohrabi, F.

论文摘要

我们介绍了通过旋转附近的（d〜22 pc），明亮的（J〜9 mag）M3.5矮人LTT 3780（TOI-732）绕过的两个过渡系外行星（TESS）观察到的两个过渡行星的发现和表征。我们通过基于地面的光度法确认行星及其与LTT 3780的关联，并使用用carmenes光谱仪测量的精确径向速度确定其质量。由Carmenes确定的高分辨率光谱确定的精确恒星参数证实，LTT 3780是Mid-M矮人，有效温度为T_eff = 3360 +\ -51 K，log（G）的表面引力（G）= 4.81 +/- 0.04（CGS），并及其含量为[Fe/H] = 0.09 +/----------------- 0.379 +/- 0.016 m_sun和r_star的半径= 0.382 +/- 0.012 r_sun。半径为1.35^{+0.06} _ { - 0.06} r _earth的半径为1.35^{+0.24^{+0.24} _ { - 0.23} m_earth，质量为2.34} r _earth，Ultra-Short-Period Planet LTT 3780 B（P_B = 0.77 D）的质量为1.35^{+0.06} _ { - 0.06} r _ERTH 5.24^{+0.94} _ { - 0.81} g cm^{ - 3}与岩石，陆地构图一起将地球大小的行星的种群与。外行星，LTT 3780 C，轨道周期为12.25 d，半径为2.42^{+0.10} _ { - 0.10} r _earth，质量为6.29^{+0.63} _ { - 0.61} _ { - 0.61} m_earth，和平均密度为2.45^0.45^{+0.45^{+0.44} cm^{ - 3}属于密集的子纳普人群。由于两个行星位于半径间隙的相对侧，该行星系统是测试行星形成，进化和大气模型的绝佳目标。特别是，LTT 3780 C是James Webb太空望远镜进行大气研究的理想对象。

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 T_eff = 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_star = 0.379 +/- 0.016 M_sun and a radius of R_star = 0.382 +/- 0.012 R_sun. The ultra-short-period planet LTT 3780 b (P_b = 0.77 d) with a radius of 1.35^{+0.06}_{-0.06} R_earth, a mass of 2.34^{+0.24}_{-0.23} M_earth, and a bulk density of 5.24^{+0.94}_{-0.81} 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_earth, mass of 6.29^{+0.63}_{-0.61} M_earth, and mean density of 2.45^{+0.44}_{-0.37} 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 an excellent 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.

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