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A hot terrestrial planet orbiting the bright M dwarf L 168-9 unveiled by TESS

N. Astudillo-Defru, R. Cloutier, S. X. Wang, J. Teske, R. Brahm, C. Hellier, G. R. Ricker, R. K. Vanderspek, D. W. Latham, S. Seager, J. N. Winn, J. M. Jenkins, K. A. Collins, Stassun K. G., C. Ziegler, J.-M. Almenara, D. R. Anderson, E. Artigau, X. Bonfils, F. Bouchy, C. Briceño, R. P. Butler, D. Charbonneau, D. M. Conti, J. Crane, I. J. M. Crossfield, M. B. Davies, X. Delfosse, R. F. Díaz, R. Doyon, D. Dragomir, J. D. Eastman, N. Espinoza, Z. Essack, F. Feng, P. Figueira, T. Forveille, T. Gan, A. Glidden, N. Guerrero, R. Hart, T. Henning, E. P. Horch, G. Isopi, J. S. Jenkins, A. Jordán, J. F. Kielkopf, N. M. Law, C. Lovis, F. Mallia, A. W. Mann, J. R. de Medeiros, C. Melo, R. E. Mennickent, L. Mignon, F. Murgas, D. A. Nusdeo, F. Pepe, H. Relles, M. Rose, N. C. Santos, D. Ségransan, S. Shectman, A. Shporer, J. C. Smith, P. Torres-Papaqui, S. Udry, J. G. Winters, G. Zhou

Abstract
We report the detection of a transiting super-Earth-sized planet (R = 1.39 ± 0.09 R) in a 1.4-day orbit around L 168-9 (TOI-134), a bright M1V dwarf (V = 11, K = 7.1) located at 25.15 ± 0.02 pc. The host star was observed in the first sector of the Transiting Exoplanet Survey Satellite (TESS) mission. For confirmation and planet mass measurement purposes, this was followed up with ground-based photometry, seeing-limited and high-resolution imaging, and precise radial velocity (PRV) observations using the HARPS and Magellan/PFS spectrographs. By combining the TESS data and PRV observations, we find the mass of L 168-9 b to be 4.60 ± 0.56 M and thus the bulk density to be 1.74−0.33+0.44 times higher than that of the Earth. The orbital eccentricity is smaller than 0.21 (95% confidence). This planet is a level one candidate for the TESS mission’s scientific objective of measuring the masses of 50 small planets, and it is one of the most observationally accessible terrestrial planets for future atmospheric characterization.

Keywords
stars: individual: L 168-9; planetary systems; stars: late-type; techniques: photometric; techniques: radial velocities; Astrophysics - Earth and Planetary Astrophysics; Astrophysics - Solar and Stellar Astrophysics

Notes
Full Tables B.1 and B.2 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/636/A58.

Partially based on observations made with the HARPS instrument on the ESO 3.6 m telescope under the program IDs 198.C-0838(A), 0101.C-0510(C), and 1102.C-0339(A) at Cerro La Silla (Chile).

This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. NASA Hubble Fellow.

Astronomy and Astrophysics
Volume 636, Article Number A58, Number of pages 13
2020 April

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Instituto de Astrofísica e Ciências do Espaço Universidade do Porto Faculdade de Ciências da Universidade de Lisboa
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia