Status Report

Three Red Suns in the Sky: A Transiting, Terrestrial Planet in a Triple M Dwarf System at 6.9 Parsecs

By SpaceRef Editor
June 26, 2019
Filed under , , ,

Jennifer G. Winters, Amber A. Medina, Jonathan M. Irwin, David Charbonneau, Nicola Astudillo-Defru, Elliott P. Horch, Jason D. Eastman, Eliot Vrijmoet, Todd J. Henry, Hannah Diamond-Lowe, Elaine Winston, Xavier Bonfils, George R. Ricker, Roland Vanderspek, David W. Latham, Sara Seager, Joshua N. Winn, Jon M. Jenkins, St’ephane Udry, Dr. Joseph D. Twicken, Johanna K. Teske, Peter Tenenbaum, Francesco Pepe, Felipe Murgas, Philip S. Muirhead, Jessica Mink, Christophe Lovis, Alan M. Levine, S’ebastien L’epine, Wei-Chun Jao, Christopher E. Henze, G’abor Fur’esz, Thierry Forveille, Pedro Figueira, Gilbert A. Esquerdo, Courtney D. Dressing, Rodrigo F. D’iaz, Xavier Delfosse, Chris J. Burke, Franois Bouchy, Perry Berlind, Jose-Manuel Almenara

(Submitted on 24 Jun 2019)

We present the discovery from TESS data of LTT 1445Ab. At a distance of 6.9 parsecs, it is the second nearest transiting exoplanet system found to date, and the closest one known for which the primary is an M dwarf. The host stellar system consists of three mid-to-late M dwarfs in a hierarchical configuration, which are blended in one TESS pixel. We use follow-up observations from MEarth and the centroid offset analysis in the TESS data validation report to determine that the planet transits the primary star in the system. The planet has a radius 1.35 R_Earth, an orbital period of 5.35882 days, and an equilibrium temperature of 428 K. With radial velocities from HARPS, we place a three-sigma upper mass limit of 8.4 M_Earth on the candidate. The planet provides one of the best opportunities to date for the spectroscopic study of the atmosphere of a terrestrial world. The presence of stellar companions of similar spectral type may facilitate such ground-based studies by providing a calibration source to remove telluric variations. In addition, we present a detailed characterization of the host stellar system. We use high-resolution spectroscopy and imaging to rule out the presence of any other close stellar or brown dwarf companions. Nineteen years of photometric monitoring of A and BC indicates a moderate amount of variability, in agreement with the observed low-level, short-term variability in the TESS light curve data. We derive a preliminary astrometric orbit for the BC pair that reveals an edge-on and eccentric configuration. The presence of a transiting planet in this system raises the possibility that the entire system is co-planar, which implies that the system may have formed from the early fragmentation of an individual protostellar core.

Comments: Submitted to AJ; 21 pages, 8 tables, 7 figures

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

Cite as: arXiv:1906.10147 [astro-ph.EP] (or arXiv:1906.10147v1 [astro-ph.EP] for this version)

Submission history

From: Jennifer Winters  

[v1] Mon, 24 Jun 2019 18:01:07 UTC (2,062 KB)

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