Volume 619, November 2018
|Number of page(s)||10|
|Section||Letters to the Editor|
|Published online||22 November 2018|
Letter to the Editor
TESS’s first planet
A super-Earth transiting the naked-eye star π Mensae⋆
Dipartimento di Fisica, Università degli Studi di Torino, Via Pietro Giuria 1, 10125
2 Department of Astronomy, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
3 Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, 439 92 Onsala, Sweden
4 Leiden Observatory, University of Leiden, PO Box 9513, 2300 RA Leiden, The Netherlands
5 Stellar Astrophysics Centre, Deparment of Physics and Astronomy, Aarhus University, Ny Munkegrade 120, 8000 Aarhus C, Denmark
6 Astronomy Department and Van Vleck Observatory, Wesleyan University, Middletown, CT 06459, USA
7 Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, 8041 Graz, Austria
8 Departamento de Astrofísica, Universidad de La Laguna, 38206 Tenerife, Spain
9 Instituto de Astrofísica de Canarias, C/ Vía Láctea s/n, 38205 La Laguna, Tenerife, Spain
10 Rheinisches Institut für Umweltforschung, Abteilung Planetenforschung an der Universität zu Köln, Aachener Strasse 209, 50931 Köln, Germany
11 Institute of Planetary Research, German Aerospace Center, Rutherfordstrasse 2, 12489 Berlin, Germany
12 IRFU, CEA, Université Paris-Saclay, 91191 Gif-sur-Yvette, France
13 Université Paris Diderot, AIM, Sorbonne Paris Cité, CEA, CNRS, 91191 Gif-sur-Yvette, France
14 Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Princeton, NJ 08544, USA
15 Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenberg, Germany
16 Department of Astronomy and McDonald Observatory, University of Texas at Austin, 2515 Speedway, Stop C1400 Austin, TX 78712, USA
Accepted: 28 September 2018
We report on the confirmation and mass determination of π Men c, the first transiting planet discovered by NASA’s TESS space mission. π Men is a naked-eye (V = 5.65 mag), quiet G0 V star that was previously known to host a sub-stellar companion (π Men b) on a longperiod (Porb = 2091 days), eccentric (e = 0.64) orbit. Using TESS time-series photometry, combined with Gaia data, published UCLES at AAT Doppler measurements, and archival HARPS at ESO-3.6m radial velocities, we found that π Men c is a close-in planet with an orbital period of Porb = 6.27 days, a mass of Mc = 4.52 ± 0.81 M⊕, and a radius of Rc = 2.06 ± 0.03 R⊕. Based on the planet’s orbital period and size, π Men c is a super-Earth located at, or close to, the radius gap, while its mass and bulk density suggest it may have held on to a significant atmosphere. Because of the brightness of the host star, this system is highly suitable for a wide range of further studies to characterize the planetary atmosphere and dynamical properties. We also performed an asteroseismic analysis of the TESS data and detected a hint of power excess consistent with the seismic values expected for this star, although this result depends on the photometric aperture used to extract the light curve. This marginal detection is expected from pre-launch simulations hinting at the asteroseismic potential of the TESS mission for longer, multi-sector observations and/or for more evolved bright stars.
Key words: planetary systems / planets and satellites: detection / planets and satellites: fundamental parameters / planets and satellites: terrestrial planets / stars: fundamental parameters
The entire RV data (Tables A.1, A.3 and full Table A.2) are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (220.127.116.11) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/619/L10
© ESO 2018
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