Habitable Zones & Global Climate

Spectroscopic Monitoring Of M dwarf Gl 514. A Super-Earth On An Eccentric Orbit Moving In And Out Of The Habitable Zone

By Keith Cowing
April 14, 2022
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Spectroscopic Monitoring Of M dwarf Gl 514. A Super-Earth On An Eccentric Orbit Moving In And Out Of The Habitable Zone
Schematic representation of a few possible orbits for planet Gl 514 b (blue ellipses), randomly selected taking into account the parameter values and their errors of our adopted solution (Table 5, second column). The best-fit orbit is shown with a dashed black line. The red star identify one of the foci of the ellipses occupied by the host star Gl 514 b, and the green annulus corresponds to the conservative habitable zone.

We investigated the presence of planetary companions around the nearby (7.6 pc) and bright (V=9 mag) early-type M dwarf Gl 514, analysing 540 radial velocities collected over nearly 25 years with the HIRES, HARPS, and CARMENES spectrographs.

The data are affected by time-correlated signals at the level of 2-3 ms−1 due to stellar activity, that we filtered out testing three different models based on Gaussian process regression. As a sanity cross-check, we repeated the analyses using HARPS radial velocities extracted with three different algorithms. We used HIRES radial velocities and Hipparcos-Gaia astrometry to put constraints on the presence of long-period companions, and we analysed TESS photometric data.

We found strong evidence that Gl 514 hosts a super-Earth on a likely eccentric orbit, residing in the conservative habitable zone for nearly 34% of its orbital period. The planet Gl 514 b has minimum mass mbsinib=5.2±0.9 MEarth, orbital period Pb=140.43±0.41 days, and eccentricity eb=0.45+0.15−0.14. No evidence for transits is found in the TESS light curve. There is no evidence for a longer period companion in the radial velocities and, based on astrometry, we can rule out a ∼0.2 MJup planet at a distance of ∼3−10 au, and massive giant planets/brown dwarfs out to several tens of au.

We discuss the possible presence of a second low-mass companion at a shorter distance from the host than Gl 514 b. Gl 514 b represents an interesting science case to study the habitability of planets on eccentric orbits.

We advocate for additional spectroscopic follow-up to get more accurate and precise planetary parameters. Further follow-up is also needed to investigate sub \ms and shorter period signals.

A Quarter Century of Spectroscopic Monitoring Of The Nearby M dwarf Gl 514. A Super-Earth On An Eccentric Orbit Moving In And Out Of The Habitable Zone

M. Damasso, M. Perger, J. M. Almenara, D. Nardiello, M. Pérez-Torres, A. Sozzetti, N. C. Hara, A. Quirrenbach, X. Bonfils, M. R. Zapatero Osorio, N. Astudillo-Defru, J. I. González Hernández, A. Suárez Mascareño, P. J. Amado, T. Forveille, J. Lillo-Box, Y. Alibert, J. A. Caballero, C. Cifuentes, X. Delfosse, P. Figueira, D. Galadí-Enríquez, A. P. Hatzes, Th. Henning, A. Kaminski, M. Mayor, F. Murgas, D. Montes, M. Pinamonti, A. Reiners, I. Ribas, V. J. S. Béjar, A. Schweitzer, M. Zechmeister

Comments: 34 pages, accepted for publication in Astronomy & Astrophysics
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2204.06376 [astro-ph.EP] (or arXiv:2204.06376v1 [astro-ph.EP] for this version)
Submission history
From: Mario Damasso
[v1] Wed, 13 Apr 2022 13:35:26 UTC (13,686 KB)

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