Exoplanets & Exomoons

Planetary Companions Orbiting The M Dwarfs GJ 724 And GJ 3988. A CARMENES And IRD Collaboration

By Keith Cowing
Status Report
October 10, 2023
Filed under , , , , , , , , , ,
Planetary Companions Orbiting The M Dwarfs GJ 724 And GJ 3988. A CARMENES And IRD Collaboration
RVs over time for the best model (1P(5 d-ecc) + dSHO-GP28 d) fitted to the HARPS (top) and CARMENES (bottom) RVs of GJ 724. The GP component of the model is plotted as the orange solid line. The black lines show the median of 10 000 samples from the posterior and the grey shaded areas denote the 68 %, 95 %, and 99 % confidence intervals, respectively. Instrumental RV offsets were subtracted from the measurements and the model, and the error bars include the jitter added in quadrature. The residuals after subtracting the median model are shown in the lower panel. — astro-ph.EP

We report the discovery of two exoplanets around the M dwarfs GJ 724 and GJ 3988 using the radial velocity (RV) method. We obtained a total of 153 3.5 m Calar Alto/CARMENES spectra for both targets and measured their RVs and activity indicators.

We also added archival ESO/HARPS data for GJ 724 and infrared RV measurements from Subaru/IRD for GJ 3988. We searched for periodic and stable signals to subsequently construct Keplerian models, considering different numbers of planets, and we selected the best models based on their Bayesian evidence.

Gaussian process (GP) regression was included in some models to account for activity signals. For both systems, the best model corresponds to one single planet. The minimum masses are 10.75+0.96−0.87 and 3.69+0.42−0.41 Earth-masses for GJ 724 b and GJ 3988 b, respectively. Both planets have short periods (P < 10 d) and, therefore, they orbit their star closely (a < 0.05 au). GJ 724 b has an eccentric orbit (e = 0.577+0.055−0.052), whereas the orbit of GJ 3988 b is circular.

The high eccentricity of GJ 724 b makes it the most eccentric single exoplanet (to this date) around an M dwarf. Thus, we suggest a further analysis to understand its configuration in the context of planetary formation and architecture. In contrast, GJ 3988 b is an example of a common type of planet around mid-M dwarfs.

P. Gorrini, J. Kemmer, S. Dreizler, R. Burn, T. Hirano, F. J. Pozuelos, M. Kuzuhara, J. A. Caballero, P. J. Amado, H. Harakawa, T. Kudo, A. Quirrenbach, A. Reiners, I. Ribas, V. J. S. Béjar, P. Chaturvedi, C. Cifuentes, D. Galadí-Enríquez, A. P. Hatzes, A. Kaminski, T. Kotani, M. Kürster, J. H. Livingston, M. J. López González, D. Montes, J. C. Morales, F. Murgas, M. Omiya, E. Pallé, E. Rodríguez, B. Sato, A. Schweitzer, Y. Shan, T. Takarada, L. Tal-Or, M. Tamura, S. Vievard, M. R. Zapatero Osorio, M. Zechmeister

Comments: A&A in press
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2310.05599 [astro-ph.EP](or arXiv:2310.05599v1 [astro-ph.EP] for this version)
Submission history
From: Paula Gorrini
[v1] Mon, 9 Oct 2023 10:35:12 UTC (13,005 KB)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻