Exoplanets & Exomoons

Discovery And Mass Measurement Of The Hot, Transiting, Earth-sized Planet GJ 3929 b

By Keith Cowing
February 3, 2022
Filed under
Discovery And Mass Measurement Of The Hot, Transiting, Earth-sized Planet GJ 3929 b
Results for the CARMENES RV from the joint fit with the transits. The black lines show the median of 10 000 samples from the posterior and the blue shaded areas denote the 68 %, 95 %, and 99 % credibility intervals, respectively. The orange line shows the GP model. Error bars of the measurements include the instrumental jitter added in quadrature. The residuals after subtracting the median models are shown in the lower panels of each plot. Top: RVs over time. Bottom: RVs phase-folded to the periods of the transiting planet (left) and the 14.3 d signal (right)

We report the discovery of GJ 3929 b, a hot Earth-sized planet orbiting the nearby M3.5 V dwarf star, GJ 3929 (G 180–18, TOI-2013).

Joint modelling of photometric observations from TESS sectors 24 and 25 together with 73 spectroscopic observations from CARMENES and follow-up transit observations from SAINT-EX, LCOGT, and OSN yields a planet radius of Rb=1.150+/−0.040 Rearth, a mass of Mb=1.21+/−0.42 Mearth, and an orbital period of Pb=2.6162745+/−0.0000030 d.

The resulting density of ρb=4.4+/−1.6 g/cm−3 is compatible with the Earth’s mean density of about 5.5 g/cm−3. Due to the apparent brightness of the host star (J=8.7 mag) and its small size, GJ 3929 b is a promising target for atmospheric characterisation with the JWST. Additionally, the radial velocity data show evidence for another planet candidate with P[c]=14.303+/−0.035 d, which is likely unrelated to the stellar rotation period, Prot=122+/−13 d, which we determined from archival HATNet and ASAS-SN photometry combined with newly obtained TJO data.

J. Kemmer, S. Dreizler, D. Kossakowski, S. Stock, A. Quirrenbach, J. A. Caballero, P. J. Amado, K. A. Collins, N. Espinoza, E. Herrero, J. M. Jenkins, D. W. Latham, J. Lillo-Box, N. Narita, E. Pallé, A. Reiners, I. Ribas, G. Ricker, E. Rodríguez, S. Seager, R. Vanderspek, R. Wells, J. Winn, F. J. Aceituno, V. J. S. Béjar, T. Barclay, P. Bluhm, P. Chaturvedi, C. Cifuentes, K. I. Collins, M. Cortés-Contreras, B.-O. Demory, M. M. Fausnaugh, A. Fukui, Y. Gómez Maqueo Chew, D. Galadí-Enríquez, T. Gan, M. Gillon, A. Golovin, A. P. Hatzes, T. Henning, C. Huang, S. V. Jeffers, A. Kaminski, M. Kunimoto, M. Kürster, M. J. López-González, M. Lafarga, R. Luque, J. McCormac, K. Molaverdikhani, D. Montes, J. C. Morales, V. M. Passegger, S. Reffert, L. Sabin, P. Schöfer, N. Schanche, M. Schlecker, U. Schroffenegger, R. P. Schwarz, A. Schweitzer, A. Sota, P. Tenenbaum, T. Trifonov, S. Vanaverbeke, M. Zechmeister

Comments: 24 pages; accepted for publication in A&A
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2202.00970 [astro-ph.EP] (or arXiv:2202.00970v1 [astro-ph.EP] for this version)
Submission history
From: Jonas Kemmer
[v1] Wed, 2 Feb 2022 11:31:35 UTC (3,777 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) 🖖🏻