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Almenara, JM, Bonfils, X, Otegi, JF, Attia, O, Turbet, M, Astudillo-Defru, N, Collins, KA, Polanski, AS, Bourrier, V, Hellier, C, Ziegler, C, Bouchy, F, Briceno, C, Charbonneau, D, Cointepas, M, Collins, KI, Crossfield, I, Delfosse, X, Diaz, RF, Dorn, C, Doty, JP, Forveille, T, Gaisne, G, Gan, T, Helled, R, Hesse, K, Jenkins, JM, Jensen, ELN, Latham, DW, Law, N, Mann, AW, Mao, S, McLean, B, Murgas, F, Myers, G, Seager, S, Shporer, A, Tan, TG, Twicken, JD and Winn, J (2022) GJ 3090 b: one of the most favourable mini-Neptune for atmospheric characterisation. Astronomy and Astrophysics: a European journal, 665. ISSN 0004-6361
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Abstract
We report the detection of GJ 3090 b (TOI-177.01), a mini-Neptune on a 2.9-day orbit transiting a bright (K = 7.3 mag) M2 dwarf located at 22 pc. The planet was identified by the Transiting Exoplanet Survey Satellite and was confirmed with the High Accuracy Radial velocity Planet Searcher radial velocities. Seeing-limited photometry and speckle imaging rule out nearby eclipsing binaries. Additional transits were observed with the LCOGT, Spitzer, and ExTrA telescopes. We characterise the star to have a mass of 0.519 ± 0.013 M⊙ and a radius of 0.516 ± 0.016 R⊙. We modelled the transit light curves and radial velocity measurements and obtained a planetary mass of 3.34 ± 0.72 ME, a radius of 2.13 ± 0.11 RE, and a mean density of 1.89−0.45+0.52 g cm−3. The low density of the planet implies the presence of volatiles, and its radius and insolation place it immediately above the radius valley at the lower end of the mini-Neptune cluster. A coupled atmospheric and dynamical evolution analysis of the planet is inconsistent with a pure H–He atmosphere and favours a heavy mean molecular weight atmosphere. The transmission spectroscopy metric of 221−46+66 means that GJ 3090 b is the second or third most favorable mini-Neptune after GJ 1214 b whose atmosphere may be characterised. At almost half the mass of GJ 1214 b, GJ 3090 b is an excellent probe of the edge of the transition between super-Earths and mini-Neptunes. We identify an additional signal in the radial velocity data that we attribute to a planet candidate with an orbital period of 13 days and a mass of 17.1−3.2+8.9 ME, whose transits are not detected.
Item Type: | Article |
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Additional Information: | Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. This article is published in open access under the Subscribe-to-Open model. Subscribe to A&A to support open access publication. |
Subjects: | Q Science > QA Mathematics Q Science > QB Astronomy Q Science > QB Astronomy > QB460 Astrophysics Q Science > QB Astronomy > QB600 Planets. Planetology Q Science > QC Physics |
Divisions: | Faculty of Natural Sciences > School of Chemical and Physical Sciences |
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Depositing User: | Symplectic |
Date Deposited: | 09 Nov 2022 16:28 |
Last Modified: | 09 Nov 2022 16:28 |
URI: | https://eprints.keele.ac.uk/id/eprint/11658 |