Details

Autor(en) / Beteiligte

• Almenara, J. M.
• Bonfils, X.
• Otegi, J. F.
• Attia, O.
• Turbet, M.
• Astudillo-Defru, N.
• Collins, K. A.
• Polanski, A. S.
• Bourrier, V.
• Hellier, C.
• Ziegler, C.
• Bouchy, F.
• Briceno, C.
• Charbonneau, D.
• Cointepas, M.
• Collins, K. I.
• Crossfield, I.
• Delfosse, X.
• Diaz, R. F.
• Dorn, C.
• Doty, J. P.
• Forveille, T.
• Gaisné, G.
• Gan, T.
• Helled, R.
• Hesse, K.
• Jenkins, J. M.
• Jensen, E. L. N.
• Latham, D. W.
• Law, N.
• Mann, A. W.
• Mao, S.
• McLean, B.
• Murgas, F.
• Myers, G.
• Seager, S.
• Shporer, A.
• Tan, T. G.
• Twicken, J. D.
• Winn, J.

Titel

GJ 3090 b: one of the most favourable mini-Neptune for atmospheric characterisation

Ist Teil von

• Astronomy and astrophysics (Berlin), 2022-09, Vol.665, p.A91

Ort / Verlag

EDP Sciences

Erscheinungsjahr

2022

Link zum Volltext

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• 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 M E , a radius of 2.13 ± 0.11 R E , 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 M E , whose transits are not detected.