Exoplanets & Exomoons

TOI-2084 b and TOI-4184 b: Two New Sub-Neptunes Around M Dwarf Stars

By Keith Cowing
Status Report
June 28, 2023
Filed under , , , , , ,
TOI-2084 b and TOI-4184 b: Two New Sub-Neptunes Around M Dwarf Stars
TESS target pixel file images of TOI-2084 observed in Sector 16 (left panel) and TOI-4184 observed in Sector 1 (right panel), made by tpfplotter (Aller et al. 2020). Red dots show the location of Gaia DR3 sources, and the red shaded region shows the photometric apertures used to extract the photometric measurements. — astro-ph.EP

We present the discovery and validation of two TESS exoplanets orbiting nearby M dwarfs: TOI-2084b, and TOI-4184b. We characterized the host stars by combining spectra from Shane/Kast and Magellan/FIRE, SED (Spectral Energy Distribution) analysis, and stellar evolutionary models.

In addition, we used Gemini-South/Zorro & -North/Alopeke high-resolution imaging, archival science images, and statistical validation packages to support the planetary interpretation. We performed a global analysis of multi-colour photometric data from TESS and ground-based facilities in order to derive the stellar and planetary physical parameters for each system.

We find that TOI-2084b and TOI-4184b are sub-Neptune-sized planets with radii of Rp = 2.47 +/- 0.13R_Earth and Rp = 2.43 +/- 0.21R_Earth, respectively. TOI-2084b completes an orbit around its host star every 6.08 days, has an equilibrium temperature of T_eq = 527 +/- 8K and an irradiation of S_p = 12.8 +/- 0.8 S_Earth. Its host star is a dwarf of spectral M2.0 +/- 0.5 at a distance of 114pc with an effective temperature of T_eff = 3550 +/- 50 K, and has a wide, co-moving M8 companion at a projected separation of 1400 au. TOI-4184b orbits around an M5.0 +/- 0.5 type dwarf star (Kmag = 11.87) each 4.9 days, and has an equilibrium temperature of T_eq = 412 +/- 8 K and an irradiation of S_p = 4.8 +/- 0.4 S_Earth.

TOI-4184 is a metal poor star ([Fe/H] = -0.27 +/- 0.09 dex) at a distance of 69 pc with an effective temperature of T_eff = 3225 +/- 75 K. Both planets are located at the edge of the sub-Jovian desert in the radius-period plane. The combination of the small size and the large infrared brightness of their host stars make these new planets promising targets for future atmospheric exploration with JWST.

K. Barkaoui, M. Timmermans, A. Soubkiou, B.V. Rackham, A. J. Burgasser, J. Chouqar, F.J. Pozuelos, K.A. Collins, S.B. Howell, R. Simcoe, C. Melis, K.G. Stassun, J. Tregloan-Reed, M. Cointepas, M. Gillon, X. Bonfils, E. Furlan, C.L. Gnilka, J.M. Almenara, R. Alonso, Z. Benkhaldoun, M. Bonavita, F. Bouchy, A. Burdanov, P. Chinchilla, F. Davoudi, L. Delrez, O. Demangeon, M. Dominik, B.-O. Demory, J. de Wit, G. Dransfield, E. Ducrot, A. Fukui, T. C. Hinse, M.J. Hooton, E. Jehin, J. M. Jenkins, U. G. Jørgensen, D. W. Latham, L. Garcia, S. Carrazco-Gaxiola, M. Ghachoui, Y. Gómez Maqueo Chew, M.N. Günther, J. McCormac, F. Murgas, C. A. Murray, N. Narita, P. Niraula, P. P. Pedersen, D. Queloz, R. Rebolo-López, G. Ricker, L. Sabin, S. Sajadian, N. Schanche, R. P. Schwarz, S. Seager, D. Sebastian, R. Sefako, S. Sohy, J. Southworth, G. Srdoc, S. J. Thompson, A. H. M. J. Triaud, R. Vanderspek, R. D. Wells, J. N. Winn, S. Zúñiga-Fernández

Comments: Accepted for publication in A&A
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2306.15095 [astro-ph.EP] (or arXiv:2306.15095v1 [astro-ph.EP] for this version)
Submission history
From: Khalid Barkaoui
[v1] Mon, 26 Jun 2023 22:26:23 UTC (7,660 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) 🖖🏻