학술논문
TOI-2257 b: A highly eccentric long-period sub-Neptune transiting a nearby M dwarf
Document Type
Working Paper
Author
Schanche, N.; Pozuelos, F. J.; Günther, M. N.; Wells, R. D.; Burgasser, A. J.; Chinchilla, P.; Delrez, L.; Ducrot, E.; Garcia, L. J.; Chew, Y. Gómez Maqueo; Jofré, E.; Rackham, B. V.; Sebastian, D.; Stassun, K. G.; Stern, D.; Timmermans, M.; Barkaoui, K.; Belinski, A.; Benkhaldoun, Z.; Benz, W.; Charbonneau, D.; Christiansen, Jessie L.; Collins, Karen A.; Demory, B. -O.; Dévora-Pajares, M.; de Wit, J.; Dragomir, D.; Dransfield, G.; Furlan, E.; Ghachou, M.; Gillon, M.; Gnilka, C.; Gómez-Muñoz, M. A.; Guerrero, N.; Harris, M.; Heng, K.; Henze, C. E.; Hesse, K.; Howell, S. B.; Jehin, E.; Jenkins, J.; Jensen, Eric L. N.; Kunimoto, M.; Latham, D. W.; Lester, K.; McLeod, Kim K.; Mireles, I.; Murray, C. A.; Niraula, P.; Pedersen, P. P.; Queloz, D.; Quintana, E. V.; Ricker, G.; Rudat, A.; Sabin, L.; Safonov, B.; Schroffenegger, U.; Scott, N.; Seager, S.; Strakhov, I.; Triaud, A. H. M. J.; Vanderspek, R.; Vezie, M.; Winn, J.
Source
A&A 657, A45 (2022)
Subject
Language
Abstract
Thanks to the relative ease of finding and characterizing small planets around M dwarf stars, these objects have become cornerstones in the field of exoplanet studies. The current paucity of planets in long-period orbits around M dwarfs make such objects particularly compelling as they provide clues about the formation and evolution of these systems. In this study, we present the discovery of TOI-2257 b (TIC 198485881), a long-period (35 d) sub-Neptune orbiting an M3 star at 57.8pc. Its transit depth is about 0.4%, large enough to be detected with medium-size, ground-based telescopes. The long transit duration suggests the planet is in a highly eccentric orbit ($e \sim 0.5$), which would make it the most eccentric planet that is known to be transiting an M-dwarf star. We combined TESS and ground-based data obtained with the 1.0-m SAINT-EX, 0.60-m TRAPPIST-North and 1.2-m FLWO telescopes to find a planetary size of 2.2 $R_{\oplus}$ and an orbital period of 35.19 days. In addition, we make use of archival data, high-resolution imaging, and vetting packages to support our planetary interpretation. With its long period and high eccentricity, TOI-2257 b falls in a novel slice of parameter space. Despite the planet's low equilibrium temperature ($\sim$ 256 K), its host star's small size ($R_* = 0.311 \pm{0.015}$) and relative infrared brightness (K$_{mag}$ = 10.7) make it a suitable candidate for atmospheric exploration via transmission spectroscopy.
Comment: 18 pages, 12 figures, 2 appendices, Accepted for publication in Astronomy and Astrophysics
Comment: 18 pages, 12 figures, 2 appendices, Accepted for publication in Astronomy and Astrophysics