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09 November 2021
Article (Scientific journals)
TOI-2257 b: A highly eccentric long-period sub-Neptune transiting a nearby M dwarf
Schanche, N.; Pozuelos, F. J.  ; Günther, M. N. et al.
2022 • In Astronomy and Astrophysics, 657, p. 45
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Keywords :
Astrophysics - Earth and Planetary Astrophysics
Abstract :
[en] 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.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Schanche, N.
Pozuelos, F. J.  
Günther, M. N.
Wells, R. D.
Burgasser, A. J.
Chinchilla, P.
Delrez, Laetitia ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Exotic
Ducrot, Elsa ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Exotic
Garcia, Lionel  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Exotic
Gómez Maqueo Chew, Y.
Jofré, E.
Rackham, B. V.
Sebastian, Daniel ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Exotic
Stassun, K. G.
Stern, David ;  Université de Liège - ULiège > GIGA Platform Genomics
Timmermans, Mathilde ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Exotic
Barkaoui, Khalid ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Exotic
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, Michaël  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Exotic
Gnilka, C.
Gómez-Muñoz, M. A.
Guerrero, N.
Harris, M.
Heng, K.
Henze, C. E.
Hesse, K.
Howell, S. B.
Jehin, Emmanuel  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Origines Cosmologiques et Astrophysiques (OrCa)
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.
More authors (54 more) Less
Language :
English
Title :
TOI-2257 b: A highly eccentric long-period sub-Neptune transiting a nearby M dwarf
Publication date :
01 January 2022
Journal title :
Astronomy and Astrophysics
ISSN :
0004-6361
eISSN :
1432-0746
Publisher :
EDP Sciences, Les Ulis, France
Volume :
657
Pages :
A45
Peer reviewed :
Peer Reviewed verified by ORBi
European Projects :
FP7 - 336480 - SPECULOOS - SPECULOOS: searching for habitable planets amenable for biosignatures detection around the nearest ultra-cool stars
Funders :
CE - Commission Européenne

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