Author:
Bonfanti A.,Brady M.,Wilson T.G.,Venturini J.,Egger J.A.,Brandeker A.,Sousa S.G.,Lendl M.,Simon A.E.,Queloz D.,Olofsson G.,Adibekyan V.,Alibert Y.,Fossati L.,Hooton M.J.,Kubyshkina D.,Luque R.,Murgas F.,Mustill A.J.,Santos N.C.,Van Grootel V.,Alonso R.,Asquier J.,Bandy T.,Bárczy T.,Barrado Navascues D.,Barros S.C.,Baumjohann W.,Bean J.,Beck M.,Beck T.,Benz W.,Bergomi M.,Billot N.,Borsato L.,Broeg C.,Collier Cameron A.,Csizmadia Sz.,Cubillos P.E.,Davies M.B.,Deleuil M.,Deline A.,Delrez L.,Demangeon O.D.S.,Demory B.-O.,Ehrenreich D.,Erikson A.,Fortier A.,Fridlund M.,Gandolfi D.,Gillon M.,Güdel M.,Günther M.N.,Heitzmann A.,Helling Ch.,Hoyer S.,Isaak K.G.,Kasper D.,Kiss L.,Lam K.W.F.,Laskar J.,Lecavelier des Etangs A.,Magrin D.,Maxted P.F.L.,Mordasini C.,Nascimbeni V.,Ottensamer R.,Pagano I.,Pallé E.,Peter G.,Piotto G.,Pollacco D.,Ragazzoni R.,Rando N.,Rauer H.,Ribas I.,Scandariato G.,Ségransan D.,Seifahrt A.,Smith A.M.S.,Stalport M.,Stefánsson G.,Steinberger M.,Stürmer J.,Szabó M. Gy.,Thomas N.,Udry S.,Villaver E.,Walton N.A.,Westerdorff K.,Zingales T.
Abstract
TOI-732 is an M dwarf hosting two transiting planets that are located on the two opposite sides of the radius valley. Inferring a reliable demographics for this type of systems is key to understanding their formation and evolution mechanisms. By doubling the number of available space-based observations and increasing the number of radial velocity (RV) measurements, we aim at refining the parameters of TOI-732\,b and c. We also use the results to study the slope of the radius valley and the density valley for a well-characterised sample of M-dwarf exoplanets. We performed a global Markov chain Monte Carlo analysis by jointly modelling ground-based light curves and CHEOPS and TESS observations, along with RV time series both taken from the literature and obtained with the MAROON-X spectrograph. The slopes of the M-dwarf valleys were quantified via a support vector machine (SVM) procedure. TOI-732\,b is an ultrashort-period planet $ d) with a radius $R_b=1.325_ oplus $, a mass $M_b=2.46 oplus $, and thus a mean density $ $, while the outer planet at $P=12.252284 d has oplus $, $M_c=8.04_ oplus $, and thus $ $. Even with respect to the most recently reported values, this work yields uncertainties on the transit depths and on the RV semi-amplitudes that are smaller up to a factor of sim \,1.6 and sim \,2.4 for TOI-732\,b and c, respectively. Our calculations for the interior structure and the location of the planets in the mass-radius diagram lead us to classify TOI-732\,b as a super-Earth and TOI-732\,c as a mini-Neptune. Following the SVM approach, we quantified $ $, which is flatter than for Sun-like stars. In line with former analyses, we note that the radius valley for M-dwarf planets is more densely populated, and we further quantify the slope of the density valley as $ Compared to FGK stars, the weaker dependence of the position of the radius valley on the orbital period might indicate that the formation shapes the radius valley around M dwarfs more strongly than the evolution mechanisms.
Funder
ERC
SNSF
SNSA
CRT
European Union
CNES
Deutsche Forschungsgemeinschaft
Agence Nationale pour la Recherche
STFC
NASA
city of Szombathely
UKSA
Universidad de La Laguna
Spanish Ministry of Universities
EU Next Generation
Spanish Ministry of Economics and Competitiveness
JSPS KAKENHI
JSPS
JST PRESTO
NAOJ
National Science Foundation Graduate Research Fellowship
NKFIH
Hungarian Academy of Science
nccr planets
Swedish National Space Agency
FCT
Swiss National Science Foundation
Swiss Space Office
Simons Foundation
Agencia Estatal de Investigación of the Ministerio de Ciencia e Innovación
ERDF
Centre of Excellence “Severo Ochoa”
Centre of Excellence “María de Maeztu”
CHEOPS ASI-INAF
Austrian Science Fund
BELSPO
Université de Liège
FEDER
SERI
Subject
Space and Planetary Science,Astronomy and Astrophysics