Characterising TOI-732 b and c: New insights into the M-dwarf radius and density valley★,★★
Artikel i vetenskaplig tidskrift, 2024
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. Aims. 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. Methods. 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. Results. TOI-732 b is an ultrashort-period planet (P = 0.76837931−+000000004200000039 days) with a radius Rb = 1.325+−00057058 R☉, a mass Mb = 2.46 ± 0.19 M☉, and thus a mean density ρb = 5.8+−1008 g cm−3, while the outer planet at P = 12.252284 ± 0.000013 days has Rc = 2.39+−001011 R☉, Mc = 8.04+−005048 M☉, and thus ρc = 3.24+−005543 g cm−3. 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 ∼1.6 and ∼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 d log Rp,valley/d log P = −0.065+−00024013, 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 d log ρ̂valley/d log P = −0.02+−001204. Conclusions. 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.
techniques: photometric
techniques: radial velocities
stars: fundamental parameters
planets and satellites: fundamental parameters
Författare
A. Bonfanti
Institut fur Weltraumforschung
M. Brady
University of Chicago
T.G. Wilson
The University of Warwick
J. Venturini
Université de Genève
J. A. Egger
Universität Bern
A. Brandeker
Stockholms universitet
S. G. Sousa
Universidade do Porto
M. Lendl
Université de Genève
A.E. Simon
Universität Bern
D. Queloz
Eidgenössische Technische Hochschule Zürich (ETH)
University of Cambridge
G. Olofsson
Stockholms universitet
V. Adibekyan
Universidade do Porto
Y. Alibert
Universität Bern
L. Fossati
Institut fur Weltraumforschung
M.J. Hooton
University of Cambridge
D. Kubyshkina
Institut fur Weltraumforschung
R. Luque
University of Chicago
F. Murgas
Universidad de la Laguna
Instituto de Astrofísica de Canarias
A. J. Mustill
Lunds universitet
N. C. Santos
Universidade do Porto
V. Van Grootel
Universite de Liège
R. Alonso
Universidad de la Laguna
Instituto de Astrofísica de Canarias
J. Asquier
European Space Research and Technology Centre (ESA ESTEC)
T. Bandy
Universität Bern
T. Bárczy
Admatis
D. Barrado Navascues
Centro de Astrobiologia (CAB)
S.C.C. Barros
Universidade do Porto
W. Baumjohann
Institut fur Weltraumforschung
Jacob L. Bean
University of Chicago
M. Beck
Université de Genève
T. Beck
Universität Bern
W. Benz
Universität Bern
M. Bergomi
Istituto nazionale di astrofisica (INAF)
N. Billot
Université de Genève
L. Borsato
Istituto nazionale di astrofisica (INAF)
C. Broeg
Universität Bern
A. Collier Cameron
University of St Andrews
Szilard Csizmadia
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
P. E. Cubillos
Institut fur Weltraumforschung
Istituto nazionale di astrofisica (INAF)
M. B. Davies
Lunds universitet
M. Deleuil
Laboratoire d'Astrophysique de Marseille
A. Deline
Université de Genève
L. Delrez
Universite de Liège
O. Demangeon
Universidade do Porto
B.O. Demory
Universität Bern
D. Ehrenreich
Université de Genève
Anders Erikson
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
A. Fortier
Universität Bern
Malcolm Fridlund
Universiteit Leiden
Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik
D. Gandolfi
Universita degli Studi di Torino
Michaël Gillon
Universite de Liège
M. Gudel
Universität Wien
Maximilian N. Günther
European Space Research and Technology Centre (ESA ESTEC)
A. Heitzmann
Université de Genève
Ch. Helling
Institut fur Weltraumforschung
Technische Universität Graz
S. Hoyer
Laboratoire d'Astrophysique de Marseille
K. Isaak
European Space Research and Technology Centre (ESA ESTEC)
D. Kasper
University of Chicago
L. L. Kiss
Magyar Tudomanyos Akademia
Eötvös Loránd University (ELTE)
K. W.F. Lam
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
J. Laskar
Observatoire de Paris
A. L. des Etangs
Institut d 'Astrophysique de Paris
D. Magrin
Istituto nazionale di astrofisica (INAF)
P. Maxted
Keele University
C. Mordasini
Universität Bern
Valerio Nascimbeni
Istituto nazionale di astrofisica (INAF)
R. Ottensamer
Universität Wien
I. Pagano
Istituto nazionale di astrofisica (INAF)
Enric Palle
Universidad de la Laguna
Instituto de Astrofísica de Canarias
G. Peter
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
Giampaolo P. Piotto
Istituto nazionale di astrofisica (INAF)
Università di Padova
D. Pollacco
The University of Warwick
R. Ragazzoni
Istituto nazionale di astrofisica (INAF)
Università di Padova
N. Rando
European Space Research and Technology Centre (ESA ESTEC)
H. Rauer
Technische Universität Berlin
Freie Universität Berlin
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
I. Ribas
Institut d'Estudis Espacials de Catalunya (IEEC)
Institut de Ciències de l'Espai (ICE) - CSIC
Gaetano Scandariato
Istituto nazionale di astrofisica (INAF)
D. Segransan
Université de Genève
A. Seifahrt
University of Chicago
A. M.S. Smith
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
M. Stalport
Universite de Liège
G. Stefánsson
Princeton University
M. Steinberger
Institut fur Weltraumforschung
J. Stürmer
Landessternwarte Heidelberg-Königstuhl
G.M. Szabó
Eötvös Loránd University (ELTE)
Nicolas Thomas
Universität Bern
S. Udry
Université de Genève
E. Villaver
Universidad de la Laguna
Instituto de Astrofísica de Canarias
N. A. Walton
University of Cambridge
K. Westerdorff
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
Tiziano Zingales
Istituto nazionale di astrofisica (INAF)
Università di Padova
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 682 A66Ämneskategorier
Astronomi, astrofysik och kosmologi
DOI
10.1051/0004-6361/202348180