Planets observed with CHEOPS: Two super-Earths orbiting the red dwarf star TOI-776
Artikel i vetenskaplig tidskrift, 2024
Context. M-dwarf stars are the most common of potential exoplanet host stars in the Galaxy. It is therefore very important to understand planetary systems orbiting such stars and to determine the physical parameters of such planets with high precision. Also with the launch of the James Webb Space Telescope (JWST) the observation of atmospheric parameters of planets orbiting these stars has begun. It is therefore required to determine properties of potential targets. Aims. Two planets around the red dwarf TOI-776 were detected by TESS. The objective of our study was to use transit observations obtained by the CHEOPS space mission to improve the current precision of the planetary radii, as well as additional radial velocity (RV) data in order to improve mass estimates of the two planets. Using these quantities, we wanted to derive the bulk densities of those planets, improving the precision in earlier results, and use this information to put them in context of other exoplanetary systems involving very low mass stars. Methods. Utilizing new transit data from the CHEOPS satellite and its photometric telescope, we obtained very high precision planetary transit measurements. Interpretation of these provides updated planetary radii, along with other system parameters. A concurrent ESO large observing program using the high precision spectrograph HARPS has doubled the available radial velocity data. Calculating the power spectrum of a number of stellar activity indices we update the previously estimated stellar rotation period to a lower value. Results. The CHEOPS data provide precise transit depths of 909 and 1177 ppm translating into radii of Rb = 1.798-0.077+0.078 R⊕ and Rc = 2.047-0.078+0.081 R⊕, respectively. Our interpretation of the radial velocities and activity indicator time series data estimates a stellar rotation period for this early M dwarf of ~21.1 days. A further multi-dimensional Gaussian process approach confirm this new estimate. By performing a Skew-Normal (SN) fit onto the Cross Correlation Functions we extracted the RV data and the activity indicators to estimate the planetary masses, obtaining Mb = 5.0-1.6+1.6 M⊕ and Mc = 6.9-2.5+2.6 M⊕. Conclusions. We improve the precision in planetary radius for TOI-776 b and c by a factor of more than two. Our data and modelling give us parameters of both bodies consistent with mini-Neptunes, albeit with a relatively high density. The stellar activity of TOI-776 is found to have increased by a factor larger than 2 since the last set of observations.
techniques: photometric
techniques: spectroscopic
planets and satellites: individual: TOI-776 c
planets and satellites: individual: TOI-776 b
planets and satellites: detection
stars: individual: LP 961-53
Författare
Malcolm Fridlund
Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik
Universiteit Leiden
Iskra Georgieva
Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik
A. Bonfanti
Institut fur Weltraumforschung
Y. Alibert
Universität Bern
Carina Persson
Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik
D. Gandolfi
Universita degli Studi di Torino
M. Beck
Université de Genève
A. Deline
Université de Genève
S. Hoyer
Laboratoire d'Astrophysique de Marseille
G. Olofsson
Stockholms universitet
T.G. Wilson
University of St Andrews
O. Barragán
University of Oxford
L. Fossati
Institut fur Weltraumforschung
A. J. Mustill
Lunds universitet
A. Brandeker
Stockholms universitet
A. Hatzes
Thüringer Landessternwarte Tautenburg
H.-G. Florén
Stockholms universitet
Umberto Simola
4Pharma Ltd
M.J. Hooton
Universität Bern
University of Cambridge
R. Luque
Instituto de Astrofisica de Andalucía (IAA)
University of Chicago
S. G. Sousa
Universidade do Porto
J. A. Egger
Universität Bern
A. Antoniadis-Karnavas
Universidade do Porto
S. Salmon
Université de Genève
V. Adibekyan
Universidade do Porto
R. Alonso
Instituto de Astrofísica de Canarias
Universidad de la Laguna
G. Anglada
Institut de Ciències de l'Espai (ICE) - CSIC
Institut d'Estudis Espacials de Catalunya (IEEC)
T. Bárczy
Admatis
D. Barrado Navascues
European Space Astronomy Centre (ESAC)
S.C.C. Barros
Universidade do Porto
W. Baumjohann
Institut fur Weltraumforschung
T. Beck
Universität Bern
W. Benz
Universität Bern
X. Bonfils
Institut de Planétologie et d’Astrophysique de Grenoble (IPAG)
C. Broeg
Universität Bern
J. Cabrera
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
S. Charnoz
Institut de Physique du Globe de Paris
A. Collier Cameron
University of St Andrews
Szilard Csizmadia
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
M. B. Davies
Lunds universitet
H. Deeg
Universidad de la Laguna
Instituto de Astrofísica de Canarias
M. Deleuil
Laboratoire d'Astrophysique de Marseille
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)
M. Esposito
Thüringer Landessternwarte Tautenburg
A. Fortier
Universität Bern
Michaël Gillon
Universite de Liège
M. Gudel
Universität Wien
Kevin Heng
University Of Leicester
Universität Bern
K. Isaak
European Space Research and Technology Centre (ESA ESTEC)
L. L. Kiss
Magyar Tudomanyos Akademia
Eötvös Loránd University (ELTE)
Judith Korth
Lunds universitet
J. Laskar
Observatoire de Paris
A. L. des Etangs
Institut d 'Astrophysique de Paris
M. Lendl
Université de Genève
J.H. Livingston
The Graduate University for Advanced Studies (SOKENDAI)
National Institutes of Natural Sciences
National Astronomical Observatory of Japan
University of Tokyo
C. Lovis
Université de Genève
D. Magrin
Istituto nazionale di astrofisica (INAF)
P. Maxted
Keele University
A. Muresan
Valerio Nascimbeni
Istituto nazionale di astrofisica (INAF)
R. Ottensamer
Universität Wien
I. Pagano
Istituto nazionale di astrofisica (INAF)
Enric Palle
Instituto de Astrofísica de Canarias
G. Peter
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
Giampaolo P. Piotto
Università di Padova
Istituto nazionale di astrofisica (INAF)
D. Pollacco
The University of Warwick
D. Queloz
University of Cambridge
Eidgenössische Technische Hochschule Zürich (ETH)
R. Ragazzoni
Istituto nazionale di astrofisica (INAF)
Università di Padova
N. Rando
European Space Research and Technology Centre (ESA ESTEC)
H. Rauer
Freie Universität Berlin
Technische Universität Berlin
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
S. Redfield
Wesleyan University
I. Ribas
Institut d'Estudis Espacials de Catalunya (IEEC)
Institut de Ciències de l'Espai (ICE) - CSIC
N. C. Santos
Universidade do Porto
Gaetano Scandariato
Istituto nazionale di astrofisica (INAF)
D. Segransan
Université de Genève
L. M. Serrano
Universita degli Studi di Torino
A.E. Simon
Universität Bern
A. M.S. Smith
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
Manfred B. Steller
Institut fur Weltraumforschung
G.M. Szabó
Eötvös Loránd University (ELTE)
Nicolas Thomas
Universität Bern
S. Udry
Université de Genève
Vincent Van Eylen
University College London (UCL)
V. Van Grootel
Universite de Liège
N. A. Walton
University of Cambridge
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 684 A12Ämneskategorier
Astronomi, astrofysik och kosmologi
DOI
10.1051/0004-6361/202243838