Discovery of two warm mini-Neptunes with contrasting densities orbiting the young K3V star TOI-815
Artikel i vetenskaplig tidskrift, 2024
We present the discovery and characterization of two warm mini-Neptunes transiting the K3V star TOI-815 in a K–M binary system. Analysis of its spectra and rotation period reveal the star to be young, with an age of 200+−400200 Myr. TOI-815b has a 11.2-day period and a radius of 2.94 ± 0.05 R+ with transits observed by TESS, CHEOPS, ASTEP, and LCOGT. The outer planet, TOI-815c, has a radius of 2.62 ± 0.10 R+, based on observations of three nonconsecutive transits with TESS; targeted CHEOPS photometry and radial velocity follow-up with ESPRESSO were required to confirm the 35-day period. ESPRESSO confirmed the planetary nature of both planets and measured masses of 7.6 ± 1.5 M+ (ρP = 1.64+−003331 g cm−3) and 23.5 ± 2.4 M+ (ρP = 7.2+−1110 g cm−3), respectively. Thus, the planets have very different masses, which is unusual for compact multi-planet systems. Moreover, our statistical analysis of mini-Neptunes orbiting FGK stars suggests that weakly irradiated planets tend to have higher bulk densities compared to those undergoing strong irradiation. This could be ascribed to their cooler atmospheres, which are more compressed and denser. Internal structure modeling of TOI-815b suggests it likely has a H-He atmosphere that constitutes a few percent of the total planet mass, or higher if the planet is assumed to have no water. In contrast, the measured mass and radius of TOI-815c can be explained without invoking any atmosphere, challenging planetary formation theories. Finally, we infer from our measurements that the star is viewed close to pole-on, which implies a spin-orbit misalignment at the 3σ level. This emphasizes the peculiarity of the system’s orbital architecture, and probably hints at an eventful dynamical history.
techniques: radial velocities
techniques: photometric
planets and satellites: composition
stars: individual: TOI-815
planets and satellites: detection
planets and satellites: formation
Författare
A. Psaridi
Université de Genève
H. P. Osborn
Universität Bern
F. Bouchy
Université de Genève
M. Lendl
Université de Genève
Léna Parc
Université de Genève
N. Billot
Université de Genève
C. Broeg
Universität Bern
S.G. Sousa
Universidade do Porto
V. Adibekyan
Universidade do Porto
Omar Attia
Université de Genève
A. Bonfanti
Institut fur Weltraumforschung
Hritam Chakraborty
Université de Genève
Karen A. Collins
Harvard-Smithsonian Center for Astrophysics
Jeanne Davoult
Universität Bern
E. Delgado Mena
Universidade do Porto
N. Grieves
Université de Genève
T. Guillot
Observatoire de la Cote d'Azur
A. Heitzmann
Université de Genève
R. Helled
Universität Zürich
Coel Hellier
Keele University
Jon M. Jenkins
NASA Ames Research Center
Henrik Knierim
Universität Zürich
A. Krenn
Institut fur Weltraumforschung
Jack J. Lissauer
NASA Ames Research Center
R. Luque
University of Chicago
D. Rapetti
NASA Ames Research Center
N. C. Santos
Universidade do Porto
Olga Suárez
Observatoire de la Cote d'Azur
J. Venturini
Université de Genève
Francis P. Wilkin
Union College
T.G. Wilson
The University of Warwick
J. N. Winn
Princeton University
C. Ziegler
Stephen F. Austin State University
Tiziano Zingales
Università di Padova
Y. Alibert
Universität Bern
A. Brandeker
Stockholms universitet
J. A. Egger
Universität Bern
D. Gandolfi
Universita degli Studi di Torino
M.J. Hooton
University of Cambridge
A. Tuson
University of Cambridge
S. Ulmer-Moll
Université de Genève
L. Abe
Observatoire de la Cote d'Azur
R. Allart
Université de Montréal
R. Alonso
Instituto de Astrofísica de Canarias
D. Anderson
The University of Warwick
G. A. Escudé
Institut de Ciències de l'Espai (ICE) - CSIC
T. Bárczy
Admatis
D. Barrado
Centro de Astrobiologia (CAB)
S.C.C. Barros
Universidade do Porto
W. Baumjohann
Institut fur Weltraumforschung
M. Beck
Université de Genève
T. Beck
Universität Bern
W. Benz
Universität Bern
X. Bonfils
Institut de Planétologie et d’Astrophysique de Grenoble (IPAG)
L. Borsato
Istituto nazionale di astrofisica (INAF)
V. Bourrier
Université de Genève
D. R. Ciardi
California Institute of Technology (Caltech)
A. Collier Cameron
University of St Andrews
S. Charnoz
Institut de Physique du Globe de Paris
M. Cointepas
Université de Genève
Szilard Csizmadia
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
P. E. Cubillos
Institut fur Weltraumforschung
G. Lo Curto
European Southern Observatory Santiago
M. B. Davies
Lunds universitet
Tansu Daylan
Washington University in St. Louis
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
C. Dorn
Eidgenössische Technische Hochschule Zürich (ETH)
X. Dumusque
Université de Genève
D. Ehrenreich
Université de Genève
Anders Erikson
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
A. L. des Etangs
Institut d 'Astrophysique de Paris
D. de Miguel
Airbus Group
A. Fortier
Universität Bern
L. Fossati
Institut fur Weltraumforschung
Yolanda G.C. Frensch
Université de Genève
Malcolm Fridlund
Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik
Universiteit Leiden
Michaël Gillon
Universite de Liège
M. Gudel
Universität Wien
Maximilian N. Günther
European Space Research and Technology Centre (ESA ESTEC)
J. Hagelberg
Université de Genève
Ch. Helling
Institut fur Weltraumforschung
S. Hoyer
Laboratoire d'Astrophysique de Marseille
K. Isaak
European Space Research and Technology Centre (ESA ESTEC)
L. L. Kiss
Magyar Tudomanyos Akademia
K. W.F. Lam
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
J. Laskar
Observatoire de Paris
B. Lavie
Université de Genève
C. Lovis
Université de Genève
D. Magrin
Istituto nazionale di astrofisica (INAF)
L. Marafatto
Istituto nazionale di astrofisica (INAF)
P. Maxted
Keele University
S. McDermott
Protologic LLC
Djamel Mékarnia
Observatoire de la Cote d'Azur
C. Mordasini
Universität Bern
F. Murgas
Universidad de la Laguna
Valerio Nascimbeni
Istituto nazionale di astrofisica (INAF)
L. D. Nielsen
European Southern Observatory (ESO)
G. Olofsson
Stockholms universitet
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
Don L. Pollacco
The University of Warwick
D. Queloz
University of Cambridge
Roberto Ragazzoni
Università di Padova
Devin Ramos
Union College
N. Rando
European Space Research and Technology Centre (ESA ESTEC)
H. Rauer
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
C. Reimers
Universität Wien
I. Ribas
Institut de Ciències de l'Espai (ICE) - CSIC
S. Seager
Massachusetts Institute of Technology (MIT)
D. Segransan
Université de Genève
Gaetano Scandariato
Istituto nazionale di astrofisica (INAF)
A.E. Simon
Universität Bern
A. M.S. Smith
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
M. Stalport
Universite de Liège
Manfred B. Steller
Institut fur Weltraumforschung
G.M. Szabó
Eötvös Loránd University (ELTE)
Nicolas Thomas
Universität Bern
T. Pritchard
NASA Goddard Space Flight Center
S. Udry
Université de Genève
C. Corral Van Damme
European Space Research and Technology Centre (ESA ESTEC)
V. Van Grootel
Universite de Liège
E. Villaver
Instituto de Astrofísica de Canarias
I. Walter
Deutsches Zentrums für Luft- und Raumfahrt (DLR)
N. A. Walton
University of Cambridge
Cristilyn N. Watkins
Harvard-Smithsonian Center for Astrophysics
Richard G West
The University of Warwick
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 685 A5Ämneskategorier
Meteorologi och atmosfärforskning
Astronomi, astrofysik och kosmologi
DOI
10.1051/0004-6361/202348678