TESS and CHEOPS discover two warm sub-Neptunes transiting the bright K-dwarf HD 15906
Journal article, 2023
We report the discovery of two warm sub-Neptunes transiting the bright (G = 9.5 mag) K-dwarf HD 15906 (TOI 461, TIC 4646810). This star was observed by the Transiting Exoplanet Survey Satellite (TESS) in sectors 4 and 31, revealing two small transiting planets. The inner planet, HD 15906 b, was detected with an unambiguous period but the outer planet, HD 15906 c, showed only two transits separated by ∼ 734 d, leading to 36 possible values of its period. We performed follow-up observations with the CHaracterising ExOPlanet Satellite (CHEOPS) to confirm the true period of HD 15906 c and improve the radius precision of the two planets. From TESS, CHEOPS, and additional ground-based photometry, we find that HD 15906 b has a radius of 2.24 ± 0.08 R and a period of 10.924709 ± 0.000032 d, whilst HD 15906 c has a radius of 2.93+−000607 R and a period of 21.583298+−00000055000052 d. Assuming zero bond albedo and full day-night heat redistribution, the inner and outer planet have equilibrium temperatures of 668 ± 13 K and 532 ± 10 K, respectively. The HD 15906 system has become one of only six multiplanet systems with two warm (700 K) sub-Neptune sized planets transiting a bright star (G ≤ 10 mag). It is an excellent target for detailed characterization studies to constrain the composition of sub-Neptune planets and test theories of planet formation and evolution.
planets and satellites: fundamental parameters
planets and satellites: detection
stars: fundamental parameters
techniques: photometric
stars: individual: HD 15906 (TOI 461, TIC 4646810)
Author
A. Tuson
University of Cambridge
D. Queloz
Swiss Federal Institute of Technology in Zürich (ETH)
University of Cambridge
H. P. Osborn
Massachusetts Institute of Technology (MIT)
University of Bern
T.G. Wilson
University of St Andrews
M.J. Hooton
University of Cambridge
University of Bern
M. Beck
University of Geneva
M. Lendl
University of Geneva
G. Olofsson
Stockholm University
A. Fortier
University of Bern
A. Bonfanti
Institut fur Weltraumforschung
A. Brandeker
Stockholm University
L. A. Buchhave
Technical University of Denmark (DTU)
A. Collier Cameron
University of St Andrews
D. R. Ciardi
National Aeronautics and Space Administration (NASA)
K. A. Collins
Harvard-Smithsonian Center for Astrophysics
D. Gandolfi
University of Turin
Z. Garai
Eötvös Loránd University (ELTE)
Slovak Academy of Sciences
S. Giacalone
University of California
J. Gomes da Silva
University of Porto
S. B. Howell
National Aeronautics and Space Administration (NASA)
J. A. Patel
Stockholm University
Carina Persson
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
L. M. Serrano
University of Turin
S. G. Sousa
University of Porto
S. Ulmer-Moll
University of Bern
University of Geneva
A. Vanderburg
Massachusetts Institute of Technology (MIT)
C. Ziegler
Stephen F. Austin State University
Y. Alibert
University of Bern
R. Alonso
University of La Laguna
Instituto de Astrofísica de Canarias
G. Anglada
Spanish National Research Council (CSIC)
Centre Tecnològic de Telecomunicacions de Catalunya (CTTC)
T. Bárczy
Admatis
D. Barrado Navascues
Centro de Astrobiologia (CAB)
S.C.C. Barros
University of Porto
W. Baumjohann
Institut fur Weltraumforschung
T. Beck
University of Bern
W. Benz
University of Bern
N. Billot
University of Geneva
X. Bonfils
Institut de Planétologie et d’Astrophysique de Grenoble (IPAG)
L. Borsato
Istituto nazionale di astrofisica (INAF)
C. Broeg
University of Bern
J. Cabrera
German Aerospace Center (DLR)
S. Charnoz
Institut de Physique du Globe de Paris
D. Conti
American Association of Variable Star Observers
Szilard Csizmadia
German Aerospace Center (DLR)
P. E. Cubillos
Istituto nazionale di astrofisica (INAF)
Institut fur Weltraumforschung
M. B. Davies
Lund University
M. Deleuil
Laboratoire d'Astrophysique de Marseille
L. Delrez
University of Liège
O. Demangeon
University of Porto
B.O. Demory
University of Bern
D. Dragomir
University of New Mexico
Courtney D. Dressing
University of California
D. Ehrenreich
University of Geneva
Anders Erikson
German Aerospace Center (DLR)
Zahra Essack
Massachusetts Institute of Technology (MIT)
J. Farinato
Istituto nazionale di astrofisica (INAF)
L. Fossati
Institut fur Weltraumforschung
Malcolm Fridlund
Leiden University
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Elise Furlan
National Aeronautics and Space Administration (NASA)
H. Gill
University of California
Michaël Gillon
University of Liège
Crystal Gnilka
National Aeronautics and Space Administration (NASA)
E. Gonzales
University of California
M. Gudel
University of Vienna
Maximilian N. Günther
European Space Agency (ESA)
S. Hoyer
Laboratoire d'Astrophysique de Marseille
K. Isaak
European Space Agency (ESA)
Jon M. Jenkins
National Aeronautics and Space Administration (NASA)
L.L. Kiss
Eötvös Loránd University (ELTE)
Hungarian Academy of Sciences
J. Laskar
Paris Observatory
D. W. Latham
Harvard-Smithsonian Center for Astrophysics
N. Law
The University of North Carolina System
A. L. des Etangs
Institut d 'Astrophysique de Paris
G. Lo Curto
European Southern Observatory Santiago
C. Lovis
University of Geneva
R. Luque
University of Chicago
D. Magrin
Istituto nazionale di astrofisica (INAF)
A. Mann
The University of North Carolina System
P. Maxted
Keele University
Michel Mayor
University of Geneva
S. McDermott
Protologic LLC
M. Mecina
University of Vienna
C. Mordasini
University of Bern
A. Mortier
University of Birmingham
Valerio Nascimbeni
Istituto nazionale di astrofisica (INAF)
R. Ottensamer
University of Vienna
I. Pagano
Istituto nazionale di astrofisica (INAF)
E. Palle
Instituto de Astrofísica de Canarias
G. Peter
German Aerospace Center (DLR)
Giampaolo P. Piotto
Istituto nazionale di astrofisica (INAF)
University of Padua
D. Pollacco
The University of Warwick
T. Pritchard
National Aeronautics and Space Administration (NASA)
Roberto Ragazzoni
University of Padua
Istituto nazionale di astrofisica (INAF)
N. Rando
European Space Agency (ESA)
F. Ratti
European Space Agency (ESA)
H. Rauer
German Aerospace Center (DLR)
Freie Universität Berlin
Technische Universität Berlin
I. Ribas
Centre Tecnològic de Telecomunicacions de Catalunya (CTTC)
Spanish National Research Council (CSIC)
George R. Ricker
Massachusetts Institute of Technology (MIT)
M. Rieder
University of Bern
N. C. Santos
University of Porto
Monthly Notices of the Royal Astronomical Society
0035-8711 (ISSN) 1365-2966 (eISSN)
Vol. 523 2 3090-3118Subject Categories (SSIF 2011)
Astronomy, Astrophysics and Cosmology
DOI
10.1093/mnras/stad1369