Two warm Neptunes transiting HIP 9618 revealed by TESS and Cheops
Journal article, 2023

HIP 9618 (HD 12572, TOI-1471, TIC 306263608) is a bright (G = 9.0 mag) solar analogue. TESS photometry revealed the star to have two candidate planets with radii of 3.9 ± 0.044 R (HIP 9618 b) and 3.343 ± 0.039 R (HIP 9618 c). While the 20.77291 d period of HIP 9618 b was measured unambiguously, HIP 9618 c showed only two transits separated by a 680-d gap in the time series, leaving many possibilities for the period. To solve this issue, CHEOPS performed targeted photometry of period aliases to attempt to recover the true period of planet c, and successfully determined the true period to be 52.56349 d. High-resolution spectroscopy with HARPS-N, SOPHIE, and CAFE revealed a mass of 10.0 ± 3.1M for HIP 9618 b, which, according to our interior structure models, corresponds to a 6.8 ± 1.4 per cent gas fraction. HIP 9618 c appears to have a lower mass than HIP 9618 b, with a 3-sigma upper limit of <18M. Follow-up and archival RV measurements also reveal a clear long-term trend which, when combined with imaging and astrometric information, reveal a low-mass companion (0.08+−000512M☉) orbiting at 26.0+−111900 au. This detection makes HIP 9618 one of only five bright (K < 8 mag) transiting multiplanet systems known to host a planet with P > 50 d, opening the door for the atmospheric characterization of warm (Teq < 750 K) sub-Neptunes.

occultations

eclipses

binaries: spectroscopic

planets and satellites: detection

surveys

Author

H. P. Osborn

Massachusetts Institute of Technology (MIT)

University of Bern

G. Nowak

University of La Laguna

Instituto de Astrofísica de Canarias

Nicolaus Copernicus University

G. Hebrard

Institut d 'Astrophysique de Paris

T. Masseron

Instituto de Astrofísica de Canarias

University of La Laguna

J. Lillo-Box

European Space Astronomy Centre (ESAC)

E. Palle

University of La Laguna

Instituto de Astrofísica de Canarias

A. Bekkelien

University of Geneva

H.-G. Florén

Stockholm University

P. Guterman

Laboratoire d'Astrophysique de Marseille

A.E. Simon

University of Bern

V. Adibekyan

University of Porto

Allyson Bieryla

Harvard-Smithsonian Center for Astrophysics

L. Borsato

Istituto nazionale di astrofisica (INAF)

A. Brandeker

Stockholm University

D. R. Ciardi

National Aeronautics and Space Administration (NASA)

A. Collier Cameron

University of St Andrews

K. A. Collins

Harvard-Smithsonian Center for Astrophysics

J. A. Egger

University of Bern

D. Gandolfi

University of Turin

M.J. Hooton

University of Cambridge

University of Bern

D. W. Latham

Harvard-Smithsonian Center for Astrophysics

M. Lendl

University of Geneva

E. C. Matthews

Max Planck Society

University of Geneva

A. Tuson

University of Cambridge

S. Ulmer-Moll

University of Geneva

A. Vanderburg

Massachusetts Institute of Technology (MIT)

T.G. Wilson

University of St Andrews

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

Institute of Space Studies of Catalonia (IEEC)

Institute of Space Sciences (ICE) - CSIC

L. Arnold

Centre national de la recherche scientifique (CNRS)

J. Asquier

European Space Research and Technology Centre (ESA ESTEC)

D. Barrado Y Navascues

Centro de Astrobiologia (CAB)

W. Baumjohann

Institut fur Weltraumforschung

T. Beck

University of Bern

A. A. Belinski

Moscow State University

W. Benz

University of Bern

F. Biondi

Max Planck Institute for Extraterrestrial Physics

Istituto nazionale di astrofisica (INAF)

I. Boisse

Laboratoire d'Astrophysique de Marseille

X. Bonfils

Institut de Planétologie et d’Astrophysique de Grenoble (IPAG)

C. Broeg

University of Bern

L. A. Buchhave

Technical University of Denmark (DTU)

T. Bárczy

Admatis

S.C.C. Barros

University of Porto

J. Cabrera

German Aerospace Center (DLR)

C. Cardona Guillen

Instituto de Astrofísica de Canarias

University of La Laguna

Ilaria Carleo

Instituto de Astrofísica de Canarias

University of La Laguna

A. Castro-González

European Space Astronomy Centre (ESAC)

S. Charnoz

Institut de Physique du Globe de Paris

Jessie L. Christiansen

National Aeronautics and Space Administration (NASA)

Pía Cortés-Zuleta

Laboratoire d'Astrophysique de Marseille

Szilard Csizmadia

German Aerospace Center (DLR)

S. Dalal

Institut d 'Astrophysique de Paris

M. B. Davies

Lund University

M. Deleuil

Laboratoire d'Astrophysique de Marseille

X. Delfosse

Institut de Planétologie et d’Astrophysique de Grenoble (IPAG)

L. Delrez

University of Liège

B.O. Demory

University of Bern

A. B. Dunlavey

National Aeronautics and Space Administration (NASA)

D. Ehrenreich

University of Geneva

Anders Erikson

German Aerospace Center (DLR)

R. B. Fernandes

University of Arizona

A. Fortier

University of Bern

T. Forveille

Institut de Planétologie et d’Astrophysique de Grenoble (IPAG)

L. Fossati

Institut fur Weltraumforschung

Malcolm Fridlund

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics

Leiden University

Michaël Gillon

University of Liège

Robert Goeke

Massachusetts Institute of Technology (MIT)

M. V. Goliguzova

Moscow State University

E. Gonzales

University of California

Maximilian N. Günther

European Space Research and Technology Centre (ESA ESTEC)

M. Gudel

University of Vienna

N. Heidari

Laboratoire d'Astrophysique de Marseille

C. E. Henze

NASA Ames Research Center

S. B. Howell

NASA Ames Research Center

S. Hoyer

Laboratoire d'Astrophysique de Marseille

J. I. Frey

University of Bern

K. Isaak

European Space Research and Technology Centre (ESA ESTEC)

Jon M. Jenkins

NASA Ames Research Center

F. Kiefer

Institut d 'Astrophysique de Paris

Paris Observatory

L.L. Kiss

Eötvös Loránd University (ELTE)

Hungarian Academy of Sciences

Judith Korth

Lund University

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics

P. Maxted

Keele University

J. Laskar

Paris Observatory

A. L. des Etangs

Institut d 'Astrophysique de Paris

C. Lovis

University of Geneva

M. B. Lund

National Aeronautics and Space Administration (NASA)

R. Luque

University of Chicago

D. Magrin

Istituto nazionale di astrofisica (INAF)

J. M. Almenara

Institut de Planétologie et d’Astrophysique de Grenoble (IPAG)

E. Martioli

Institut d 'Astrophysique de Paris

Laboratorio Nacional de Astrofisica, Itajuba

M. Mecina

University of Vienna

J. V. Medina

Space Telescope Science Institute (STScI)

D. Moldovan

Google Inc.

M. Morales-Calderon

European Space Astronomy Centre (ESAC)

Giuseppe Morello

Instituto de Astrofísica de Canarias

University of La Laguna

C. Moutou

Institut de Recherche en Astrophysique et Planétologie (IRAP)

F. Murgas

University of La Laguna

Instituto de Astrofísica de Canarias

Eric L.N. Jensen

Swarthmore College

Monthly Notices of the Royal Astronomical Society

0035-8711 (ISSN) 1365-2966 (eISSN)

Vol. 523 2 3069-3089

Exoplanet diversity with satellite studies

Swedish National Space Board (174/18), 2019-02-04 -- 2023-08-01.

Subject Categories

Astronomy, Astrophysics and Cosmology

DOI

10.1093/mnras/stad1319

More information

Latest update

9/15/2023