Precise mass determination for the keystone sub-Neptune planet transiting the mid-type M dwarf G 9-40
Artikel i vetenskaplig tidskrift, 2022

Context. Despite being a prominent subset of the exoplanet population discovered in the past three decades, the nature and provenance of sub-Neptune-sized planets is still one of the open questions in exoplanet science. Aims. For planets orbiting bright stars, precisely measuring the orbital and planet parameters of the system is the best approach to distinguish between competing theories regarding their formation and evolution. Methods. We obtained 69 new radial velocity observations of the mid-M dwarf G 9-40 with the CARMENES instrument to measure for the first time the mass of its transiting sub-Neptune planet, G 9-40 b, discovered in data from the K2 mission. Results. Combined with new observations from the TESS mission during Sectors 44, 45, and 46, we are able to measure the radius of the planet to an uncertainty of 3.4% (R-b = 1.900 +/- 0.065 R-circle plus) and determine its mass with a precision of 16% (M-b = 4.00 +/- 0.63 M-circle plus). The resulting bulk density of the planet is inconsistent with a terrestrial composition and suggests the presence of either a water-rich core or a significant hydrogen-rich envelope. Conclusions. G 9-40 b is referred to as a keystone planet due to its location in period-radius space within the radius valley. Several theories offer explanations for the origin and properties of this population and this planet is a valuable target for testing the dependence of those models on stellar host mass. By virtue of its brightness and small size of the host, it joins L 98-59 d as one of the two best warm (T-eq similar to 400 K) sub-Neptunes for atmospheric characterization with JWST, which will probe cloud formation in sub-Neptune-sized planets and break the degeneracies of internal composition models.

planetary systems

stars: low-mass

stars: individual: G 9-40

techniques: radial velocities

techniques: photometric

Författare

R. Luque

University of Chicago

Instituto de Astrofisica de Andalucía (IAA)

G. Nowak

Universidad de la Laguna

Instituto de Astrofísica de Canarias

T. Hirano

Astrobiology Center, Japan

D. Kossakowski

Max-Planck-Gesellschaft

E. Palle

Instituto de Astrofísica de Canarias

Universidad de la Laguna

M. C. Nixon

University of Cambridge

G. Morello

Universidad de la Laguna

Instituto de Astrofísica de Canarias

P. J. Amado

Instituto de Astrofisica de Andalucía (IAA)

S. H. Albrecht

Aarhus Universitet

J. A. Caballero

European Space Astronomy Centre (ESAC)

C. Cifuentes

European Space Astronomy Centre (ESAC)

W. D. Cochran

The University of Texas at Austin

H. J. Deeg

Instituto de Astrofísica de Canarias

Universidad de la Laguna

S. Dreizler

Georg-August-Universität Göttingen

E. Esparza-Borges

Instituto de Astrofísica de Canarias

Universidad de la Laguna

A. Fukui

Instituto de Astrofísica de Canarias

University of Tokyo

D. Gandolfi

Universita degli Studi di Torino

E. Goffo

Universita degli Studi di Torino

Thüringer Landessternwarte Tautenburg

E. W. Guenther

Thüringer Landessternwarte Tautenburg

A. P. Hatzes

Thüringer Landessternwarte Tautenburg

T. Henning

Max-Planck-Gesellschaft

P. Kabath

Czech Academy of Sciences

K. Kawauchi

Universidad de la Laguna

Instituto de Astrofísica de Canarias

Judith Korth

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik

T. Kotani

National Astronomical Observatory of Japan

T. Kudo

National Astronomical Observatory of Japan

M. Kuzuhara

National Astronomical Observatory of Japan

M. Lafarga

The University of Warwick

K. W. F. Lam

Deutsches Zentrums für Luft- und Raumfahrt (DLR)

J. Livingston

Astrobiology Center, Japan

The Graduate University for Advanced Studies (SOKENDAI)

National Astronomical Observatory of Japan

J. C. Morales

Institut d'Estudis Espacials de Catalunya (IEEC)

Consejo Superior de Investigaciones Científicas (CSIC)

Alexandra Muresan

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik

F. Murgas

Instituto de Astrofísica de Canarias

Universidad de la Laguna

N. Narita

Instituto de Astrofísica de Canarias

Astrobiology Center, Japan

University of Tokyo

H. L. M. Osborne

University College London (UCL)

H. Parviainen

Instituto de Astrofísica de Canarias

Universidad de la Laguna

V. M. Passegger

University of Oklahoma

Hamburger Sternwarte

Carina Persson

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik

A. Quirrenbach

Universität Heidelberg

S. Redfield

Wesleyan University

S. Reffert

Universität Heidelberg

A. Reiners

Georg-August-Universität Göttingen

I Ribas

Consejo Superior de Investigaciones Científicas (CSIC)

Institut d'Estudis Espacials de Catalunya (IEEC)

L. M. Serrano

Universita degli Studi di Torino

M. Tamura

University of Tokyo

Astrobiology Center, Japan

National Astronomical Observatory of Japan

V. Van Eylen

University College London (UCL)

N. Watanabe

University of Tokyo

M. R. Zapatero Osorio

Centro de Astrobiología (INTA-CSIC)

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 666 A154

Ämneskategorier

Meteorologi och atmosfärforskning

Astronomi, astrofysik och kosmologi

Annan fysik

DOI

10.1051/0004-6361/202244426

Mer information

Senast uppdaterat

2022-11-16