2022A&A...666A.154L


Query : 2022A&A...666A.154L

2022A&A...666A.154L - Astronomy and Astrophysics, volume 666A, 154 (2022/10-1)

Precise mass determination for the keystone sub-Neptune planet transiting the mid-type M dwarf G 9-40.

LUQUE R., NOWAK G., HIRANO T., KOSSAKOWSKI D., PALLE E., NIXON M.C., MORELLO G., AMADO P.J., ALBRECHT S.H., CABALLERO J.A., CIFUENTES C., COCHRAN W.D., DEEG H.J., DREIZLER S., ESPARZA-BORGES E., FUKUI A., GANDOLFI D., GOFFO E., GUENTHER E.W., HATZES A.P., HENNING T., KABATH P., KAWAUCHI K., KORTH J., KOTANI T., KUDO T., KUZUHARA M., LAFARGA M., LAM K.W.F., LIVINGSTON J., MORALES J.C., MURESAN A., MURGAS F., NARITA N., OSBORNE H.L.M., PARVIAINEN H., PASSEGGER V.M., PERSSON C.M., QUIRRENBACH A., REDFIELD S., REFFERT S., REINERS A., RIBAS I., SERRANO L.M., TAMURA M., VAN EYLEN V., WATANABE N. and ZAPATERO OSORIO M.R.

Abstract (from CDS):


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% (Rb = 1.900 ± 0.065 R) and determine its mass with a precision of 16% (Mb = 4.00 ± 0.63 M). 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 (Teq ∼ 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.

Abstract Copyright: © R. Luque et al. 2022

Journal keyword(s): planetary systems - techniques: photometric - techniques: radial velocities - stars: low-mass - stars: individual: G 9-40

Simbad objects: 20

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Number of rows : 20
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 PM J02489-1432W PM* 02 48 59.2728446101 -14 32 14.942011299       12.677 10.72 M2.0 22 0
2 NAME PM J03455+3706b Pl 03 45 33.6408895592 +37 06 43.999247912           ~ 22 0
3 PM J03455+3706 PM* 03 45 33.6408895592 +37 06 43.999247912   14.755 13.217 12.935   ~ 16 0
4 NAME L 231-32c Pl 04 33 39.7200127728 -51 57 22.435373160           ~ 32 0
5 NAME PM J04343+4302b Pl 04 34 22.4953034088 +43 02 14.692100424           ~ 22 0
6 TOI-269 PM* 05 03 23.0610114456 -54 10 37.924879404   15.969 14.410 13.920   M2 9 0
7 HD 260655c Pl? 06 37 10.7988015297 +17 33 53.333221083           ~ 11 0
8 LP 424-4 PM* 07 59 05.8395356736 +15 23 29.236065000   13.5   11.934   M2.0V 125 1
9 NAME L 98-59 d Pl 08 18 07.6214406393 -68 18 46.805365587           ~ 50 0
10 K2-146b Pl 08 40 06.4242250368 +19 05 34.430759088           ~ 21 0
11 NAME G 9-40b Pl 08 58 52.3297250887 +21 04 34.200161052           ~ 10 0
12 G 9-40 LP* 08 58 52.3297250887 +21 04 34.200161052   15.477 13.821 13.427   M2V 23 0
13 LSPM J1008+6916b Pl 10 08 51.8069885952 +69 16 35.560317504           ~ 33 0
14 NAME G 162-44c Pl 10 18 35.1372361341 -11 43 00.243355403           ~ 29 0
15 NAME LP 961-53b Pl 11 54 18.3921193416 -37 33 09.837719244           ~ 26 0
16 BD+11 2576 PM* 13 29 59.7858994351 +10 22 37.784532575 11.728 10.524 9.029 8.07 7.013 M1.0V 260 0
17 BD+25 3173 PM* 16 58 08.8496107083 +25 44 38.974052855 12.342 11.139 9.655 8.685 7.602 M2V 227 1
18 G 139-21 PM* 17 15 18.9339850845 +04 57 50.066612336       14.394   M4.5V 326 1
19 HD 197481b Pl? 20 45 09.5324974119 -31 20 27.237889841           ~ 107 0
20 CD-60 8051 PM* 23 20 07.5245143451 -60 03 54.644648069   12.45 11.02 10.584   M2V 45 0

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