Issue |
A&A
Volume 689, September 2024
|
|
---|---|---|
Article Number | A132 | |
Number of page(s) | 28 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361/202450047 | |
Published online | 10 September 2024 |
Revisiting the dynamical masses of the transiting planets in the young AU Mic system: Potential AU Mic b inflation at ~20 Myr
1
Instituto de Astrofísica de Canarias (IAC),
Calle Vía Láctea s/n,
38205
La Laguna,
Tenerife,
Spain
2
Departamento de Astrofísica, Universidad de La Laguna (ULL),
38206
La Laguna,
Tenerife,
Spain
3
Centro de Astrobiología (CAB), CSIC-INTA,
ESAC Campus, Camino bajo del castillo s/n,
28692,
Villanueva de la Cañada,
Madrid,
Spain
4
Sub-department of Astrophysics, Department of Physics, University of Oxford,
Oxford
OX1 3RH,
UK
5
Osservatorio Astrofisico di Torino,
Via Osservatorio 20,
10025
Pino Torinese,
Italy
6
Institut d’Estudis Espacials de Catalunya (IEEC),
Calle Gran Capital 2–4,
08034
Barcelona,
Spain
7
Institut de Ciéncies de l’Espai (CSIC-IEEC),
UAB Campus, Calle de Can Magrans s/n,
08193
Bellaterra,
Barcelona,
Spain
8
Institut für Astrophysik und Geophysik, Georg-August-Universität Göttingen,
Friedrich-Hund-Platz 1,
37077
Göttingen,
Germany
9
Landessternwarte, Zentrum für Astronomie der Universität Heidelberg,
Königstuhl 12,
69117
Heidelberg,
Germany
10
Instituto de Astrofísica de Andalucía (IAA-CSIC),
Glorieta de la Astronomía s/n,
18008,
Granada,
Spain
11
Centro Astronómico Hispano en Andalucía (CAHA),
Observatorio de Calar Alto, Sierra de los Filabres,
04550
Gérgal,
Spain
12
Thüringer Landessternwarte Tautenburg,
07778
Tautenburg,
Germany
13
Dipartimento di Fisica, Universita degli Studi di Torino,
via Pietro Giuria 1,
10125
Torino,
Italy
14
Max-Planck-Institut für Astronomie,
Königstuhl 17,
69117
Heidelberg,
Germany
15
Department of Astronomy & Astrophysics, University of Chicago,
Chicago,
IL
60637,
USA
16
Departamento de Física de la Tierra y Astrofísica and IPARCOS-UCM (Instituto de Física de Partículas y del Cosmos de la UCM), Facultad de Ciencias Físicas, Universidad Complutense de Madrid,
28040
Madrid,
Spain
17
Hamburger Sternwarte,
Gojenbergsweg 112,
21029
Hamburg,
Germany
18
Steward Observatory and Department of Astronomy, The University of Arizona,
Tucson,
AZ
85721,
USA
Received:
20
March
2024
Accepted:
5
July
2024
Context. Understanding planet formation is important in the context of the origin of planetary systems in general and of the Solar System in particular, as well as to predict the likelihood of finding Jupiter, Neptune, and Earth analogues around other stars.
Aims. We aim to precisely determine the radii and dynamical masses of transiting planets orbiting the young M star AU Mic using public photometric and spectroscopic datasets.
Methods. We performed a joint fit analysis of the TESS and CHEOPS light curves and more than 400 high-resolution spectra collected with several telescopes and instruments. We characterise the stellar activity and physical properties (radius, mass, density) of the transiting planets in the young AU Mic system through joint transit and radial velocity fits with Gaussian processes.
Results. We determine a radius of Rpb = 4.79 ± 0.29 R⊕, a mass of Mpb = 9.0 ± 2.7 M⊕, and a bulk density of ρpb = 0.49 ± 0.16 g cm−3 for the innermost transiting planet AU Mic b. For the second known transiting planet, AU Mic c, we infer a radius of Rpc = 2.79 ± 0.18 R⊕, a mass of Mpc = 14.5 ± 3.4 M⊕, and a bulk density of ρpc = 3.90 ± 1.17 g cm−3. According to theoretical models, AU Mic b may harbour an H2 envelope larger than 5% by mass, with a fraction of rock and a fraction of water. AU Mic c could be made of rock and/or water and may have an H2 atmosphere comprising at most 5% of its mass. AU Mic b has retained most of its atmosphere but might lose it over tens of millions of years due to the strong stellar radiation, while AU Mic c likely suffers much less photo-evaporation because it lies at a larger separation from its host. Using all the datasets in hand, we determine a 3σ upper mass limit of Mp[d] sin i = 8.6 M⊕ for the AU Mic’d’ TTV-candidate. In addition, we do not confirm the recently proposed existence of the planet candidate AU Mic ’e’ with an orbital period of 33.4 days. We investigated the level of the radial velocity variations and show that it is lower at longer wavelength with smaller changes from one observational campaign to another.
Key words: techniques: photometric / techniques: radial velocities / planets and satellites: general / planets and satellites: individual: AUMic b / planets and satellites: individual: AUMic c / stars: low-mass
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
This article is published in open access under the Subscribe to Open model. Subscribe to A&A to support open access publication.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.