Issue |
A&A
Volume 673, May 2023
|
|
---|---|---|
Article Number | A140 | |
Number of page(s) | 20 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361/202245649 | |
Published online | 23 May 2023 |
Characterisation of the upper atmospheres of HAT-P-32 b, WASP-69 b, GJ 1214 b, and WASP-76 b through their He I triplet absorption
1
Instituto de Astrofísica de Andalucía (IAA-CSIC),
Glorieta de la Astronomía s/n,
18008
Granada,
Spain
e-mail: puertas@iaa.es
2
Centro de Astrobiología (CSIC-INTA), ESAC,
Camino bajo del castillo s/n,
28692
Villanueva de la Cañada, Madrid,
Spain
3
Thüringer Landessternwarte Tautenburg,
Sternwarte 5,
07778
Tautenburg,
Germany
4
Institut für Astrophysik, Georg-August-Universität,
Friedrich-Hund-Platz 1,
37077
Göttingen,
Germany
5
Leiden Observatory, Leiden University,
Postbus 9513,
2300 RA,
Leiden,
The Netherlands
6
Instituto de Astrofísica de Canarias (IAC),
Calle Vía Láctea s/n,
38200
La Laguna, Tenerife,
Spain
7
Departamento de Astrofísica, Universidad de La Laguna,
38026
La Laguna, Tenerife,
Spain
8
Universitäts-Sternwarte, Ludwig-Maximilians-Universität München,
Scheinerstrasse 1,
81679
München,
Germany
9
Exzellenzcluster Origins,
Boltzmannstrasse 2,
85748
Garching,
Germany
10
Landessternwarte, Zentrum für Astronomie der Universität Heidelberg,
Königstuhl 12,
69117
Heidelberg,
Germany
11
Institut de Ciències de l’Espai (CSIC-IEEC), Campus UAB,
c/ de Can Magrans s/n,
08193
Bellaterra, Barcelona,
Spain
12
Institut d’Estudis Espacials de Catalunya (IEEC),
08034
Barcelona,
Spain
Received:
8
December
2022
Accepted:
17
March
2023
Characterisation of atmospheres undergoing photo-evaporation is key to understanding the formation, evolution, and diversity of planets. However, only a few upper atmospheres that experience this kind of hydrodynamic escape have been characterised. Our aim is to characterise the upper atmospheres of the hot Jupiters HAT-P-32b and WASP-69 b, the warm sub-Neptune GJ 1214 b, and the ultra-hot Jupiter WASP-76 b through high-resolution observations of their He I triplet absorption. In addition, we also reanalyse the warm Neptune GJ 3470 b and the hot Jupiter HD 189733 b. We used a spherically symmetric 1D hydrodynamic model coupled with a non-local thermodynamic equilibrium model for calculating the He I triplet distribution along the escaping outflow. Comparing synthetic absorption spectra with observations, we constrained the main parameters of the upper atmosphere of these planets and classify them according to their hydrodynamic regime. Our results show that HAT-P-32 b photo-evaporates at (130 ± 70) ×1011 g s−1 with a hot (12 400 ± 2900 K) upper atmosphere; WASP-69 b loses its atmosphere at (0.9 ± 0.5) ×1011 g s−1 and 5250 ± 750 K; and GJ 1214b, with a relatively cold outflow of 3750 ± 750 K, photo-evaporates at (1.3 ± 1.1) ×1011 g s−1. For WASP-76 b, its weak absorption prevents us from constraining its temperature and mass-loss rate significantly; we obtained ranges of 6000–17 000 K and 23.5 ± 21.5 ×1011 g s−1. Our reanalysis of GJ 3470 b yields colder temperatures, 3400 ± 350 K, but practically the same mass-loss rate as in our previous results. Our reanalysis of HD 189733 b yields a slightly higher mass-loss rate, (1.4 ± 0.5) × 1011 g s−1, and temperature, 12 700 ± 900 K compared to previous estimates. We also found that HAT-P-32 b, WASP-69 b, and WASP-76 b undergo hydrodynamic escape in the recombination-limited regime, and that GJ 1214 b is in the photon-limited regime. Our results support that photo-evaporated outflows tend to be very light, H/He ≳ 98/2. The dependences of the mass-loss rates and temperatures of the studied planets on the respective system parameters (X-ray and ultraviolet stellar flux, gravitational potential) are well explained by the current hydrodynamic escape models.
Key words: planets and satellites: atmospheres / planets and satellites: individual: HAT-P-32 b / planets and satellites: individual: WASP-69 b / planets and satellites: individual: WASP-76 b / planets and satellites: individual: GJ 1214 b
© The Authors 2023
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.
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