Confirmation of an He I evaporating atmosphere around the 650-Myr-old sub-Neptune HD 235088 b (TOI-1430 b) with CARMENES
Artikel i vetenskaplig tidskrift, 2023
HD 235088 (TOI-1430) is a young star known to host a sub-Neptune-sized planet candidate. We validated the planetary nature of HD 235088 b with multiband photometry, refined its planetary parameters, and obtained a new age estimate of the host star, placing it at 600- 800 Myr. Previous spectroscopic observations of a single transit detected an excess absorption of He I coincident in time with the planet candidate transit. Here, we confirm the presence of He I in the atmosphere of HD 235088 b with one transit observed with CARMENES. We also detected hints of variability in the strength of the helium signal, with an absorption of -0.91 ± 0.11%, which is slightly deeper (2γ) than the previous measurement. Furthermore, we simulated the He I signal with a spherically symmetric 1D hydrodynamic model, finding that the upper atmosphere of HD 235088 b escapes hydrodynamically with a significant mass loss rate of (1.5-5) × 1010 g s-1 in a relatively cold outflow, with T = 3125 ±375 K, in the photon-limited escape regime. HD 235088 b (Rp = 2.045 ± 0.075 R⊕) is the smallest planet found to date with a solid atmospheric detection - not just of He I but any other atom or molecule. This positions it a benchmark planet for further analyses of evolving young sub-Neptune atmospheres.
Stars: individual: HD 235088
Planets and satellites: individual: HD 235088 b
Techniques: photometric
Planets and satellites: atmospheres
Techniques: spectroscopic
Författare
J. Orell-Miquel
Instituto de Astrofísica de Canarias
Universidad de la Laguna
M. Lampon
Instituto de Astrofisica de Andalucía (IAA)
M. López-Puertas
Instituto de Astrofisica de Andalucía (IAA)
M. Mallorquín
Instituto de Astrofísica de Canarias
Universidad de la Laguna
F. Murgas
Universidad de la Laguna
Instituto de Astrofísica de Canarias
A. Peláez-Torres
Instituto de Astrofísica de Canarias
Universidad de la Laguna
Enric Palle
Universidad de la Laguna
Instituto de Astrofísica de Canarias
E. Esparza-Borges
Universidad de la Laguna
Instituto de Astrofísica de Canarias
J. Sanz-Forcada
European Space Astronomy Centre (ESAC)
H. M. Tabernero
Centro de Astrobiologia (CAB)
L. Nortmann
Georg-August-Universität Göttingen
E. Nagel
Georg-August-Universität Göttingen
H. Parviainen
Universidad de la Laguna
Instituto de Astrofísica de Canarias
M. Zapatero-Osorio
Centro de Astrobiologia (CAB)
J. A. Caballero
Centro de Astrobiologia (CAB)
S. Czesla
Thüringer Landessternwarte Tautenburg
C. Cifuentes
Centro de Astrobiologia (CAB)
Giuseppe Morello
Instituto de Astrofísica de Canarias
Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik
A. Quirrenbach
Landessternwarte Heidelberg-Königstuhl
P. J. Amado
Instituto de Astrofisica de Andalucía (IAA)
A. Fernández-Martín
Calar Alto Astronomical Observatory
A. Fukui
National Institutes of Natural Sciences
Instituto de Astrofísica de Canarias
T. Henning
Max-Planck-Gesellschaft
Kiyoe Kawauchi
University of Tokyo
Jerome P. De Leon
University of Tokyo
K. Molaverdikhani
Landessternwarte Heidelberg-Königstuhl
Ludwig-Maximilians-Universität München (LMU)
D. Montes
IPARCOS-UCM (Instituto de Física de Partículas y del Cosmos)
Norio Narita
University of Tokyo
Instituto de Astrofísica de Canarias
National Institutes of Natural Sciences
A. Reiners
Georg-August-Universität Göttingen
I. Ribas
Institut de Ciències de l'Espai (ICE) - CSIC
Institut d'Estudis Espacials de Catalunya (IEEC)
A. Sánchez-López
Instituto de Astrofisica de Andalucía (IAA)
A. Schweitzer
Universität Hamburg
M. Stangret
Istituto nazionale di astrofisica (INAF)
F. Yan
University of Science and Technology of China
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 677 A56Ämneskategorier
Astronomi, astrofysik och kosmologi
DOI
10.1051/0004-6361/202346445