학술논문
Confirmation of an He I evaporating atmosphere around the 650-Myr-old sub-Neptune HD235088 b (TOI-1430 b) with CARMENES
Document Type
Working Paper
Author
Orell-Miquel, J.; Lampón, M.; López-Puertas, M.; Mallorquín, M.; Murgas, F.; Peláez-Torres, A.; Pallé, E.; Esparza-Borges, E.; Sanz-Forcada, J.; Tabernero, H. M.; Nortmann, L.; Nagel, E.; Parviainen, H.; Osorio, M. R. Zapatero; Caballero, J. A.; Czesla, S.; Cifuentes, C.; Morello, G.; Quirrenbach, A.; Amado, P. J.; Fernández-Martín, A.; Fukui, A.; Henning, Th.; Kawauchi, K.; de Leon, J. P.; Molaverdikhani, K.; Montes, D.; Narita, N.; Reiners, A.; Ribas, I.; Sánchez-López, A.; Schweitzer, A.; Stangret, M.; Yan, F.
Source
A&A 677, A56 (2023)
Subject
Language
Abstract
HD235088 (TOI-1430) is a young star known to host a sub-Neptune-sized planet candidate. We validated the planetary nature of HD235088 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 HD235088 b with one transit observed with CARMENES. We also detected hints of variability in the strength of the helium signal, with an absorption of $-$0.91$\pm$0.11%, which is slightly deeper (2$\sigma$) than the previous measurement. Furthermore, we simulated the He I signal with a spherically symmetric 1D hydrodynamic model, finding that the upper atmosphere of HD235088 b escapes hydrodynamically with a significant mass loss rate of (1.5-5) $\times$10$^{10}$g s$^{-1}$, in a relatively cold outflow, with $T$=3125$\pm$375 K, in the photon-limited escape regime. HD235088 b ($R_{p}$ = 2.045$\pm$0.075 R$_{\oplus}$) 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.
Comment: Accepted for publication in A&A. 17 pages, 18 figures
Comment: Accepted for publication in A&A. 17 pages, 18 figures