Bibliographic Details
| Title: |
Confirmation of an He I evaporating atmosphere around the 650-Myr-old sub-Neptune HD235088 b (TOI-1430 b) with CARMENES |
| Authors: |
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) |
| Publication Year: |
2023 |
| Collection: |
Astrophysics |
| Subject Terms: |
Astrophysics - Earth and Planetary Astrophysics |
| More Details: |
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 |
| Document Type: |
Working Paper |
| DOI: |
10.1051/0004-6361/202346445 |
| Access URL: |
http://arxiv.org/abs/2307.05191 |
| Accession Number: |
edsarx.2307.05191 |
| Database: |
arXiv |
