학술논문
Planetary system around LTT 1445A unveiled by ESPRESSO: Multiple planets in a triple M-dwarf system
Document Type
Working Paper
Author
Lavie, B.; Bouchy, F.; Lovis, C.; Osorio, M. Zapatero; Deline, A.; Barros, S.; Figueira, P.; Sozzetti, A.; Hernandez, J. I. Gonzalez; Lillo-Box, J.; Rodrigues, J.; Mehner, A.; Damasso, M.; Adibekyan, V.; Alibert, Y.; Prieto, C. Allende; Cristiani, S.; DOdorico, V.; Di Marcantonio, P.; Ehrenreich, D.; Santos, R. Genova; Curto, G. Lo; Martins, C. J. A. P.; Micela, G.; Molaro, P.; Nunes, N.; Palle, E.; Pepe, F.; Poretti, E.; Rebolo, R.; Santos, N.; Sousa, S.; Mascareno, A. Suarez; Tabrenero, H.; Udry, S.
Source
A&A 673, A69 (2023)
Subject
Language
Abstract
We present radial velocity follow-up obtained with ESPRESSO of the M-type star LTT 1445A (TOI-455), for which a transiting planet b with an orbital period of~5.4 days was detected by TESS. We report the discovery of a second transiting planet (LTT 1445A c) and a third non-transiting candidate planet (LTT 1445A d) with orbital periods of 3.12 and 24.30 days, respectively. The host star is the main component of a triple M-dwarf system at a distance of 6.9 pc. We used 84 ESPRESSO high-resolution spectra to determine accurate masses of 2.3$\pm$0.3 $\mathrm{M}_\oplus$ and 1.0$\pm$0.2 $\mathrm{M}_\oplus$ for planets b and c and a minimum mass of 2.7$\pm$0.7 $\mathrm{M}_\oplus$ for planet d. Based on its radius of 1.43$\pm0.09$ $\mathrm{R}_\oplus$ as derived from the TESS observations, LTT 1445A b has a lower density than the Earth and may therefore hold a sizeable atmosphere, which makes it a prime target for the James Webb Space Telescope. We used a Bayesian inference approach with the nested sampling algorithm and a set of models to test the robustness of the retrieved physical values of the system. There is a probability of 85$\%$ that the transit of planet c is grazing, which results in a retrieved radius with large uncertainties at 1.60$^{+0.67}_{-0.34}$ $\mathrm{R}_\oplus$. LTT 1445A d orbits the inner boundary of the habitable zone of its host star and could be a prime target for the James Webb Space Telescope.
Comment: 31 pages, 20 figures Accepted A&A
Comment: 31 pages, 20 figures Accepted A&A