Dr. Astudillo-Defru, Nicola

2021, Dr. Astudillo-Defru, Nicola, Murgas, F., Bonfils, X., Crossfield, I., Almenara, J., Livingston, J., Stassun, K., Korth, J., Orell-Miquel, J., Morello, G., Eastman, J., Lissauer, J., Kane, S., Morales, F., Werner, M., Gorjian, V., Benneke, B., Dragomir, D., Matthews, E., Howell, S., Ciardi, D., Gonzales, E., Matson, R., Beichman, C., Schlieder, J., Collins, K., Collins, K., Jensen, E., Evans, P., Pozuelos, F., Gillon, M., Jehin, E., Barkaoui, K., Artigau, E., Bouchy, F., Charbonneau, D., Delfosse, X., Díaz, R., Doyon, R., Figueira, P., Forveille, T., Lovis, C., Melo, C., Gaisné, G., Pepe, F., Santos, N., Ségransan, D., Udry, S., Goeke, R., Levine, A., Quintana, E., Guerrero, N., Mireles, I., Caldwell, D., Tenenbaum, P., Brasseur, C., Ricker, G., Vanderspek, R., Latham, D., Seager, S., Winn, J., Jenkins, J.

Context. The NASA mission TESS is currently doing an all-sky survey from space to detect transiting planets around bright stars. As part of the validation process, the most promising planet candidates need to be confirmed and characterized using follow-up observations. Aims. In this article, our aim is to confirm the planetary nature of the transiting planet candidate TOI-674b using spectroscopic and photometric observations. Methods. We use TESS, Spitzer, ground-based light curves, and HARPS spectrograph radial velocity measurements to establish the physical properties of the transiting exoplanet candidate TOI-674b. We perform a joint fit of the light curves and radial velocity time series to measure the mass, radius, and orbital parameters of the candidate. Results. We confirm and characterize TOI-674b, a low-density super-Neptune transiting a nearby M dwarf. The host star (TIC 158588995, V = 14.2 mag, J = 10.3 mag) is characterized by its M2V spectral type with M⋆ = 0.420 ± 0.010 M⊙, R⋆ = 0.420 ± 0.013 R⊙, and Teff = 3514 ± 57 K; it is located at a distance d = 46.16 ± 0.03 pc. Combining the available transit light curves plus radial velocity measurements and jointly fitting a circular orbit model, we find an orbital period of 1.977143 ± 3 × 10−6 days, a planetary radius of 5.25 ± 0.17 R⊕, and a mass of 23.6 ± 3.3 M⊕ implying a mean density of ρp =0.91 ± 0.15 g cm−3. A non-circular orbit model fit delivers similar planetary mass and radius values within the uncertainties. Given the measured planetary radius and mass, TOI-674b is one of the largest and most massive super-Neptune class planets discovered around an M-type star to date. It is found in the Neptunian desert, and is a promising candidate for atmospheric characterization using the James Webb Space Telescope.