TOI-1231 b: A Temperate, Neptune-sized Planet Transiting the Nearby M3 Dwarf NLTT 24399 ...

• Main Authors: Jensen, E.L.N., Villanueva, S., Guillot, T., Burke, C.J., Mann, A.W., Teske, J.K., Shectman, S.A., Huang, C.X., Collins, K.A., Schmider, F.-X., Mollire, P., Jenkins, J.M., Ciardi, D., Ziegler, C., Rodriguez, J.E., Triaud, A.H.M.J., Marie-Sainte, W., Feng, F., Cointepas, M., Wohler, B., Schlieder, J.E., Eastman, J.D., Abe, L., Stevens, D.J., Schwarz, R.P., Mékarnia, D., Charbonneau, D., Latham, D.W., Gupta, A.F., Stassun, K.G., Dragomir, D., Youngblood, A., García Muñoz, A., Ricker, G.R., Butler, R.P., Matson, R.A., Mamajek, E.E., Pepper, J., Seager, S., Burt, J.A., Crane, J.D., Brasseur, C.E., Daylan, T., Howell, S.B., Berta-Thompson, Z.K., Law, N., Crouzet, N., Agabi, A., Kreidberg, L., Halverson, S.P.
• Format: Text
• Language: English
• Published: American Astronomical Society 2021
• Subjects: Hubble; Antarc*; Antarctica
• Online Access: https://dx.doi.org/10.17615/3vbz-9m98; https://cdr.lib.unc.edu/concern/articles/5712mh342

We report the discovery of a transiting, temperate, Neptune-sized exoplanet orbiting the nearby (d = 27.5 pc), M3V star TOI-1231 (NLTT 24399, L 248-27, 2MASS J10265947-5228099). The planet was detected using photometric data from the Transiting Exoplanet Survey Satellite and followed up with observations from the Las Cumbres Observatory and the Antarctica Search for Transiting ExoPlanets program. Combining the photometric data sets, we find that the newly discovered planet has a radius of {3.65}_{-0.15}^{+0.16}\,{R}_{\oplus } and an orbital period of 24.246 days. Radial velocity measurements obtained with the Planet Finder Spectrograph on the Magellan Clay telescope confirm the existence of the planet and lead to a mass measurement of 15.5 3.3 M ⊕. With an equilibrium temperature of just 330 K, TOI-1231 b is one of the coolest small planets accessible for atmospheric studies thus far, and its host star's bright near-infrared brightness (J = 8.88, Ks = 8.07) makes it an exciting target for the Hubble Space ...