1. The Discovery and Follow-up of Four Transiting Short-period Sub-Neptunes Orbiting M dwarfs
- Author
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Hori, Y., Fukui, A., Hirano, T., Narita, N., de Leon, J. P., Ishikawa, H. T., Hartman, J. D., Morello, G., García, N. Abreu, Hernández, L. Álvarez, Béjar, V. J. S., Calatayud-Borras, Y., Carleo, I., Enoc, G., Esparza-Borges, E., Fukuda, I., Galán, D., Geraldía-González, S., Hayashi, Y., Ikoma, M., Ikuta, K., Isogai, K., Kagetani, T., Kawai, Y., Kawauchi, K., Kimura, T., Kodama, T., Korth, J., Kusakabe, N., Laza-Ramos, A., Livingston, J. H., Luque, R., Miyakawa, K., Mori, M., Torres, S. Muñoz, Murgas, F., Orell-Miquel, J., Palle, E., Parviainen, H., Peláez-Torres, A., Puig-Subirá, M., Sánchez-Benavente, M., Sosa-Guillén, P., Stangret, M., Terada, Y., Watanabe, N., Bakos, G. Á., Barkaoui, K., Beichman, C., Benkhaldoun, Z., Boyle, A. W., Ciardi, D. R., Clark, C. A., Collins, K. A., Collins, K. I., Conti, D. M., Crossfield, I. J. M., Everett, M. E., Furlan, E., Ghachoui, M., Gillon, M., Gonzales, E. J., Higuera, J., Horne, K., Howell, S. B., Jehin, E., Lester, K. V., Lund, M. B., Matson, R., Matthews, E. C., Pozuelos, F. J., Safonov, B. S., Schlieder, J. E., Schwarz, R. P., Sefako, R., Srdoc, G., Strakhov, I. A., Waalkes, W. C., Ziegler, C., Charbonneau, D., Essack, Z., Timmermans, M., Guerrero, N. M., Harakawa, H., Hedges, C., Ishizuka, M., Jenkins, J. M., Konishi, M., Kotani, T., Kudo, T., Kurokawa, T., Kuzuhara, M., Nishikawa, J., Omiya, M., Ricker, G. R., Seager, S., Serizawa, T., Striegel, S., Tamura, M., Ueda, A., Vanderspek, R., Vievard, S., and Winn, J. N.
- Subjects
Astrophysics - Earth and Planetary Astrophysics - Abstract
Sub-Neptunes with $2-3R_\oplus$ are intermediate in size between rocky planets and Neptune-sized planets. The orbital properties and bulk compositions of transiting sub-Neptunes provide clues to the formation and evolution of close-in small planets. In this paper, we present the discovery and follow-up of four sub-Neptunes orbiting M dwarfs (TOI-782, TOI-1448, TOI-2120, and TOI-2406), three of which were newly validated by ground-based follow-up observations and statistical analyses. TOI-782 b, TOI-1448 b, TOI-2120 b, and TOI-2406 b have radii of $R_\mathrm{p} = 2.740^{+0.082}_{-0.079}\,R_\oplus$, $2.769^{+0.073}_{-0.068}\,R_\oplus$, $2.120\pm0.067\,R_\oplus$, and $2.830^{+0.068}_{-0.066}\,R_\oplus$ and orbital periods of $P = 8.02$, $8.11$, $5.80$, and $3.08$\,days, respectively. Doppler monitoring with Subaru/InfraRed Doppler instrument led to 2$\sigma$ upper limits on the masses of $<19.1\ M_\oplus$, $<19.5\ M_\oplus$, $<6.8\ M_\oplus$, and $<15.6\ M_\oplus$ for TOI-782 b, TOI-1448 b, TOI-2120 b, and TOI-2406 b, respectively. The mass-radius relationship of these four sub-Neptunes testifies to the existence of volatile material in their interiors. These four sub-Neptunes, which are located above the so-called ``radius valley'', are likely to retain a significant atmosphere and/or an icy mantle on the core, such as a water world. We find that at least three of the four sub-Neptunes (TOI-782 b, TOI-2120 b, and TOI-2406 b) orbiting M dwarfs older than 1 Gyr, are likely to have eccentricities of $e \sim 0.2-0.3$. The fact that tidal circularization of their orbits is not achieved over 1 Gyr suggests inefficient tidal dissipation in their interiors., Comment: Accepted for publication in AJ, 32 pages, 17 figures, 6 tables
- Published
- 2024