TOI-1416: A system with a super-Earth planet with a 1.07 d period

• Published in: Astronomy and astrophysics (Berlin) Vol. 677; p. A12
• Main Authors: Deeg, H. J., Georgieva, I. Y., Nowak, G., Persson, C. M., Cale, B. L., Murgas, F., Pallé, E., Godoy-Rivera, D., Dai, F., Ciardi, D. R., Murphy, J. M. Akana, Beck, P. G., Burke, C. J., Cabrera, J., Carleo, I., Cochran, W. D., Collins, K. A., Csizmadia, Sz, El Mufti, M., Fridlund, M., Fukui, A., Gandolfi, D., García, R. A., Guenther, E. W., Guerra, P., Grziwa, S., Isaacson, H., Isogai, K., Jenkins, J. M., Kábath, P., Korth, J., Lam, K. W. F., Latham, D. W., Luque, R., Lund, M. B., Livingston, J. H., Mathis, S., Mathur, S., Narita, N., Orell-Miquel, J., Osborne, H. L. M., Parviainen, H., Plavchan, P. P., Redfield, S., Rodriguez, D. R., Schwarz, R. P., Seager, S., Smith, A. M. S., Van Eylen, V., Van Zandt, J., Winn, J. N., Ziegler, C.
• Format: Journal Article
• Language: English
• Published: Heidelberg EDP Sciences 01.09.2023
• Subjects: Dwarf stars; Earth; Extrasolar planets; Magma; Planetary systems; Planets and satellites: composition; Planets and satellites: detection; Planets and satellites: individual: TOI-1416 b; Planets and satellites: terrestrial planets; Techniques: radial velocities; Terrestrial planets; Transit
• ISSN: 0004-6361; 1432-0746; 1432-0746
• DOI: 10.1051/0004-6361/202346370

TOI-1416 (BD+42 2504, HIP 70705) is a V =10 late G- or early K-type dwarf star. TESS detected transits in its Sectors 16, 23, and 50 with a depth of about 455 ppm and a period of 1.07 days. Radial velocities (RVs) confirm the presence of the transiting planet TOI-1416 b , which has a mass of 3.48 ± 0.47 M ⊕ and a radius of 1.62 ± 0.08 R ⊕ , implying a slightly sub-Earth density of 4.50 −0.83 +0.99 g cm −3 . The RV data also further indicate a tentative planet, c , with a period of 27.4 or 29.5 days, whose nature cannot be verified due to strong suspicions of contamination by a signal related to the Moon’s synodic period of 29.53 days. The nearly ultra-short-period planet TOI-1416 b is a typical representative of a short-period and hot ( T eq ≈ 1570 K) super-Earth-like planet. A planet model of an interior of molten magma containing a significant fraction of dissolved water provides a plausible explanation for its composition, and its atmosphere could be suitable for transmission spectroscopy with JWST. The position of TOI-1416 b within the radius-period distribution corroborates the idea that planets with periods of less than one day do not form any special group. It instead implies that ultra-short-period planets belong to a continuous distribution of super-Earth-like planets with periods ranging from the shortest known ones up to ≈30 days; their period-radius distribution is delimited against larger radii by the Neptune Desert and by the period-radius valley that separates super-Earths from sub-Neptune planets. In the abundance of small, short-periodic planets, a notable plateau has emerged between periods of 0.6–1.4 days, which is compatible with the low-eccentricity formation channel. For the Neptune Desert, its lower limits required a revision due to the increasing population of short-period planets; for periods shorter then 2 days, we establish a radius of 1.6 R ⊕ and a mass of 0.028 M jup (corresponding to 8.9 M ⊕ ) as the desert’s lower limits. We also provide corresponding limits to the Neptune Desert against the planets’ insolation and effective temperatures.