Radial velocity confirmation of a hot super-Neptune discovered by TESS with a warm Saturn-mass companion
/ Authors
E. Knudstrup, D. Gandolfi, G. Nowak, C. Persson, E. Furlan, J. Livingston, E. Matthews, M. Lundkvist, M. Winther, J. L. Rørsted
and 52 more authors
S. Albrecht, E. Goffo, I. Carleo, H. Deeg, K. Collins, N. Narita, H. Isaacson, S. Redfield, F. Dai, T. Hirano, J. A. Murphy, C. Beard, L. Buchhave, S. Cary, A. Chontos, I. Crossfield, W. Cochran, D. Conti, P. Dalba, M. Esposito, S. Fajardo-Acosta, S. Giacalone, S. Grunblatt, P. Guerra, A. Hatzes, R. Holcomb, F. G. Horta, A. Howard, D. Huber, J. Jenkins, P. Kab'ath, S. Kane, J. Korth, K. Lam, K. Lester, R. Matson, K. McLeod, J. Orell-Miquel, F. Murgas, E. Pallé, A. Polanski, G. Ricker, P. Robertson, R. Rubenzahl, J. Schlieder, S. Seager, A. Smith, P. Tenenbaum, E. Turtelboom, R. Vanderspek, L. Weiss, J. Winn
/ Abstract
We report the discovery and confirmation of the planetary system TOI-1288. This late G dwarf harbours two planets: TOI-1288 b and TOI-1288 c. We combine TESS space-borne and ground-based transit photometry with HARPS-N and HIRES high-precision Doppler measurements, which we use to constrain the masses of both planets in the system and the radius of planet b. TOI-1288~b has a period of $2.699835^{+0.000004}_{-0.000003}$ d, a radius of $5.24 \pm 0.09$ R$_\oplus$, and a mass of $42 \pm 3$ M$_\oplus$, making this planet a hot transiting super-Neptune situated right in the Neptunian desert. This desert refers to a paucity of Neptune-sized planets on short period orbits. Our 2.4-year-long Doppler monitoring of TOI-1288 revealed the presence of a Saturn-mass planet on a moderately eccentric orbit ($0.13^{+0.07}_{-0.09}$) with a minimum mass of $84 \pm 7$ M$_\oplus$ and a period of $443^{+11}_{-13}$ d. The 5 sectors worth of TESS data do not cover our expected mid-transit time for TOI-1288 c, and we do not detect a transit for this planet in these sectors.