Radial velocity confirmation of a hot super-Neptune discovered by TESS with a warm Saturn-mass companion
McLeod, K. K.; Dai, F.; Gandolfi, D.; Hirano, T.; Korth, J.; Hatzes, A. P.; Smith, A. M. S.; Narita, N.; Cochran, W. D.; Palle, E.; Persson, C. M.; Nowak, G.; Knudstrup, E.; Rørsted, J. L.; Winther, M. L.; Collins, K. A.; Deeg, H. J.; Esposito, M.; Goffo, E.; Jenkins, J. M.; Lam, K. W. F.; Redfield, S.; Seager, S.; Ricker, G.; Vanderspek, R.; Winn, J.; Buchhave, L. A.; Murgas, F.; Isaacson, H.; Furlan, E.; Orell-Miquel, J.; Carleo, I.; Beard, C.; Chontos, A.; Dalba, P. A.; Giacalone, S.; Grunblatt, S. K.; Huber, D.; Polanski, A. S.; Robertson, P.; Turtelboom, E.; Weiss, L.; Kabáth, P.; Guerra, P.; Livingston, J.; Schlieder, J. E.; Tenenbaum, P.; Howard, A. W.; Matthews, E.; Crossfield, I.; Matson, R.; Conti, D.; Holcomb, R.; Kane, S.; Lundkvist, M. S.; Albrecht, S. H.; Akana Murphy, J. M.; Cary, S.; Fajardo-Acosta, S.; Horta, F. G.; Lester, K. V.; Rubenzahl, R.
Denmark, Spain, Italy, Sweden, United States, Japan, Switzerland, Germany, Czech Republic
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 ± 0.09 R⊕, and a mass of 42 ± 3 M⊕, 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-yr-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 ± 7 M⊕ and a period of $443^{+11}_{-13}$ d. The five 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.