TOI-969: a late-K dwarf with a hot mini-Neptune in the desert and an eccentric cold Jupiter
Deleuil, M.; Stassun, K.; Gandolfi, D.; Korth, J.; Narita, N.; Butler, R. P.; Crane, J. D.; Palle, E.; Persson, C. M.; Winn, J. N.; Adibekyan, V.; Hoyer, S.; Sousa, S. G.; Barrado, D.; Barros, S. C. C.; Collins, K. A.; Demangeon, O. D. S.; Esposito, M.; Jenkins, J. M.; Luque, R.; Muresan, A.; Osborn, H. P.; Ricker, G. R.; Santos, N. C.; Seager, S.; Lillo-Box, J.; Mousis, O.; Wheatley, P. J.; Díaz, R. F.; Latham, D. W.; Schwarz, R. P.; Morello, G.; Dumusque, X.; Hellier, C.; Fukui, A.; Giacalone, S.; Santerne, A.; Kreidberg, L.; Charbonneau, D.; Rodriguez, J. E.; Howell, S. B.; Cloutier, R.; Zhou, G.; Caldwell, D. A.; Vezie, M.; Acuña, L.; Hojjatpanah, S.; Nielsen, L. D.; Armstrong, D. J.; Quinn, S. N.; Hawthorn, F.; Shporer, A.; Osborn, A.; Savel, A. B.; Wang, S. X.; Teske, J.; Eastman, J. D.; Mireles, I.; Aguichine, A.; Shectman, S. A.; Gill, H.; Azevedo Silva, T.; Irwin, J. M.; Falk, B.; Serrano Bell, J.
Spain, Italy, United Kingdom, United States, Germany, Switzerland, Sweden, Portugal, France, Japan, Argentina, China, Australia
Abstract
Context. The current architecture of a given multi-planetary system is a key fingerprint of its past formation and dynamical evolution history. Long-term follow-up observations are key to complete their picture.
Aims: In this paper, we focus on the confirmation and characterization of the components of the TOI-969 planetary system, where TESS detected a Neptune-size planet candidate in a very close-in orbit around a late K-dwarf star.
Methods: We use a set of precise radial velocity observations from HARPS, PFS, and CORALIE instruments covering more than two years in combination with the TESS photometric light curve and other ground-based follow-up observations to confirm and characterize the components of this planetary system.
Results: We find that TOI-969 b is a transiting close-in (Pb ~ 1.82 days) mini-Neptune planet (mb = 9.1−1.0+1.1 M⊕, Rb = 2.765−0.097+0.088 R⊕), placing it on the lower boundary of the hot-Neptune desert (Teq,b = 941 ± 31 K). The analysis of its internal structure shows that TOI-969 b is a volatile-rich planet, suggesting it underwent an inward migration. The radial velocity model also favors the presence of a second massive body in the system, TOI-969 c, with a long period of Pc = 1700−280+290 days, a minimum mass of mc sin ic = 11.3−0.9+1.1 MJup, and a highly eccentric orbit of ec = 0.628−0.036+0.043.
Conclusions: The TOI-969 planetary system is one of the few around K-dwarfs known to have this extended configuration going from a very close-in planet to a wide-separation gaseous giant. TOI-969 b has a transmission spectroscopy metric of 93 and orbits a moderately bright (G = 11.3 mag) star, making it an excellent target for atmospheric studies. The architecture of this planetary system can also provide valuable information about migration and formation of planetary systems.