TOI-969: a late-K dwarf with a hot mini-Neptune in the desert and an eccentric cold Jupiter
Creators: name: Lillo-Box, J.
name: Gandolfi, D.
name: Armstrong, D. J.
name: Collins, K. A.
name: Nielsen, L. D.
name: Luque, R.
name: Korth, J.
name: Sousa, S. G.
name: Quinn, S. N.
name: Acuña, L.
name: Howell, S. B.
name: Morello, G.
name: Hellier, C.
name: Giacalone, S.
name: Hoyer, S.
name: Stassun, K.
name: Palle, E.
name: Aguichine, A.
name: Mousis, O.
name: Adibekyan, V.
name: Silva, T. Azevedo
name: Barrado, D.
name: Deleuil, M.
name: Eastman, J. D.
name: Hawthorn, F.
name: Irwin, J. M.
name: Jenkins, J. M.
name: Latham, D. W.
name: Muresan, A.
name: Persson, C. M.
name: Santerne, A.
name: Santos, N. C.
name: Savel, A. B.
name: Osborn, H. P.
name: Teske, J.
name: Wheatley, P. J.
name: Winn, J. N.
name: Barros, S. C. C.
name: Butler, R. P.
name: Caldwell, D. A.
name: Charbonneau, D.
name: Cloutier, R.
name: Crane, J. D.
name: Demangeon, O. D. S.
name: Díaz, R. F.
name: Dumusque, X.
name: Esposito, M.
name: Falk, B.
name: Gill, H.
name: Hojjatpanah, S.
name: Kreidberg, L.
name: Mireles, I.
name: Osborn, A.
name: Ricker, G. R.
name: Rodriguez, J. E.
name: Schwarz, R. P.
name: Seager, S.
name: Bell, J. Serrano
name: Shectman, S. A.
name: Shporer, A.
name: Vezie, M.
name: Wang, S. X.
name: Zhou, G.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: 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. 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. 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. We find that TOI-969 b is a transiting close-in ($P_b\sim 1.82$ days) mini-Neptune planet ($m_b=9.1^{+1.1}_{-1.0}$ M$_{\oplus}$, $R_b=2.765^{+0.088}_{-0.097}$ R$_{\oplus}$), thus placing it on the {lower boundary} of the hot-Neptune desert ($T_{\rm eq,b}=941\pm31$ 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 $P_c=1700^{+290}_{-280}$ days and a minimum mass of $m_{c}\sin{i_c}=11.3^{+1.1}_{-0.9}$ M$_{\rm Jup}$, and with a highly-eccentric orbit of $e_c=0.628^{+0.043}_{-0.036}$. 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 it orbits a moderately bright ($G=11.3$ mag) star, thus becoming an excellent target for atmospheric studies. The architecture of this planetary system can also provide valuable information about migration and formation of planetary systems.
description: Accepted for publication in A&amp;A. 25 pages, 15 figures, 12 tables