TOI-969: a late-K dwarf with a hot mini-Neptune in the desert and an eccentric cold Jupiter

Full list of authors: Lillo-Box, J.; Gandolfi, D.; Armstrong, D. J.; Collins, K. A.; Nielsen, L. D.; Luque, R.; Korth, J.; Sousa, S. G.; Quinn, S. N.; Acuña, L.; Howell, S. B.; Morello, G.; Hellier, C.; Giacalone, S.; Hoyer, S.; Stassun, K.; Palle, E.; Aguichine, A.; Mousis, O.; Adibekyan, V.; Azevedo Silva, T.; Barrado, D.; Deleuil, M.; Eastman, J. D.; Fukui, A.; Hawthorn, F.; Irwin, J. M.; Jenkins, J. M.; Latham, D. W.; Muresan, A.; Narita, N.; Persson, C. M.; Santerne, A.; Santos, N. C.; Savel, A. B.; Osborn, H. P.; Teske, J.; Wheatley, P. J.; Winn, J. N.; Barros, S. C. C.; Butler, R. P.; Caldwell, D. A.; Charbonneau, D.; Cloutier, R.; Crane, J. D.; Demangeon, O. D. S.; Díaz, R. F.; Dumusque, X.; Esposito, M.; Falk, B.; Gill, H.; Hojjatpanah, S.; Kreidberg, L.; Mireles, I.; Osborn, A.; Ricker, G. R.; Rodriguez, J. E.; Schwarz, R. P.; Seager, S.; Serrano Bell, J.; Shectman, S. A.; Shporer, A.; Vezie, M.; Wang, S. X.; Zhou, G.--This is an Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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. © The Authors 2023.
J.L-B. acknowledges financial support received from “la Caixa” Foundation (ID 100010434) and from the European Unions Horizon 2020 research and innovation programme under the Marie Slodowska-Curie grant agreement No 847648, with fellowship code LCF/BQ/PI20/11760023. This research has also been partly funded by the Spanish State Research Agency (AEI) Projects No.PID2019-107061GB-C6l and No. MDM-2017-0737 Unidad de Excelencia “Maria de Maeztu” – Centro de Astrobiología (INTA-CSIC). R.L. acknowledges financial support from the Spanish Ministerio de Ciencia e Innovación, through project PID2019-109522GB-C52, and the Centre of Excellence “Severo Ochoa” award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709). DJ.A. acknowledges support from the STFC via an Ernest Rutherford Fellowship (ST/R00384X/1). S.G.S acknowledges the support from FCT through Estimulo FCT contract nr.CEECIND/00826/2018 and POPH/FSE (EC). G.M. has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 895525. S.H. acknowledges CNES funding through the grant 837319. The French group acknowledges financial support from the French Programme National de Planétologie (PNP, INSU). This work is partly financed by the Spanish Mnistry of Economics and Competitiveness through grants PGC2018-098153-B-C31. We acknowledge the support by FCT – Fundação para a Ciência e a Tecnologia through national funds and by FEDER through COMPETE2020 – Programa Operacional Competitividade e Internacionalização by these grants: UID/FIS/04434/2019; UIDB/04434/2020; UIDP/04434/2020; PTDC/FIS-AST/32113/2017 & POCI-01-0145-FEDER-032113; PTDC/FISAST/28953/2017 & POCI-01-0145-FEDER-028953. P.J.W is supported by an STFC consolidated grant (ST/T000406/1). F.H. is funded by an STFC studentship. T.A.S acknowledges support from the Fundação para a Ciência e a Tecnologia (FCT) through the Fellowship PD/BD/150416/2019 and POCH/FSE (EC). C.M.P. acknowledges support from the SNSA (dnr 65/19P). This work has been carried out within the framework of the National Centre of Competence in Research (NCCR) PlanetS supported by the Swiss National Science Foundation. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement SCORE No 851555). O.D.S.D. is supported in the form of work contract (DL 57/2016/CP1364/CT0004) funded by national funds through Fundação para a Ciência e a Tecnologia (FCT). M.E. acknowledges the support of the DFG priority programSPP 1992 “Exploring the Diversity of Extrasolar Planets” (HA 3279/12-1). A.O. is funded by an STFC studentship. J.K. gratefully acknowledge the support of the Swedish National Space Agency (SNSA; DNR 2020-00104). This work makes use of observations from the LCOGT network. This paper is based on observations made with the MuSCAT3 instrument, developed by the Astrobiology Center and under financial supports by ISPS KAKENHI (IP18H05439) and 1ST PRESTO (IPMIPR1775), at Faulkes Telescope North on Maui, HI, operated by the Las Cumbres Observatory. Some of the observations in the paper made use of the High-Resolution Imaging instrument Zorro obtained under Gemini LLP Proposal Number: GN/S-2021A-LP-105. Zorro was funded by the NASA Exoplanet Exploration Program and built at the NASA Ames Research Center by Steve B. Howell, Nie Scott, Elliott P. Horch, and Emmett Quigley. Zorro was mounted on the Gemini North (and/or South) telescope of the international Gemini Observatory, a program of NSF’s OIR Lab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. on behalf of the Gemini partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigación y Desarrollo (Chile), Ministerio de Ciencia, Tecnología e Innovación (Argentina), Ministério da Ciência, Tecnologia, Inovações e Comunicações (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea). We acknowledge the use of public TESS data from pipelines at the TESS Science Office and at the TESS Science Processing Operations Center. Resources supporting this work were provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center for the production of the SPOC data products. The MEarth Team gratefully acknowledges funding from the David and Lucile Packard Fellowship for Science and Engineering (awarded to D.C.). This material is based upon work supported by the National Science Foundation under grants AST-0807690, AST-1109468, AST-1004488 (Alan T. Waterman Award), and AST-1616624, and upon work supported by the National Aeronautics and Space Administration under Grant No. 80NSSC18K0476 issued through the XRP Program. This work is made possible by a grant from the John Templeton Foundation. The opinions expressed in this publication are those of the authors and do not necessarily reflect the views of the John Templeton Foundation. This research made use of Astropy, (a community-developed core Python package for Astronomy, Astropy Collaboration 2013, 2018), SciPy (Virtanen et al. 2020), matplotlib (a Python library for publication quality graphics Hunter 2007), and numpy (Harris et al. 2020). This research has made use of NASA’s Astrophysics Data System Bibliographic Services. This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France.
With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2021-001131-S).