@article{b3930b24894e4281b57a6b481a102314,
title = "Validation of TOI-1221 b: A Warm Sub-Neptune Exhibiting Transit Timing Variations around a Sun-like Star",
abstract = "We present a validation of a long-period ( 91.68278-0.00041+0.00032 days) transiting sub-Neptune planet, TOI-1221 b (TIC 349095149.01), around a Sun-like (m V = 10.5) star. This is one of the few known exoplanets with a period >50 days, and belongs to the even smaller subset of which have bright enough hosts for detailed spectroscopic follow-up. We combine Transiting Exoplanet Survey Satellite light curves and ground-based time-series photometry from the Perth Exoplanet Survey Telescope (0.3 m) and Las Cumbres Observatory global telescope network (1.0 m) to analyze the transit signals and rule out nearby stars as potential false-positive sources. High-contrast imaging from the Southern Astrophysical Research Telescope and Gemini/Zorro rule out nearby stellar contaminants. Reconnaissance spectroscopy from CHIRON sets a planetary scale upper mass limit on the transiting object (1.1 and 3.5 M Jup at 1σ and 3σ, respectively) and shows no sign of a spectroscopic binary companion. We determine a planetary radius of Rp=2.91-0.12+0.13R⊕, placing it in the sub-Neptune regime. With a stellar insolation of S=6.06-0.77+0.85S⊕, we calculate a moderate equilibrium temperature of T eq = 440 K, assuming no albedo and perfect heat redistribution. We find a false-positive probability from the TRICERATOPS tool of FPP = 0.0014 ± 0.0003 as well as other qualitative and quantitative evidence to support the statistical validation of TOI-1221 b. We find significant evidence (>5σ) of oscillatory transit timing variations, likely indicative of an additional nontransiting planet.",
author = "Christopher Mann and David Lafreni{\'e}re and Diana Dragomir and Quinn, {Samuel N.} and Tan, {Thiam Guan} and Collins, {Karen A.} and Howell, {Steve B.} and Carl Ziegler and Mann, {Andrew W.} and Stassun, {Keivan G.} and Kristiansen, {Martti H.} and Hugh Osborn and Tabetha Boyajian and Nora Eisner and Coel Hellier and Ricker, {George R.} and Roland Vanderspek and Latham, {David W.} and S. Seager and Winn, {Joshua N.} and Jenkins, {Jon M.} and Villase{\~n}or, {Jesus Noel} and Brian McLean and Pamela Rowden and Guillermo Torres and Caldwell, {Douglas A.} and Collins, {Kevin I.} and Schwarz, {Richard P.}",
note = "Funding Information: C.M. and D.L. acknowledge funding from the Trottier Family Foundation in their support of the Trottier Institute for Research on Exoplanets (iREx). They also acknowledge individual funding from the Natural Sciences and Engineering Research Council (NSERC) of Canada. D.D. acknowledges support from the TESS Guest Investigator Program grant Nos. 80NSSC21K0108 and 80NSSC22K0185. S.Q. acknowledges support from the TESS GI Program under grant No. 80NSSC21K1056. M.H.K. thanks Allan R. Schmitt for making his light-curve examining software LcTools freely available. The work of H.P.O. has been carried out within the framework of the National Centre of Competence in Research PlanetS supported by the Swiss National Science Foundation under grant Nos. 51NF40_182901 and 51NF40_205606, for which we acknowledge the financial support of the SNSF. This paper made use of data collected by the TESS mission and are publicly available from the Mikulski Archive for Space Telescopes (MAST) operated by the Space Telescope Science Institute (STScI). Funding for the TESS mission is provided by NASAs Science Mission Directorate. 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. This work has set the stage for a follow-up mass measurement of TOI-1221 b, a planet that matches the TESS Mission Level One Science Requirement of determining the masses of fifty (50) planets with radii less than 4 R . This research has made use of the Exoplanet Follow-up Observation Program website, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. This work makes use of observations from the LCOGT network. Part of the LCOGT telescope time was granted by NOIRLab through the Mid-Scale Innovations Program (MSIP). MSIP is funded by the NSF. This paper was based in part on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Minist{\'e}rio da Ci{\^e}ncia, Tecnologia e Inova{\c c}{\~o}es (MCTI/LNA) do Brasil, the US National Science Foundations NOIRLab, the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU). Observations in the paper (Program ID: GN/S-2021A-LP-105) made use of the High-Resolution Imaging instrument Zorro. Zorro was funded by the NASA Exoplanet Exploration Program and built at the NASA Ames Research Center by Steve B. Howell, Nic Scott, Elliott P. Horch, and Emmett Quigley. Zorro was mounted on the Gemini South telescope of the international Gemini Observatory, a program of NSFs NOIRLab, 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 Observatory partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigaci{\'o}n y Desarrollo (Chile), Ministerio de Ciencia, Tecnolog{\'i}a e Innovaci{\'o}n (Argentina), Minist{\'e}rio da Ci{\^e}ncia, Tecnologia, Inova{\c c}{\~o}es e Comunica{\c c}{\~o}es (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea). This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. This work has made use of data from the European Space Agency Gaia ( https://www.cosmos.esa.int/gaia ), processed Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium ). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. ⊕ Publisher Copyright: {\textcopyright} 2023. The Author(s). Published by the American Astronomical Society.",
year = "2023",
month = may,
day = "1",
doi = "10.3847/1538-3881/acc8d4",
language = "English (US)",
volume = "165",
journal = "Astronomical Journal",
issn = "0004-6256",
publisher = "IOP Publishing Ltd.",
number = "5",
}