The TESS-Keck Survey. VIII. Confirmation of a Transiting Giant Planet on an Eccentric 261 Day Orbit with the Automated Planet Finder Telescope

Creators: Dalba, Paul A.; Kane, Stephen R.; Dragomir, Diana; Villanueva, Steven; Collins, Karen A.; Jacobs, Thomas Lee; LaCourse, Daryll M.; Gagliano, Robert; Kristiansen, Martti H.; Omohundro, Mark; Schwengeler, Hans M.; Terentev, Ivan A.; Vanderburg, Andrew; Fulton, Benjamin; Isaacson, Howard; Van Zandt, Judah; Howard, Andrew W.; Thorngren, Daniel P.; Howell, Steve B.; Batalha, Natalie M.; Chontos, Ashley; Crossfield, Ian J. M.; Dressing, Courtney D.; Huber, Daniel; Petigura, Erik A.; Robertson, Paul; Roy, Arpita; Weiss, Lauren M.; Behmard, Aida; Beard, Corey; Brinkman, Casey L.; Giacalone, Steven; Hill, Michelle L.; Lubin, Jack; Mayo, Andrew W.; Močnik, Teo; Akana Murphy, Joseph M.; Polanski, Alex S.; Rice, Malena; Rosenthal, Lee J.; Rubenzahl, Ryan A.; Scarsdale, Nicholas; Turtelboom, Emma V.; Tyler, Dakotah; Benni, Paul; Boyce, Pat; Esposito, Thomas M.; Girardin, E.; Laloum, Didier; Lewin, Pablo; Mann, Christopher R.; Marchis, Franck; Schwarz, Richard P.; Srdoc, Gregor; Steuer, Jana; Sivarani, Thirupathi; Unni, Athira; Eisner, Nora L.; Fetherolf, Tara; Li, Zhexing; Yao, Xinyu; Pepper, Joshua; Ricker, George R.; Vanderspek, Roland; Latham, David W.; Seager, S.; Winn, Joshua N.; Jenkins, Jon M.; Burke, Christopher J.; Eastman, Jason D.; Lund, Michael B.; Rodriguez, David R.; Rowden, Pamela; Ting, Eric B.; Villaseñor, Jesus Noel

Abstract

We report the discovery of TOI-2180 b, a 2.8 M_J giant planet orbiting a slightly evolved G5 host star. This planet transited only once in Cycle 2 of the primary Transiting Exoplanet Survey Satellite (TESS) mission. Citizen scientists identified the 24 hr single-transit event shortly after the data were released, allowing a Doppler monitoring campaign with the Automated Planet Finder telescope at Lick Observatory to begin promptly. The radial velocity observations refined the orbital period of TOI-2180 b to be 260.8 ± 0.6 days, revealed an orbital eccentricity of 0.368 ± 0.007, and discovered long-term acceleration from a more distant massive companion. We conducted ground-based photometry from 14 sites spread around the globe in an attempt to detect another transit. Although we did not make a clear transit detection, the nondetections improved the precision of the orbital period. We predict that TESS will likely detect another transit of TOI-2180 b in Sector 48 of its extended mission. We use giant planet structure models to retrieve the bulk heavy-element content of TOI-2180 b. When considered alongside other giant planets with orbital periods over 100 days, we find tentative evidence that the correlation between planet mass and metal enrichment relative to stellar is dependent on orbital properties. Single-transit discoveries like TOI-2180 b highlight the exciting potential of the TESS mission to find planets with long orbital periods and low irradiation fluxes despite the selection biases associated with the transit method.

Additional Information

© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2021 September 24; revised 2021 November 19; accepted 2021 December 6; published 2022 January 13. The authors recognize and acknowledge the cultural role and reverence that the summit of Maunakea has within the indigenous Hawaiian community. We are deeply grateful to have the opportunity to conduct observations from this mountain. The authors would like to thank the anonymous referee for helpful comments that improved this paper. We also thank Jack Lissauer for interesting conversations about giant planets that guided some of our analysis. We thank Ken and Gloria Levy, who supported the construction of the Levy Spectrometer on the Automated Planet Finder. We thank the University of California and Google for supporting Lick Observatory and the UCO staff for their dedicated work scheduling and operating the telescopes of Lick Observatory. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. This paper includes data collected by the TESS mission. Funding for the TESS mission is provided by NASA's Science Mission Directorate. We acknowledge the use of public TESS data from pipelines at the TESS Science Office and 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 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 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 paper includes data collected with the TESS mission, obtained from the MAST data archive at the Space Telescope Science Institute (STScI). The STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. We acknowledge the use of public TESS data from pipelines at the TESS Science Office and the TESS Science Processing Operations Center. 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 NSF. P.D. is supported by a National Science Foundation (NSF) Astronomy and Astrophysics Postdoctoral Fellowship under award AST-1903811. E.A.P. acknowledges the support of the Alfred P. Sloan Foundation. L.M.W. is supported by the Beatrice Watson Parrent Fellowship and NASA ADAP grant 80NSSC19K0597. A.C. is supported by the NSF Graduate Research Fellowship, grant No. DGE 1842402. D.H. acknowledges support from the Alfred P. Sloan Foundation, the National Aeronautics and Space Administration (80NSSC21K0652), and the National Science Foundation (AST-1717000). I.J.M.C. acknowledges support from the NSF through grant AST-1824644. R.A.R. is supported by the NSF Graduate Research Fellowship, grant No. DGE 1745301. C.D.D. acknowledges the support of the Hellman Family Faculty Fund, the Alfred P. Sloan Foundation, the David & Lucile Packard Foundation, and the National Aeronautics and Space Administration via the TESS Guest Investigator Program (80NSSC18K1583). J.M.A.M. is supported by the NSF Graduate Research Fellowship, grant No. DGE-1842400. J.M.A.M. also acknowledges the LSSTC Data Science Fellowship Program, which is funded by LSSTC, NSF Cybertraining grant No. 1829740, the Brinson Foundation, and the Moore Foundation; his participation in the program has benefited this work. T.F. acknowledges support from the University of California President's Postdoctoral Fellowship Program. N.E. acknowledges support from the UK Science and Technology Facilities Council (STFC) under grant code ST/R505006/1. D.D. acknowledges support from TESS Guest Investigator Program grant 80NSSC19K1727 and NASA Exoplanet Research Program grant 18-2XRP18_2-0136. M.R. is supported by the National Science Foundation Graduate Research Fellowship Program under grant No. DGE-1752134. P.D. thanks the Walmart of Yucca Valley, California, for frequent and prolonged use of its wireless internet to upload hundreds of gigabytes of data. Facilities: Keck:I (HIRES) - , Automated Planet Finder (Levy) - , TESS - , Gemini:Gillett ('Alopeke) - , LCOGT. Software: batman (Kreidberg 2015), EXOFASTv2 (Eastman et al. 2013; Eastman 2017; Eastman et al. 2019), lightkurve (Lightkurve Collaboration et al. 2018), RadVel (Fulton et al. 2018), SpecMatch (Petigura 2015; Petigura et al. 2017), AstroImageJ (Collins et al. 2017), LcTools (Schmitt et al. 2019).

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