TOI-1842b: A Transiting Warm Saturn Undergoing Reinflation around an Evolving Subgiant

Creators: Wittenmyer, Robert A.; Clark, Jake T.; Trifonov, Trifon; Addison, Brett C.; Wright, Duncan J.; Stassun, Keivan G.; Horner, Jonathan; Lowson, Nataliea; Kielkopf, John; Kane, Stephen R.; Plavchan, Peter; Shporer, Avi; Zhang, Hui; Bowler, Brendan P.; Mengel, Matthew W.; Okumura, Jack; Rabus, Markus; Johnson, Marshall C.; Harbeck, Daniel; Tronsgaard, René; Buchhave, Lars A.; Collins, Karen A.; Collins, Kevin I.; Gan, Tianjun; Jensen, Eric L. N.; Howell, Steve B.; Furlan, E.; Gnilka, Crystal L.; Lester, Kathryn V.; Matson, Rachel A.; Scott, Nicholas J.; Ricker, George R.; Vanderspek, Roland; Latham, David W.; Seager, S.; Winn, Joshua N.; Jenkins, Jon M.; Rudat, Alexander; Quintana, Elisa V.; Rodriguez, David R.; Caldwell, Douglas A.; Quinn, Samuel N.; Essack, Zahra; Bouma, Luke G.

Abstract

The imminent launch of space telescopes designed to probe the atmospheres of exoplanets has prompted new efforts to prioritize the thousands of transiting planet candidates for follow-up characterization. We report the detection and confirmation of TOI-1842b, a warm Saturn identified by TESS and confirmed with ground-based observations from Minerva-Australis, NRES, and the Las Cumbres Observatory Global Telescope. This planet has a radius of 1.04^(+0.06)_(−0.05) R_J, a mass of 0.214^(+0.040)_(−0.038) M_J, an orbital period of 9.5739^(+0.0002)_(−0.0001) days, and an extremely low density (ρ = 0.252 ± 0.091 g cm⁻³). TOI-1842b has among the best known combinations of large atmospheric scale height (893 km) and host-star brightness (J = 8.747 mag), making it an attractive target for atmospheric characterization. As the host star is beginning to evolve off the main sequence, TOI-1842b presents an excellent opportunity to test models of gas giant reinflation. The primary transit duration of only 4.3 hours also makes TOI-1842b an easily-schedulable target for further ground-based atmospheric characterization.

Additional Information

© 2022. The American Astronomical Society. Content from this work may be used under the terms of the Creative Commons Attribution 4.0 license. 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 10; revised 2021 November 11; accepted 2021 November 30; published 2022 January 21. We respectfully acknowledge the traditional custodians of all lands throughout Australia, and recognize their continued cultural and spiritual connection to the land, waterways, cosmos, and community. We pay our deepest respects to all Elders, ancestors, and descendants of the Giabal, Jarowair, and Kambuwal nations, upon whose lands the Minerva-Australis facility at Mt Kent is situated. Minerva-Australis is supported by Australian Research Council LIEF Grant LE160100001, Discovery Grant DP180100972, Mount Cuba Astronomical Foundation, and institutional partners University of Southern Queensland, UNSW Sydney, MIT, Nanjing University, George Mason University, University of Louisville, University of California Riverside, University of Florida, and The University of Texas at Austin. 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, Nic 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). This work makes use of observations from the LCOGT network. B.A. is supported by Australian Research Council Discovery Grant DP180100972. Funding for the TESS mission is provided by NASA's Science Mission directorate. We acknowledge the use of public TESS Alert data from pipelines at the TESS Science Office and at the TESS Science Processing Operations Center. 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. 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 paper includes data collected by the TESS mission, which are publicly available from the Mikulski Archive for Space Telescopes (MAST). This paper is partially based on observations made with the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias. 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. Facilities: TESS - , Minerva-Australis - , NOT/FIES - , LCOGT/NRES - , Exoplanet Archive. - Software: AstroImageJ (Collins et al. 2017), isochrones (Morton 2015), ispec (Blanco-Cuaresma et al. 2014; Blanco-Cuaresma 2019), Tapir (Jensen 2013), BANZAI (McCully et al. 2018), Wotan (Hippke et al. 2019), SPOC pipeline (Jenkins et al. 2016), batman (Kreidberg 2015), Exo-Striker (Trifonov 2019).

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