TOI-1749: an M dwarf with a Trio of Planets including a Near-resonant Pair

Full list of authors: Fukui, A.; Korth, J.; Livingston, J. H.; Twicken, J. D.; Osorio, M. R. Zapatero; Jenkins, J. M.; Mori, M.; Murgas, F.; Ogihara, M.; Narita, N.; Pallé, E.; Stassun, K. G.; Nowak, G.; Ciardi, D. R.; Alvarez-Hernandez, L.; Béjar, V. J. S.; Casasayas-Barris, N.; Crouzet, N.; de Leon, J. P.; Esparza-Borges, E.; Soto, D. Hidalgo; Isogai, K.; Kawauchi, K.; Klagyivik, P.; Kodama, T.; Kurita, S.; Kusakabe, N.; Luque, R.; Madrigal-Aguado, A.; Rodriguez, P. Montanes; Morello, G.; Nishiumi, T.; Orell-Miquel, J.; Oshagh, M.; Parviainen, H.; Sánchez-Benavente, M.; Stangret, M.; Terada, Y.; Watanabe, N.; Chen, G.; Tamura, M.; Bosch-Cabot, P.; Bowen, M.; Eastridge, K.; Freour, L.; Gonzales, E.; Guerra, P.; Jundiyeh, Y.; Kim, T. K.; Kroer, L. V.; Levine, A. M.; Morgan, E. H.; Reefe, M.; Tronsgaard, R.; Wedderkopp, C. K.; Wittrock, J.; Collins, K. A.; Hesse, K.; Latham, D. W.; Ricker, G. R.; Seager, S.; Vanderspek, R.; Winn, J.; Bachelet, E.; Bowman, M.; McCully, C.; Daily, M.; Harbeck, D.; Volgenau, N. H.
We report the discovery of one super-Earth- (TOI-1749b) and two sub-Neptune-sized planets (TOI-1749c and TOI-1749d) transiting an early M dwarf at a distance of 100 pc, which were first identified as planetary candidates using data from the TESS photometric survey. We have followed up this system from the ground by means of multiband transit photometry, adaptive optics imaging, and low-resolution spectroscopy, from which we have validated the planetary nature of the candidates. We find that TOI-1749b, c, and d have orbital periods of 2.39, 4.49, and 9.05 days, and radii of 1.4, 2.1, and 2.5 R ⊕, respectively. We also place 95% confidence upper limits on the masses of 57, 14, and 15 M ⊕ for TOI-1749b, c, and d, respectively, from transit timing variations. The periods, sizes, and tentative masses of these planets are in line with a scenario in which all three planets initially had a hydrogen envelope on top of a rocky core, and only the envelope of the innermost planet has been stripped away by photoevaporation and/or core-powered mass-loss mechanisms. These planets are similar to other planetary trios found around M dwarfs, such as TOI-175b,c,d and TOI-270b,c,d, in the sense that the outer pair has a period ratio within 1% of 2. Such a characteristic orbital configuration, in which an additional planet is located interior to a near 2:1 period-ratio pair, is relatively rare around FGK dwarfs. © 2021. The American Astronomical Society. All rights reserved.
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 at the TESS Science Processing Operations Center (SPOC). 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 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 by the TESS mission that are publicly available from the Mikulski Archive for Space Telescopes (MAST). This paper is based on observations made with the MuSCAT3 instrument, developed by the Astrobiology Center and under financial supports by JSPS KAKENHI (JP18H05439) and JST PRESTO (JPMJPR1775), at Faulkes Telescope North on Maui, HI, operated by the Las Cumbres Observatory. Based on observations obtained with the Samuel Oschin 48 inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. Z.T.F. is supported by the National Science Foundation under grant No. AST-1440341 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, the University of Washington, Deutsches Elektronen-Synchrotron and Humboldt University, Los Alamos National Laboratories, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, and Lawrence Berkeley National Laboratories. Operations are conducted by COO, IPAC, and UW. This work is partly supported by JSPS KAKENHI grant Nos. JP17H04574, JP18H01265, and JP18H05439, Grant-in-Aid for JSPS Fellows grant No. JP20J21872, JST PRESTO grant No. JPMJPR1775, and a University Research Support Grant from the National Astronomical Observatory of Japan (NAOJ). This work is also partly financed by the Spanish Ministry of Economics and Competitiveness through grants PGC2018-098153-B-C31 and PID2019-109522GB-C53. J.K. gratefully acknowledges the support of the Swedish National Space Agency (DNR 2020-00104). G.M. has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Skodowska-Curie grant agreement No. 895525. M.T. is supported by JSPS KAKENHI grant Nos.18H05442, 15H02063, and 22000005.
With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.