Discovery of a massive giant planet with extreme density around the sub-giant star TOI-4603

Creators: Khandelwal, Akanksha; Sharma, Rishikesh; Chakraborty, Abhijit; Chaturvedi, Priyanka; Ulmer-Moll, Solène; Ciardi, David R.; Boyle, Andrew W.; Baliwal, Sanjay; Bieryla, Allyson; Latham, David W.; Prasad, Neelam J. S. S. V.; Nayak, Ashirbad; Lendl, Monika; Mordasini, Christoph

Abstract

We present the discovery of a transiting massive giant planet around TOI-4603, a sub-giant F-type star from NASA's Transiting Exoplanet Survey Satellite (TESS). The newly discovered planet has a radius of 1.042_(−0.035)^(+0.038) R_J and an orbital period of 7.24599_(−0.00021)^(+0.00022) days. Using radial velocity measurements with the PARAS and TRES spectrographs, we determined the planet's mass to be 12.89_(−0.57)^(+0.58) M_J, resulting in a bulk density of 14.1_(−1.6)^(+1.7) g cm⁻³. This makes it one of the few known massive giant planets with an extreme density. It lies in the transition mass region of massive giant planets and low-mass brown dwarfs, an important addition to the population of fewer than five known objects in this mass range. The eccentricity of 0.325 ± 0.020 and an orbital separation of 0.0888 ± 0.0010 AU from its host star suggest that the planet is likely undergoing high-eccentricity tidal migration. We find a fraction of heavy elements of 0.13_(−0.06)^(+0.05) and metal enrichment of the planet (Z_P/Z_(star)) of 4.2_(−2.0)^(+1.6). Detection of such systems will enable us to gain valuable insights into the governing mechanisms of massive planets and improve our understanding of their dominant formation and migration mechanisms.

Additional Information

© The Authors 2023. 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. This article is published in open access under the Subscribe to Open model. Subscribe to A&A to support open access publication. We acknowledge the generous support from PRL-DOS (Department of Space, Government of India) and the director of PRL for the PARAS spectrograph funding for the exoplanet discovery project and research grant for AK and SB. PC acknowledges the generous support from Deutsche Forschungsgemeinschaft (DFG) of the grant HA3279/11-1. We acknowledge the help from Kapil Kumar, Vishal Shah, and all the Mount-Abu, TLS, and Palomar observatory staff for their assistance during the observations. This work was also supported by the Thüringer Ministerium für Wirtschaft, Wissenschaft und Digitale Gesellschaft. This work has been carried out within the framework of the NCCR PlanetS supported by the Swiss National Science Foundation under grants 51NF40_182901 and 51NF40_205606. We generously acknowledge Dr. Rafael Brahm for providing the grids to determine the spectroscopic parameters using zaspe. PC generously acknowledges Dr. Eike W. Guenther for his contribution in the spectroscopic observations from TCES. This research has made use of the SIMBAD database and the VizieR catalogue access tool, operated at CDS, Strasbourg, France. This research has made use of the Exoplanet Follow-up Observation Program (ExoFOP; DOI: 10.26134/ExoFOP5) 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). This work has made use of the Transiting ExoPlanet catalogue (TEPcat) database. We would like to thank the anonymous referee for his/her numerous good suggestions which improved the quality of the paper.

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