Khandelwal, AkankshaAkankshaKhandelwalSharma, RishikeshRishikeshSharmaChakraborty, AbhijitAbhijitChakrabortyChaturvedi, PriyankaPriyankaChaturvediUlmer-Moll, SolèneSolèneUlmer-MollCiardi, David R.David R.CiardiBoyle, Andrew W.Andrew W.BoyleBaliwal, SanjaySanjayBaliwalBieryla, AllysonAllysonBierylaLatham, David W.David W.LathamPrasad, Neelam J.S.S.V.Neelam J.S.S.V.PrasadNayak, AshirbadAshirbadNayakLendl, MonikaMonikaLendlMordasini, ChristophChristophMordasini2025-08-312025-08-312023-04-0110.1051/0004-6361/2022456082-s2.0-85153331318https://d8.irins.org/handle/IITG2025/26847We 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-RJ 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-MJ, 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 (ZP/Zstar) 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.trueMethods: observational | Techniques: photometric | Techniques: radial velocitiesArticlehttps://www.aanda.org/articles/aa/pdf/2023/04/aa45608-22.pdf143207461 April 20236L7arJournal6