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

• DOI: 10.48350/188223
• Publication Date: 2023-04-01
• Authors: Akanksha Khandelwal; Rishikesh Sharma; Abhijit Chakraborty; Priyanka Chaturvedi; Solène Ulmer-Moll; David R. Ciardi; Andrew W. Boyle; Sanjay Baliwal; Allyson Bieryla; David W. Latham; Neelam J. S. S. V...; Ashirbad Nayak; Monika Lendl; Christoph Mordasini
• Keywords: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics - Solar and Stellar Astrophysics; 13. Climate action; Space and Planetary Science; 530 Physics; 520 Astronomy; FOS: Physical sciences; Astronomy and Astrophysics; 620 Engineering; 520; Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics - Earth and Planetary Astrophysics

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 RJand an orbital period of 7.24599−0.00021+0.00022days. 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+1.7g 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+0.05and 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.