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Three hot Jupiter exoplanets discovered with TESS

Using NASA's Transiting Exoplanet Survey Satellite (TESS), an international team of astronomers has detected three new hot Jupiter exoplanets orbiting three distant K dwarf stars. The finding was reported in a research paper June 5 on the arXiv pre-print server.

TESS is conducting a survey of about 200,000 of the brightest stars using four cameras, with the main goal of detecting transiting extrasolar worlds. Since the start of its mission in 2018, it has identified about 7,600 candidate exoplanets (TESS Objects of Interest, or TOI), of which 632 have been confirmed.

Now, three new alien worlds have been added to the list of confirmed TESS exoplanets. A group of astronomers led by Yolanda Frensch of the Geneva Observatory in Switzerland, reports that transit signals were identified in the light curves of three K-dwarfs, namely: TOI-2969, TOI-2989 and TOI-5300 (located 530, 635 and 530 light years away, respectively). The planetary nature of these signals was confirmed by ground-based follow-up observations.

"In this paper, we confirm and characterize three hot Jupiters transiting mid-K dwarfs, contributing mass measurements to this still relatively unexplored population," the researchers wrote.

With a mass of approximately three Jupiter masses, TOI-2989 b is the most massive exoplanet reported in the study. It has a radius of 1.12 Jupiter radii and its bulk density is estimated to be at a level of 2.7 g/cm³. The planet orbits its host every 3.12 days at a distance of 0.038 AU from it. The equilibrium temperature of TOI-2989 b was calculated to be around 1,000 K.

TOI-2969 b is about 10% larger and 16% more massive than Jupiter, which yields a bulk density of about 1.1 g/cm³. The planet is at a distance of around 0.026 AU from the parent star, has an orbital period of 1.82 days, and its equilibrium temperature was estimated to be 1,186 K.

TOI-5300 b is the smallest and the least massive exoplanet out of the three—it has a radius of about 0.88 Jupiter radii and its mass is only 0.6 Jupiter masses, hence its bulk density is around 1.1 g/cm³. The planet orbits TOI-5300 every 2.26 days at a distance of some 0.029 AU from it, and its equilibrium temperature was calculated to be 1,043 K.

Based on the derived properties, the astronomers classified all the three exoplanets as non-inflated hot Jupiters. They added that the estimated heavy element masses in their interior are significantly higher when compared to other known hot Jupiters around K dwarfs.

Summing up the results, the researchers note that the newfound alien worlds are good targets for follow-up atmospheric studies, with TOI-2969 b being the most promising candidate.