PRL Ahmedabad Researchers discover ‘Hot Jupiter’ HD 82139b

• 18 Nov 2021

• Scientists from the Ahmedabad-based Physical Research Laboratory (PRL) have discovered an exoplanet that is 725 light years away from us and orbiting an ageing star that has 1.5 times the mass of our Sun.
• The star is known as HD 82139 as per the Henry Draper catalogue and TOI 1789 as per the TESS catalogue. Hence, the planet is known as TOI 1789b or HD 82139b as per the IAU nomenclature.
• This newly discovered star-planet system is a very unique - the planet orbits the host star in just 3.2 days, thus placing it very-very close to the star at a distance of 0.05 AU (roughly one-tenth the distance between Sun and Mercury).
• There are less than 10 such close-in systems known among the zoo of exoplanets known so far.
• Because of the close proximity of the planet to its host star, it is extremely heated with a surface temperature reaching up to 2000 K, and hence an inflated radius, making it one of the lowest density planets known (density of 0.31 gram per cc). Such close-in exoplanets around stars (with distance less than 0.1 AU) with masses between 0.25 to a few Jupiter mass are called "Hot-Jupiters".

(Image Source: ISRO)