Indian astronomers discover new exoplanet, rare stars hotter than sun

Indian astronomers have added another feather to their cap as they recently made two new discoveries - an exoplanet 1.4 times the size of Jupiter and a rare class of radio stars hotter than the sun.

The first discovery was made by a team from Ahembdabad’s Physical Research Laboratory (PRL) recently. The researchers discovered an exoplanet 1.4 times the size of Jupiter, orbiting an ageing star that is 1.5 times that of our sun and located 725 light-years away.

The new exoplanet, dubbed TOI 1789b, was discovered by Professor Abhijit Chakraborty and his team using the Advanced Radial-velocity Abu-sky Search (Paras) optical fibre-fed spectrograph - the first of its kind in India - on the 1.2-metre Telescope of PRL at its Mt. Abu Observatory.

The exoplanet’s mass is discovered to be 70 per cent that of Jupiter, a discovery that was made using Paras, which can measure the mass of an exoplanet.

The measurements were taken between December 2020 and March 2021. ISRO added that in April 2021, it acquired additional follow-up readings from the TCES spectrograph from Germany and independent photometric observations from the PRL’s 43-cm telescope at Mt. Abu.

TOI 1789b orbits its sun in just 3.2 days, putting it at a distance of 0.05 AU from the star (roughly one-tenth the distance between sun and Mercury). Amongst the numerous exoplanets known so far, there are less than ten such close-in systems.

Due to its closeness to its host star, the planet is intensely hot, with a surface temperature of up to 2000K. It also has an expanded radius with a density of 0.31 gram per cc, making it one of the lowest density planets known.

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