Lagatar24 Desk
New Delhi, Nov.17: Indian astronomers have identified a planet larger than Jupiter that is orbiting a star in its system too close. TOI 1789b is an exoplanet that orbits an ageing star that is 1.5 times the mass of our Sun and is situated 725 light-years away.
The discovery was made by Professor Abhijit Chakraborty’s exoplanet search and study group at the Physical Research Laboratory (PRL) in Ahmedabad. The planet was discovered using the Advanced Radial-velocity Abu-sky Search (PARAS) optical fibre-fed spectrograph.
This is the second such exoplanet identified in the PRL by astronomers utilising PARAS at the 1.2 m Mt. Abu telescope; the first being K2-236b, a sub-Saturn-sized exoplanet discovered in 2018 at a distance of 600 light-years. Between December 2020 and March 2021, scientists observed the planet.
“It’s one among the few evolved stars in the area with a neighbouring planet. The discovery of such systems will aid our understanding of the mechanisms that cause inflation in hot Jupiters, as well as provide a window into the evolution of planets orbiting stars on the main sequence branch,” astronomers stated in a paper published in the journal Monthly Notices of the Royal Astronomical Society.
The planet’s mass is 70% that of Jupiter, and its size is around 1.4 times that of Jupiter, according to ongoing measurements. Follow-up observations with the TCES spectrograph in Germany revealed that it was a one-of-a-kind system in which the planet orbits the host star 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).
Due to this close proximity of the planet to its host star, it is extremely heated with a surface temperature reaching up to 2000 Kelvin giving it an inflated radius one of the lowest density planets known. “The detection of such system enhances our understanding of various mechanisms responsible for inflation in hot Jupiters and the formation and evolution of planetary systems around evolving and ageing stars,” it added.
According to the Indian Space and Research Organisation (Isro), among the menagerie of exoplanets identified so far, there are less than ten such close-in systems.
The unexpected discovery comes only weeks after Indian astronomers discovered a novel approach for studying a planet beyond our solar system’s atmosphere. Using ground-based radars and observatories, astronomers at the Indian Institute of Astrophysics devised a method for studying the atmospheres of these planets by examining polarisation fingerprints or variations in the scattering intensity of light.
