Making India a part of an elite list of countries to have discovered planets around stars, Indian scientists have now discovered an exoplanet around 600 light years away from Earth. Led by Prof Abhijit Chakraborty of Physical Research Laboratory (PRL), Ahmedabad, the team discovered the planet that is larger than Neptune, but smaller than Saturn.
According to Indian Space Research Organization (ISRO), the planet – which is currently named EPIC 211945201b or K2-236b – is 27 times the mass of Earth and orbits so close to its parent star that it goes around the star in under 20 days. With the distance between the planet and its star being so close, the surface temperature of the planet is around 600°C.
How was the planet discovered?
The discovery was made using indigenously designed “PRL Advance Radial-velocity Abu-sky Search” (PARAS) spectrograph which, according to ISRO, is one of the few existing spectrographs that can carry out precise measurements. The device is situated at Guru Shikhar Observatory in Mount Abu, Rajasthan.
Indian scientists focused their attention on the star after NASA’s K2 (Kepler) mission, which is a space observatory, detected a change in the star’s brightness levels while observing it. The PRL scientists continued observing the star for about 1.5 years. By measuring the amount of the starlight blocked, the team was able to determine the size of the planet. As the planet orbits quite close to its Sun-like star, the star wobbles and its light shifts, which PARAS spectrograph used to determine the planet’s mass — a measurement necessary for such discoveries.
According to ISRO:
“Based on the mass and radius, model-dependent calculations suggest that the heavy elements, like ice, silicates, and iron content is 60-70 % of the total mass.”
Because the surface temperature of the planet is too high and because it does not fall in the star’s habitable zone, it is highly unlikely for life to exist there. However, the discovery is important “for understanding the formation mechanism of such super-Neptune or sub-Saturn kind of planets, that are too close to the host star”.