In a first for Indian science, team from Ahmedabad finds an exoplanet

Indian researchers have discovered their first exoplanet orbiting a star 600 light years away from earth. Planets that orbit around stars other than the sun are called exoplanets.

The discovery came after a team, led by Abhijit Chakraborty of the Physical Research Laboratory (PRL), Ahmedabad, spent one and half years studying data on the light emitted by the planet’s host star, EPIC 211945201 or K2-236. The planet will be called EPIC 211945201b or K2-236b.

“We report here strong evidence for a sub-Saturn around EPIC 211945201 and confirm its planetary nature,” reported their research paper, accepted for publication in American Astronomical Society’s Astronomical Journal.

“This is one of the exciting areas of research,” Anil Bhardwaj, director of PRL, said. “Currently, we know only our solar system.” What makes the discovery even more special is that the exoplanet is similar to earth in mass, according to Bhardwaj.

Exoplanet discovery has become a hot area for research in recent years. As of June 2 there were 3,786 confirmed exoplanets in 2834 systems. But there are only 22 other systems where the exoplanets have masses between 10-70 of earth’s mass and radii between 4 to 8 the radius of the earth, which have been measured with a high degree of precision.

Scientists did not directly observe the planet but monitored the changes in the wavelength of light emitting from the star to deduce the presence of another body in its star system.

For planets to support any form of life, liquid water is a necessity. There is a band around stars that create conditions conducive for hosting liquid water on a planet’s surface, which is sometimes referred to as the habitable zone or “Goldilocks” zone.

The surface temperature on EPIC 211945201b is around 600 degrees C, because it is 7 times closer to its host star, than earth is from the sun, making it a less likely candidate to host life.

The body emerged as a planetary candidate based on data from NASA’s Kepler 2 mission. However the key part of exoplanet discovery is confirming its planetary nature.

An independent measurement of the mass of the body was required to clinch the discovery.

This was made possible by the commissioning of the PRL Advance Radial-velocity Abu-sky Search” (PARAS), a precise and stabilised high resolution spectrograph that was integrated with the 1.2m Telescope at PRL’s Gurushikhar Observatory in Mount Abu, Rajasthan.