Optical polarisation phenomenon Current Affairs - 2020
Scientists for first time have observed Optical polarisation phenomenon (polarised light emitted by rapidly rotating stars) after it was predicted by Indian astrophysicist and Nobel laureate Subrahmanyan Chandrasekhar 70 years ago.
Optical polarisation phenomenon is a measure of the orientation of the oscillations of a light beam to its direction of travel.
The phenomenon was observed using High Precision Polarimetric Instrument (HIPPI), world’s most sensitive astronomical polarimeter to detect polarised light from Regulus, one of brightest stars in night sky about 79 light years away.
The equipment provided unprecedented insights into star, which is in constellation Leo. It allowed scientists to determine its rate of spinning and orientation in space of star’s spin axis. It was observed that Regulus is rotating so quickly with a spin rate of 96.5% of angular velocity (approximately 320 kilometres per second) for break-up.
Subrahmanyan Chandrasekhar in 1946 had first predicted that some stars could be emitting polarised light from their edges. Based on his idea, Astronomers J Patrick Harrington and George W Collins II predicted in 1968 predicted that polarised light will be emitted by rapidly rotating star because its shape gets distorted into a squished oblate shape as it spins too fast.
He was Indian American astrophysicist who was awarded the 1983 Nobel Prize for Physics with William A. Fowler for his theoretical studies of physical processes of importance to structure and evolution of stars. His mathematical treatment of stellar evolution had yielded many of best current theoretical models of later evolutionary stages of massive stars and black holes. The Chandrasekhar limit (maximum mass of a stable white dwarf star) has been named after him.