Hemant Kumar Rout By

Express News Service

BHUBANESWAR: In a revolutionary breakthrough in the field of gravitational deflection, a group of astronomers led by Odia scientist Kailash Chandra Sahu has successfully validated Albert Einstein’s general theory of relativity by measuring mass of an isolate object in the galaxy.

Though Einstein had provided first evidence of the theory using the effect of the deflection of light from a background star by the gravitational field of the Sun, he was then pessimistic about its real time application and maintained that there is no hope to observe the phenomenon directly.



The scientists and researchers from the US-based Space Telescope Science Institute (STSI) have finally been able to see this asymmetric phenomenon in action in a star other than Sun by using the superior angular resolution of the Hubble Space Telescope (HST).

Sahu and his team applied the concept to a white dwarf Stein 2051 B which crossed close in front of a more distant normal star. They measured the tiny shifts in the apparent position of the background star through astrometric micro-lensing with the help of HST. The apparent motion matched the prediction of general relativity and it helped them determine the mass of the white dwarf. A native of nondescript coastal village Bellagam in Ganjam district, Sahu (57), fondly known as planet hunter, was a gold medalist in Physics from Berhampur University in 1977.

He did his PhD in Astronomy from Gujarat University in 1985 and researched at Institute of Astrophysics in Paris and Spain before joining STSI in 1995. The noted scientist was the youngest among his five brothers.

One of Sahu’s favourite works was to search for exo-planets in the galactic bulge through a large HST programme Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS). The programme involved monitoring of about 300,000 stars towards the galactic bulge using an advanced camera system on board HST, to search for transiting extra-solar planets. This led to the discovery of 16 planets, including five ultra-short-period planets in 2006.

The new findings on theory of relativity has, however, amazed the astro physicists. “Earlier, measuring the mass of stars was a formidable task. Sahu and his team have used a good technique which will be helpful in measuring the mass of any isolate object with the help of bending of lights due to gravitational deflection,” said Prof Ajit Mohan Srivastava of Institute of Physics, here.

Chief Minister Naveen Patnaik has congratulated the scientist. “Odisha born astronomer Kailash Sahu creates history, does what Einstein himself said was not possible,” he tweeted.

Our work opens an entirely new method for measuring the masses of stars. The mass provides the most important information about a star. If you know the mass of a star, you will know its size, how bright it will be, how long it will live, and what will happen after it dies. Yet, there is no direct method to measure the mass of a single star.

The theory about the white dwarfs (the dead remnant of almost all stars, including sun) was developed by S Chandrasekhar in 1930 in his Nobel-prize winning calculations. Astronomers have been using this theory, but this did not have much experimental confirmation. Our results provide a solid confirmation of that theory.

The scientist had last visited Bellagam in October 2016 when he was busy with this research work. He had submitted the results for publication during his stay in the village, using the excellent internet facilities at TEC-HUB, which is being run by his nephew Srikant Kumar Sahu.

As told by Kailash Chandra Sahu to The Express