Cosmic Gun

How doest it fire?

Biplab Das

Astrophysicists from Kolkata-based S N Bose National Centre for Basic Sciences and Centre for Space Physics (affiliated to the University of Calcutta) have finally found an explanation for the unusual behaviour of a star 3,000 parsecs (1 parsec equals 3.26 light years) away. Named ss433, the star ejects matter every minute like a gun firing bullets - each as bulky as one ten-thousandth of earth's mass and escaping into space with one fourth the speed of light. 

Ever since ss433's discovery 25 years ago, the scientists have wondered where the matter for the "bullets" was coming from. They have now found ss433 sucks in matter from a companion star. "ss433 lies at the heart of a supernova remnant called W 50, a leftover of an exploded star that emits radiation and matter. The expanding debris of W 50 is adding to its (ss433) bullet firing nature. It emits radio waves and infrared radiation as well as life-producing elements like carbon, nitrogen and oxygen," says lead researcher Sandip Chakrabarti. 

The discovery follows an analysis of recent satellite data. "The star showed a flare of X-ray emissions which was twice the emissions observed last year," says Chakrabarti. The next increase in flare is expected at the end of January. The scientists say ss433 is a part of a binary (two star) system 100,000 years old. And it will last another 50,000 years. In a paper soon to be published in the Monthly Notices of Royal Astronomical Society, Chakrabarti predicts the binary system will shortly evolve into a black hole. The black hole will have a mass of 3 solar mass (three times the mass of sun), he adds.