New Delhi, India

Some stars which have existed from ancient ages and are orbiting the central supermassive black hole of the Milk Way, appear youthful despite their age.

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However, the secret behind their young look is dark and gory. These zombie-like stars have gobbled up their own neighbours. This was revealed in a study carried out by Northwestern University. 

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Survivors of stellar cannibalism losing mass

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The astrophysicists used a new model for tracing the violent journeys of 1,000 simulated stars which have been orbiting a central supermassive black hole, known as Sagittarius A* (Sgr A*), in our galaxy.

The region, which is so densely packed with stars, commonly faces brutal stellar collisions.

"The closest star to our sun is about four light-years away. Within that same distance near the supermassive black hole, there are more than a million stars. It's an incredibly crowded neighbourhood. On top of that, the supermassive black hole has a really strong gravitational pull. As they orbit the black hole, stars can move at thousands of kilometres per second," said Northwestern's Sanaea C. Rose, who headed the research.

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The new study, which simulated the effects of these intense collisions, found that collision survivors are likely losing mass and turning into low-mass stars. There are also possibilities that they are merging with other stars and becoming massive as well as rejuvenated in appearance.

"The region around the central black hole is dense with stars moving at extremely high speeds," said Rose added.

"It's a bit like running through an incredibly crowded subway station in New York City during rush hour. If you aren't colliding with other people, then you are passing very closely by them. For stars, these near collisions still cause them to interact gravitationally. We wanted to explore what these collisions and interactions mean for the stellar population and characterize their outcomes," she said.

This research was presented by Rose at the American Physical Society's (APS) April meeting in Sacramento, California. 

(With inputs from agencies)