Fast spinning star Regulus
The discovery about Regulus comes almost 50 years after it was first predicted that rapidly rotating stars would emit polarised light - Representational ImageREUTERS/David Gray CHINA

For the first time, it has been observed that Regulus, one of the brightest stars in the night sky, emits light in a special way and is rotating so quickly that it is close to "flying apart".

A team of scientists from Australia, the US, and the UK got unprecedented insights into the bluish first magnitude star, which is located almost 79 light years away from Earth in constellation Leo, with the help of High Precision Polarimetric Instrument (HIPPI) – the world's most sensitive astronomical polarimeter.

They pointed the instrument to Regulus and observed that it emits polarised light – the phenomenon in which light waves get rotated in a particular direction.

Combining that information with sophisticated computer models developed at the University of New South Wales (UNSW), they determined the approximate rotation rate of Regulus at a whopping 320km/second.

That's something like travelling to Sydney from Canberra within a second.

Dr Daniel Cotton, from UNSW's School of Physics, said, "We found Regulus is rotating so quickly it is close to flying apart, with a spin rate of 96.5 percent of the angular velocity for break-up".

The discovery about Regulus, published in the journal Nature Astronomy, comes almost 50 years after it was first predicted that rapidly rotating stars would emit polarised light.

In 1968, astronomers J Patrick Harrington and George W Collins II used a series of calculations from Nobel-winning physicist Subrahmanyan Chandrasekhar to predict that a fast-spinning star would emit polarised light due to the rapid rotation that distorts its shape.

The predictions led to the development of a plethora of instruments for detecting polarisation, but none proved fruitful until HIPPI was brought into use.

"It has previously been extremely difficult to measure these properties of rapidly rotating stars," Dr Cotton added.

"Yet the information is crucial for understanding the life cycles of most of the hottest and largest stars in the galaxies, which are the ones that produce the heaviest elements, such as iron and nickel, in interstellar space."