Earliest snapshot of nova captured

The immense fireball was first spotted by an amateur astronomer

The nova was discovered on 14 August 2013 by Japanese amateur astronomer Koichi Itagaki.

Credit: Jimmy Westlake, Colarado Mountain College via Wikimedia Commons

A nova has provided scientists with the earliest ever observations of one of these rare events. Found in the constellation of Delphinus last year, the object has given insight into how these thermonuclear fireballs change as the gas expands and cools.

A nova occurs when one of the stars in a binary system begins to leech hydrogen gas off of the other star in the pair, forming an ocean of gas on its surface.

“After drawing about as much mass as the entire planet Saturn, the pressure reaches a critical point, then boom!” says Professor Peter Tuthill from the University of Sydney. “The stellar surface turns into one titanic hydrogen bomb hurling a fireball out into space and propelling a formerly dim, obscure star system into prominence as a nova in our night skies,” Professor Tuthill said.

The nova was discovered on 14 August 2013 by Japanese amateur astronomer Koichi Itagaki, and was soon named Nova Delphinus 2013.

Within 15 hours of its discovery, 24 hours after the nova first happened, astronomers pointed the Centre for High Angular Resolution Astronomy (CHARA) Array towards the object to image the fireball, measuring its size and shape. The array used six telescopes to create a telescope with an equivalent diameter of more than 300m. Over the next two months the array created high-resolution images of the nova as it developed.

When it was first measured, the size of the fireball was roughly the size of the Earth’s orbit, but when it was last measured 43 days after it detonated, the fireball had expanded over 20 times, to around the size of Neptune’s orbit. Rather than expanding in a perfectly uniform way, images show that the nova is slightly elliptical in shape.

Despite the massive explosion, the star at the heart of it all has remained unscathed. It will eventually go nova again, but probably not in our lifetimes. Luckily there are other stars out there that will eventually flare up, letting us study the phenomena once again.

"Although novae often play second fiddle in the popular imagination to their more famous big cousins - the supernovae - they are a truly remarkable celestial phenomenon,” says Tuthill.


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