The fireball of a nova explosion from a white dwarf star has been captured by astronomers in remarkable detail — the first time such an cosmic event has been recorded in action.
This particular fireball explosion happened some 14,800 light-years away from Earth, and originated in a star known as Nova Delphinus located in the constellation of Delphinus, or the Dolphin constellation.
The explosion happened nearly 15,000 years ago and we're only now finding out about it. But those 15 millennia gave astronomers time to build high-tech telescopes and point them in the right direction.
A nova explosion is what happens when a white dwarf — a dead star about the size of the Earth but with the mass of the sun — steals hydrogen from its parent star until it becomes unbalanced. The overwhelming intake of mass eventually triggers a thermonuclear fusion explosion and out races a giant fireball.
A team of international astronomers witnessed the explosion using space-observation technology known as the CHARA Array, which amasses the light from six optical telescopes to capture super high resolution imagery. The CHARA Array is located in Los Angeles but managed by astronomers at Atlanta's Georgia State University.
"We are really lucky to be collaborating with the team running the CHARA array in Southern California," Peter Tuthill, astronomer at the University's Sydney Institute for Astronomy, said in a statement. "They are able, using its state of the art technology, to make the exquisitely fine measurements necessary to witness this event."
The time-lapse images allowed scientists to learn new details about how a nova explosion happens. Astronomers were surprised to find the exploding star expanding in layers.
"The interesting thing for me, were the multiple shells seen as the nova explodes," Michael Ireland, a researcher the Australian National University, told Discovery News.
"There's a main shell expanding at about 600 kilometres per second, but then there were also semi-transparent shells further out going even faster. So we could see both the optically thick inner shell, and the transparent outer shells expanding at the same time."
But astronomers still aren't sure what makes up the different layers. To find out (as usual) will require more research. The white dwarf explosion was detailed this week in the latest issue of the journal Nature.
