July 21, 2006 — Astronomers have discovered that a piggish, belching little star might just bust a gut — spilling secrets about the universe in the process.
The scene of interstellar swilling is called RS Ophiuchi, a dense and voracious white dwarf star with what looks to be a red giant companion star that is footing all the dining bills.
RS Ophiuchi has a long history of outbursts every 20 years or so, which astronomers — using new radio, infrared and X-ray observations — now ascribe to thermonuclear burps when the white dwarf eats too heartily from the red giant.
Here’s how they think it works: As the red giant material is sucked down onto the white dwarf and piles up on its surface, the pressure at the bottom of the pile builds up until it’s enough to trigger a thermonuclear explosion, said astronomer Jennifer Sokoloski of the Harvard-Smithsonian Center for Astrophysics.
Such an explosion happened on Feb. 12, and astronomers have since been gathering data with an armada of modern space and ground-based telescopes.
"It’s incredible," said Sokoloski, who coauthored one of two papers about the rare, ongoing event, which appear in the July 20 edition of Nature.
At thousands of miles per second, the blast wave from the explosion crashes through the gassy, dusty nebula region created by the red giant, lighting it up in visible light, infrared radiation, radio waves and even X-rays.
The explosion actually made RS Ophiuchi visible to the naked eye, if you knew where to look, she reported.
The multi-spectral lightshow has been giving astrophysicists an unprecedented opportunity to test theories about how such explosions are shaped, and how they propagate through space.
That, in turn, is more broadly important to astronomers because this little white dwarf appears on the verge of a much larger explosion – an obliterating supernova – of a special type used to measure the size of the universe.
"This object is a low-energy analogue of a supernova," explained astrophysicist Michael Bode of Liverpool John Moores University, referencing the Feb. 12 explosion.
