New space X-ray source detected

Astronomers studying a nearby galaxy with NASA's Chandra X-ray Observatory have detected a rare type of star system with a black hole that has begun glowing with a new X-ray source.

Astronomers studying a nearby galaxy with NASA's Chandra X-ray Observatory have detected a rare type of star system with a black hole that has begun glowing with a new X-ray source.

HT Image

Usually, when astronomers study the galaxy, called Centaurus A, it's the giant X-ray jets emanating from its heart that steal the show, according to Gregory Sivakoff of Ohio State University.

But when his team studied Centaurus A with the Chandra X-ray Observatory - named after Indian-American physicist Subrahmanyan Chandrasekhar, known for determining the mass limit for white dwarf stars to become neutron stars - they saw a new X-ray source.

This X-ray source wasn't there during the last survey of the galaxy in 2003, but it shined throughout the time of the new observations, from March to May of 2007.

Sivakoff discussed the results in a press briefing on Wednesday at the American Astronomical Society meeting in Austin, Texas.

The newly bright object is most likely a binary star system, Sivakoff said. The two stars may have formed at the same time, with one much more massive than the other.

The bigger star evolved more quickly, and collapsed to form a black hole. It is now slowly devouring its companion. Such binary systems are thought to be extremely rare.

But this is the second bright, transient X-ray binary system discovered in Centaurus A and that is the problem, Sivakoff said.

"When we look at other galaxies like Centaurus A, we don't see these bright, transient X-ray binaries," he said. "But now we've found two such objects in Centaurus A and the implication is that we may not understand these objects as well as we thought we did."

"So right now, our discovery is actually pointing to a puzzle rather than a solution.