New X-ray source in nearby galaxy spawns mystery

Jan 09, 2008
New X-ray source in nearby galaxy spawns mystery
X-ray sources appear and disappear in the nearby galaxy Centaurus A. Astronomers at Ohio State University and their colleagues detected a new X-ray source in the galaxy in 2007 using NASA's Chandra X-ray Observatory. The new source -- likely a binary star system that contains a black hole -- appears in the center of the image. Credit: Animation by Gregory Sivakoff, courtesy of Ohio State University

Astronomers studying a nearby galaxy have spied a rare type of star system -- one that contains a black hole that suddenly began glowing brightly with X-rays.

Though this type of star system is supposed to be rare, it's the second such system discovered in that galaxy, called Centaurus A.

The discovery suggests that astronomers have more to learn about the lives and deaths of massive stars in galaxies such as our own.

Normally when astronomers study Centaurus A, it's the giant X-ray jets emanating from the heart of the galaxy that steal the show, explained Gregory Sivakoff, a postdoctoral researcher in astronomy at Ohio State University. The jets extend from the galaxy for 13,000 light years in different directions.

But when his team studied Centaurus A with NASA's Chandra X-ray Observatory starting in March 2007, they saw a new X-ray source -- much smaller than the X-ray jets, but still glowing brightly. The 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.

Because it hadn't been seen before, the astronomers classified the object as a “transient” X-ray source, meaning that the object had been there before 2007, but had only recently brightened enough to stand out.

Sivakoff discussed the results in a press briefing Wednesday, January 9, 2008 at the American Astronomical Society meeting in Austin, Texas.

The newly bright object, dubbed CXOU J132518.2-430304, is most likely a binary star system, the researchers concluded. The two stars likely formed at the same time, with one much more massive than the other. The more massive 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's 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.”

Because Centaurus A is near to our galaxy, astronomers have long hoped to use it as a Rosetta stone for studying other galaxies with black holes.

As astronomers piece together an explanation for the existence of the newly-discovered binary system, they may gain a better understanding of how black holes form from massive stars and how binary systems evolve.

“These binary systems are signposts of the massive stars that once existed in galaxies like Centaurus A. To understand the massive stars, we must first know how to read the signs,” he said.

Source: Ohio State University

Explore further: Hubble view: Wolf-Rayet stars, intense and short-lived

Related Stories

Former federal agent pleads guilty to stealing bitcoins

5 hours ago

A former undercover federal agent pleaded guilty to extortion and related charges after acknowledging he channeled more than $700,000 in digital currency from the Silk Road online drug bazaar he was investigating.

Cities, regions, demand bigger climate say

5 hours ago

Leaders of city and regional governments gathered Wednesday in the French city of Lyon, in the grips of a western European heatwave, to demand a bigger stake in the global push to curb global warming.

Hewlett-Packard moves forward with plan to split in two

5 hours ago

Hewlett-Packard is moving forward with plans to split into two companies, filing paperwork to create a new entity that will sell commercial technology, while a separate spinoff will sell personal computers and printers.

Recommended for you

Hubble view: Wolf-Rayet stars, intense and short-lived

Jul 03, 2015

This NASA/European Space Agency (ESA) Hubble Space Telescope picture shows a galaxy named SBS 1415+437 (also called SDSS CGB 12067.1), located about 45 million light-years from Earth. SBS 1415+437 is a Wolf-Rayet ...

NASA image: Stellar sparklers that last

Jul 03, 2015

While fireworks only last a short time here on Earth, a bundle of cosmic sparklers in a nearby cluster of stars will be going off for a very long time. NGC 1333 is a star cluster populated with many young ...

Light echo helps researchers map out parts of galaxy

Jul 03, 2015

Thousands of years before humans invented agriculture, a bright burst of X-rays left the dense neutron star Circinus X-1, located in the faint Southern constellation Circinus. A year and a half ago, those ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

Quantum_Conundrum
not rated yet Jan 09, 2008
"Black hole" has become the new catch phrase in science.

Can't explain it? That's easy!

"Blackholedidit!"

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.