March 19, 2013
Black Hole And Red Dwarf Intertwined In 2-Hour Tango Of Death
Lee Rannals for redOrbit.com — Your Universe Online
Astronomers using ground and space telescopes around the world have revealed a black hole and a star, intertwined in a cosmic tango together.
Astronomers writing in Astronomy & Astrophysics say they have observed a black hole, known as MAXI J1659-152, and a red dwarf with a mass only 20 percent that of the Sun orbiting each other every 2.4 hours. The two cosmic bodies sit over half a million miles away from each other, but are undergoing a one-sided dance to death.
[ Watch the Video: Animation Of Binary System ]
MAXI J1659-152 and its companion were discovered in September 2010 by NASA's Swift space telescope when it picked up what was initially thought to be a gamma ray burst. Japan's MAXI telescope on the International Space Station also picked up a bright X-ray source at the same spot later that day.
After astronomers performed more observations from both ground and space telescopes, they determined the X-rays coming from the black hole were due to MAXI J1659-152 feeding off material from the tiny red dwarf.
The team used the European Space Agency's (ESA) XMM-Newton space telescope to observe several regularly-spaced "dips" in light. Astronomers use dips like this to unveil objects orbiting a star, or in this case, a star orbiting an object. Dips are most commonly used to help find exoplanets orbiting around a star. As the planet passes in front of the star from Earth's perspective, light emitted from the star slightly dims, or dips, revealing the object.
Astronomers using XMM-Newton kept an eye on the two cosmic companions during an uninterrupted 14.5-hour observation. The uneven rim of the black hole's accretion disc would briefly obscure the X-rays being emitted every 2.4 hours, alerting the team of the red dwarf. The 2.4 hour orbital period sets a new record for black hole X-ray binary systems, breaking the previous record-holder's 3.2-hour orbit, which was set by Swift J1753.5—0127.
According to ESA, the red dwarf is the fastest moving star ever seen in an X-ray binary system, moving at about 1.2 million miles per hour.
“The companion star revolves around the common [center] of mass at a dizzying rate, almost 20 times faster than Earth orbits the Sun. You really wouldn´t like to be on such a merry-go-round in this Galactic fair!” says lead author Erik Kuulkers of ESA´s European Space Astronomy Center in Spain.
In January, local redOrbit astronomer John P. Mills, PhD interviewed Kelly Holley-Bockelmann, an assistant professor of Astronomy at Vanderbilt University, in a podcast asking specifically about how black holes form. The podcast How Stars Die And Black Holes Form is available on redOrbit, and offers great insight for anyone hoping to learn a little more about one of the Universe's biggest mysteries.