World's Smallest Black Hole Discovered by a 'Heartbeat'

A team of researchers and astronomers believe that they have identified the smallest black hole found yet with the help of its X-ray pattern "heartbeat."

Until now, this X-ray "heartbeat," so called because of its resemblance to an electrocardiogram, has been used to discover only one other black hole system.

NASA astronomers located the system in the direction of the constellation Scorpio, although the exact distance is not well established. The position could be more than 65,000 light-years away or as close as 16,000 light-years.

Coined IGR J17091-3624 based on its astronomical position, the binary system reportedly consists of a normal star with a black hole that may weigh less than three times the sun's mass.

The record-holder for wide-ranging X-ray variability is another black hole binary system named GRS 1915+105. This system is unusual in displaying more than a dozen highly structured patterns, typically lasting between seconds and hours.

"We think that most of these patterns represent cycles of accumulation and ejection in an unstable disk, and we now see seven of them in IGR J17091," said Tomaso Belloni at Brera Observatory in Merate, Italy. "Identifying these signatures in a second black hole system is very exciting."

Astronomers became aware of this binary system in 2003. The researchers were able to recognize the signal from this system owing to its likeness to another black hole system called GRS 1915+105 that pulses in a similar way.