Youngest black hole in Milky Way may have been discovered

By Paul Harper

The most recent black hole formed in the Milky Way galaxy. Photo / Harvard-Smithsonian Center for Astrophysics
The most recent black hole formed in the Milky Way galaxy. Photo / Harvard-Smithsonian Center for Astrophysics

Astronomers believe they may have discovered the youngest black hole in the Milky Way galaxy.

The black hole appears in a supernova remnant, called W49B, captured in an image created by X-rays from NASA's Chandra X-ray Observatory in blue and green, radio data from the NSF's Very Large Array in pink, and infrared data from Caltech's Palomar Observatory in yellow.

The remnant is about one thousand years old, as seen from Earth, and is at a distance about 26,000 light years away.

The findings are to be published in a paper in the Astrophysical Journal.

The supernova remnant appears to be the product of a rare explosion in which matter is ejected at high speeds along the poles of a rotating star.

"W49B is the first of its kind to be discovered in the galaxy," said Laura Lopez, who led the study at the Massachusetts Institute of Technology. "It appears its parent star ended its life in a way that most others don't."

Usually when a massive star runs out of fuel, the central region of the star collapses, triggering a chain of events that quickly culminate in a supernova explosion. Most of these explosions are generally symmetrical, with the stellar material blasting away more or less evenly in all directions.

However, in the W49B supernova, material near the poles of the doomed rotating star was ejected at a much higher speed than material emanating from its equator. Jets shooting away from the star's poles mainly shaped the supernova explosion and its aftermath.

"In addition to its unusual signature of elements, W49B also is much more elongated and elliptical than most other remnants," said paper co-author Enrico Ramirez-Ruiz, of the University of California.

"This is seen in X-rays and several other wavelengths and points to an unusual demise for this star."

Most of the time, massive stars that collapse into supernovas leave a dense spinning core called a neutron star. Astronomers can often detect these neutron stars through their X-ray or radio pulses.

However, with W49B, no evidence has been found for a neutron star, implying an even more exotic object might have formed in the explosion, that is, a black hole.

- nzherald.co.nz

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