The Milky Way’s central black hole may have turned nearby red giant stars blue

A powerful blast from the supermassive black hole may explain a lack of large, red stars there.

Innumerable stars reside within 1.6 light-years of the Milky Way’s central black hole. But this same crowded neighborhood has fewer red giants — luminous stars that are large and cool — than expected.

Now astrophysicists have a new theory why: The supermassive black hole, Sagittarius A*, launched a powerful jet of gas that ripped off the red giants’ outer layers. That transformed the stars into smaller red giants or stars that are hotter and bluer, Michal Zajaček, an astrophysicist at the Polish Academy of Sciences in Warsaw, and colleagues suggest in a paper published online November 12 in the Astrophysical Journal.

Today Sagittarius A* is quiet, but two enormous bubbles of gamma-ray-emitting gas rooted at the center of the Milky Way tower far above and below the galaxy’s plane (SN: 12/9/20). These gas bubbles imply the black hole sprang to life some 4 million years ago when something fell into it.

Continued...
Source

X-RAY: CXC/NASA, D. WANG ET AL./UMASS; RADIO: MEERKAT/SARAO

The Milky Way’s galactic center, shown here in radio waves (red) and x-rays (green and blue), has a supermassive black hole that may have whittled away nearby red giants.

Source / Image Courtesy

stronomers may have discovered a new kind of survival story: a star that had a brush with a giant black hole and lived to tell the tale through exclamations of X-rays.