The faint green glow you see in that picture is not an early harbringer of Hallowe’en spooks. It’s hydrogen gas clouds found recently nearby W26, a future supernova in the star cluster Westerlund 1.
Image: A “super star cluster”, Westerlund 1, which is about 16,000 light-years from Earth. It can be found in the southern constellation of Ara. The picture was taken from the European Southern Observatory’s VLT Survey Telescope. Credit: ESO/VPHAS+ Survey/N. Wright
The European Southern Observatory’s VLT Survey Telescope in Chile spotted the hydrogen in the cluster, which has hundreds of huge stars that are only believed to be a few million years old. (Our solar system, by comparison, is about 4.5 billion years old.)
“Such glowing clouds around massive stars are very rare, and are even rarer around a red supergiant— this is the first ionised nebula discovered around such a star,” the European Southern Observatory stated.
“W26 itself would be too cool to make the gas glow; the astronomers speculate that the source of the ionizing radiation may be either hot blue stars elsewhere in the cluster, or possibly a fainter, but much hotter, companion star to W26.”
Funny enough, the nebula that surrounds the red supergiant is similar to the one surrounding SN1987A, a star that exploded as a fairly bright supernova in 1987. “Studying objects like this new nebula around W26 will help astronomers to understand the mass loss processes around these massive stars, which eventually lead to their explosive demise,” ESO added.