Astronomers think they saw a star exploding out of a giant gas bubble

[Judi Lynn]

Basically just a cosmic cocoon.
By Mary Beth Griggs 3 hours ago

It appeared as a flash of light on the arm of a distant spiral galaxy. It outshone neighboring stars, an attention-grabbing display of brilliance that peaked after 2.2 days in the sky. Then it was gone, dimming slowly into the background even as researchers raced to focus more telescopes on the ephemeral event.

It was too fast for a typical supernova, which tend to gradually build and recede as a star enters that last phase of its life, exploding in an astronomical fireworks show that can persist for months. Astronomers had noticed about a dozen other events like this in the past, a class of stellar phenomenon all their own: fast-evolving, luminous transients or FELTs.

No one was sure what they were. A star that tried and failed to go supernova would be fast, but also much fainter. The afterglow of a gamma ray burst? Possible, but gamma ray bursts are rare, and this didn’t quite fit. Two neutron stars slamming into each other? Also too faint. Something driven by a black hole drawing in surrounding matter? Possible, but the contortions to make the scenario fit the data made it unlikely.

Then, in 2015, the Kepler space telescope noticed this latest FELT on the arm of a distant galaxy. Snapping an image of that segment of the sky every 30 minutes, it provided a more detailed view of the rapid rise and fall of the FELT than had been seen before.

More:
https://www.popsci.com/supernova-gas-bubble-felts?dom=rss-default&src=syn#page-2