University of Wisconsin, Whitewater | 2020 Jun 03
Astronomers announced the discovery of a ghostly, almost perfectly circular, arc of ultraviolet emission centered on the handle of the Big Dipper and stretching 30 degrees across the Northern sky. If the arc were extended, it would completely encircle the Big Dipper with a diameter of 60 degrees. ...
The arc, stretching beyond the constellation Ursa Major, is 30 degrees long, a fraction of a degree thick, and made of compressed, energized interstellar gas. The source of the energy and the arc shape indicate an advancing shock wave from a stellar explosion or supernova which occurred 60 degrees above the plane of the Milky Way Galaxy. The distance and age of the explosion which created the shock wave is highly uncertain. The team estimates that the explosion occurred more than 100,000 years ago at a distance of approximately 600 light years.
Because the full circle covers nearly 2,700 square degrees of sky, the blast may have been partially responsible for creating a clearing of gas and dust above the sun. "This region of the sky is known for several interstellar windows used to study the properties of galaxies outside the Milky Way. This arc may be evidence for one of the explosions that created these windows," said Benjamin. ...
Discovery of a 30-degree-long ultraviolet arc in Ursa Major ~ A. Bracco et al
- Astronomy & Astrophysics 636:L8 (Apr 2020) DOI: 10.1051/0004-6361/202037975
- arXiv.org > astro-ph > arXiv:2004.03175 > 07 Apr 2020