The mystery of the humongous Christmas space explosion
On Christmas Day 2010, NASA's Swift satellite detected a massive, sustained gamma-ray burst whose cause still leaves astronomers baffled.
The Christmas sky last year was lit up by an extraordinarily powerful and mysteriously long-lasting explosion in space that scientists now suggest was a comet smacking into a dense star or a peculiar supernova death.Skip to next paragraph
Radiation from gamma-ray bursts, the most powerful explosions ever seen in the universe, strikes Earth's atmosphere from random directions in space about twice a day. These bursts can be roughly divided into two kinds, ones lasting less than two seconds, and ones lasting up to minutes.
Scientists think shorter gamma-ray bursts are generally caused by merging neutron stars — dead stars made up of super-dense neutron matter. Longer bursts are typically thought to originate from hypernovas, in which giant stars that explode as incredibly powerful supernovas spew two opposing jets of energy as they die; we see them head-on as bursts. [Photos of Great Supernova Explosions]
However, researchers suspect a number of mysterious events of completely different origins could mimic gamma-ray bursts. Such might be the case with the Christmas burst, formally known as GRB 101225A.
"It is important to understand gamma-ray bursts to get some global picture of the life and death of massive stars," said astronomer Christina Thöne of the Institute of Astrophysics in Andalusia, Spain. "Massive stars are ultimately the ones that decide what elements are present, created and recycled in the gas in our and any other galaxy."
Now scientists have two competing explanations for the Christmas burst: a cosmic impact on a dead star in our galaxy, or a peculiar supernova in a distant galaxy.
Based on the length and brightness of the burst, astrophysicist Sergio Campana at the Astronomical Observatory of Brera in Italy and his colleagues suggest that a minor body such as a comet or asteroid crashed into a neutron star.
"I think this is the discovery of a completely new astrophysical phenomenon that has not been envisaged before," Campana told SPACE.com.