Duration of
Christmas 2010
gamma-ray burst
1,088
seconds
Median duration of
long gamma-ray bursts
detected by Swift
48
seconds
A mysterious burst in the universe
Gamma-ray excess may have come from collision or merger
By Nadia Drake
The unusually bright and long-lived
gamma-ray burst that appeared in
the skies on December 25, 2010, is an
enigmatic holiday gift that isn’t quite
unwrapped yet.
A year later, scientists trying to catch
the culprit behind the perplexing explosion detected by NASA’s Swift satellite
have arrived at two completely different answers, both presented in the Dec. 1
Nature. One theory involves a small
object, such as an asteroid or comet, passing too close to a neutron star and going
out in a gamma blaze of glory. The other
theory suggests that a stellar merger
followed by a dim supernova explosion
delivered the bizarre Christmas burst.
Christina Thöne, an astronomer at
the Astrophysical Institute of Andalucía
in Granada, Spain, says she and her colleagues considered “all kinds of weird
theories” before settling on the stellar merger scenario. In that version, a
A neutron star merging with its com-
panion (shown) may have triggered an
unusual gamma-ray burst seen in 2010.
neutron star slowly spirals in toward a
massive helium star, eventually colliding
and producing a cataclysmic explosion of
gamma rays. Then, a faint supernova goes
off roughly 10 days later, an event that
could explain anomalies in the Christmas
gamma-ray burst’s fading light.
The second theory also required
some creative thinking. Calculations by
Sergio Campana, an astrophysicist at
Italy’s Brera Astronomical Observatory
in Merate, and his team suggest that if an
object half the mass of the dwarf planet
Ceres were shredded by a neutron star, it
would produce enough debris to trigger a
prolonged gamma-ray expulsion.
Of course, the burst could still be the
product of an even more exotic event, says
astrophysicist Enrico Ramirez-Ruiz of
the University of California, Santa Cruz.
“I think this object is unique enough that
it could certainly be attributed to something we haven’t thought of.”
Go to http://www.rockauto.com
Go to http://www.rockauto.com
