Now you see it.
Supernova 2005ap (bottom)
briefly outshines its whole galaxy and several neighboring galaxies (A-D)
after appearing in a sky survey.
Credit: SDSS/R. Quimby/ McDonald Obs./University of Texas,
Just as in sports, astronomical records are made to be broken, and
the latest one is a doozy: a supernova that briefly outshone the sun by a
factor of 100 billion, doubling the brilliance of the previous record
holder. Astronomers don't yet know which particular conditions could have
triggered such "extraordinary luminosity," as the team that discovered the
supernova writes in the 20 October issue of The Astrophysical Journal
Letters. But whatever those conditions are, they figure to cause a
theoretical rethinking of these titanic explosions.
Stars--those peaceful pinpoints of light in the night sky--are actually
cauldrons of extreme temperatures and pressures. When the nuclear
reactions that power them run out of fuel, the sun can no longer resist
their own intense gravity; they collapse and trigger the massive
explosions called supernovae. Astronomers have used automated sky searches
to collect data on supernovae for decades. The findings have become so
routine that scientists have classified supernovae into neat little
categories, such as Type Ia, whose brightness occurs with such consistency
it has become the standard candle for computing distances to other
The new findings may challenge this orderliness. Supernova 2005ap seems
to defy classification. The team of astronomers who discovered it--led by
Robert Quimby of the California Institute of Technology (Caltech) in
Pasadena--tentatively have labeled the 4.7 billion light-years away
ex-star a Type II-L supernova because of its brightness and because its
light spectrum shows a primarily hydrogen content. But the researchers are
at a loss to explain the supernova's spectacular incandescence.
"We really don't know what made 2005ap so luminous," Quimby says. "Our
best guess is that prior to the explosion, the star cast off some shell of
material, and the supernova ejecta later collided with this shell." The
problem, he says, is there still needs to be an unusually powerful engine
driving the ejecta, so 2005ap could represent a new and rare class of
supernovae. Some clues include the fact that the explosion achieved its
peak brilliance far more rapidly than normal and then nearly as quickly
dimmed. Also, the supernova's light spectrum shows the presence of forms
of carbon, nitrogen, and oxygen atoms that are considered unprecedented.
Only sightings of similarly bright supernovae will help solve the mystery,
and Quimby is optimistic they will be found.
With the discovery of 2005ap--and its record-holding predecessor,
called 2006gy (ScienceNOW,
7 May)--"the supernova bestiary is clearly enlarged," says astronomer Shri
Kulkarni, also of Caltech but not involved in the research. He says
because both events "are much more energetic than ordinary supernovae,"
they might somehow be linked to the same phenomena, such as gamma ray
bursts or the birth of black holes.
Original article: Science Now