Hubble captures exploding star 311.
(photo credit: NASA, ESA, A. Riess (STScI and JHU), and S. Rodney)
NASA's Hubble Space Telescope has looked deep into the
distant universe and detected the feeble glow of a star that exploded
more than 9 billion years ago. The sighting is the first finding of an
ambitious survey that will help astronomers place better constraints on
the nature of dark energy: the mysterious repulsive force that is
causing the universe to fly apart ever faster.
astronomers have harnessed the power of Hubble to unravel the mysteries
of the universe," said John Grunsfeld, associate administrator for
NASA’s Science Mission Directorate in Washington. "This new observation
builds upon the revolutionary research using Hubble that won astronomers
the 2011 Nobel Prize in Physics, while bringing us a step closer to
understanding the nature of dark energy which drives the cosmic
acceleration." As an astronaut, Grunsfeld visited Hubble three times,
performing a total of eight spacewalks to service and upgrade the
The stellar explosion, nicknamed SN Primo, belongs to a special class
called Type Ia supernovae, which are bright beacons used as distance
markers for studying the expansion rate of the universe. Type Ia
supernovae likely arise when white dwarf stars, the burned-out cores of
normal stars, siphon too much material from their companion stars and
SN Primo is the farthest Type Ia supernova with its
distance confirmed through spectroscopic observations. In these types of
observations, a spectrum splits the light from a supernova into its
constituent colors. By analyzing those colors, astronomers can confirm
its distance by measuring how much the supernova's light has been
stretched, or red-shifted, into near-infrared wavelengths because of the
expansion of the universe.
The supernova was discovered as part
of a three-year Hubble program to survey faraway Type Ia supernovae,
opening a new distance realm for searching for this special class of
stellar explosion. The remote supernovae will help astronomers determine
whether the exploding stars remain dependable cosmic yardsticks across
vast distances of space in an epoch when the cosmos was only one-third
its current age of 13.7 billion years.
Called the CANDELS+CLASH
Supernova Project, the census uses the sharpness and versatility of
Hubble's Wide Field Camera 3 (WFC3) to assist astronomers in the search
for supernovae in near-infrared light and verify their distance with
spectroscopy. CANDELS is the Cosmic Assembly Near-infrared Deep
Extragalactic Legacy Survey and CLASH is the Cluster Lensing and
Supernova Survey with Hubble.
"In our search for supernovae, we
had gone as far as we could go in optical light," said Adam Riess, the
project's lead investigator, at the Space Telescope Science Institute
and The Johns Hopkins University in Baltimore, Md. "But it's only the
beginning of what we can do in infrared light. This discovery
demonstrates that we can use the Wide Field Camera 3 to search for
supernovae in the distant universe."
The new results were presented on Jan. 11 at the American Astronomical Society meeting in Austin, Texas.
supernova team's search technique involved taking multiple
near-infrared images over several months, looking for a supernova's
faint glow. After the team spotted the stellar blast in October 2010,
they used WFC3's spectrometer to verify SN Primo's distance and to
decode its light, finding the unique signature of a Type Ia supernova.
The team then re-imaged SN Primo periodically for eight months,
measuring the slow dimming of its light.
By taking the census,
the astronomers hope to determine the frequency of Type Ia supernovae
during the early universe and glean insights into the mechanisms that
"If we look into the early universe and measure a
drop in the number of supernovae, then it could be that it takes a long
time to make a Type Ia supernova," said team member Steve Rodney of The
Johns Hopkins University. "Like corn kernels in a pan waiting for the
oil to heat up, the stars haven't had enough time at that epoch to
evolve to the point of explosion. However, if supernovae form very
quickly, like microwave popcorn, then they will be immediately visible,
and we'll find many of them, even when the universe was very young. Each
supernova is unique, so it's possible that there are multiple ways to
make a supernova."
If astronomers discover that Type Ia
supernovae begin to depart from how they expect them to look, they might
be able to gauge those changes and make the measurements of dark energy
more precise. Riess and two other astronomers shared the 2011 Nobel
Prize in Physics for discovering dark energy 13 years ago, using Type Ia
supernova to plot the universe's expansion rate.This article was first published at www.newswise.com