Screen-use options: These files are created for viewing on your monitor
Print-use download options: These files are designed to fit on letter-size paper
Highest-quality download options: The best resolution available
ABOUT THIS IMAGE:
These images taken by NASA's Hubble Space Telescope reveal a new type of stellar explosion produced from the merger of two compact objects.
Hubble spotted the outburst while looking at the aftermath of a short- duration gamma-ray burst, a mysterious flash of intense high-energy radiation that appears from random directions in space. Short-duration blasts last at most a few seconds. They sometimes, however, produce faint afterglows in visible and near-infrared light that continue for several hours or days and help astronomers pinpoint the exact location of the burst.
In the image at left, the galaxy in the center produced the gamma-ray burst, designated GRB 130603B. The galaxy, cataloged as SDS J112848.22+170418.5, resides almost 4 billion light-years away. A probe of the galaxy with Hubble's Wide Field Camera 3 on June 13, 2013, revealed a glow in near-infrared light at the source of the gamma-ray burst, shown in the image at top, right. When Hubble observed the same location on July 3, the source had faded, shown in the image at below, right. The fading glow provided key evidence that it was the decaying fireball of a new type of stellar blast called a kilonova.
Kilonovas are about 1,000 times brighter than a nova, which is caused by the eruption of a white dwarf. But they are 1/10th to 1/100th the brightness of a typical supernova, the self-detonation of a massive star.
Object Names: GRB 130603B, SDS J112848.22+170418.5
Image Type: Astronomical/Annotated
Credit: NASA, ESA, N. Tanvir (University of Leicester), A. Fruchter (STScI), and A. Levan (University of Warwick)
NASA's Hubble Space Telescope recently provided the strongest evidence yet that short-duration gamma ray bursts are produced by the merger of two small, super-dense stellar objects.
The evidence is in the detection of a new kind of stellar blast called a
kilonova, which results from the energy released when a pair of compact objects
crash together. Hubble observed the fading fireball from a kilonova last month,
following a short gamma ray burst (GRB) in a galaxy almost 4 billion light-years
from Earth. A kilonova had been predicted to accompany a short-duration GRB, but
had not been seen before.
"This observation finally solves the mystery of the origin of short gamma ray
bursts," said Nial Tanvir of the University of Leicester in the United Kingdom.
Tanvir lead a team of researchers using Hubble to study the recent
short-duration GRB. "Many astronomers, including our group, have already
provided a great deal of evidence that long-duration gamma ray bursts (those
lasting more than two seconds) are produced by the collapse of extremely massive
stars. But we only had weak circumstantial evidence that short bursts were
produced by the merger of compact objects. This result now appears to provide
definitive proof supporting that scenario."
The team's results appear Saturday, Aug., 3 in a special online edition of
the journal Nature.
A kilonova is about 1,000 times brighter than a nova, which is caused by the
eruption of a white dwarf. The self-detonation of a massive star, a supernova,
can be as much as 100 times brighter than a kilonova. Gamma ray bursts are
mysterious flashes of intense high-energy radiation that appear from random
directions in space. Short-duration blasts last at most a few seconds, but they
sometimes produce faint afterglows in visible and near-infrared light that
continue for several hours or days. The afterglows have helped astronomers
determine that GRBs lie in distant galaxies.
Astrophysicists have predicted short-duration GRBs are created when a pair of
super-dense neutron stars in a binary system spiral together. This event happens
as the system emits gravitational radiation, creating tiny waves in the fabric
of space-time. The energy dissipated by the waves causes the two stars to sweep
closer together. In the final milliseconds before the explosion, the two stars
merge into a death spiral that kicks out highly radioactive material. This
material heats up and expands, emitting a burst of light.
In a recent science paper Jennifer Barnes and Daniel Kasen of the University
of California at Berkeley and the Lawrence Berkeley National Laboratory
presented new calculations predicting how kilonovas should look. They predicted
the same hot plasma producing the radiation also will block the visible light,
causing the gusher of energy from the kilonova to flood out in near-infrared
light over several days.
An unexpected opportunity to test this model came June 3 when NASA' s Swift
space telescope picked up the extremely bright gamma ray burst, cataloged as GRB
130603B. Although the initial blast of gamma rays lasted just one-tenth of a
second, it was roughly 100 billion times brighter than the subsequent kilonova
flash.
From June 12-13, Hubble searched the location of the initial burst, spotting
a faint red object. An independent analysis of the data from another research
team confirmed the detection. Subsequent Hubble observations on July 3 revealed
the source had faded away, therefore providing the key evidence the infrared
glow was from an explosion accompanying the merger of two objects.
For images and more information on the kilonova, visit:
For more information about the Hubble Space Telescope, visit:
NASA
Guillermo Gonzalo Sánchez Achutegui
No hay comentarios:
Publicar un comentario