This is a nice bit of
interpretation and it may even be true.
Meanwhile we have our source for the earliest observation of a super
nova on record. This is all very good.
It also shows us how rich our
mapping efforts are becoming. We are
quickly reaching the point in which every human being can become an
observational scientist tasked with watching and reviewing his own section of
the sky.
We have already defined the need
for every human eyeball to pay attention to a specific
bit of water shed in order to
share the information. Now we add a star
cell map.
Today the amount of data been
gathered is staggering and we must enlist everyone.
2,000-Year-Old Supernova Mystery Solved By NASA Telescopes
By SPACE.com Staff Mon, 24 Oct, 2011
Two NASA space telescopes have helped solve some of the most enduring
mysteries of the first documented report of star explosion — an ancient
supernova spotted nearly 2,000 years ago, scientists say.
In 185 A.D., Chinese astronomers witnessed what they called a
mysterious "guest star" that appeared in the sky and lingered for
about eight months. It wasn't until the 1960s that scientists determined that
this cosmic object was the first
documented observation of a supernova that signaled the violent death
of a distant star.
Now, infrared views of the supernova from NASA's Spitzer Space
Telescope and the Wide-field Infrared Survey Explorer (WISE) reveal that the
star explosion detonated inside a region of space that was relatively free of
gas and dust. This allowed the star's explosion to travel out much farther and
faster than expected, researchers said.
"This supernova remnant got really big, really fast," said
Brian Williams, an astronomer at North Carolina
State University
in Raleigh
Williams is the lead author of the new study, which is detailed online
in the Astrophysical Journal.
Ancient supernova
The ancient supernova, called RCW
86, is located about 8,000 light-years from Earth. But while its location
was known, much of its details were shrouded in mystery.
One enigma is the fact that the star's spherical remains are larger
than expected. If the star's
exploded guts could be seen in infrared light in the sky today, they would
take up more space than the full moon, researchers said.
By combining the new data from Spitzer and WISE with existing
information from NASA's Chandra X-Ray Observatory and the European Space
Agency's XMM-Newton Observatory, astronomers were able to grasp the missing
pieces of the puzzle.
They found that RCW 86 is a so-called Type
Ia supernova, triggered by the relatively peaceful death of a star similar
to our sun. This star shrank into a dense star called a white dwarf before
siphoning matter, or fuel, from a nearby companion star. The white dwarf is
then thought to have exploded in a brilliant supernova explosion.
"A white dwarf is like a smoking cinder from a burnt-out
fire," Williams said. "If you pour gasoline on it, it will
explode."
The study showed for the first time that a white dwarf can create a
cavitylike empty region of space around itself before exploding in a Type Ia
supernova event. The presence of a cavity would explain why the remnants of RCW
86 are so big, researchers said.
When the explosion occurred, the cavity would have allowed the
resulting ejected material to spew out unimpeded by gas and dust. This would
also have allowed the star's remains to be cast out rapidly.
More cosmic clues
Using Spitzer and WISE, the researchers measured the temperature of the
dust that makes up the RCW 86 remnant. They then calculated how much gas had to
be present inside the supernova remnant to heat the dust to those temperatures.
They found that the supernova remnant existed in a low-density
environment for much of its life, which points to the presence of a cavity.
Earlier, scientists suspected that RCW 86 formed from a so-called
core-collapse supernova, which occurs when a star's core reaches a tipping
point mass and implodes. Core-collapse supernovas are the most powerful type of
supernova.
While there were hints of a cavity around RCW 86, at that time
the phenomenon was only associated with core-collapse supernovas. In these
cosmic blasts, massive stars blow material away from them before they explode,
which carves out dust-free voids around them.
Yet, Williams and his colleagues were able to rule out the possibility
of RCW 86 being a core-collapse
supernova. X-ray data from Chandra and XMM-Newton indicated that the object
consisted of high amounts of iron, which is traditionally a clear indicator of
a Type Ia supernova.
Combining these observations with infrared data, the astronomers were
able to show that RCW 86 was a Type Ia explosion in a cavity.
"Modern astronomers unveiled one secret of a two-millennia-old
cosmic mystery only to reveal another," said Bill Danchi, Spitzer and WISE
program scientist at NASA Headquarters in Washington, D.C. "Now, with
multiple observatories extending our senses in space, we can fully appreciate
the remarkable physics behind this star's death throes, yet still be as in awe
of the cosmos as the ancient astronomers."
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