The
super-supernova SN2007bi is an example of a "pair-instability"
breakdown, and that's like calling an atomic bomb a
"plutonium-pressing" device. At sizes of around four megayottagrams
(that's thirty-two zeros) giant stars are supported against
gravitational collapse by gamma ray pressure. The hotter the core, the
higher the energy of these gamma rays - but if they get too energetic,
these gamma rays can begin pair production: creating an
electron-positron matter-antimatter pair out of pure energy as they
pass an atom. Yes, this does mean that the entire stellar core acts as
a gigantic particle accelerator.
The antimatter annihilates
with its opposite, as antimatter is wont to do, but the problem is that
the speed of antimatter explosion - which is pretty damn fast - is
still a critical delay in the gamma-pressure holding up the star. The
outer layers sag in, compressing the core more, raising the
temperature, making more energetic gamma rays even more likely to make
antimatter and suddenly the whole star is a runaway nuclear reactor
beyond the scale of the imagination. The entire thermonuclear core
detonates at once, an atomic warhead that's not just bigger than the
Sun - it's bigger than the Sun plus the mass of another ten close by
stars.
The entire star explodes. No neutron star, no
black hole, nothing left behind but an expanding cloud of newly
radioactive material and empty space where once was the most massive
item you can actually have without ripping space. The explosion alone
triggers alchemy on a suprasolar scale, converting stars' worth of
matter into new radioactive elements.
And we saw this. This
really happened. Someday, somewhere, another massive explosion will occur and no one will be left to tweet it.
Most astronomers today believe that one of
the plausible reasons we have yet to detect intelligent life in the
universe is due to the deadly effects of local supernova explosions
that wipe out all life in a given region of a galaxy.
While there is, on average, only one supernova per galaxy per
century, there is something on the order of 100 billion galaxies in the
observable Universe. Taking 10 billion years for the age of the
Universe (it's actually 13.7 billion, but stars didn't form for the
first few hundred million), Dr. Richard Mushotzky of the NASA Goddard
Space Flight Center, derived a figure of 1 billion supernovae per year,
or 30 supernovae per second in the observable Universe!
Certain
rare stars -real killers -type 11 stars, are core-collapse hypernova
that generate deadly gamma ray bursts (GRBs). These long burst objects
release 1000 times the non-neutrino energy release of an ordinary
"core-collapse" supernova. Concrete proof of the core-collapse GRB
model came in 2003.
It was made possible in part to a
fortuitously "nearby" burst whose location was distributed to
astronomers by the Gamma-ray Burst Coordinates Network (GCN). On March
29, 2003, a burst went off close enough that the follow-up observations
were decisive in solving the gamma-ray burst mystery. The optical
spectrum of the afterglow was nearly identical to that of supernova
SN1998bw. In addition, observations from x-ray satellites showed the
same characteristic signature of "shocked" and "heated" oxygen that's
also present in supernovae. Thus, astronomers were able to determine
the "afterglow" light of a relatively close gamma-ray burst (located
"just" 2 billion light years away) resembled a supernova.
It
isn't known if every hypernova is associated with a GRB. However,
astronomers estimate only about one out of 100,000 supernovae produce a
hypernova. This works out to about one gamma-ray burst per day, which
is in fact what is observed.
What is almost certain is
that the core of the star involved in a given hypernova is massive
enough to collapse into a black hole (rather than a neutron star). So
every GRB detected is also the "birth cry" of a new black hole.
Scientists
at the American Astronomical Society's 215th meeting, in Washington DC,
said earlier this week that new observations of T Pyxidis in the
constellation Pyxis (the compass) using the International Ultraviolet
Explorer satellite, indicate the white dwarf is part of a close binary
system with a sun, and the pair are 3,260 light-years from Earth and
much closer than the previous estimate of 6,000 light-years.

The white dwarf in the T Pyxidis system is a recurrent nova, which
means it undergoes nova (thermonuclear) eruptions around every 20
years. The most recent known events were in 1967, 1944, 1920, 1902, and
1890. These explosions are nova rather than supernova events, and do
not destroy the star, and have no effect on Earth. The astronomers do
not know why the there has been a longer than usual interval since the
last nova eruption.
Astronomers believe the nova
explosions are the result of an increase of mass as the dwarf siphons
off hydrogen-rich gases from its stellar companion. When the mass
reaches a certain limit a nova is triggered. It is unknown whether
there is a net gain or loss of mass during the siphoning/explosion
cycle, but if the mass does build up the so-called Chandrasekhar Limit
could be reached, and the dwarf would then become a Type 1a supernova.
In this event the dwarf would collapse and detonate a massive explosion
resulting in its total destruction. This type of supernova releases 10
million times the energy of a nova.
Observations of the
white dwarf during the nova eruptions suggest its mass is increasing,
and pictures from the Hubble telescope of shells of material expelled
during the previous explosions support the view. Models estimate the
white dwarf's mass could reach the Chandrasekhar Limit in around 10
million years or less.
According to the scientists the
supernova would result in gamma radiation with an energy equivalent to
1,000 solar flares simultaneously - enough to threaten Earth by
production of nitrous oxides that would damage and perhaps destroy the
ozone layer. The supernova would be as bright as all the other stars in
the Milky Way put together. One of the astronomers, Dr Edward Sion,
from Villanova University in Pennsylvania, said the supernova could
occur "soon" on the timescales familiar to astronomers and geologists,
but this is a long time in the future in human terms.
Astronomers
think supernova explosions closer than 100 light years from Earth would
be catastrophic, but the effects of events further away are unclear and
would depend on how powerful the supernova is. The research team
postulate it could be close enough and powerful enough to damage Earth,
possibly severely, although other researchers, such as Professor
Fillipenko of the Berkeley Astronomy Department, disagree with the
calculations and believe the supernova, if it occurred, would be
unlikely to damage the planet.
Luke McKinney with Casey Kazan
Ok, say we take the fastest spaceship ever launched in order to escape the future blast. We jump onto a ship that speeds 30 km per second to opposite direction. That is 10e-5 times the speed of light. In 10 million years we would have put another 1000 light-years of distance between us and the explosion, or 30% on top of the current distance. But, there would be no Earth to shield us.
Looks like we are doomed. Damn.
Posted by: qed | April 09, 2010 at 03:12 AM
And we have an energy shortage here? Send Capt. Kirk with a dump truck to get us a load!
Posted by: Merlins Tears | April 09, 2010 at 06:35 AM
No question we live in a violent -- and dangerous -- universe. All the more reason we need to start spreading out -- and working on a functional interstellar drive.
Posted by: stargazer | April 09, 2010 at 08:15 AM
It looks like 40 km per second would just about do it then.
Or, better start engineering an enhanced heliosphere!
Posted by: SB | April 09, 2010 at 10:09 AM
This is the size of a fart that comse from your mom. Owned
Posted by: Thomas Pynchon | April 09, 2010 at 11:33 AM
The last thing the universe needs is the spread of humankind. If there's any karma, supreme being, whatever, humanity will never leave this planet to infest any other place.
Posted by: David Joseph Loesam | April 09, 2010 at 12:17 PM
@ stargazer
Why? What benefits do you feel there are to gain for the ultimate survival of the human race?
What I am saying is that while an individual's desire for survival is understandable, does that necessarily translate into a need for the infinite survival of humanity...
Posted by: TM | April 09, 2010 at 12:27 PM
This is pretty epic... Also, with the expansion of humanity, I would hope that by the time that is possible, we would have matured as a society to where one wouldn't consider it an "infestation".
WTB Star Trek times now!
Posted by: Alex | April 09, 2010 at 12:31 PM
Although this threat is real, in an Astronomical POV - it HAS been real for centuries upon centuries. Yet we worry only when the mainstream articles like this give us insight to let us be able to worry.
I would be cautious of allotting too much negative energy to anything (fear, worry, anxiety, etc). There are things that feed off of it. Bleed acceptance.
Posted by: Dain Miller | April 09, 2010 at 12:56 PM
so a star 200x the size of our own, exploded, and the resulting gas cloud expanded to 50x the size of the sun? Typo?
Posted by: earth | April 09, 2010 at 01:20 PM
This star exploded billions of years ago. Its billions of light years away, before humanity even existed.
Posted by: science | April 09, 2010 at 01:50 PM
Wow, scientists are pretty narrow minded, with exponential progress in technology, and the fact that we are likely to have nanorobotics and AI pretty soon (at least compared to 10M years) I don't think we have to worry. Nanorobots would easily sheild us from anything the universe can naturally produce, funny how most cosmologists seem to not have even read "Engines of Creation" or "The singularity is near". They should broaden their scientific education, it seems like all they know is exploiding stars/black holes, then they look out their office window and conclude "we're all doomed." ...
Posted by: James Gentile | April 09, 2010 at 02:09 PM
the star that exploded was 200x the MASS of our Sun; not 200x the diameter.
A 200x increase in mass (given the same density of material as our Sun) would mean an increase in diameter of approximately 5.85x (cube root of 200, as the sun/stars are spheres).
of course the original diameter could have been larger or smaller depending on the actual density of the star before it exploded.
When referencing a star size in context of black holes, neutron stars, supernovae, and other related phenomenon the references (in relation to our Sun) are always in relation the Mass of the star.
As in : a collapsing star who's remnant exceeds ~3-4x the Sun will collapse into a black hole.
here the reference to the Sun is really solar mass(es).
Posted by: Fred Sanford | April 09, 2010 at 02:11 PM
I think that was a lousy explanation of Anti-Matter. There is no "anti-matter" reactor from what I learned about in physics. I think it was called the law of conservation of energy. For a star to create anti-matter and then destroy it would be a net zero sum game. What might be more likely is that anti-matter gets stored in the star and gets used up randomly, thereby creating large fluctuations in the core temperature.
My two cents.
Posted by: eddie | April 09, 2010 at 03:09 PM
NERDS!!!!!!!!
Posted by: Fred "The Ogre" Palowakski | April 09, 2010 at 05:01 PM
to : Thomas Pynchon......Not all humans are like you !
Posted by: greg | April 09, 2010 at 05:21 PM
Authors of articles like these often do not make it clear just where these stars are. Are they in our own galaxy or in another galaxy? If there is a scientific fact that should be repeated in such articles so that non-astronomers like me might eventually remember it, that fact would be the scale of our galaxy in light years and the average distance to our neighboring galaxies, in light years.
Posted by: Ben | April 09, 2010 at 05:33 PM
You could drill into an asteroid and use it for shielding. If you had 10 girls, plus 10 million frozen sperm and eggs, you could repopulate world.
Posted by: Mike A | April 09, 2010 at 07:25 PM
Wow....
today must have been a bad day for alot of you.
Posted by: dmarx | April 09, 2010 at 07:51 PM
More important then this article is how do I clear up this rash
Posted by: Mikey The Monster | April 09, 2010 at 08:03 PM
I crap bigger than that.
Posted by: Don McArthur | April 09, 2010 at 08:05 PM
what does derka think about this?
Posted by: im from texas | April 09, 2010 at 09:06 PM
@eddie,
Storing antimatter in a star would be pretty impossible. You are right about the creation of antimatter being a zero-sum game. The point was that the creation/destruction of electron/positron pairs decreases the gamma ray "pressure" holding up the outer layers of the star. This causes these layers to collapse inward, increasing the pressure/temperature of the core, increasing the gamma ray production, increasing the antimatter production. . .
Of course it looks like the mention of anti-matter was more of an attention getter to get people to read an article about anti-matter generators.
Posted by: Naters | April 09, 2010 at 11:08 PM
"humanity will never leave this planet to infest any other place."
Wow, thanks for sharing your self-deprecating insecurities with all of us.
Posted by: dr | April 09, 2010 at 11:09 PM
I just hope that supernova holds up long enough for some long-distant descendant of ours, possibly machine-based, to figure out what on earth they were thinking when they came up with Stargate:Universe...
Posted by: Duglarri | April 09, 2010 at 11:54 PM