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Exploding Star May Have Damaged Life on Earth
Reedo writes "Scientists have proposed that an ancient supernova may have damaged our ozone layer, wreaking havok on terrestrial life. Previously no one had realized that a cluster of stars could have been so close to the earth during that time. But don't worry about it happening again anytime soon. The next expected supernova is nearly 500,000 light-years away and is too far from the earth to cause any damage."
Note that, the article claims that the next star in that cluster expected to go supernova is 500,000 light years away.
Of course, it also claims that that star is Antares, which is actually about 600 light years away.
From the article:
The next member of the gang expected to go supernova is Antares, which at almost 500,000 light-years away is too distant to rattle our planet, they say.
What kind of dope are these astronomers smoking? Antares is 500 light years away.
Still quite distant, but 500000 light years will place you well outside the Milky way. It's about as far as the Magellanic clouds.
The Galactic core is closer than that, the last I checked. Andromeda is about 2 million LY away, if I recall right. Let's see.
Antares = 520 light years
CNN cites the Scorpius-Centaurus OB Association of stars which is actually about 470 light years away.
So CNN was off only by a factor of a thousand. Interesting theory, if they can get the facts right.
"It is a greater offense to steal men's labor, than their clothes"
"But Maiz-Appellanis and Benitez did some detective work and came up with the likely culprit -- a volatile star pack known as the Scorpius-Centaurus OB Association, which passed relatively near the solar system several million years ago."
A google search turned up:
The association is embedded in a large roughly circular structure; this is a huge bubble of hot gas created by the stellar winds of the numerous massive stars in the association and by several super-nova explosions, which happened in the Scorpius Centaurus association during the last few million years.
So supernovas have happened in our local bubble, and evidently quite close.
Crystal Meth: Would you ingest somthing made from a poisonous gas and an explosive metal? You do it every day -- Salt!
Please read the paper before dismissing the theory.
This article points out that some stars in the cluster could have been as close as 130 light-years away around 2 million years ago. The local bubble itself is only 150 light-years across, so the earth would have been within the necessary range for damage to occur.
There's also a theory floating around that a star in the cluster actually made the local bubble.
Crystal Meth: Would you ingest somthing made from a poisonous gas and an explosive metal? You do it every day -- Salt!
Perhaps you should read the article (the scientific paper that is, not the CNN article) before dismissing it as "insultingly ludicrous."
The local bubble is thought to have formed approx. 10 million years ago, not 5-6 billion.
The paper also references works that show that the various subgroups which make up the Scorpius-Centaurus OB association, have produced plenty of supernova's in the past.
Warning: Some ideologies on the Net are smaller than they appear.
The fossil record is "tied to" Darwinian theory only in that the latter is the most successful explanation of the former. Fossils are found things, not theoretical constructs. Determining their sge depends a lot on physics (through radioactive dating) but only weakly, if at all, on biology.
The Mongrel Dogs Who Teach
These finds are unrelated to the theory of evolution. The theory of evolution is one of sciences most impressive theories which has withstood attacks both fair and foul. The basic theory doesn't rely on super nova's millions of years ago.
The theory of evolution doesn't have circular dependencies on the fossil record. That's just creationist wishful thinking.
When you mention errors in radiometric dating, do you refer to the unaccuracies that science knows and accounts for, or do you refer to delibrate misuse of radiometric dating by Steve Austin (the creationist, not the wrestler)?
If NDT was incorrect, the science behind this (ie. supernova ~2 million years ago killed off lots of marine life) would still stand.
Warning: Some ideologies on the Net are smaller than they appear.
best place to lay any media inaccuracies to rest.
here it is again, www.badastronomy.com
Although no-one has mentioned it on there bulletin board yet. Real astronomers visit this board, indeed a real one runs it.
This star group the article refers to is around 500 light years away, not 500,000. Next time, CNN should assign this "reporter" to cover trends in hairstyles or sightings of Elvis or some other topic the "reporter" might be capable of understanding.
Or maybe this is just another example of Time Warner math coming from CNN's parent, the same arithmetic that shows the record studios to be losing billions of dollars due to music "piracy". The multiples are probably similar in both instances.
This all possible, yes, but it's also extremely unlikely.
First the possible. A quick, back of a napkin calculation shows that a supernovae at around 3 light years would appear roughly as bright as the sun (depending on the circumstances). A good opprtunity to work on your tan, for a few days anyway. Nothing to really worry about, but if you're skinned, slap on some SP-40.
Now, if it's much closer, you might have some problems. At ~1.5 light years, the supernova is 4 times as bright as the sun, and at ~1 light year, it's 9 times as bright. Hooray, we know what an inverse square law is.
The real problem is this: there aren't that many stars nearby. The closest, Proxima Centauri, is 4.2 light years away. And there's no chance of it ever going supernova - only comparatively massive stars manage that. Within 10 light years of us, there are only 12 stars (and that includes Sol). Of those there is only one that's ever going to go supernovae - Sirius, at a distance of 8.6 ly. And that's an exceptional case. You have to go to the 70th nearest star before you find another star in the same situation - Altair, at 16.8 ly.
Now, even with Sirius and Altair, they're going to be shining for millions of years to come. Now, what they're suggesting is that one of those really rare large stars just happened to be really close to us when it's lifetime of tens of millions of years came to a close. Right.
Time for those astronomers to come down from the mountain - the altitude seems to be having an effect.
I havent read the article, shoot me ;-) But my guess is that they just look for the most massive star in the solar neighbourhood. The reasoning is:
1) a star can only use about 10% of the available hydrogen, before more rapid evolutionary mechanisms set is (ie before some of them go boom)
2) only 0.7% of the rest mass energy is turned into energy
3) the relation between luminosity (L) and mass (M) is:
- M proportional to L^4 (for massive stars)
Thus nuclear time scale (tn):
tn = 0.007*0.1*Mc^2/L ( = 10^10 year for the Sun)
for other massive stars:
tn = (M/Msun)/(L/Lsun) * 10^10 yr
= (M/Msun)/(M^4/Msun) *10^10yr
= M^-3 * 10^10 yr
so if one would find a 10 Msun star nearby, you could expect it to go boom in 10 million years. In other words, a cosmic 'blink of the eye'.
We are all in the gutter, but some of us are looking at the stars
It probably should be clarified that the statement about Antares being the next probable supernova really meant "Antares is the next likely SN candidate in that cluster". For quite some time, astronomers have been keeping an eye on Eta Carinae, which is about somewhere between 7.5K and 10K light years away, but could possibly let go at any time. It will likely be quite harmless except to astronauts and orbiting spacecraft (there is some discussion regarding whether it could become a gamma ray burster), but quite spectacular to see. There just aren't any sufficiently massive stars close enough to us to really worry about supernovas anytime soon.
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