Sun's Dark Companion 'Nemesis' Not So Likely

TravisTR passes along a story about the death of Nemesis. "The data that once suggested the Sun is orbited by a distant dark companion now raises even more questions... The periodicity [of mass extinctions] is a matter of some controversy among paleobiologists but there is a growing consensus that something of enormous destructive power happens every 26 or 27 million years. The question is what? ... another idea first put forward in the 1980s is that the Sun has a distant dark companion called Nemesis that sweeps through the Oort cloud every 27 million years or so, sending a deadly shower of comets our way. ... [Researchers] have brought together a massive set of extinction data from the last 500 million years, a period that is twice as long as anybody else has studied. And their analysis shows an excess of extinctions every 27 million years, with a confidence level of 99%. That's a clear, sharp signal over a huge length of time. At first glance, you'd think it clearly backs the idea that a distant dark object orbits the Sun every 27 million years. But ironically, the accuracy and regularity of these events is actually evidence against Nemesis' existence."

Comments

period of passing through the galaxy ecliptics?

[Kvasio]

isn't this the most simple explaination? Most stars in Mily Way arms are known to bounce up and down the ecliptic.

Re:period of passing through the galaxy ecliptics?

[sunspot42]

The sun doesn't just orbit the center of the galaxy, though. It also moves up and down relative to the galactic plane. Some have suggested that whenever the solar system reverses direction in that oscillation, very bad things happen, possibly due to the Oort Cloud experiencing some lag in reversing direction relative to the rest of the system. The sun essentially winds up off-center in the Oort Cloud, and in comparison to normal periods a lot of comets get kicked into the inner solar system as a result of this imbalance.

Re:period of passing through the galaxy ecliptics?

[evilviper]

isn't this the most simple explaination? [sic]

No, the most simplest explanation is that it's all an imagined phenomenon. A statistical anomaly due to selection bias, miscalculation, or vastly incomplete data-set... A ghost. Occam's Razor says so.

Re:period of passing through the galaxy ecliptics?

[jc42]

The sun doesn't just orbit the center of the galaxy, though. It also moves up and down relative to the galactic plane. Some have suggested that whenever the solar system reverses direction in that oscillation, very bad things happen, ...

That's close to a conventional explanation, but off by 1/4 cycle. The extreme high/low points of the solar system's bobbing orbit are outside the galactic plane, and would be the low-danger points. The rough parts of the (approx. 60 million year) cycle are the two crossings through the central part of the galactic plane, which are the densest portions. During the crossings, the solar system is zipping through the galactic plane at a few hundred km/s, producing lots of collisions with whatever rubble happens to be there.

Part of the explanation from the astronomers who've done the studies is that, although we're about in the middle of the galactic plane right now, we're actually in a "Local Bubble" about 300 light years across, so there's not much galactic rubble in the solar system right now. There are low-density bubbles like this scattered around, the results of things like supernova explosions in the distant past.

Stick around for another million years or so, and we'll exit the local bubble. There might be some nice fireworks then, and perhaps another mass extinction.

Of course, we are going through a mass extinction event right now, but it's an unusual one with a known causative agent that's not astronomical. It seems that a new top-level predator has recently evolved, which has been devastating the ecosystem all over the planet. This will probably confuse the paleontologists in the future, since they'll see a mass extinction during a crossing of the galactic plane, but won't see any evidence at all of the impact that presumably caused it. They'll also see the evidence of a species with high intelligence, but of course that couldn't be the cause, because you wouldn't expect a highly-intelligent species to destroy its own ecosystem, right? So the extinction event will remain a mystery.

Re:How long since last time

[cduffy]

Read the Fine Article.

We've got lots of time -- we're only 11 million years into this cycle.

Second comment debunks

[Xtifr]

The second comment under the article seems to be a pretty serious debunking. I'm not going to take sides or tell you who's right and wrong because I don't know, but I will note that arXiv (the source for the claims) is for pre-prints and is not peer-reviewed.

Re:Second comment debunks

[Randle_Revar]

that's the third comment.

Here is a bit from the second comment:

The fact is that with modern and better paleontological data any peridocity is rejected, as easily checked with autocorrelation [Alroy, 2008]:

"Quantitatively, extinction rates in the Fossil Record 2 family data (3) and Sepkoski’s family and genus data (1, 2) are not correlated with themselves at any time lag (49), which is a necessary condition for periodicity to hold. That said, analyses of origination rates in all three datasets (49, 50) suggest short-term autocorrelation. However, the current dataset shows no autocorrelation in either kind of rate (Fig. S1), and a standard spectral analysis (Fig. S2) also suggests purely random variation through the time series (i.e., white noise)."

Re:How long since last time

[vakuona]

"Fine". Seriously!? And here I thought it was...

Re:11 million years

[Surt]

Crap, we're screwed. We are not good at planning ahead. If only we'd had more time.

Re:How long since last time

[cheesee]

From FTA:

There is a smidgeon of good news. The last extinction event in this chain happened 11 million years ago so, in theory at least, we have plenty of time to work out where the next catastrophe is coming from.

Thank God!

[mangu]

11 million years

At first I read "1.1 million years" and was really worried

Re:How long since last time

[shentino]

I predict a nuclear holocaust before then, honestly.

Re:How long since last time

[steelfood]

Damn, and here I was, holding out that it would be December 21st, 2012.

I think I understand

[by (1706743)]

Sun's Dark Companion 'Nemesis' Not So Likely

"Nemesis" is the codename for the next MySQL release, to which Oracle is giving the ax. After the 5.1 debacle, I'm not surprised the database is being touted as a "Sun's Dark Companion."

Odd, I just got this weird feeling that I'm being offtopic.

Re:How long since last time

[anorlunda]

Better still, read the comment to the article by Torbjorn at the same URL as the article. Torbjorn calls it "Bad research, worse article" and he makes a pretty strong case.

Re:How long since last time

[ibsteve2u]

And, in a stunning display of randomness (or a 1% solution, depending upon your perspective), nemesis sent meteors crashing down into the keyboards of everybody who modded me down...

BadAstronomer said something similar

[magsol]

...only it was a larger multiple: somewhere in the vicinity of every 150-180 million years. However, in this case, it's due to our solar system's z-axis oscillation with respect to the rest of the Milky Way galaxy. The dust and gas of the galaxy acts as a shield against cosmic radiation, but every 150-180 million years, our solar system reaches the z-edge of the galaxy and is maximally exposed to the elements.

What accounts for the 5-7 other mass extinctions within that time frame, however, I defer to TFA.

Debunked nicely in the comments

[wealthychef]

Read the comment "Bad research, worse article" in the comments section. "Melott has made an arxiv carrier of various kinds of pattern searches and catastrophism scenarios in data. (What I would like to call "pseudoscience conspirationism".) " To sum it up, this article is probably sensationalist psuedoscience and there is nothing to see here.

Re:How long since last time

[c6gunner]

I quit reading when I got to "stealth creationist". That's the sort of ad hominem crap that's typical of Slashdot comments.

I quit reading after I got to the word "the". That's the sort of crap that's typical of Slashdot comments.

Re:How long since last time

[biryokumaru]

Nope. It's always been fine. Read the fine article. Read the fine manual. Your wife and I were fine last night. Always just been fine.

I thought Suns dark companion was

[mevets]

Oracle, who are probably going to cause an extinction much earlier than this....

Re:How long since last time

[sortius_nod]

Wooosh

Re:How long since last time

[TubeSteak]

I quit reading after I got to the word "the". That's the sort of crap that's typical of Slashdot comments.

I quit reading after I got to Slashdot

Re:I am doubtful

[sunspot42]

Check out the Wikipedia article on the Oort Cloud. The Oort Cloud is thought to be well over a light year across. Out on its fringes the influence of the sun's gravity isn't much stronger than the pull of nearby stars, or the galactic core itself. So whenever the oscillation reverses direction and the sun begins moving back toward the galactic plane, a lot of stuff out on the fringes doesn't move neatly with it. Some of it will become gravitationally unbound from the solar system, but some of it will find its orbit perturbed and start heading inward. Whether that's enough stuff to lead to mass extinctions here on Earth is another matter.

This article mentions disk tides, encountered most strongly as the Sol system passes thru the galactic plane, as the possible culprit in disturbing the Oort Cloud on a regular basis:

http://www.americanscientist.org/issues/pub/perturbing-the-oort-cloud

Re:11 million years

[vlm]

We have no proof that we're the first, and frankly if we were extinguished tomorrow the statistical odds are that in 5 million years time there will be no single trace of evidence left that we were ever here. To assume that no species in the billion years or so prior to our arrival reached this level is... well it's absurd.

For a geologist it would be pretty trivial to figure out. Merely analyze the distribution and size of mineral deposits of various ages. Why thats odd, all of the coal that was near the surface 5 million years ago is missing, although the stuff thats buried "too deep" 5 million years ago is still here. Same game for oil/gas, oddly enough all the large deposits that were onshore or close to shore 5M years ago are gone, how odd. Another fun one would be our trash heaps. WTF is all this indium ore near all this relatively pure glass ore? How come we find silicon deposits from 5 million years ago that are occasionally ridiculously pure except for commercially useful P-type and N-type semiconductor impurities? Finally, assuming the highly evolved cockroaches that have taken over have advanced beyond us, they'd also notice that certain technologies that they use have not been exploited, 5M years ago they were obviously pretty good at burning this "oil" stuff but they clearly never figured out how to refine boron into anti-matter reactor shielding, or mined graphite to make monocrystaline carbon fiber space elevators, much like a hundred years ago hyperpurified silicon and large lumps of pure uranium metal were not industrially produced.