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Nemesis: Sol's evil twin?


Sampa

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Come on, guys. Are some of you actually still talking about this as if it had any chance of being real? Despite the fact that conclusive counterevidence has been presented years ago, as pointed out by several different people in this thread? Even if you don't know a thing about mass extinctions, how gravitational perturbation works, or what the WISE survey is, it doesn't take more than the most cursory of Google searches to learn all about them. Again guys, come on. This is the science labs subforum. At least try to consider hard science in your argumentation.

For starters, it would be great if the proponents of the hypothesis could agree on what they mean with Nemesis. Is it a binary partner to our Sun that currently exists in our Solar system? Is it a star that may have formed in the solar system in the past but has since been ejected? Is it a rogue star that merely traveled through our solar system at some point in the past? You seem to be using all of these definitions interchangably, making the discussion pointless and unscientific, because you cannot prove or disprove something that keeps changing definition.

For the sake of this post, I'm going with the OP's definition that Nemesis is a hypothesized companion star currently residing in our solar system. This is incidentally also the definition used by the people who originally came up with the idea (though they went with a brown dwarf, not a star). Now, because work is slow today, I'm going to fight my boredom by systematically debunking some of the pro-arguments found in this thread.

With enough debris surrounding it, it could be nearly indistinguishable from the spatial environment around it.

There is no such thing as a debris cloud that can hide a star. It's not just unlikely - it is quite literally physically impossible. Any mass of matter anywhere near that size morphs into an accretion disk through its own gravitational attraction and spawns planets. As in, multiple planets. We're talking enough matter to create a small solar system here. And in the process of accretion, it gets really hot and bright. We can see planetary formation processes hundreds of lightyears away because it is such an extremely conspicuous event.

Plausible, as no one knows where it is in the sky

False: we do very well know where it is (or rather, would be, if it existed) in the sky.

For starters, all objects in the solar system formed in the same plane. That is because of the aformentioned accretion disk of matter, which is always planar (not just in our solar system, but in ALL solar systems). This constrains the location of any further bodies in the solar system to a very small area, which happens to be intensely studied precisely because that's where additional objects are expected to be found.

Some of the objects that form later gain an inclination with respect to the solar system plane, through gravitational interaction with other objects. However, if Nemesis is to be a star, it must have at bare minimum 75 times the mass of Jupiter. At bare minimum! There is no object in the solar system apart from the Sun itself that is massive enough to change the inclination of such a body by even 1°. Even if you combined all the not-Sun mass in the solar system into one super-body, it would still not be enough. (And for what it's worth, even combining all the not-Sun mass in the solar system doesn't come anywhere near the amount of mass required to make the tiniest of stars.)

Then, there's WISE, the Wide-field Infrared Survey Explorer. An infrared space telescope launched in 2009, it performed an all-sky survey. I've underlined this for emphasis: it literally photographed the entire sky. It photographed every single arcsecond of it at least 8-10 times over the course of 10 months. Claiming that we haven't found Nemesis because it is somewhere we haven't looked is nonsense, because WISE looked everywhere. And it wasn't the first all-sky survey either - merely the highest resolution and most recent to be completed. There is even another running right now with an even higher resolution, called Gaia.

WISE was able to detect a Neptune-sized object out to 700 AU (it found none), a Jupiter-sized object out to 1 lightyear (it found none), and a 3x Jupiter-sized object out to 10 lightyears (if it found any, they were in other solar systems). For Nemesis to be a companion star to the Sun, WISE would have to have missed an object greater than 75 times the size of Jupiter, which is actively undergoing fusion, at a distance of 1 lightyear or less... and missed it 10 times in a row. All other all-sky surveys before WISE would also have to have missed it every single time.

Even if Nemesis was a brown dwarf and not a proper star, it would still have to field at least 12 times Jupiter's mass and would still be detectable by WISE with ease. We have found and catalogued over 1800 brown dwarfs to date, all of which are significantly farther away than Nemesis would be.

Yes, but it wasn't looking for M8-class red dwarfs that were already cataloged. That will escape notice.

In the same way a bonfire will escape your notice if you are looking for fireflies at night, yes...

What about relative motion making it stationary and thereby unnoticable?

If Nemesis is to be a binary companion star to our Sun, it must move against the backdrop of the Milky Way. Therefore this does not apply.

It's one of the more interesting and less implausible theories to have no particularly good evidence.

To be a theory, it requires at least a small bit of supporting evidence. Currently the only supporting evidence is: Erm, zero. Therefore this is a hypothesis, not a theory.

The hypothesis is based on the fact that nobody can explain the strange periodic nature of extinction events, which caused a team of scientists more than 30 years ago to propose that one possible explanation could be that such a body existed. At that point in time, our knowledge about our solar system and the nature of planetary systems as a whole, as well as the available data to work with, was just a tiny fraction of what we have today.

Even the purely hypothetical link to mass extinctions has already been disproven since then:

"In 2010, Melott & Bambach re-examined the fossil data, including the now-improved dating, and using a second independent database in addition to that Raup & Sepkoski had used. They found evidence for a signal showing an excess extinction rate with a 27-million-year periodicity, now going back 500 million years, and at a much higher statistical significance than in the older work. They also determined that this periodicity is inconsistent with the Nemesis hypothesis." - quoting Wikipedia, referencing this source.

Also, because the existence of such a body has already been systematically disproven by astronomers with very high confidence, this is not "one of the less implausible" hypotheses, but rather one of the most implausible ones. It would require extraordinary circumstances, ones approaching physics-defying by our current understanding of physics, to have a realistic chance to turn out correct.

It's easy to miss what is right in front of you sometimes.

Not with computer-aided flagging of anything out of the ordinary, in combination with the data being publicly available for perusal by anyone in the world with an internet connection.

To sum up: right now there is overwhelming evidence publicly available that says "there is no such thing as Nemesis", as per the definition given by the OP in this thread. Evidence to the point where the hypothesis can be pretty much discarded off hand until someone brings up a convincing argument that cannot be instantly dismantled with basic knowledge of astronomy. The Nemesis hypothesis should be considered an amusing anecdote from a time gone by, not as a serious scientific contender today.

Edited by Streetwind
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To be a theory, it requires at least a small bit of supporting evidence. Currently the only supporting evidence is: Erm, zero. Therefore this is a hypothesis, not a theory.

The hypothesis is based on the fact that nobody can explain the strange periodic nature of extinction events, which caused a team of scientists more than 30 years ago to propose that one possible explanation could be that such a body existed. At that point in time, our knowledge about our solar system and the nature of planetary systems as a whole, as well as the available data to work with, was just a tiny fraction of what we have today.

Even the purely hypothetical link to mass extinctions has already been disproven since then:

"In 2010, Melott & Bambach re-examined the fossil data, including the now-improved dating, and using a second independent database in addition to that Raup & Sepkoski had used. They found evidence for a signal showing an excess extinction rate with a 27-million-year periodicity, now going back 500 million years, and at a much higher statistical significance than in the older work. They also determined that this periodicity is inconsistent with the Nemesis hypothesis." - quoting Wikipedia, referencing this source.

Also, because the existence of such a body has already been systematically disproven by astronomers with very high confidence, this is not "one of the less implausible" hypotheses, but rather one of the most implausible ones. It would require extraordinary circumstances, ones approaching physics-defying by our current understanding of physics, to have a realistic chance to turn out correct.

To be sure, when I said "less implausible theory" I meant less implausible than, say, Nibiru, and 'theory' in the sense that ideas like that are typically called "theories."

Maybe in my desire to be polite I wasn't clear enough about that. I don't think it's any more likely than Atlantis.

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Most of those double/triple stars of course belong to galactic arms or bulge, I presume.

Just because most of stars do.

While the Sun stands between arms, far from bulge,

So, those "most stars" rub one against another much more often than Sun does.

Of course, they interact much more intensively.

While the Sun is so lonely, so forgotten... Far from the madding crowd.

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Ok, astronomers have discovered that at least two thirds of the stars in the milky way are binary, meaning the stars,come in pairs. Some astronomers theorise that Sol, our sun, is no different.

25% of all animal species are beetles. Therefore there is a good chance that one of your neighbours is actually a beetle.

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To be sure, when I said "less implausible theory" I meant less implausible than, say, Nibiru, and 'theory' in the sense that ideas like that are typically called "theories."

Maybe in my desire to be polite I wasn't clear enough about that. I don't think it's any more likely than Atlantis.

Nibiru?

*googles that*

...umm. Wow :D You are correct, that is worse than the Nemesis hypothesis.

25% of all animal species are beetles. Therefore there is a good chance that one of your neighbours is actually a beetle.

...this explains so much! :0.0:

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Come on, guys. Are some of you actually still talking about this as if it had any chance of being real? Despite the fact that conclusive counterevidence has been presented years ago, as pointed out by several different people in this thread? Even if you don't know a thing about mass extinctions, how gravitational perturbation works, or what the WISE survey is, it doesn't take more than the most cursory of Google searches to learn all about them. Again guys, come on. This is the science labs subforum. At least try to consider hard science in your argumentation.

It's going to keep happening.

https://en.wikipedia.org/wiki/Mars_hoax

"The hoax, which has since resurfaced every year from 2005 through 2015..."

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Nibiru?

*googles that*

...umm. Wow :D You are correct, that is worse than the Nemesis hypothesis.

Yeah. Nemesis is "plausible" in the sense that it doesn't resort to mystical mumbo jumbo (mostly). It's still a fringe "theory" (again, using this in the colloquial sense to avoid a ruder terminology for what I think of that).

Much like a counter-earth, it's one of those things that from a certain perspective is fascinating as a concept of something that might have at one time been not entirely unreasonable to speculate on. I would never take that seriously, though.

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This thing does not exist at ALL. Most believe that "Nemesis" causes extinctions every 26,000 years. Name me 3 extinctions that happened between now and 78,000 years ago. No? Bam, proven non-existence.
You mean 26 MILLION years... It has a 26 million year orbital period.

There's evidence for 3 major extinctions between now and 35 million years ago. Only 1 was probably not caused by bolide impacts, and that was the Holocene, and it's still ongoing.

https://en.wikipedia.org/wiki/Holocene_extinction

https://en.wikipedia.org/wiki/Middle_Miocene_disruption

https://en.wikipedia.org/wiki/Eocene%E2%80%93Oligocene_extinction_event

Edited by _Augustus_
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Two points:

First, I still maintain, as a person who actually regularly uses the data, that it'd be pretty easy for WISE to have missed a red dwarf relatively nearby. You have to be looking for that kind of thing to see it. Yes, it'd be like missing a bonfire right next to you with binoculars - which is pretty easy, if you happen not to look toward the bonfore.

Second, I don't think this makes Nemesis any more likely. The arguments against its existence are far too good, and the arguments for its existence are redolent of too much Velikovsky.

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Two points:

First, I still maintain, as a person who actually regularly uses the data, that it'd be pretty easy for WISE to have missed a red dwarf relatively nearby. You have to be looking for that kind of thing to see it. Yes, it'd be like missing a bonfire right next to you with binoculars - which is pretty easy, if you happen not to look toward the bonfore.

Second, I don't think this makes Nemesis any more likely. The arguments against its existence are far too good, and the arguments for its existence are redolent of too much Velikovsky.

Yeah, but it could explain the Sednoids, and solve a lot of solar system formation theory problems.
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First, I still maintain, as a person who actually regularly uses the data, that it'd be pretty easy for WISE to have missed a red dwarf relatively nearby. You have to be looking for that kind of thing to see it. Yes, it'd be like missing a bonfire right next to you with binoculars - which is pretty easy, if you happen not to look toward the bonfore.
Well, yes. But throw in IRAF, 2MASS, and Akari...
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Hey, I agree with you there. I think it highly unlikely based purely on telescopic evidence that Nemesis exists. Dynamical arguments pretty much rule it out entirely, to my mind.

I mean, yes, it could exist, but personally I think that's less likely than the explanation that intelligent aliens in space-ships are behind the braiding of Saturn's rings. (And just to be clear, no, I don't believe that.)

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