Michael C. Emmert (guest) 10 Sep 2009 01:09
A little naming problem here…
I had a problem with the Nemesis hypothesis, namely that any such object could not have lasted the age of the Solar system without getting ripped away by the passing stars you mentioned. That's a serious objection.
My interest in this was rekindled when infrared images of other stars were published. They have Oort clouds and Kuiper belts also. Because we are far outside of those systems, we can easily see them, in contrast to our own Kuiper belt & Oort cloud, which are spread out all over the sky. According to current theory, Kuiper belts should be flat, like a pancake. However, many of them (about 1/2) are thick toruses, like a bagel. It occurred to me that the "Nemesis" mechanism would work much better if the object perturbed the closer Kuiper belt, rather than the Oort cloud. The Kuiper belt is much denser than the Oort cloud.
This doesn't answer the question of "Nemesis" getting ripped away by a passing star. So I started a debate on a popular space website to see if anybody had anything to say about that. Indeed they did.
Richard Muller had done an analysis of spherules ejected from lunar craters. When an object hits the Moon, molten droplets are splashed out of them. The liquid state releases argon-40 which had been trapped in the droplet material; this argon-40 is the decay product of potassium-40, which has a half-life of 1.2 billion years. When the droplet freezes, potassium-40 decay products are again trapped within the material. What all this means is that the spherule can now be dated with the potassium/argon technique.
The result showed that there were three periods of bombardment of the Moon. One occured 3.5 billion years ago. Most scientists (and me, too) think this was caused by a chaotic disturbance of Jupiter and Saturn, which shook asteroids loose from the main asteroid belt. Another weak peak showed up at 1.2 billion years ago then died away.
The third peak was interesting. It started about 500 million years ago and apparently is still going on today. That could be interpreted as "Nemesis" getting ripped away by one of those passing stars from an orbit which was originally much closer and more circular into a highly eccentric orbit with the required 26 million year period.
That was interesting enough to put it on GravitySimulator to see what happened. There exist images on the internet which plot the orbits of all known Kuiper belt objects. I created a flat, artificial Kuiper belt, a disc like theory says it's supposed to be, then created various objects orbiting the Sun. An object with 16 Jupiter masses will disturb such a belt quite like what we see in the real Kuiper belt today within about 20 orbits (520 million years). I tried one Jupiter mass after I was informed that J.D. Hill at Los Alamos had simulated a Jupiter passing through the inner solar system without wrecking it. I was surprised to get a null result, just a couple of comets came out. At three Jupiter masses I started to see some effect, but it was kind of anemic. Any "Nemesis" object would have to be between about 5 and 25 Jupiter masses, I think. What happens here is that the object's Hill sphere (different Hill, btw) needs to be big enough to engulf lots of objects. Those objects on the opposite side of the Solar system are not much affected.
A peculiarity in the Kuiper belt has been noted; most objects found are in the invariant plane, but it's not at all unusual to find objects with highly inclined orbits. This has been likened to heating up half a cup of coffee without heating up the other half. That's exactly what I saw on the 16 Jmass simulation, the one that "looked" most similar to the real Kuiper belt.
As with any long integration, these results should be viewed as illustrative rather than an exact depiction. I have changed my mind about "Nemesis" from "Nah, there ain't no such of a thing" to "this is an interesting hypothesis which is worth futher pursuit".
A couple of disclaimers here; first of all, if "Nemesis" exists it's not due back for millions of years. Congress doesn't fund projects that will take millions of years. Secondly, I don't believe all mass extincions are due to cometary impacts. The deadly Permian-Triassic extinction was probably caused by the release of magma with a reducing chemistry which sucked the oxygen out of the air. The Megafaunal Extinction (of most interest to contemporary man because it took out the PaleoIndians) seems to have been caused by a change in ocean circulation patterns. Junk your clunker and get a Prius or Volt or moped or something.
Lastly…
…I wrote a song about the subject of this site. It was called, "Captain Button". Captain Button broke off from his formation of A-10 Warthog airplanes and disappeared at about the same time as the Heaven's Gate cult incident. Hoping he had ejected I tried to make it humorous, sort of Captain Button meets Heaven's Gate. It had the hardest lick I ever played on a guitar when Captain Button downs the drink the guru offered him and I managed to pull it off (Matt the Electrician was watchng, didn't want to be embarrassed), wasn't blazingly fast but I had to strike harmonics and bend strings all over the neck, it sounded pretty bizzarre (and I needed to make faces, too). I never mentioned Heaven's Gate, these cults come and go, but Captain Button was a public figure and they were looking for him. Alas, they found Captain Button's remains and I had to stop doing the song.
It wasn't funny any more.
