Most comets may have extra-solar origin

Many famous comets may have formed in other Solar Systems, a new theory proposes.

Most theory's I've come across go with the formation of comets being formed in or around the Solar system, but a new theory has been put forward by an international group of astronomers led by Dr Harold Levison from the Southwest Research Institute in Colorado, US.


"The formation of the Oort cloud has long been a mystery, Up until now, astronomers thought that this spherical cloud of comets lying at the outermost edge of the Solar System might have formed in the Sun's protoplanetary disk - a cloud of gas and matter that gave birth to planets, some 4.6 billion years ago"

The new theory goes with the idea comets came from elsewhere!

"If we assume that the Sun's observed proto-planetary disk can be used to estimate the indigenous population of the Oort cloud, we can conclude that more than 90% of the observed Oort cloud comets have an extra-solar origin,"

Source

I find that difficult to believe. All of the long period comets that have been observed to date (that have had their orbits accurately calculated) have been shown to be gravitationally bound to the Sun. In other words, their orbits are very eccentric ellipses, with eccentricities less than 1.0.

Quite a few have eccentricities very slightly greater than 1.0 when they are passing through the inner solar system, but that is simply because of the transition from barycentric to heliocentric motion. Beyond the orbits of the major planets, comet orbital motion is based on the centre of mass of the Solar System, rather than the centre of mass of the Sun. The giant planets (particularly Jupiter and Saturn) exert an appreciable gravitational influence on the Sun, causing it to "wobble". It is this shift in the Sun's position that makes it appear as though some comets have hyperbolic orbits. However, when they leave the realm of the major planets, their orbits are almost always elliptical.

The only comet that is known to have a truly hyperbolic orbit is C/1980 E1 Bowell, and this is because it had a close encounter with Jupiter in December 1980. The comet passed approximately 34 million kilometres from the planet, and received a gravitational boost sufficient to overcome solar escape velocity. It is now on a one way trip to the stars.

reply to post by Mogget



Hi Mogget, Yes all you say is true, but the point here is the formation of the comets, i.e. where did they come from, the new theory is suggesting the comets weren’t formed in the Sun's protoplanetary disk in the beginning as previously thought, they are suggesting the Sun wasn't born alone but in a cluster, thus the gravitational field may have been strong enough to pull a large cloud of comets originally formed in other solar systems, and hey.. It aint my theory, but it's fascinating all the same...

This comet that got a bost of enough speed to escape the solar system.
Proves it quite possible that alest some comets may very be from other systems and were captured millions of years agaio.
If these comets were collected millions of years agaio they would now be in stable orbits and i believe this is what they think is part of the prosess

There is a simple, widely ignored answer to this, we have 2 stars in our solar system:

www.binaryresearchinstitute.org...

theustuff so just were is it this other Star is hiding humm?
You realize just how uneducated that belief is?
There are 100000 of people scanning the sky's for every possible thing stars comets radio singles Not just NASA .
If there was a Star or even planet the size of Jupiter every one would know it.
A star or planet the size of Jupiter doesn't just send out light so wile you may not see it with a telescope a radio reviver will have NO problem what so ever of seeing it as stars and planets create all kinds of radio, Gama, micro magmatic fields and dozens more YOU DON'T NEED a telescope to see.
So wake up in science class go get the equipment your self and prove this not so star is there.
there is one and only one thing that could be BIG (bigger then a star even)
that may be a part of our system we wouldn't know about.
and that would be a black hole as they dont let any thing escape so we couldnt see it at all. so if you insist on believing we ahve another large body in our system alest believe in one thats possible

Originally posted by xxcalbier
theustuff so just were is it this other Star is hiding humm?
You realize just how uneducated that belief is?

Actually the case the poster is refering to is not the 'nibiru' 'this star is appoaching going to travel thruough the inner solar system'. Instead this is the nemisis there is a brown dwarf somewhere in the outer ort cloud distance that is gravitionally bound to the sun. The theory has been suggested by quite a few prominent researchers and there is some evidence it may be correct.

reply to post by theuhstuf


Hi theuhstuff,

Whilst I’m not against the idea we may be in a binary system, so far there has been no evidence (to my knowledge) that backs that up, even the BRI say in the paper you linked to: “if it exists”

If there is another star belonging to our system it could be thousands of years (if in a very long elliptical orbit) before we even know anything about it, and as they say it could well be a dark binary, or a relatively small black hole. (cue the nibiru/2012 believers) so as of yet (like the institutes’ theory), there is no scientific evidence to support it, yes I agree this could well explain some comets coming from another source other than the solar system as we know it, I think the Southwest Research Institute in this instance are talking about a cluster of stars that spread out over millions of years, the Sun taking some of the comets from other systems through gravitational pull as it moves away, not a binary system. Who’s to say they are wrong or right, at this moment in time this is still just a theory.





[edit on 11-6-2010 by Majestic RNA]