Many famous comets originally formed in other solar systems

Jun 10, 2010
Comet

Many of the most well known comets, including Halley, Hale-Bopp and, most recently, McNaught, may have been born in orbit around other stars, according to a new theory by an international team of astronomers led by a scientist from the Southwest Research Institute (SwRI) in Boulder, Colo.

Dr. Hal Levison (SwRI), Dr. Martin Duncan (Queen's University, Kingston, Canada), Dr. Ramon Brasser (Observatoire de la Côte d'Azur, France) and Dr. David Kaufmann (SwRI) used computer simulations to show that the may have captured small icy bodies from its sibling stars while it was in its birth star cluster, thereby creating a reservoir for observed comets.

While the Sun currently has no companion stars, it is believed to have formed in a cluster containing hundreds of closely packed stars that were embedded in a dense cloud of gas. During this time, each star formed a large number of small icy bodies (comets) in a disk from which planets formed. Most of these comets were gravitationally slung out of these prenatal planetary systems by the newly forming giant planets, becoming tiny, free-floating members of the cluster.

The Sun's cluster came to a violent end, however, when its gas was blown out by the hottest young stars. These new models show that the Sun then gravitationally captured a large cloud of comets as the cluster dispersed.

"When it was young, the Sun shared a lot of spit with its siblings, and we can see that stuff today," says lead author Levison.

"The process of capture is surprisingly efficient and leads to the exciting possibility that the cloud contains a potpourri that samples material from a large number of stellar siblings of the Sun," says co-author Duncan.

Evidence for the team's scenario comes from the roughly spherical cloud of comets, known as the Oort cloud, that surrounds the Sun, extending halfway to the nearest star. It has been commonly assumed this cloud formed from the Sun's proto-planetary disk. However, because detailed models show that comets from the produce a much more anemic cloud than observed, another source is required.

Levison says, "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 percent of the observed Oort cloud comets have an extra-solar origin."

"The formation of the Oort cloud has been a mystery for over 60 years and our work likely solves this long-standing problem," says Brasser.

Explore further: Spectacular supernova's mysteries revealed

More information: The article, "Capture of the Sun's Oort Cloud from Stars in its Birth Cluster," by Levison, Duncan, Brasser and Kaufmann, was published in the June 10 issue of Science Express.

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omatumr
1.8 / 5 (5) Jun 10, 2010
Comets were formed and sent on their highly elliptical orbits by the supernova explosion that gave birth to the solar system five billion years (5 Gyr) ago ["Isotopes of tellurium, xenon and krypton in the Allende meteorite retain record of nucleosynthesis", Nature 277 (1979) 615-620].

With kind regards,
Oliver K. Manuel
jsa09
5 / 5 (5) Jun 11, 2010
Just wondering where in this article it says that particular comets were formed under different stars. I don't dispute the possibility but a possibility is not a fact.
Many famous comets originally formed in other solar systems
I know, it is just a heading but the very important word "may" has been left out.
kevinrtrs
1 / 5 (9) Jun 11, 2010
Sighhhh... since no explanation can be found for the existence of comets and just as importantly why they still exist after 4.5 Ga, it has now become necessary to invent another story. This is just that - another story.
To date, there has been ZERO sighting or detections or confirmation of the existence of any so-called Oort cloud. This is rather surprising seeing that we have such wonderful new technology to do all kinds of scanning of far-away galaxies etc. Hence believing there is an Oort cloud is like having a religion - you give your life to the hope that someone somewhere will one day find it. hopefully before you pass on.
If no replenishment source can be found for comets, we'll be forced to come to the conclusion that the solar system cannot be 4.5 Ga old. An hence we'll need to have a serious re-think.
Of course if we insist that the solar system is 4.5Ga old in spite of all evidence against that idea, we'll have to continue inventing stories.
Skeptic_Heretic
5 / 5 (6) Jun 11, 2010
Sighhhh... since no explanation can be found for the existence of comets and just as importantly why they still exist after 4.5 Ga, it has now become necessary to invent another story.
Why wouldn't they exist?
To date, there has been ZERO sighting or detections or confirmation of the existence of any so-called Oort cloud.
False. The Oort cloud is a well vetted theory and has been observationally and mathematically confirmed. We've never had a direct observation of the Oort cloud, but I've never had a direct observation of you either. I'm fairly sure you still exist.
This is rather surprising seeing that we have such wonderful new technology to do all kinds of scanning of far-away galaxies etc.
Can you see your way around your house in a blackout at midnight with all the windows covered over? Probably not, because nothing within your house is emitting light. Distance isn't the only difficulty to overcome.
gwrede
4.3 / 5 (7) Jun 11, 2010
the Oort cloud, that surrounds the Sun, extending halfway to the nearest star.
Well, that in itself should be sufficient for an ongoing exchange of comets between the Sun and its immediate neighbors. No reason to believe the other stars don't have their Oort clouds too, also extending halfway to the Sun.

And with the Sun travelling in space, it has had the pleasure of exchanging comets with numerous other stars during its billions of years.

Thus, it would be a surprise if more than a small fraction of our Oort cloud comets were from the Sun's early days.
Quantum_Conundrum
1.6 / 5 (5) Jun 11, 2010
Reminds me of the panspermia theory of life:

"Since we can't explain how it formed around our sun, we'll just pass the buck and assume it formed around a different star."

Nevermind the fact that if the model shows it couldn't form here, then it would stand to reason that it wouldn't form around any other star from the same cluster either, seeing as how they should have all been under very similar conditions.
yyz
5 / 5 (2) Jun 11, 2010
A recent widely publicized paper found that the dwarf star Gliese 710 has a 86% chance of plowing into our Oort Cloud in some 1.5 Myr ( http://arxiv.org/abs/1003.2160 ) notes that the triple star Algol (with a total mass of 5.8 Msolar) passed 2.5 parsecs from the sun roughly 7.5 Myr ago. This paper details over 50 stars that have/will pass within 5 parsecs of the solar system over +-10 Myr (including Gliese 710). Given the age of the sun, conditions for the transfer of Oort Cloud bodies will likely be met many times over. I should note the papers I have linked were only looking at the possibility of perturbations of the Oort Cloud over time.
yyz
5 / 5 (2) Jun 11, 2010
Ooops, something got lost in translation. After the first link: A 1999 paper ( "Stellar encounters with the Oort Cloud based on Hipparchos data" http://iopscience...1042.pdf ) notes......
navneetcsgowda
Jun 21, 2010
This comment has been removed by a moderator.
Skeptic_Heretic
not rated yet Jun 21, 2010
IS THERE LIFE ON OTHER SOLAR SYSTEM?

That isn't a question any longer.
The question is, what type of life will we find in other planetary systems?