I have a question on planetary system formations.

[captdude]

A lot of the readings I have done on solar system formation discuss the migration of gas giants within the systems. My question is - if Jupiter moved from its present position to within the orbits of Venus and Mars or if it migrated outward in the opposite direction (or even inward and then back out again), what would the effect be upon our own solar system?
I ask this question because I would think the effect would be profound. Therefore, if (If I am wrong in my assumption the point is moot) it is common for large planets within alien systems to migrate inward or outward from their parent stars, and if this migration rearranges the planetary order within the system, wouldn't this mean we should see a wide variety of alien solar system make ups?

 

[yevaud]

Hi.

Well, yes and no. The migration of hot Gas Giants outwards (and also smaller, rocky bodies inward) is usually early on in the evolution of a solar system. T-Tauri stage through the first 500 million years, using some very rough times from our own solar system as an example.

It also depends on perturbations. No system of planets is totally stable, and any solar system can, over longer periods of time, eject a body clean out and away (though some configurations of planets in orbit around their primary(s) are less stable than others). So once we begin to actually image all bodies down to Mars size, there will be many surprises.

That help?

 

[captdude]

I looked online and found some information concerning my question. I liked the reference to the billiard ball effect.

http://www.msnbc.msn.com/id/39895369/ns/technology_and_science-space

After planets form a protoplanetary disk, researchers had thought only giant planets spiraled inward. Instead, where current models predict no small planets, the researchers found a surplus.

"I don't know for sure what's missing from the models, but I have a few guesses," Howard told Space.com. "One guess is that the disks of gas that planets are thought to migrate within during the birth of solar systems are more complicated than the models allow for. Another guess is that many small planets in a solar system may undergo a phase of scattering off of each other after the gas clears, a sort-of planetary billiard balls."

Based on these statistics, the researchers suggest NASA's Kepler mission to survey 156,000 faint stars for planets will detect 120 to 260 "plausibly terrestrial worlds" orbiting near some 10,000 nearby G and K dwarf stars.

"This is a first estimate, and the real number could be 1-in-8 instead of 1-in-4," Howard said. "But it's not 1-in-100, which is glorious news."

 

[yevaud]

Well, if you take into account the Terminal Bombardment Phase - neatly demonstrated by all of those nifty craters all over the Moon - then it's fairly apparent that early on, numerous smaller, rocky bodies were migrating inwards.

 

[captdude]

A very good point.

 

[MeteorWayne]

I would have to honestly say the answer as of now is we don't know. We are still gathering statistics on exoplanetary systems; and still struggling to understand our own. After all, it's been barely more than a decade since we discovered the first exoplanet. There's a half dozen hypotheses about how our own system developed.

There's a lot more data, assimilation, and analysis to be performed before we have a firm idea of how planetary systems work.

Wayne

 

[yevaud]

Covering some thinking on the migration of planets:

http://www.physics.sfsu.edu/~gmarcy/pla ... ation.html

http://www.astro.umd.edu/~hannah/researchint.html

 

[MeteorWayne]

Thanx for the links...
A lot of data and analysis still to be assimilated; I'd bet 5 years from now, we will have a much different undertanding of the process.

 

[neilsox]

I agree there are lots of possibilities, some of which change what we have considered fundamentals. In a dusty disk, small pieces get slowed more than large pieces, so inward migration will be slight for large pieces compared to small. The idea that large pieces clear their orbit, may be trivial as a sling shot maneuver is more likely than capture. The outward migration is not likely until the dust is at least partially cleared, as the strong solar wind is mostly absorbed by the dust within about 10 million kilometers of the star. The sling shot maneuvers tend to produce highly elliptical orbits, so it is hard to understand why large pieces are mostly in near round orbits. Neil

 

[captdude]

I absolutely agree with your statement MW. With a complete sample of one with which to extrapolate, (although we are receiving the data from other partial samples at this point) the golden-age of exo-planetary science has just begun.

However, having said that; I am still wondering what the effect would be if jupiter moved across the orbits of the inner planets in either direction. Would it rearrange the system EVERY time? Is there a scenario where NO planets would be disturbed.? Or would it be something in between? (I have read nothing, and dont have enough information to make an informed guess although I would lean towards the former instead of the latter)

 

[3488]

Thing is Neil, is that as Wayne & Yevaud both explained earlier we have only a detailed pattern of one solar system, ours.

We are finding others for sure, though after the Gliese 581g farce, we now cannot think that all detections to date are that confident (Vogt did no favours by shooting off like that & as a result all of the other planets around Gliese 581 must now be treated with suspicion & similar elsewhere detected by the same method) , though the few we have imaged directly, transits & have heat signatures (hot Jupiters) we do know physically exist for sure.

Kepler over the next two years & possibly longer (I hope much longer). will give us a giant grab bag of many solar systems (inner solar systems anyway) around many stellar types & stars of varying ages, from newborns to ageing red giants.

Improved IR observations, increased visual spatial resolutions from telescopes due to be built, further Hubble Space Telescope obs & radial observations from stable platforms in space or on the Moon in time (as opposed to a geologically active planet, with a dense atmosphere like Earth), will uncover huge numbers.

For instance the star Zeta Leporis, part of the constellation of Lepus, appears to have the mother of all asteroid belts. The star is virtually a twin of Sirius, an A type with approx 25 solar luminosity & is thought to be part of the Castor group, which includes Fomalhaut & Vega, stars that share a general common proper motion through space & are of the same age.

Fomaulhaut has been seen to have an extra solar planet visualy, up to three Jupiter masses in the protoplanetary disk.

These will all start forming a picture of the planetary formation process in general & also around particular types of stars.

We are still not sure of how Jupiter & Saturn formed. Did they form around super Earths or did they form from condensation points or do we have one of each??????

There is some evidence that Jupiter has migrated inwards from the Galileo atmospheric probe data, with the abundance of noble gases, although I suppose these could have been imported from comets.

Andrew Brown.

 

[3488]

Hi captdude,

It would most likely scatter them. Either putting let's say Mercury into the Sun, & the others in highly elliptical orbits or even lets say ejecting Earth from the solar system entirely (I suspect there are more rogue planets, asteroids & comets in the Milky Way alone than there are stars in the local group of galaxies combined).

It is dependent on Jupiter's trajectory, but having a 318 Earth massed planet crossing the orbits of Mercury, Venus, Earth & Mars would have a drastic effect in one way or another.

There is no evidence to really suggest that Jupiter has been closer to the Sun than now, or ever will do, if anything the opposite. As the SUn loses mass, the planetary orbits are likely to expand proportionally, so Jupiter is anything is likey to recede once again, unless out Solar System has a close encounter with another star in the future (unlikely but not impossible).

Andrew Brown.