Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: DocN on 28/03/2006 21:54:03
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Could Jupiter be a "failed star" formation perhaps because of a lack in the mass needed for fusion processes? I beleive it is known that many stars are binary--that is, have a partner star and some even have tow--that is, three revolving stars. I have read that some of Jupiter's and Saturn's moons may have life forms or the materials needed for the creation of life. And, what can we make of the rings of Saturn being similar to the galactic rings now being reported, where new star formations are taking place? Or, could these large gas planets be "offsprings" of our sun--that formed at the same time as the sun?
Doc
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I believe what you say is correct, Jupiter was not big enough to get nuclear reactions started. How much biggere would it need to be ... ?
Certainly many stars are binary (and new) research shows that a binary system can have planets!)
I think the materials for life are proably common but it doesn't follow that there is life. Liquid water is the most important thing?
The solar system formed during the same process and the age of the sun and planets is the same.
Saturns rings are debris I believe, if enough material clumped together anywhere it could form a star.... I need to find out about galactic rings now ....
Dr B
Istanbul
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These recent jupiter related thread may be of interest
http://www.thenakedscientists.com/forum/topic.asp?TOPIC_ID=2899
http://www.thenakedscientists.com/forum/topic.asp?TOPIC_ID=3189
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The expression "failed star" is a typical journalistic rubbish statement implying that an inanimate object was trying to achive something. Jupiter is what it is!
During their frormation, stars form multiple systems and or planets and probably both, as a means of getting rid of excess angular momentum, which if concentrated in a single star, would cause it to be rotationally unstable. In fact one of the early (now unpopular) images of the formation of the solar system was the planets flying off the surface of the sun as it contracted because if all the angular momentum in the orbits of the planets was concentrated in the sun it would indeed fly apart.
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God says so!
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I don't know anything about "typical journalistic rubbish" just that perhaps Jupiter along with our sun, might have developed into a binary system. I understand that we still do not even understand how our moon formed. Thanks for the above, interesting websites, neilap.
Doc
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The moon is generally agreed to have formed as a consequence of a collision between the proto-Earth and a Mars sized planetesimal. Some of the material that was thrown into orbit by this collision then coalesced to form the moon. Detailed mathematical models of the process can now duplicate all the orbital characteristics of the Earth Moon system, while the unusual compostion of the moon is also wholly explained by this theory.
You are correct that the sun could have formed a binary system, as most stars are in multiple systems. However, Jupiter is a couple of orders of magnitude away from being large enough to become a star, so the possibility was never very real.
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SoulSurfer is a bit of an expert where angular momentum is concerned, so maybe he can answer this:-
Ever since I 1st saw a diagram of the solar system, I've puzzled over why the inner planets are so much smaller than the outer planets (Pluto excepted).
If, as I have read, the sun & planets formed from a rotating mass of gas, would an aggregation of particles have the same angular momentum as they would had they remained separate? What I mean is, if particles start aggregating at distance d from the centre of rotation, would they stay at that distance, pulling in other particles by gravitational attraction, or would d gradually increase along with the mass of the aggregating particles?
I'm trying to get a picture of whether rings of gas formed due to gravity, which then aggregated as planets by sucking in more particles from the ring(the rings would have been what are now planetary orbits), or whether a clumping process took place whereby particles were pulled in from an area and, as the accumulation continued, some force or other then moved those aggregations into stable orbits.
I think what I'm trying to get at is whether the orbit defined the amount of mass that aggregated, or the amount of mass aggregated defined the orbit. I've just got a little nag at the back of my mind that says angular momentum would have been important in the process.
[xx(]
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I am no expert, but I think some of the reason is that the gas giants are mostly made up of... gas, closer to the sun this will get blown away by the solar wind, leaving the less volatile rocky minerals. I guess most of the stuff that was in the inner solar system got blown into the outer.
Also remember that the circumference of an orbit increases as you go out, so you have more volume to collect stuff from even if the density is lower... I don't know the formulae so couldn't say which way it will go
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quote:
Originally posted by daveshorts
I am no expert, but I think some of the reason is that the gas giants are mostly made up of... gas, closer to the sun this will get blown away by the solar wind, leaving the less volatile rocky minerals. I guess most of the stuff that was in the inner solar system got blown into the outer.
Also remember that the circumference of an orbit increases as you go out, so you have more volume to collect stuff from even if the density is lower... I don't know the formulae so couldn't say which way it will go
The solar wind sounds plausible. However, I remember reading somewhere that the Earth may have formed before the sun. If that's the case, I would imagine it's true of all the inner planets. It would also, I think, have some bearing on whether the expulsion of matter by the solar wind was responsible.
I did wonder about the circumference of the orbit making a difference as to how much material would be available; but I thought further from the centre the gas may thin out sufficiently that it would balance it out.
Then there's the asteroid belt. I've often wondered about that too. It seems strange that such a region should fall between the rocky planets and the gas giants. Why not, for instance, between Jupiter and Saturn? It suggests to me that maybe there's a limit to how far from a star a rocky planet can form. That would possibly add weight to your solar wind suggestion. It also makes me again wonder about angular momentum.
Again, I discount Pluto as I'm sure that's just an Oort object that got lost, and not a genuine "planet". But the existence of the Oort cloud would raise questions about the solar wind being responsible. If only the lighter particles were expelled by the solar wind, how did the Oort cloud form? Does it comprise previously-itinerrant objects that happened to get caught in our sun's gravitational field?
My brain hurts. I need coffee. [xx(]
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The inner planets are small because the temperature in the solar nebula was too high to allow ices to form. This limited the composition of the planets to NiFe and silicates. Further out, beyond the 'snow line' ice formed a significant part of the proto-giants. The increased bulk led to a runaway expansion as their larger gravitational field pulled in more and more material.
A planet would have formed in the region of the Asteroid belt, but for the gravitational disruption of Jupiter.
During these processes there were not necessarily neat rings of matter from which planets condensed. The early solar system was a pretty hairy place with planetesimals up to the size of Mars flying around on quite erratic orbits, colliding, fragmenting, reforming, some being thrown out of the system entirely.
The Earth formed after the sun, though the proto-Earth may well have been in existence before the sun actually ignited and while it was in its T-Tauri stage.
The Oort cloud origin is being currently debated. It now seems likely that most of the objects in it formed further into the solar system, between Jupiter and Neptune, and then got ejected by gravitational interactions. (Personally, I think we shall find that there are multiple origins - in situ, interstellar captures, and inner system, beyond the ice line.)
What did I miss?
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quote:
The inner planets are small because the temperature in the solar nebula was too high to allow ices to form. This limited the composition of the planets to NiFe and silicates. Further out, beyond the 'snow line' ice formed a significant part of the proto-giants. The increased bulk led to a runaway expansion as their larger gravitational field pulled in more and more material.
Ah, so there's an inner limit for the formation of gas planets rather than an outer limit for the formation of rocky planets?
I think you've explained very adequately. I shall put what you've said through my mental mill & see if any further questions raise their ugly heads.
Thank you.
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quote:
Originally posted by DoctorBeaver
Ah, so there's an inner limit for the formation of gas planets rather than an outer limit for the formation of rocky planets?
Exactly so. However, it is worth noting that many of the over one hundred and fifty exoplanets (planets orbiting other stars) that have been discovered so far are what are known as Hot Jupiters. These are gas giants orbiting very close to their parent star - I think in some instances closer than Mercury is to our sun.
But these did not form there. They formed beyond the 'snow line' just like our gas giants, then migrated inwards. The theoreticians have a pretty good grasp on the general mechanisms involved in such migration (gravitational interaction with dust/gas disc, friction with the disc, and interference with other giants).
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If they're that close they must be orbiting damned fast! And that would certainly raise other questions - such as the interaction between the planet & the solar wind. At that distance and the speed they must be travelling at, I would imagine there's some very strong electromagnetic waves being generated. Or what about drag on the planet?
This is getting harder & harder for my poor little brain [:(]
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Some of those exoplanets are twelve times as big as Jupiter but still are not big enough to start fusing atoms.
One such star broke orbit after it's star died and is wandering free, and is considered to be the oldest known planet.
I was looking for it and got this http://www.extrasolar.net/planettour.asp?PlanetID=19
Only 3.87 times Jupiter.
On the other side of things, brown dwarfs with their Iron clouds and Iron rain, when will they cool down and become planets, if ever?
http://www.eso.org/outreach/press-rel/pr-2005/pr-12-05.html Newer stuff here. Five times Jupiter.
And here 11 times Jupiter's mass http://en.wikipedia.org/wiki/Exoplanet
Does fission or fusion heat the Earth's interior? It must happen in Jupiter too. I read that one of gas giants or all of them emits more heat than it absorbs from the sun times 4.
Titanscape
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The excess heat from Jupiter (it radiates twice what it receives, as does Saturn) is due to one or more of the following:
1. Residual heat of planetary formation.
2. Gravitational contraction.
3. Helium condensation at the solid hydrogen core.
4. Fission from lithophile radioactives in the inner core (which is around ten Earth masses, probably)
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