Solar system creation questions

porkchopsnapplesauce · Jan 28, 2009

Hi All,I am having some trouble wrapping my head around some items dealing with solar system creation.  I would guess the main issues I am having has to do with my lack of a scientific background and trouble grasping the sizes/distances involved.  However, if anyone could recommend some good books or articles I would appreciate it.  I have been through wiki but it hasn’t been much of a helpA few of the things I am having problems with at the moment are1) The distribution of heavy elements in our solar system.  I was under the impression that these would have to be created in a star which indicates that perhaps our solar system was the result of a past Super Nova.  I am having some trouble following how that process would work and why they would not be more distributed across our solar system2) The inner planets are something else that is causing me problems.  My understanding is that the current theory states that the Sun is the result of a Gas/dust cloud collapsing upon itself.  What I don’t understand is why the particles that created the inner planets did not collapse into the Sun as well.  Were they evenly distributed across the original gas cloud at some point, or did the rocky materials migrate within the solar system at certain points within the solar systems life?My understanding of solar system creation really just comes from wiki, so any help would be appreciated

origin · Jan 29, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'>1) The distribution of heavy elements in our solar system.  I was under the impression that these would have to be created in a star which indicates that perhaps our solar system was the result of a past Super Nova.  I am having some trouble following how that process would work and why they would not be more distributed across our solar system</DIV>The general theory is: Our star and solar system are the result of a collapse of a molecular cloud that contained heavy elements that were from nearby supernovas.  It is beleived that these heavy elements are relatively evenly distributed across the solar system.Replying to: <DIV CLASS='Discussion_PostQuote'>2) The inner planets are something else that is causing me problems.  My understanding is that the current theory states that the Sun is the result of a Gas/dust cloud collapsing upon itself.  What I don’t understand is why the particles that created the inner planets did not collapse into the Sun as well.  Were they evenly distributed across the original gas cloud at some point, or did the rocky materials migrate within the solar system at certain points within the solar systems life?My understanding of solar system creation really just comes from wiki, so any help would be appreciated Posted by porkchopsnapplesauce</DIV>The sun most likely directly reflects the makeup of the gas cloud that collapsed, which indicates that the major constituents of the cloud were hydrogen and helium.  These elemental ratios can also be seen in the gas giants, jupiter and saturn.  Now why are the inner planets rocky?  Because the lighter elements were 'blown away' by the newly formed sun.  This is a very brief and general description.  The best thing to do is to go to the library and take out an astronomy text book (first year introduction to astronomy).  All of these books will discuss the current theory on the formation of the solar system - in one chapter most likely.  Good luck.edited to fix formating <div class="Discussion_UserSignature"> </div>

Saiph · Jan 29, 2009

I think you're caught up on the difference between the rocky planets, and the gas giants.  IF  the four inner planets had been able to hold hydrogen and helium, the distribution of elements would be basically the same across all the planets and solar system. Now, to discuss why the two sets of planets differ, according to some leading theories at any rate:1)  Due to their proximity to the sun, the inner planets did not form as large as the outer planets.  Because of this they can't hold onto the very light (and the most abundant) elements of hydrogen and helium.  Throw in the increased influence of both the sun's light (a.k.a. heat) and the solar wind at their positions, and what they do keep has a tendency to be boiled and/or stripped off.  All of this leads to the inner planets only keeping the rocky core.  The gas giants also have these elements, but they are burried deep underneath the hydrogen and helium atmosphere, and smeared across a larger volume of space do the interior conditions of a gas giant. 2)   The sun is something like 98% of the solar systems mass, by itself.  Jupiter is almost all of the rest of it.  Basically everything did fall into the sun! Many of the particles that were in the region of the inner planets did fall into the sun...just not all of them.  Same for the outer planets too.  What you're looking at are the lucky leftovers that were in stable orbits, and weren't jostled out it during the planetary formation. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

origin · Jan 29, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'> 2)   The sun is something like 98% of the solar systems mass, by itself.  Jupiter is almost all of the rest of it.  Basically everything did fall into the sun! Many of the particles that were in the region of the inner planets did fall into the sun...just not all of them.  Same for the outer planets too.  What you're looking at are the lucky leftovers that were in stable orbits, and weren't jostled out it during the planetary formation. Posted by Saiph</DIV> Well put.  This is a very simply put explanation that puts the whole 'enchilada' into perspective. <div class="Discussion_UserSignature"> </div>

michaelmozina · Jan 29, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'> 2)   The sun is something like 98% of the solar systems mass, by itself.  Jupiter is almost all of the rest of it.  Basically everything did fall into the sun! Many of the particles that were in the region of the inner planets did fall into the sun...just not all of them.  Same for the outer planets too.  What you're looking at are the lucky leftovers that were in stable orbits, and weren't jostled out it during the planetary formation. Posted by Saiph</DIV>That was a really excellent presentation of current solar system formation theory by the way.  The only thing I can add is that there does seem to be evidence of a supernova explosion in our neck of the woods. http://www.spaceref.com/news/viewpr.html?pid=17308It should also be noted that even if only a tiny percentage of the sun is composed of heavy elements, the fact it contains most of the mass of the solar system also means that it does contain significant quantifies (compared to Earth) of heavy elements too. It simply has significantly more of the lighter elements as well. <div class="Discussion_UserSignature"> It seems to be a natural consequence of our points of view to assume that the whole of space is filled with electrons and flying electric ions of all kinds. - Kristian Birkeland </div>

porkchopsnapplesauce · Jan 29, 2009

ThanksI didn't realize that the outer planets had rocky cores as well.  When I was watching "The Universe" the other day I thought they said that Jupiter was made up completely of gas.  Still would be interested in recommendations for a good book on the planets and the solar system creation thoughThanks

UFmbutler · Jan 29, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'> ThanksI didn't realize that the outer planets had rocky cores as well.  When I was watching "The Universe" the other day I thought they said that Jupiter was made up completely of gas.  Still would be interested in recommendations for a good book on the planets and the solar system creation thoughThanks   Posted by porkchopsnapplesauce</DIV>Well, technically we don't have definitive evidence of a rocky core inside Jupiter.  It makes sense that there would be one, but it hasn't been confirmed yet.  It is generally believed that there has to be one though since it would be difficult physically for an entirely gas giant planet to form.  The other outer planets though, without a doubt, have rocky  cores. <div class="Discussion_UserSignature"> </div>

BoJangles · Jan 29, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'>That was a really excellent presentation of current solar system formation theory by the way.  The only thing I can add is that there does seem to be evidence of a supernova explosion in our neck of the woods. http://www.spaceref.com/news/viewpr.html?pid=17308It should also be noted that even if only a tiny percentage of the sun is composed of heavy elements, the fact it contains most of the mass of the solar system also means that it does contain significant quantifies (compared to Earth) of heavy elements too. It simply has significantly more of the lighter elements as well. Posted by michaelmozina</DIV> I couldn't get the link to work, though it may just be me atm.---An open question, what is the ratio of metals to H and He in a supernova, and is it the case there must have been a lot of hydrogen and helium around 4 billion years ago, being the sun is composed primary of these components.What's left to fuse after a supernova ? nothing really ( im assuming )  <div class="Discussion_UserSignature"> -------------- Let me start out with the standard disclaimer ... I am an idiot, I know almost nothing, I haven’t taken calculus, I don’t work for NASA, and I am one-quarter Bulgarian sheep dog. With that out of the way, I have several stupid questions... *** A few months blogging can save a few hours in research *** </div>

Saiph · Jan 30, 2009

Jupiter doesn't have, and doesn't really require a true 'rocky' core.  Due to the pressures, internal temperatures, and turbulance in the core regions, it's quite likely that it has a higher concentration of the heavy elements, but that they aren't truly solid, or even a liquid.  For instance the core is believed to be (or to be surrounded by) a liquid metallic hydrogen, where the pressure is so intense, that hydrogen is acting like a liquid, and the electrons are free to roam about.  A very unusual state for hydrogen. Just so people have a ballpark idea of the sun's composition:  It's 90% Hydrogen, 10% Helium by number, and ~75% H and 25% He by mass...yes, both of those add up to 100%.  The slight difference between 100% and what H and He really add up to (a very small number, something like .01% or smaller) are what astronomers call 'metals'.  I.e. EVERYTHING ELSE on the periodic table.  Supernovae concentrations are...a little odd. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

UFmbutler · Jan 30, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'>Jupiter doesn't have, and doesn't really require a true 'rocky' core.  Due to the pressures, internal temperatures, and turbulance in the core regions, it's quite likely that it has a higher concentration of the heavy elements, but that they aren't truly solid, or even a liquid.  For instance the core is believed to be (or to be surrounded by) a liquid metallic hydrogen, where the pressure is so intense, that hydrogen is acting like a liquid, and the electrons are free to roam about.  A very unusual state for hydrogen. Posted by Saiph</DIV>I wouldn't say definitively that it doesn't.  It is generally believed that planets with masses less than ~5 jupiter masses should be able to have silicate cores.  The latest simulations suggest this (http://arxiv.org/abs/0808.2787)  (note:  I'm not sure how reputable Icarus is as a journal but I've seen other simulations that suggest the same thing).  You could be correct, but I think it's too early to say for sure one way or the other. <div class="Discussion_UserSignature"> </div>

3488 · Jan 30, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'>I wouldn't say definitively that it doesn't.  It is gene...................... Posted by UFmbutler</DIV>The upcoming JUNO mission should help resolve this issue one way or the other. Is Jupiter a giant planet or indeed a failed star? Did Jupiter form as a large terrestrial planet, but captured an enormous amount of hydrogen within a giant annulus, within the protoplanetary disk, or did Jupiter start forming as a second sun, but was cut short at 328 Earth masses? Very fundemental questions. Andrew Brown.  <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

UFmbutler · Jan 30, 2009

Elaborating on my earlier post...the fundamental question is whether Jupiter formed via the core accretion mechanism, which assumes an initial silicate core which reaches a point where it begins capturing the surrounding gas, or gravitational instability, in which gas just collapses because of the Jeans condition, as a star would.  The problem is, neither mechanism works by itself to explain our solar system, or any other known ones for that matter.  If core accretion were dominant, models predict that we should see more Neptune mass planets, whereas GI predicts more massive gas giants, like we see in many exoplanetary systems.  It is quite confusing because both "camps" strongly believe their mechanism is correct, but at the same time don't disagree with the alternative.  In other words, both can work and both most assuredly do occur to some extent, but nobody really knows the details right now.  Even if we were to find a silicate core in Jupiter, it wouldn't answer this question entirely.  Images of forming planetary systems such as Fomalhaut should help answer some questions, but we'd need more than the one(kind of 2) systems we have to look at before we can begin to gather some meaningful statistics.Even though I generally don't like planets and tend to focus on dust and star formation regions, this area of research was always quite interesting.  It illustrates a good combination of pure empirical science(i.e. looking at meteorites and seeing what they are made of) and pure theory(MHD simulations) working on a problem where we really don't understand very well at all. <div class="Discussion_UserSignature"> </div>

MeteorWayne · Jan 30, 2009

It's really amazing that 20 years ago we had no confirmed extrasolar planets and now there are 336.http://exoplanet.eu/catalog.php <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

porkchopsnapplesauce · Feb 2, 2009

Are there any predictions or calculations on how long it would have taken for the gas cloud that created our sun to collapse?

UFmbutler · Feb 2, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'> Are there any predictions or calculations on how long it would have taken for the gas cloud that created our sun to collapse?    Posted by porkchopsnapplesauce</DIV>It depends on where you stop.  Initially, when the cloud meets the Jeans criterion where gravity overcomes the outward pressure of the gas, the timescale of interest is the "free fall time".  http://en.wikipedia.org/wiki/Free-fall_time It is typically on the order of ~a million years.  It is only an approximation though, since the velocities of the gas are random and not all directed toward the center, and the density is not globally constant like the equation assumes.  It is still a good estimate though.  However, at the end of this time we don't have a star yet.  The freefall collapse is halted when the central temperature is around 30,000K.  Now we have what is known as a pre-main sequence star.  Even though it can't fuse hydrogen yet, it still radiates as the center is squeezed by gravity.  As it radiates gravitationally produced energy away, it causes the core to contract further.  At some point it becomes an optically visible object and follows what is known as the Hayashi track, until it lands on the main sequence.  This process is governed by what is known as the Kelvin-Helmholtz timescale.  For the sun it is equal to 3x10^7 yrs, an order of magnitude higher than the freefall time.  So the overall answer to your question is it took about 31 million years for the sun to collapse from the solar nebula into a hydrogen fusing main sequence star.    <div class="Discussion_UserSignature"> </div>

porkchopsnapplesauce · Feb 3, 2009

Thanks for the response UFmbutler

MeteorWayne · Feb 14, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'> Thanks for the response UFmbutler Posted by porkchopsnapplesauce</DIV> New Model of Jupiter's StructureFrom Emily Lakdawalla:http://www.planetary.org/blog/article/00001841/ This story has been lying in my inbox since Thanksgiving, but that doesn't make it any less interesting. The results of a new computer model developed by Burkhard Militzer and four coauthors suggest that deep inside the solar system's largest planet sits an inner rock-and-metal core the mass of 14 to 18 Earths, surrounded by an envelope of ices of methane, ammonia, and water, surrounded by an atmosphere of mostly hydrogen and helium containing few ices. Essentially, the model says that Jupiter = Neptune with a whole lot of hydrogen and helium around it. This makes intuitive sense -- you'd expect that, out in the outer solar system when things started forming, anything that was the mass of Jupiter would have had to pass through some stage where it had only as much mass as Neptune or Uranus, so it would have had some moment in its formation history when it looked a lot like Neptune or Uranus (compositionally anyway; when all this stuff was happening, the planets were probably a lot hotter, so they may have looked quite different). The reason this is news is that we have no good way to "see" what's going on deep inside Jupiter, so the only way to learn anything about what it looks like there is to do these sort of computer models; and past computer models have suggested that Jupiter had a core that was much smaller, smaller than seven Earths, and maybe that it had no core at all. Which makes little intuitive sense, but what can you do if that's what your models tell you? <table border="0" cellspacing="0" class="imgcenter" style="width:429px"><tbody><tr><td><div class="imgtxt">.....</div>

3488 · Feb 14, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'>New Model of Jupiter's StructureFrom Emily Lak...............Posted by MeteorWayne</DIV>Cheers Wayne,I was going to make a post about myself, but you beat me to it. It makes perfect sense IMO, that Jupiter once passed through a phase like Uranus & Neptune during it's formation. I still suspect Jupiter's growth was very quick after that point, quickly ballooning into a Saturn type object & then continued up to the current 328 Earth masses of today (did not grow much larger, but became denser instead), as a huge annulus of Hydrogen was swept from the protoplanetary disk, prior to the Sun firing up.  Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

michaelmozina · Feb 14, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'>Elaborating on my earlier post...the fundamental question is whether Jupiter formed via the core accretion mechanism, which assumes an initial silicate core which reaches a point where it begins capturing the surrounding gas, or gravitational instability, in which gas just collapses because of the Jeans condition, as a star would.  The problem is, neither mechanism works by itself to explain our solar system, or any other known ones for that matter.  If core accretion were dominant, models predict that we should see more Neptune mass planets, whereas GI predicts more massive gas giants, like we see in many exoplanetary systems.  It is quite confusing because both "camps" strongly believe their mechanism is correct, but at the same time don't disagree with the alternative.  In other words, both can work and both most assuredly do occur to some extent, but nobody really knows the details right now.  Even if we were to find a silicate core in Jupiter, it wouldn't answer this question entirely.  Images of forming planetary systems such as Fomalhaut should help answer some questions, but we'd need more than the one(kind of 2) systems we have to look at before we can begin to gather some meaningful statistics.Even though I generally don't like planets and tend to focus on dust and star formation regions, this area of research was always quite interesting.  It illustrates a good combination of pure empirical science(i.e. looking at meteorites and seeing what they are made of) and pure theory(MHD simulations) working on a problem where we really don't understand very well at all. Posted by UFmbutler</DIV>I have two questions you might be able to answer.  Since the sun emits hydrogen on a daily basis, is it possible that Jupiter and other large bodies have reached a point where then can "grow over time", or do they lose atmosphere to the solar wind somehow?  Did the Shoemaker-Levy impact shed any light on the overall "struture" of Jupiter in any way, or help settle any of these questions? <div class="Discussion_UserSignature"> It seems to be a natural consequence of our points of view to assume that the whole of space is filled with electrons and flying electric ions of all kinds. - Kristian Birkeland </div>

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