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| Birth of solar system / star questions
Posted: 9/2/2009 7:39:24 AM | I get the general concept of where stars start. Floating around in the galaxy are huge nebulae made of lots and lots of space dust and gas. This is where stars start and form their own systems... but my questions are... What sparks it? What is it that begins the process of a star and planets taking shape?
Next question would be... what's making the nebulae? | |
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| Birth of solar system / star questions
Posted: 9/2/2009 7:51:43 AM | Depends. Is this an actual "I'm curious, so inform me" type question or is this a "I've got this whacked out 'theory' like 'expansionist' tectonics and I want to argue it" question?
Most of this is available at your local library, on the internet, etc. Bottom line, what are basically referred to as "density" waves through the nebulae and compression by supernovae. Some of the finer points are still not entirely understood, but the rough figures are pretty well understood. Go out any clear night, know where to look, and you can actually see areas in our galaxy where the process is/has taken place.
As for what's "making" the nebula? Nothing. It's already made. Partly vestigial gas left over from the big bang and other elements "seeded" into nebulae by past generations of massive stars. | |
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| Birth of solar system / star questions
Posted: 9/2/2009 10:04:00 AM | As Stargazer has advised, go grab any decent book on the subject. Heck even Wiki has some pretty cool info. Hell I've even used some Wiki material to teach some of my students basic Astrophysics.
But bottom line... What "sparks" it all?
In a nutshell, gravity and a HUGE amount of time.
The gas clouds that stars are born out of are simply mind boggling in their size so, even though these clouds, made mostly of hydrogen, remains (for the most part) in a gaseous form, even a gas can collapse under it's own weight if it's large enough.
Given enough time and external stimuli like Stargazer has said, these huge clouds will eventually collapse, to the point that gravity will compress the central parts of the collapsing cloud so much that nuclear fusion will be induced.
It's a highly complex process of course. The star actually goes through several stages such as the protostar phase and pre main sequence phase. It's during the pre main sequence phase that a star becomes hot enough in it's core for fusion to begin.
The star officially becomes a main sequence star when it is no longer collapsing and will remain in this phase for the majority of it's lifetime.
The planets are also formed within the surrounding material of the collapsing star. The material closest to the star will be a little "thinner" than material further away from the star, due to the star's increasing gravity as it grows. Which may explain why the gas giants, in our Solar System at least, generally form in the outer parts of our star system.
Nonetheless, a lot of the material that coalesces to form the planets is blown away when the star finally ignites, leaving behind a lot of solid debris, planetesimals, which later coalesce into planets.
As Stargazer said, there is still a LOT of detail to work out and what we have currently are simply working theories that seem to fit the available facts. But, problem number one is that we're too far away to see planets forming in such a manner, however, advances in technology may one day enable us to see that far.
Problem number two is, just like the evolution of Life itself I guess, the process takes a really, REALLY, long time. But progress is being made and continues to be made on how OUR Solar System formed at least.
Anyway read up on it dude... It's an interesting subject. | |
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| Birth of solar system / star questions
Posted: 9/2/2009 3:04:12 PM | To my knowledge, there is a lot of Hydrogen gas in space. After the "big Bang" it is one of the primary forms of matter that was created, and there is still a LOT of it floating around.
This hydrogen came together via gravity in large cloud systems, and I mean HUGE. They created not just stars, but entire galaxies.
The gas forms into a ball, which grows more and more like a snowball. Gravity is created by mass, and the more mass it builds up, the more it attracts. It creates so much friction from the extreme weight and power of gravity trying to crush it, that the core heats up to thousands of degrees, and it begins to glow, but it is not yet a star. It may look like a large glowing Jupiter (but maybe a few times bigger).
Eventually, enough mass comes together and the extreme pressure kicks off something in the super heated core. Nuclear Fusion begins, and the ball of mass suddenly jumps to millions of degrees and becomes a new Star. It fuses hydrogen into Helium, and when it runs out of hydrogen, it fuses helium into heavier elements. ALL elements around you came from the Cores of stars, calcium in your bones, iron in your blood. Iron everywhere came from stars.
Large stars explode and create Nebulas, which contain all the heavier elements, and left over hydrogen, and this forms a new Generation star, which comes together, and with all the heavy elements floating around, planets can also come together around it. This creates a solar system.
It is thought that large deposits of Iron, and even heavier elements came from Super Novas (Very Large stars Exploding violently)
If you ever heard the term "We are made of star dust" It's True. | |
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| Birth of solar system / star questions
Posted: 9/3/2009 9:34:49 AM | here is one of the leading thoughts on how it came about. The Modern version of the big bang theory involves an INFATIONARY phase. During this phase, some force (possibly a Higg's field that settled onto a plateau where it had greater than zero energy..but those details are confusing). This non-zero higg's field acted as a sort of REPULSIVE gravity, so strong in fact that it expanded the universe at a rate doubling it every 10^-34 seconds. At that rate it would go from the size of a grain of sand to the size of our galaxy in a matter of a second. Now, by expanding so rapidly, the energy in the universe gets uniformly smoothed out (the wrinkles are now smooth), so the universe is essentially homogenious.
Now, soon after inflation starts, the Higgs field slides down to its lowest energy state, and inflation stops. Here is where quantum mechanics comes into play. Because quantum mechanics means that things are fuzzy microscopically, it means that the Higg's field does not slide to zero energy all at exactly the same time. Some parts get to zero slightly later than other parts (because of quantum uncertainty).
So, this means that the universe stops inflating and slightly different times in different areas. This creates a TINY amount of heterogeneity, or clumping of matter.
Once you have clumping, gravity takes over, (because the clump itself creates a gravity field). So, the clumps become larger larger, which increases gravity, and this cycle goes on. Soon they become dense enough to form planets and stars. and there you have it. | |
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| Birth of solar system / star questions
Posted: 9/3/2009 12:01:45 PM | Greg, as always I stand to be corrected but I think you have the right concept but the wrong scale.
Tiny anisotropies within the inflationary big bang were inflated and became the "scaffolding" of large scale structures such as galaxies and galaxy clusters.
Unfortunately, a lot of what occurred to form the universe we see today took place about 300,000 years after the Big Bang, in a period known as the cosmic "dark ages." | |
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| Birth of solar system / star questions
Posted: 9/3/2009 12:10:05 PM |
Tiny anisotropies within the inflationary big bang were inflated and became the "scaffolding" of large scale structures such as galaxies and galaxy clusters.
hhmmm, i'm not sure how this differs from what i said. Just worded differently. I'm curious about the word "scaffolding". In my mind this gives the image that the outline, or "frame" of the galaxy-wantabe was formed, and then somehow filled in by matter. To me the word is misleading. I dont think it is as much scaffolding, as it is a growing disequilebrium. All it takes is a tiny shift in the density of one area (a shift created by the quantum mechanics related to inflation) to cause increasing heterogeneity. Dont picture the clump as an obvious clump. By "clump", i mean that instead of the average of 1 billion parts per square meter, certain areas average 1.01 billion parts per square meter. hardly noticible to any observer, but enough to make an increased gravity field, therefore a spiral of increasing mass, increasing gravity, increasing mass...until we have eventually galaxies.
And what allows this tiny heterogeniety is the quantum fuzziness that happens during inflation. Otherwise, mathematically, by definition, this inflation would have perfectely spread things into a homogenious universe. | |
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| Birth of solar system / star questions
Posted: 9/3/2009 1:16:01 PM | Greg, indeed, the use of the word "scaffolding" is somewhat misleading but the idea that I mean to convey is exactly what you described...in fact, for a comparison, it's believed the densities in the first few milliseconds after the big bang would have been roughly the equivalent of the weight differences between an infinite line-up of dogs, some with dollar bills on their backs and some without.
However, we're talking cosmological scales, not galactic scales. the question referred specifically to the formation of stars and planets and what sets that off. That is entirely unique to the environment of the galaxy. However, density waves and concussive events such as supernovae are the common accepted mechanisms for stellar formations.
However, a lot of the theories have the large scale fairly pinned down - the relationship to the molecular cloud and its environment. The real challenge is explaining how molecular clouds "granularize" or break up into ever-decreasing bits, enough to form stars, red and brown dwarfs.
And what allows this tiny heterogeniety is the quantum fuzziness that happens during inflation.
I've read articles about which theorists are also giving consideration to gravity waves and even the "sound" of the big bang for fluctuations. After all, we are talking about a super-dense fluid state, even if it was for only billionths of a second. A dense "gaseous" state a few millionths of a second after that. Gives acoustical waves a medium to go through. | |
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| Birth of solar system / star questions
Posted: 9/3/2009 1:30:20 PM |
However, we're talking cosmological scales, not galactic scales. the question referred specifically to the formation of stars and planets and what sets that off. That is entirely unique to the environment of the galaxy. However, density waves and concussive events such as supernovae are the common accepted mechanisms for stellar formations.
However, a lot of the theories have the large scale fairly pinned down - the relationship to the molecular cloud and its environment. The real challenge is explaining how molecular clouds "granularize" or break up into ever-decreasing bits, enough to form stars, red and brown dwarfs.
i think we are speaking two different languages here, and neither of us are necessarily wrong. "concussive events such as supervovae are common mech. for stellar formations"? Sure, in the later universe. But the original star must have formed in the first place to lead to the initial supernovae. Thats what i'm talking about. Early universe...inflationary universe...and the heterogeneities that led to clumps of matter formed as i described.
As for molecular clouds granularizing. Well, from my point of few, this wording is also misleading. Unless there is something more current that i dont know about (which is possible), all mass formed because of a condensation of the Higg's Ocean. (i dont mean to state this as fact, just as the leading theory). The higg's ocean is a field which exists all throughout the universe, and hovers at a non-zero value. It is believed that this field was originally very wild and chaotic, but when the universe cooled to a certain temperature, the field condensed. (kind of like steam turning back into liquid). The field condensed into the Higg's ocean that is now all around us.
Before the Higg's ocean, there was no mass. Only energy. Different energy waves, such as photons. But, when the Higg's field condenced it created a medium around us (kind of analogous to the "aether" of last century).
Now that we had a medium, some forms of energy have a harder time travelling through the medium than others. Photos are not affected by it...so they have no "mass"...other types of energy, ...gluons, electrons, etc., each feel a unique amount of resistence as they travel through this Higg's Ocean.
And it is EXACTLY THAT RESISTENCE which gives each energy/wave its mass. Mass can be defined by the amount of resistence something feels travelling through the ocean!!
And thats why we see them as "particles"
greg | |
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| Birth of solar system / star questions
Posted: 9/3/2009 3:46:26 PM | In the news, I have been reading that newer forms of cosmic observation have shown super black holes existing when the universe was still young. And that stars appear to be forming rather easily around the blackholes.
Who knows what we will be able to see in the future, that we hadn't seen before.
And who knows how it will change what makes more sense when thinking about it all.
I ain't enough of a betting man to wish to give any definitive answers.
Not like I could anyway. lol  | |
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| Birth of solar system / star questions
Posted: 9/3/2009 4:40:42 PM |
In the news, I have been reading that newer forms of cosmic observation have shown super black holes existing when the universe was still young. And that stars appear to be forming rather easily around the blackholes.
Not far off at all. One of the things that astronomers have been studying has been the relationship between galaxy central black holes and their attending halo of stars - what we now view as a galaxy's central bulge - and there is a distinct relationship.
It certainly sets a standard for galaxy evolution. | |
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| Birth of solar system / star questions
Posted: 9/3/2009 5:00:13 PM | I think you're right greg, different languages and I would venture further that we are talking different phenomenon.
First of all, Higgs is not exactly proven yet and won't be - either yay or nay - until CERN has had a chance to fire up and get to work.
I'd have to do some digging through my back issues of Sky and Tel and Astronomy but, the term 'granularization' refers to a stage of life in the development of a nebula. The nebula fractures into areas of higher and lower density and fractures again until areas of density finally condense enough to form proto-stars. Again, some of the process is still not understood. What are the controlling mechanisms? What mechanisms decide which gas clouds will produce giant and supergiant stars? How do other areas develop only low-mass stars and dwarfs. These are areas of active research.
Again, these are things happening in a galaxy. Of course, it begs the questions, how did the first galaxies form and what sparked the first generations of stars. Still a mystery but an area of active research.
For a reflection of the inhomogeneities you are referring to, you would have to look to the CMB. Those anisotropies were the precursors to the galaxy clusters and voids we see today. WMAP has provided an amazing view and taught cosmologists a lot.
Of course, you're right in that it is all inter-related. Anyway, that's my understanding of it. | |
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| Birth of solar system / star questions
Posted: 9/3/2009 5:17:30 PM |
I'd have to do some digging through my back issues of Sky and Tel and Astronomy but, the term 'granularization' refers to a stage of life in the development of a nebula.
again, you are speaking of a more modern universe. No, Higg's has not been proven. But so far, there is no other theory that explains our observation's so elegantly. So until its disproven, i'll go with it. | |
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| Birth of solar system / star questions
Posted: 9/3/2009 5:50:58 PM | So to get back on topic, the OP wonders what starts off a star from a ball of gas, what causes it to become a star, and what makes the planets take shape. I believe I answered the Star part in the first post I made before it went to big bang/early universe discussions.
As for planets, Nebulas come from the destruction of much more massive stars that lived and died. These large clouds gather and begin spinning in one general direction as gravity brings things together. Once things begin moving, they kind of drag everything else with it causing the entire system to spin.
The heaviest part would likely become the Center, and also be where the star is formed. Massive amounts of gas (mostly hydrogen, and some heavier elements that started the core off) come together like a snowball rolling down a hill and becoming more massive. The core heats to millions of degrees from the pressure alone, until it reaches a breaking point in which the pressure is SO great, that 2 atoms of Hydrogen get close enough to Fuse. Once that happens, the core heats to millions of degrees as massive amounts of energy are released, and that in turn kicks off the Nuclear Fusion Process.
During this process (Before nuclear fusion kicks off), surrounding matter also clumps together. Chunks of rock and metal float around, and at very high speeds, they collide. This causes extreme heat, and melting. It also causes chunks to grow larger and attract more rocks. Some rocks just clump together so much that the pressure alone melts the core, and compresses it. Some eventually turn into rocky planets like Mars, others attract massive amounts of gas and become like Jupiter, or Neptune, Uranus, or Saturn (saturn appears to have a surface, but has a gassy atmosphere).
These processes basically clean up the space, planets collect all rock in their paths, and clean it, gas planets take most gas that is left in the outer system, and maybe even more gas when the Star Ignites Fusion.
Once the star actually ignites nuclear fusion, solar wind pushes everything else out (except for the heavier astroid/comet belts). and cleans up shop. Now you have a star, and planets surrounding them. | |
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| Birth of solar system / star questions
Posted: 9/3/2009 5:55:08 PM | saturn appears to have a surface, but has a gassy atmosphere
Looked it up :)
"Saturn is a ball made up almost entirely of hydrogen and helium. The density and temperature changes the deeper into the planet you go, but Saturn can't be said to have a solid surface. If you tried to walk on the surface of Saturn, you would fall into the planet, suffering higher temperatures and pressures until you were crushed inside the planet.
But Saturn appears to have a surface, so what are we looking at. The outer atmosphere of Saturn consists of 93% molecular hydrogen and the rest helium, with trace amounts of ammonia, acetylene, ethane, phosphine and methane. It's these trace amounts that create the visible bands and clouds that we see in pictures of Saturn.
There are three main regions in Saturn's troposphere – the part of the planet where weather is actually occurring. These three regions are completely defined by the temperature at which droplets condense into vapor and form clouds. The top visible cloud deck is made up of ammonia clouds and is found about 100 km below the top of the troposphere, in a region called the tropopause. Below that is a second cloud deck of ammonium hydrosulphide clouds. And below that, where temperatures are 0-degrees C, there are clouds of water.
Of course you can't stand on the surface of Saturn, but if you could, you would experience about 91% of Earth's gravity. In other words, if your bathroom scale says 100 kg on Earth, it would only say 91 kg on Saturn.
We have written many articles about Saturn for Universe Today. Here's an article about patterns in Saturn's atmosphere, and here's a nice picture of Saturn's clouds in silhouette.
Want more information on Saturn? Here's a link to NASA's World Book on Saturn, and here's NASA's Solar System Exploration Guide."
~http://www.universetoday.com/guide-to-space/saturn/surface-of-saturn/
Pretty cool stuff... but it's still a 'gas giant' in my books | |
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| Birth of solar system / star questions
Posted: 9/4/2009 3:15:10 AM |
Pretty cool stuff... but it's still a 'gas giant' in my books
And a gas giant it most certainly is. But remember, even hydrogen and helium can exist in different states, just like most other forms of matter. So sure, you can't walk on Saturn. The outer layers of Saturn may as well be one, rather thick, atmosphere. However, deeper within and as the pressure builds, you'll hit the liquid layer (but don't worry, you'll be LONG dead by then), to finally hit the solid core which is deeper still.
So can you "walk" on the surface of Saturn? No. But, not that's its even possible, you can "walk" in Saturn on its core.
Anyway, I have to add that the internal composition of gas giants is largely conjecture at this moment in time. | |
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| Birth of solar system / star questions
Posted: 9/4/2009 7:42:12 AM | http://www.universetoday.com/guide-to-space/saturn/surface-of-saturn/
Pretty cool stuff... but it's still a 'gas giant' in my books
Well, first of all, that article is so wrong, it's laughable. While several points may have been accurate, like composition, he fell off the wagon with the question of "weight." Clearly, the author fails to grasp the concept of "mass." Saturn is a massive gas giant. Massive enough to hold a retinue of over 60 moons and a giant ring system. Remember, just because a planet is a gas giant, that gas has mass. Which equates to gravity. If you could "stand" on the surface of gravity, your weight would be a heckuva lot higher than 91 kgs.
If you doubt how "weighty" gas can be, look at the sun. It's 99 per cent hydrogen. However, can anyone doubt the job it does keeping us in its orbit?
Saturn, like Jupiter, Uranus and Neptune, are the products of formation in the cold outer reaches of the solar nebula. It had a lot more lighter elements to accrete. | |
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| Birth of solar system / star questions
Posted: 9/4/2009 8:57:54 AM |
Uuuuummmm.....okay! I have absolutely no idea where that's relevant to the precedeing quote. Sorry.
Random thoughts... sorry... I agree with you... If one where standing on the 'surface' of Saturn... and if they weighed 100 pounds on Earth... it's more likely they would weigh a 1000 pounds on Saturn. I'm sure that isn't exact, but I don't feel like sitting here and running the numbers. | |
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| Birth of solar system / star questions
Posted: 9/4/2009 10:30:09 AM |
Funny, I remember watching these science videos about AE. They where talking about the great work he did on understanding Gravity. But then of course... out came the theory's of Strong Force, Weak Force ect... seemed like Gravity was defiantly the weakest of these forces. I don't know if that's so true when you think about the gravitational forces that it must take to hold an entire galaxy in place.
This is off topic of course, but gravity IS the weakest force that we know exists. But, on the galactic level, where we are dealing with HUGE masses, gravity is capable of holding a galaxy together.
Of course there is, currently, a slight problem with galactic rotation curves, hence why some believe dark matter, IF it really exists, is also responsible for holding the galaxy together... But when it comes to black holes, gravity reigns supreme.
It's all just a question of density. Pack enough mass into one place and gravity can become completely dominant. But, due to its weakness, this density will have to be insanely high. | |
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| Birth of solar system / star questions
Posted: 9/22/2009 12:20:52 AM | if you doubt dark matter/energy check out the electric theory of the universe. makes sense, but isn't accepted as truth.
as for the inflation period. it's a sketchy idea until we can see far enough back in time to find the radiation wall. | |
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| Birth of solar system / star questions
Posted: 9/22/2009 5:20:29 AM | [quoteif you doubt dark matter/energy check out the electric theory of the universe. makes sense, but isn't accepted as truth.
Ah yes, the "thunderbolts of the gods" thing. Major fail from the outset. Comets are not giant sparklers crossing the night sky, sorry.
as for the inflation period. it's a sketchy idea until we can see far enough back in time to find the radiation wall.
Um, like the CMB? | |
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| Birth of solar system / star questions
Posted: 9/22/2009 12:35:37 PM |
The big bang- Now there's a test of credulity.
Um, okay, a background 2.73-degree kelvin glow all over the sky, universal recessional velocity of galaxies as measured by doppler effect and a definite "development" of galaxies from less developed, more interactive and disrupted forms in the early universe versus more developed contemporaneous galaxies in and near the local group.
Do you have an alternative, or should I just look into the silence of my heart for "the truth?" | |
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| Birth of solar system / star questions
Posted: 9/22/2009 12:48:46 PM | | No no, you're right. The big bang is real. I'm just saying, if you can believe that everything sprang out of nothing, well....that's the limit test. If you can believe that, you can believe ANYTHING. Let your imagination fly baby. | |
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| Birth of solar system / star questions
Posted: 9/22/2009 12:54:03 PM | [quote\I'm just saying, if you can believe that everything sprang out of nothing, well....that's the limit test. If you can believe that, you can believe ANYTHING. Let your imagination fly baby.
Ah, I see. I stand corrected. However, imagination and vision have to be tempered by what can be proven to be true or, at the very least, plausible. Imagination is the start of the process, not the process itself or its end, at least not if you actually want to accomplish something. | |
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