It must have taken about 8 billion years for our solar system to start forming.
is it possible that other solar systems formed much earlier than this? thus there could have been other solar systems made long before our approximate proto-planets?
is it possible that other solar systems formed much earlier than this? thus there could have been other solar systems made long before our approximate proto-planets?
-
Sorry , but it took only approximately ONE billion years for the solar system to form, NOT 8. "...How long did the solar system take to form, beginning with the nebular cloud?
It took a few tens of millions of years for a protoplanetary disk with rock and ice particles to form. Rocky planetesimals gathered into terrestrial planets over another few hundred million years, and several hundred million years after that jovian plannets were forming. After yet several more hundred million years, the young Sun's wind blew away the rest of the gas and dust. Overall the process took some reasonable fraction of a billion years or so.
Could you explain again how a shock wave would have caused planet formation?
Just left on its own, a gas cloud may not have enough natural density variation to start clumping up. What often needs to happen is for some kind of shock to create a region of high density gas (smacking molecules to push them together). Then that region attracts more gas, and you know the the rest. A nearby supernova may have provided the needed shock to cause collapse of a gas and dust cloud into the Sun and the planets. ..."
http://www.phy.duke.edu/courses/055/faqs…
The problem with generation II stars forming planetary systems is that they are metal poor, which means that their proto-stellar nebulae may not have had enough heavy elements to form planetesimals and planets from.
"...The next generation of stars was born out of those materials left by the death of the first. The oldest observed stars, known as Population II, have very low metallicities;[7][8] as subsequent generations of stars were born they became more metal-enriched, as the gaseous clouds from which they formed received the metal-rich dust manufactured by previous generations. As those stars died, they returned metal-enriched material to the interstellar medium via planetary nebulae and supernovae, enriching the nebulae out of which the newer stars formed ever further. These youngest stars, including the Sun, therefore have the highest metal content, and are known as Population I stars.
It took a few tens of millions of years for a protoplanetary disk with rock and ice particles to form. Rocky planetesimals gathered into terrestrial planets over another few hundred million years, and several hundred million years after that jovian plannets were forming. After yet several more hundred million years, the young Sun's wind blew away the rest of the gas and dust. Overall the process took some reasonable fraction of a billion years or so.
Could you explain again how a shock wave would have caused planet formation?
Just left on its own, a gas cloud may not have enough natural density variation to start clumping up. What often needs to happen is for some kind of shock to create a region of high density gas (smacking molecules to push them together). Then that region attracts more gas, and you know the the rest. A nearby supernova may have provided the needed shock to cause collapse of a gas and dust cloud into the Sun and the planets. ..."
http://www.phy.duke.edu/courses/055/faqs…
The problem with generation II stars forming planetary systems is that they are metal poor, which means that their proto-stellar nebulae may not have had enough heavy elements to form planetesimals and planets from.
"...The next generation of stars was born out of those materials left by the death of the first. The oldest observed stars, known as Population II, have very low metallicities;[7][8] as subsequent generations of stars were born they became more metal-enriched, as the gaseous clouds from which they formed received the metal-rich dust manufactured by previous generations. As those stars died, they returned metal-enriched material to the interstellar medium via planetary nebulae and supernovae, enriching the nebulae out of which the newer stars formed ever further. These youngest stars, including the Sun, therefore have the highest metal content, and are known as Population I stars.
12
keywords: solar,about,nebula,hypothesis,Theoretical,question,Theoretical question about solar nebula hypothesis