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I don't claim to have all the answers. I do think though, that you ought to look at all the facts before you believe what people tell you.
There are thousands of years of facts. No one person is capable of digesting all the facts. If you tried, you'd die before you ever finished. At some point you have to use some statistical analysis and determine what is more probable and what is less probable and then apply occam's razor
Personally , I'd have to agree with those stating Jupiter is simply a gas giant. Based upon information I've gleaned , the mass is too low for even deuterium fusion. Can't wait for Juno , just wish they could get it there faster. When I was a kid , after seeing 2010 , I thought of the feasibility of attempting to ignite fusion with the H bomb , but was lacking in knowledge regarding planetary/minimum stellar masses. Now , maybe thousands of years in the future , we may possess technology to relocate Sirius B , and coalesce it with Jupiter , but this is a longshot. I can imagine the differences that would be prevalent today if it had formed into a functional M or K type dwarf. I would hope things would be at least 180 degrees different , i.e. no 'holy wars' , population evenly spread between Earth , Ganymede , Callisto , but somehow I get a pervasive feeling emotion would rear it's ugly head , and put logic to pasture , as is currently transpiring.
Personally , I'd have to agree with those stating Jupiter is simply a gas giant. Based upon information I've gleaned , the mass is too low for even deuterium fusion. Can't wait for Juno , just wish they could get it there faster. When I was a kid , after seeing 2010 , I thought of the feasibility of attempting to ignite fusion with the H bomb , but was lacking in knowledge regarding planetary/minimum stellar masses. Now , maybe thousands of years in the future , we may possess technology to relocate Sirius B , and coalesce it with Jupiter , but this is a longshot. I can imagine the differences that would be prevalent today if it had formed into a functional M or K type dwarf. I would hope things would be at least 180 degrees different , i.e. no 'holy wars' , population evenly spread between Earth , Ganymede , Callisto , but somehow I get a pervasive feeling emotion would rear it's ugly head , and put logic to pasture , as is currently transpiring.
Etacarinae
thanks for weighing in here and i'll have to read up on deuterium fusion.
O.k. most star systems in our galaxy are binary or multiple and so whats the possibility that some 4.5 billion years back jupiter was forming as a second star in our solar system? It has hydrogen and helium in similar composition to the Sun however without enough core density it couldn't spawn nuclear fusion and so henceforth a failed brown dwarf or the largest planet in our system .
Possible or not?
Yes. Jupiter is classified as a planet only because it:
is in orbit around the Sun,
has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and
has "cleared the neighborhood" around its orbit.
However, a more accurate description would be a protostar, or as you say, a failed brown dwarf. Jupiter also generates more infrared radiation than it receives from the Sun.
When they created this definition of "planet" in 2006, that declassified Pluto from planet status, they failed to consider that Jupiter does not meet #3 of their criteria, just like Pluto.
It makes one wonder. What would have happened to Jupiter if it had the combined mass of both the Trojan and Greek asteroids? Would it have been sufficient mass to spark nuclear fusion? Considering that we have already found extrasolar "planets" considerably larger than Jupiter that have not evolved into stars, the answer is most likely "no."
Yes. Jupiter is classified as a planet only because it:
is in orbit around the Sun,
has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and
has "cleared the neighborhood" around its orbit.
However, a more accurate description would be a protostar, or as you say, a failed brown dwarf. Jupiter also generates more infrared radiation than it receives from the Sun.
When they created this definition of "planet" in 2006, that declassified Pluto from planet status, they failed to consider that Jupiter does not meet #3 of their criteria, just like Pluto.
It makes one wonder. What would have happened to Jupiter if it had the combined mass of both the Trojan and Greek asteroids? Would it have been sufficient mass to spark nuclear fusion? Considering that we have already found extrasolar "planets" considerably larger than Jupiter that have not evolved into stars, the answer is most likely "no."
What's the difference between Trojan and Greek asteroids?
Using trojans as a criteria gets into a bit of a sticky wicket since the Earth itself has at least one known trojan asteroid called 2010 TK7. Earth’s First Trojan Asteroid Discovered
Hopefully, we'll have a better idea about Jupiter (and perhaps indirectly Saturn) in the near future. Just because it generates more infrared radiation that it receives from the sun, doesn't necessarily suggest that it may be a protostar or failed brown dwarf. If radiation is considered to be a factor, then I suppose the Earth itself might in a way fall into the same category. The only thing that prevents the Earth from emitting more radiation than it receives from the Sun is the rocky crust that covering it. Of course, the Earth contains more in the way of metallic elements than gasses. Volcanoes, Magma, and Volcanic Eruptions
I agree with your conclusion that Jupiter like the gas giant exoplanets which are much larger than Jupiter indicate that Jupiter never would evolve into a star. At a guess, there probably wasn't enough matter in the accretion disk of our solar system or the birth place of the Sun for it to evolve into anything more than what it is.
What's the difference between Trojan and Greek asteroids?
The Trojan Asteroids are at the Lagrangian point following Jupiter (L5), and the Greek Asteroids are at the Lagrangian point in front of Jupiter's orbit (L4). They are gravitationally bound to Jupiter's orbit.
Quote:
Originally Posted by NightBazaar
Using trojans as a criteria gets into a bit of a sticky wicket since the Earth itself has at least one known trojan asteroid called 2010 TK7. Earth’s First Trojan Asteroid Discovered
Interesting, but I think it is mislabeled. Asteroids that precede, rather than follow the planet, that are located in L4 are called Greek asteroids. The trailing asteroids, those located in L5, are Trojan asteroids. See the image above.
Quote:
Originally Posted by NightBazaar
Hopefully, we'll have a better idea about Jupiter (and perhaps indirectly Saturn) in the near future. Just because it generates more infrared radiation that it receives from the sun, doesn't necessarily suggest that it may be a protostar or failed brown dwarf. If radiation is considered to be a factor, then I suppose the Earth itself might in a way fall into the same category. The only thing that prevents the Earth from emitting more radiation than it receives from the Sun is the rocky crust that covering it. Of course, the Earth contains more in the way of metallic elements than gasses. Volcanoes, Magma, and Volcanic Eruptions
I agree with your conclusion that Jupiter like the gas giant exoplanets which are much larger than Jupiter indicate that Jupiter never would evolve into a star. At a guess, there probably wasn't enough matter in the accretion disk of our solar system or the birth place of the Sun for it to evolve into anything more than what it is.
Both Saturn and Jupiter are very interesting planets, and they could not be more different from each other. You are right about the gas giants, because of their distance from the sun in our solar system and their gaseous composition, they all generate more infrared radiation than they receive from the sun.
After some thought, I have come to realize that the size of a planet alone is not a very good judge of mass. Just in our own solar system we have Saturn and Jupiter, and while Jupiter is only slightly larger (about 14% larger) than Saturn, there is an order of magnitude difference in their mass. Even for its size Jupiter's mass is packed much denser than Saturn.
There are stars that are not much bigger than Jupiter. For example, the red dwarf OGLE-TR-122b has a diameter of 167,000 km, which is only about 16% larger than Jupiter. We have already found planets that are larger than this red dwarf, and yet they still are not "stars."
The Trojan Asteroids are at the Lagrangian point following Jupiter (L5), and the Greek Asteroids are at the Lagrangian point in front of Jupiter's orbit (L4). They are gravitationally bound to Jupiter's orbit.
The point I was alluding to is that they're both within the same orbit.
Quote:
Interesting, but I think it is mislabeled. Asteroids that precede, rather than follow the planet, that are located in L4 are called Greek asteroids. The trailing asteroids, those located in L5, are Trojan asteroids. See the image above.
Regardless of whether 2010 TK7 mislabeled or not, it's still within and influenced by the Earth's orbit. The point being that in relation to Jupiter, I don't think such asteroids serve very well with the criteria applied to Jupiter as previously mentioned.
Quote:
Both Saturn and Jupiter are very interesting planets, and they could not be more different from each other. You are right about the gas giants, because of their distance from the sun in our solar system and their gaseous composition, they all generate more infrared radiation than they receive from the sun.
Agreed. They are indeed very interesting and very different planets. For that matter, everything we've explored in the solar system are very different. Mars is the only body that seems remotely similar (in some ways) to the Earth, but even so, it's still very different. The emission of radiation from Jupiter and Saturn is probably (at least in part) related to a rocky core under extreme pressure.
Quote:
After some thought, I have come to realize that the size of a planet alone is not a very good judge of mass. Just in our own solar system we have Saturn and Jupiter, and while Jupiter is only slightly larger (about 14% larger) than Saturn, there is an order of magnitude difference in their mass. Even for its size Jupiter's mass is packed much denser than Saturn.
Agreed. This is an example of where size doesn't always matter.
Quote:
There are stars that are not much bigger than Jupiter. For example, the red dwarf OGLE-TR-122b has a diameter of 167,000 km, which is only about 16% larger than Jupiter. We have already found planets that are larger than this red dwarf, and yet they still are not "stars."
Yes, I'm somewhat familiar with it. Another interesting surprise and another example that size doesn't always matter, although OGLE-TR-122b may be close to the lowest possible limit that stars can form. While sizewise, it's about 20% larger than Jupiter, it's mass is about 100 times greater than Jupiter and density about 50 times the Sun's.
Could Jupiter be a protostar or a failed brown dwarf? I'd still say no, for the reasons previously mentioned. If there had been more dust and gasses present in the early accretion disk, and provided enough density, then perhaps they could have been. Both gas giants in the solar system seem to have swept out much of material in the disk and both probably have rocky cores deep down inside. In my opinion, in relation to our solar system they could never have become anything more than gas giant planets. But who knows? There could come a time when such planets might end up being reclassified as protostars. It gets pretty tricky. What then would be the the line of difference that separates a planet from a protostar? Would it mean that all gas giants are protostars?
It makes one wonder. What would have happened to Jupiter if it had the combined mass of both the Trojan and Greek asteroids? Would it have been sufficient mass to spark nuclear fusion?
Even if you combined all of the planets and asteroids of the solar system into Jupiter, it would still be too small to be considered a brown dwarf.
The point I was alluding to is that they're both within the same orbit.
Regardless of whether 2010 TK7 mislabeled or not, it's still within and influenced by the Earth's orbit. The point being that in relation to Jupiter, I don't think such asteroids serve very well with the criteria applied to Jupiter as previously mentioned.
Ah, very true. Which means that the 2006 definition of a "planet" clearly needs to be reworked. As our instruments become better and more sensitive, I would be willing to wager that none of the planets in our solar system have completely cleared their orbits of all debris.
Quote:
Originally Posted by NightBazaar
Agreed. They are indeed very interesting and very different planets. For that matter, everything we've explored in the solar system are very different. Mars is the only body that seems remotely similar (in some ways) to the Earth, but even so, it's still very different. The emission of radiation from Jupiter and Saturn is probably (at least in part) related to a rocky core under extreme pressure.
Agreed. This is an example of where size doesn't always matter.
Yes, I'm somewhat familiar with it. Another interesting surprise and another example that size doesn't always matter, although OGLE-TR-122b may be close to the lowest possible limit that stars can form. While sizewise, it's about 20% larger than Jupiter, it's mass is about 100 times greater than Jupiter and density about 50 times the Sun's.
Could Jupiter be a protostar or a failed brown dwarf? I'd still say no, for the reasons previously mentioned. If there had been more dust and gasses present in the early accretion disk, and provided enough density, then perhaps they could have been. Both gas giants in the solar system seem to have swept out much of material in the disk and both probably have rocky cores deep down inside. In my opinion, in relation to our solar system they could never have become anything more than gas giant planets. But who knows? There could come a time when such planets might end up being reclassified as protostars. It gets pretty tricky. What then would be the the line of difference that separates a planet from a protostar? Would it mean that all gas giants are protostars?
In astrophysics, density matters more than size. I have no idea how old the star OGLE-TR-122b may be already, but because of its density it is likely to last several trillion years.
Given that both a protostar and a brown dwarf have not achieved nuclear fusion, it is still difficult to classify Jupiter. What we do not know is the amount of mass and density required to spark hydrogen fusion, and what separates a brown dwarf or protostar from a regular gas giant, like Saturn, Neptune, or Uranus?
Ah, very true. Which means that the 2006 definition of a "planet" clearly needs to be reworked. As our instruments become better and more sensitive, I would be willing to wager that none of the planets in our solar system have completely cleared their orbits of all debris.
"Clearing the orbit" does not mean there is nothing left in a planet's orbit. It means that the planet is the only "gravitationally dominant" object in its orbit. All of the trojans, Greeks, NEOs, and other junk is tiny compared to the planet they are being dominated by.
Quote:
Given that both a protostar and a brown dwarf have not achieved nuclear fusion, it is still difficult to classify Jupiter. What we do not know is the amount of mass and density required to spark hydrogen fusion, and what separates a brown dwarf or protostar from a regular gas giant, like Saturn, Neptune, or Uranus?
Umm, Jupiter is quite clearly just a gas giant. Even the smallest possible brown dwarfs are over 10 times bigger than Jupiter. You wouldn't call Venus a "failed gas giant" just because it has an atmosphere.
However, much more interesting objects are sub-brown dwarfs. I suspect there might be some close to our solar system (at least closer than alpha centauri).
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I have no idea how old the star OGLE-TR-122b may be already, but because of its density it is likely to last several trillion years.
