Re: Re : [meteorite-list] Chondrule formation mechanism (Info Please)
an early solar system and a present asteroid belt that is very tightly zoned. In other words, the Earthly prevalence of chondrites would just be a coincidence. The evidence is that the asteroid belt is a gumbo, though, full of all sorts of things that don't belong there. The failure to find obvious sources for chondrites in the asteroid belt is one of the great nagging problems that has never been answered well, so he may have something. I'm just not sure what. Sears says one advantage of the theory is that otherwise the energy required to flash melt a solar system full of chondrules is a major fraction of the total energy available. Of course a precursor supernova that melted them would take care of that problem, too. Supernovae have a way of making short work of both problems and non-problems alike! The nearest short-term supernova candidate is HR8210 or IK Pegasi, which is incomfortably close at 150 light years. http://www.eso.org/outreach/eduoff/edu-prog/catchastar/casreports-2004/rep-310/ and http://www.newscientist.com/article.ns?id=dn2311 Of course, it could take millions of years to go super, or it could happen in 10,000 years, or it could start up tomorrow. That's what makes life so interesting. Sterling K. Webb --- - Original Message - From: Rob McCafferty [EMAIL PROTECTED] To: Pete Pete [EMAIL PROTECTED]; meteorite-list@meteoritecentral.com Sent: Wednesday, October 25, 2006 2:52 PM Subject: RE: Re : [meteorite-list] Chondrule formation mechanism (Info Please) I suppose you are correct. I suspect the iron flecks in chondrites must be stellar relics. The iron is formed in the cores of all stars. Nuclearly speaking it is the stablest of all elements (lowest binding energy per neucleon...or is it the highest, can't remember) So as a consequence it is the final fusion product in the cores of all stars which are heavy enough to get that far (red dwarf stars aren't considered massive enough to get beyond the helium burning phase). However, only supernovae spread their innards out at the end so every atom of iron was created by a supernova as indeed was every atom that isn't hydrogen, helium or lithium. All others are created in stars. However, the atoms higher in the periodic table cannot be made in stars as they require a net input of energy to fuse whereas the lighter ones relase energy. Only in a huge energy surplus can you manufacture these higher elements. This is where the supernova comes in. In that brief period where the star aoutshines an entire galaxy, there is enough excess energy to create quantities of elements up to Uranium (and possibly beyond but non of these are stable). This is a most wonderful process which not only creates all the elements needed for life but also seeds the universe with them. And not a crackpot creationist theory involving venting asteroids into space in sight. As for the ages of the iron/nickel. I'm not sure if ages are measured or if they can be. That'd be interesting if they could. It's probable that our sun and solar system are not even second or third generation. The big stars last only a short period and there's been a long time for the cycle to repeat a few times. Rob McC --- Pete Pete [EMAIL PROTECTED] wrote: Hi, all, This discussion about chondrules is fascinating! Hoping not to digress off this topic too much, but a question I have is about the metal flecks (not the later-formed iron meteorites) in any of the stonies. Have they ever been given an estimated age? If the heavy elements, such as nickel and iron, are created by a supernova, and the chondrules are in theory formed much later during the future dynamics of our solar system's nebula, would it be fair to say that the metal flecks would be billions and billions (apologies, Carl) of years OLDER than chondrules? And that they came from a distance much further than our solar system's vicinity? Considering that the supernova is exploding outward and the new elements' density is thinning out very quickly, wouldn't it be more likely that these iron and nickel flecks that eventually found a new home in our solar nebula and meteorites have come from more than one, probably a lot more, supernova? If so, why don't we see any remnants of any supernova explosion in our relative proximity? The Helix Nebula is the closest to us, at 450 light-years! http://images.google.ca/images?q=helix+nebulahl=enlr=sa=Xoi=imagesct=title Not even a wisp left... Are tiny, but very dense, nebulas even possible? I can't imagine dust-bunny nebulae. If not, would it be unreasonable to expect that our planetary nebula could have extended out to Centauri, where our closest star neighbours are? When I dwell on the Pillars of Creation photos (Orion stellar-formation nebula, http://hubblesite.org/newscenter/newsdesk/archive/releases/1995/44/image/a) that describes a small point being comparable to the breadth of our solar
Re: Re : [meteorite-list] Chondrule formation mechanism (Info Please)
supernova. Lots of theories to choose from (limit three to a customer). I think Derek Sears' theory is clever and well-thought-out and ingenious and probably wrong. He supposes that the resonant orbits from which the Earth receives its many chondrites are wall-to-wall with condrite parent bodies, that these bodies are the ONLY chondrite bodies there are, that they are few and rare, that Earth's meteorite population is specific and unique, that chondrules and their accreted chondrites were a rare and unique by-product of the early solar system and not representative of early solar materials at all. In other words, aren't we special...? Very narrow zones of unique chondrite parent bodies implies both an early solar system and a present asteroid belt that is very tightly zoned. In other words, the Earthly prevalence of chondrites would just be a coincidence. The evidence is that the asteroid belt is a gumbo, though, full of all sorts of things that don't belong there. The failure to find obvious sources for chondrites in the asteroid belt is one of the great nagging problems that has never been answered well, so he may have something. I'm just not sure what. Sears says one advantage of the theory is that otherwise the energy required to flash melt a solar system full of chondrules is a major fraction of the total energy available. Of course a precursor supernova that melted them would take care of that problem, too. Supernovae have a way of making short work of both problems and non-problems alike! The nearest short-term supernova candidate is HR8210 or IK Pegasi, which is incomfortably close at 150 light years. http://www.eso.org/outreach/eduoff/edu-prog/catchastar/casreports-2004/rep-310/ and http://www.newscientist.com/article.ns?id=dn2311 Of course, it could take millions of years to go super, or it could happen in 10,000 years, or it could start up tomorrow. That's what makes life so interesting. Sterling K. Webb --- - Original Message - From: Rob McCafferty [EMAIL PROTECTED] To: Pete Pete [EMAIL PROTECTED]; meteorite-list@meteoritecentral.com Sent: Wednesday, October 25, 2006 2:52 PM Subject: RE: Re : [meteorite-list] Chondrule formation mechanism (Info Please) I suppose you are correct. I suspect the iron flecks in chondrites must be stellar relics. The iron is formed in the cores of all stars. Nuclearly speaking it is the stablest of all elements (lowest binding energy per neucleon...or is it the highest, can't remember) So as a consequence it is the final fusion product in the cores of all stars which are heavy enough to get that far (red dwarf stars aren't considered massive enough to get beyond the helium burning phase). However, only supernovae spread their innards out at the end so every atom of iron was created by a supernova as indeed was every atom that isn't hydrogen, helium or lithium. All others are created in stars. However, the atoms higher in the periodic table cannot be made in stars as they require a net input of energy to fuse whereas the lighter ones relase energy. Only in a huge energy surplus can you manufacture these higher elements. This is where the supernova comes in. In that brief period where the star aoutshines an entire galaxy, there is enough excess energy to create quantities of elements up to Uranium (and possibly beyond but non of these are stable). This is a most wonderful process which not only creates all the elements needed for life but also seeds the universe with them. And not a crackpot creationist theory involving venting asteroids into space in sight. As for the ages of the iron/nickel. I'm not sure if ages are measured or if they can be. That'd be interesting if they could. It's probable that our sun and solar system are not even second or third generation. The big stars last only a short period and there's been a long time for the cycle to repeat a few times. Rob McC --- Pete Pete [EMAIL PROTECTED] wrote: Hi, all, This discussion about chondrules is fascinating! Hoping not to digress off this topic too much, but a question I have is about the metal flecks (not the later-formed iron meteorites) in any of the stonies. Have they ever been given an estimated age? If the heavy elements, such as nickel and iron, are created by a supernova, and the chondrules are in theory formed much later during the future dynamics of our solar system's nebula, would it be fair to say that the metal flecks would be billions and billions (apologies, Carl) of years OLDER than chondrules? And that they came from a distance much further than our solar system's vicinity? Considering that the supernova is exploding outward and the new elements
Re: Re : [meteorite-list] Chondrule formation mechanism (Info Please)
I shall be forever grateful that I saved this post. Having read an exerpt of it in Ed G's reply, I returned to the original and am forced to reiterate a previous effusive, unabashed compliment of Sterling's effective translation into laymans terms of the most simple of processes in the universe. Simple in the sense of elemental. Sterling, I hope that you can make time in your life to preserve and collect these posts. I for one, and I realize, I may be in the minority, find such threads more than words like facinating can describe. Meteorites are the glue which keeps this group together but ultimate meaning motivates some of us to touch these sublime sources of understanding and imagine our origins among the stars. Who are we? Where did we come from? Where are we going? Astrophysics, Cosmology, Chemistry, Petrology, Relativity, Sp. relativity! Holy Cow! Hindu Metaphysics. Jerry Flaherty - Original Message - From: Sterling K. Webb [EMAIL PROTECTED] To: meteorite-list@meteoritecentral.com Cc: E.P. Grondine [EMAIL PROTECTED] Sent: Friday, October 27, 2006 2:30 AM Subject: Re: Re : [meteorite-list] Chondrule formation mechanism (Info Please) Hi, Rob, Pete, Ed, List, Rob wrote: The iron is formed in the cores of all stars. Nuclearly speaking it is the stablest of all elements (lowest binding energy per neucleon...or is it the highest, can't remember) I hate it when I have to dive into thick books more suited for anchors than reading but here goes... Not all stars form iron. The one thing that determines the entire life of a star is how fat it is. An anorexic star is just another Jupiter or Super-Jupiter. At somewhere around 12-13 times the mass of Jupiter, a star starts to burn deuterium and we can really call it a star. Stars burn hydrogen. Deuterium is just regular hydrogen toting a neutron in its backpack. Slap two of them together and you get helium (and a lot of excess energy). All stars, regardless of size, start out as hydrogen burners. The D-D chain is the easiest reaction to get started but there are lots of routes from hydrogen to helium that use other elements for their intermediate stages (called proton-proton reactions) and I'm not going to type them all out. So there. Fast forward a few billion years. A star will use up all of its hydrogen. About the time it's running on fumes, the helium ash left over from burning up all your hydrogen like there was no tomorrow has sunk to the core and is getting hotter and denser. Eventually, that helium in the core starts to burn. Now, the star is a helium-burner. This nuclear heat generated in the helium-burning core causes the star to expand and expand and expand into a big gasball many times its original size: a red giant. A star has to be at least half the mass of our Sun to do this. Our Sun will do this... in another 4-5 billion years. Goodbye, Solar System. A helium burner this big will evolve carbon12-burning. Again there are many possible reactions, but most of the carbon is turned directly into oxygen16. As things get hotter, we get neon20, magnesium24, silicon28, each one is produced by slapping (fusing) a helium nucleus into the last one, hence the jump by 4, 4, 4, 4... Now, a nice little star like our Sun will just end up as a bright superdense carbon12 diamond a few thousand miles across, called a white dwarf. But if the mass of a star is 1.4 times the mass of the Sun or greater, it will just go crazy with this fusion stuff. The end result is a star with an onion structure: an outer shell of hydrogen burning surrounding a shell of helium burning, surrounding a shell of carbon burning, surrounding a shell of neon burning, surrounding a shell of oxygen burning, surrounding a shell of silicon burning, surrounding a core where the really weird stuff goes on. Silicon burning should proceed until iron is built, but it doesn't happen. By this time the heat, pressure and energies involved are so great that the LIGHT produced by the fusion becomes more powerful and energetic than all the other players! As soon as a nuclei heavier than silicon is produced, a photon on steroids knocks it apart, slaps it down, and kicks it around until it gives up those extra nucleons and crawls off in all its silicon shabbiness. Iron may get formed but it doesn't last. And, yes, iron has the HIGHEST binding energy per nucleon and a high electric charge barrier, but the real problem is that the photons produced by creating it are energetic enough to rip it apart. If you want to picture the true violence of a stellar interior, try imagining a beam of light powerful enough to smash atoms... OK, they're super-gamma rays, but they're still just light. The iron (and nickel) core forms inside the silicon burning shell as some of the iron continually being formed escapes from the cycle of birth and instant photo-death by dripping down out of sight in the core as it forms. But the iron core is doomed. Eventually
RE: Re : [meteorite-list] Chondrule formation mechanism (Info Please)
Hi, all, This discussion about chondrules is fascinating! Hoping not to digress off this topic too much, but a question I have is about the metal flecks (not the later-formed iron meteorites) in any of the stonies. Have they ever been given an estimated age? If the heavy elements, such as nickel and iron, are created by a supernova, and the chondrules are in theory formed much later during the future dynamics of our solar system's nebula, would it be fair to say that the metal flecks would be billions and billions (apologies, Carl) of years OLDER than chondrules? And that they came from a distance much further than our solar system's vicinity? Considering that the supernova is exploding outward and the new elements' density is thinning out very quickly, wouldn't it be more likely that these iron and nickel flecks that eventually found a new home in our solar nebula and meteorites have come from more than one, probably a lot more, supernova? If so, why don't we see any remnants of any supernova explosion in our relative proximity? The Helix Nebula is the closest to us, at 450 light-years! http://images.google.ca/images?q=helix+nebulahl=enlr=sa=Xoi=imagesct=title Not even a wisp left... Are tiny, but very dense, nebulas even possible? I can't imagine dust-bunny nebulae. If not, would it be unreasonable to expect that our planetary nebula could have extended out to Centauri, where our closest star neighbours are? When I dwell on the Pillars of Creation photos (Orion stellar-formation nebula, http://hubblesite.org/newscenter/newsdesk/archive/releases/1995/44/image/a) that describes a small point being comparable to the breadth of our solar system, ~4.3 light-years to Centauri isn't that far... Maybe the seldom-discussed/appreciated metal flecks are the real gems in the meteorites? Or, is the nebula in my head too dense that am I just missing something obvious? How is my logic flawed? Cheers, Pete From: Warin Roger [EMAIL PROTECTED] To: Sterling K. Webb [EMAIL PROTECTED],meteorite-list@meteoritecentral.com CC: E.P. Grondine [EMAIL PROTECTED] Subject: Re : [meteorite-list] Chondrule formation mechanism (Info Please) Date: Tue, 24 Oct 2006 16:15:53 + (GMT) Hi, all, I am surprised that nobody evoked the theory following which chondrules were formed in relatively very few privileged zones of space. They would then form through one or more impacts of relatively large asteroids, onto the parent body covered with regoliths (and even with megaregoliths). The excellent book of Derek Sears, entitled The origin of chondrules and chondrites (Cambridge Planetary Science, 2004) supports this hypothesis. In corollary, ordinary chondrites (85% on Earth) would be quite rare in cosmos, and only few parent bodies would produce chondrites. Glad to hear some comments on the above assumptions. Thanks, Roger Warin - Message d'origine De : Sterling K. Webb [EMAIL PROTECTED] À : meteorite-list@meteoritecentral.com Cc : E.P. Grondine [EMAIL PROTECTED] Envoyé le : Dimanche, 22 Octobre 2006, 20h38mn 55s Objet : Re: [meteorite-list] Chondrule formation mechanism (Info Please) Hi, Ed, Rob, This scenario (Ed's) would require that we would find a chondrule with a formation age of 3.9 Gya, I think. As far as I know, that has never happened. All chondrites (so called because they contain chondrules) are the same age: about 4.555 Gya. Chondrules are the same age (2 to 5 million years variation among chondrules) as the chondrites they occur in. The about is because the dating methods have a limit to how precisely they can resolve small age differences. Dating by lead isotopes says the solar system is 4.560 +/- 0.005 Gya old. Other systems of isotope measurements (like 147Sm/143Nd) give 4.553 +/- 0.003, and so forth. Within the limits of measurement, all chondrites are the same age, a hair younger than the solar system itself, the Class of Zero, and so are their chondrules. Meteorites that do not (never did) contain chondrules have varying ages. Lunaites are the age of that portion of the lunar crust they came from, generally quite old compared to Martians which have the formation age of the basalt flow they were chipped off of for the long haul to Earth. Irons, which formed inside a differentiating body, have younger ages; some very much younger if the differentiation took a long time (Weekeroo Station IIe is 4.340 Gya, Kodaikanal IIe 3.800 Gya, many IAB irons the same). I'm thinking that before you need to develop a theory to explain a 3.9 Gya chondrule, you'd have to actually have a 3.9 Gya chondrule. As far as I know, none with discordant ages have ever been found. In certain solar circles it would be Big News. Oddly, if you Google for oldest chondrule, you get the oldest chondrules, and if you Google for youngest chondrule, you get the oldest chondrules... on the grounds that it is young as the solar system. If you Google
Re: RE: Re : [meteorite-list] Chondrule formation mechanism (Info Please)
On Wed, 25 Oct 2006 11:52:23 -0400, you wrote: If the heavy elements, such as nickel and iron, are created by a supernova, and the chondrules are in theory formed much later during the future dynamics of our solar system's nebula, would it be fair to say that the metal flecks would be billions and billions (apologies, Carl) of years OLDER than chondrules? Of course the individual atoms in chondrules are much older than the chondrules themselves (but know knows exactly how many stellar generations ago) but as for the actual flecks of metal themselves, I think that they are concentrated by whatever mechanism it is that melts the chondrules-- like oil seperating from water, the iron/nickel seperated from the silicates (and that is more apparent in armored chondrules). Recently there has been news of studies on the decay products of short-lived supernova produced elements that show that there were supernovas very close (both in space and time) to the proto-solar system. (This article was posted 22 minutes ago as I'm finding it) http://www.cnn.com/2006/TECH/space/10/25/sun.sisters/ I believe (though I haven't googled up the articles related to it) that recent studies of elements and isotopes in certain meteorites suggest that components from at least 3 seperate supernovas contributed to the materials in the early solar system. If so, why don't we see any remnants of any supernova explosion in our relative proximity? The Helix Nebula is the closest to us, at 450 light-years! In our current position, it takes around 225 million years for one orbit of the center of the galaxy, or about 20 orbits since the birh of the sun. That's plenty of time and distance for a whole lot more than 450 light-years of drift between the sun and the nursery. __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: RE: Re : [meteorite-list] Chondrule formation mechanism (Info Please)
Thanks, Darren, Much clearer to me, now. And now I can get some sleep ;) The link you provided http://www.cnn.com/2006/TECH/space/10/25/sun.sisters/ is almost a complete answer to my post. *Note that my post was about a half hour before the news break. The odds of such a directly related news topic being released at such timing must beastronomical! I think that they are concentrated by whatever mechanism it is that melts the chondrules-- like oil separating from water, the iron/nickel separated from the silicates (and that is more apparent in armored chondrules). If they were separated and the flecks were formed then, (I see that silica, iron and nickel all melt at close to the same temp: ~1500 C) what mechanism could have brought them back together into a relatively consistent mixture of chondrule/metal flecks? Maybe simply time, gravity, and the start of the rotation of the new solar system swirling the soup? That would be the most obvious, eh? I would appreciate a reference, if anyone has one. Cheers, Pete From: Darren Garrison [EMAIL PROTECTED] Reply-To: [EMAIL PROTECTED] To: Pete Pete [EMAIL PROTECTED] CC: meteorite-list@meteoritecentral.com Subject: Re: RE: Re : [meteorite-list] Chondrule formation mechanism (Info Please) Date: Wed, 25 Oct 2006 12:55:53 -0400 On Wed, 25 Oct 2006 11:52:23 -0400, you wrote: If the heavy elements, such as nickel and iron, are created by a supernova, and the chondrules are in theory formed much later during the future dynamics of our solar system's nebula, would it be fair to say that the metal flecks would be billions and billions (apologies, Carl) of years OLDER than chondrules? Of course the individual atoms in chondrules are much older than the chondrules themselves (but know knows exactly how many stellar generations ago) but as for the actual flecks of metal themselves, I think that they are concentrated by whatever mechanism it is that melts the chondrules-- like oil seperating from water, the iron/nickel seperated from the silicates (and that is more apparent in armored chondrules). Recently there has been news of studies on the decay products of short-lived supernova produced elements that show that there were supernovas very close (both in space and time) to the proto-solar system. (This article was posted 22 minutes ago as I'm finding it) http://www.cnn.com/2006/TECH/space/10/25/sun.sisters/ I believe (though I haven't googled up the articles related to it) that recent studies of elements and isotopes in certain meteorites suggest that components from at least 3 seperate supernovas contributed to the materials in the early solar system. If so, why don't we see any remnants of any supernova explosion in our relative proximity? The Helix Nebula is the closest to us, at 450 light-years! In our current position, it takes around 225 million years for one orbit of the center of the galaxy, or about 20 orbits since the birh of the sun. That's plenty of time and distance for a whole lot more than 450 light-years of drift between the sun and the nursery. _ Experience Live Search from your PC or mobile device today. http://www.live.com/?mkt=en-ca __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: RE: Re : [meteorite-list] Chondrule formation mechanism (Info Please)
I think I may have misinterpreted this, Darren: as for the actual flecks of metal themselves, I think that they are concentrated by whatever mechanism it is that melts the chondrules-- like oil seperating from water, the iron/nickel seperated from the silicates (and that is more apparent in armored chondrules). You meant that they were separated at a minute scale - chondrule-and-fleck-size, right? Not on a vast measure, as in kilometers plus. Disregard my remix question. Cheers, Pete From: Darren Garrison [EMAIL PROTECTED] Reply-To: [EMAIL PROTECTED] To: Pete Pete [EMAIL PROTECTED] CC: meteorite-list@meteoritecentral.com Subject: Re: RE: Re : [meteorite-list] Chondrule formation mechanism (Info Please) Date: Wed, 25 Oct 2006 12:55:53 -0400 On Wed, 25 Oct 2006 11:52:23 -0400, you wrote: If the heavy elements, such as nickel and iron, are created by a supernova, and the chondrules are in theory formed much later during the future dynamics of our solar system's nebula, would it be fair to say that the metal flecks would be billions and billions (apologies, Carl) of years OLDER than chondrules? Of course the individual atoms in chondrules are much older than the chondrules themselves (but know knows exactly how many stellar generations ago) but as for the actual flecks of metal themselves, I think that they are concentrated by whatever mechanism it is that melts the chondrules-- like oil seperating from water, the iron/nickel seperated from the silicates (and that is more apparent in armored chondrules). Recently there has been news of studies on the decay products of short-lived supernova produced elements that show that there were supernovas very close (both in space and time) to the proto-solar system. (This article was posted 22 minutes ago as I'm finding it) http://www.cnn.com/2006/TECH/space/10/25/sun.sisters/ I believe (though I haven't googled up the articles related to it) that recent studies of elements and isotopes in certain meteorites suggest that components from at least 3 seperate supernovas contributed to the materials in the early solar system. If so, why don't we see any remnants of any supernova explosion in our relative proximity? The Helix Nebula is the closest to us, at 450 light-years! In our current position, it takes around 225 million years for one orbit of the center of the galaxy, or about 20 orbits since the birh of the sun. That's plenty of time and distance for a whole lot more than 450 light-years of drift between the sun and the nursery. _ Ready for the world's first international mobile film festival celebrating the creative potential of today's youth? Check out Mobile Jam Fest for your a chance to WIN $10,000! www.mobilejamfest.com __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
RE: Re : [meteorite-list] Chondrule formation mechanism (Info Please)
I suppose you are correct. I suspect the iron flecks in chondrites must be stellar relics. The iron is formed in the cores of all stars. Nuclearly speaking it is the stablest of all elements (lowest binding energy per neucleon...or is it the highest, can't remember) So as a consequence it is the final fusion product in the cores of all stars which are heavy enough to get that far (red dwarf stars aren't considered massive enough to get beyond the helium burning phase). However, only supernovae spread their innards out at the end so every atom of iron was created by a supernova as indeed was every atom that isn't hydrogen, helium or lithium. All others are created in stars. However, the atoms higher in the periodic table cannot be made in stars as they require a net input of energy to fuse whereas the lighter ones relase energy. Only in a huge energy surplus can you manufacture these higher elements. This is where the supernova comes in. In that brief period where the star aoutshines an entire galaxy, there is enough excess energy to create quantities of elements up to Uranium (and possibly beyond but non of these are stable). This is a most wonderful process which not only creates all the elements needed for life but also seeds the universe with them. And not a crackpot creationist theory involving venting asteroids into space in sight. As for the ages of the iron/nickel. I'm not sure if ages are measured or if they can be. That'd be interesting if they could. It's probable that our sun and solar system are not even second or third generation. The big stars last only a short period and there's been a long time for the cycle to repeat a few times. Rob McC --- Pete Pete [EMAIL PROTECTED] wrote: Hi, all, This discussion about chondrules is fascinating! Hoping not to digress off this topic too much, but a question I have is about the metal flecks (not the later-formed iron meteorites) in any of the stonies. Have they ever been given an estimated age? If the heavy elements, such as nickel and iron, are created by a supernova, and the chondrules are in theory formed much later during the future dynamics of our solar system's nebula, would it be fair to say that the metal flecks would be billions and billions (apologies, Carl) of years OLDER than chondrules? And that they came from a distance much further than our solar system's vicinity? Considering that the supernova is exploding outward and the new elements' density is thinning out very quickly, wouldn't it be more likely that these iron and nickel flecks that eventually found a new home in our solar nebula and meteorites have come from more than one, probably a lot more, supernova? If so, why don't we see any remnants of any supernova explosion in our relative proximity? The Helix Nebula is the closest to us, at 450 light-years! http://images.google.ca/images?q=helix+nebulahl=enlr=sa=Xoi=imagesct=title Not even a wisp left... Are tiny, but very dense, nebulas even possible? I can't imagine dust-bunny nebulae. If not, would it be unreasonable to expect that our planetary nebula could have extended out to Centauri, where our closest star neighbours are? When I dwell on the Pillars of Creation photos (Orion stellar-formation nebula, http://hubblesite.org/newscenter/newsdesk/archive/releases/1995/44/image/a) that describes a small point being comparable to the breadth of our solar system, ~4.3 light-years to Centauri isn't that far... Maybe the seldom-discussed/appreciated metal flecks are the real gems in the meteorites? Or, is the nebula in my head too dense that am I just missing something obvious? How is my logic flawed? Cheers, Pete From: Warin Roger [EMAIL PROTECTED] To: Sterling K. Webb [EMAIL PROTECTED],meteorite-list@meteoritecentral.com CC: E.P. Grondine [EMAIL PROTECTED] Subject: Re : [meteorite-list] Chondrule formation mechanism (Info Please) Date: Tue, 24 Oct 2006 16:15:53 + (GMT) Hi, all, I am surprised that nobody evoked the theory following which chondrules were formed in relatively very few privileged zones of space. They would then form through one or more impacts of relatively large asteroids, onto the parent body covered with regoliths (and even with megaregoliths). The excellent book of Derek Sears, entitled The origin of chondrules and chondrites (Cambridge Planetary Science, 2004) supports this hypothesis. In corollary, ordinary chondrites (85% on Earth) would be quite rare in cosmos, and only few parent bodies would produce chondrites. Glad to hear some comments on the above assumptions. Thanks, Roger Warin - Message d'origine De : Sterling K. Webb [EMAIL PROTECTED] À : meteorite-list@meteoritecentral.com Cc : E.P. Grondine [EMAIL PROTECTED] Envoyé le : Dimanche, 22 Octobre 2006, 20h38mn 55s Objet : Re: [meteorite-list] Chondrule formation mechanism
Re: [meteorite-list] Chondrule formation mechanism (Info Please)
are John S. Lewis The Physics and Chemistry of the Solar System. The 2 Ed. is $75, $35 used. (I was lucky; I caught it when it was remaindered out of print and bought it for $8. The other is Stuart Ross Taylor, Solar System Evolution (1992) also very expensive. I bought a copy when 1st ed. was remaindered out of print for $4. However, the 2nd Ed. (1999), much bigger, is available used for $20: http://www.bookcloseouts.com/default.asp?R=0521641306B --- - Original Message - From: E.P. Grondine [EMAIL PROTECTED] To: Sterling K. Webb [EMAIL PROTECTED] Sent: Monday, October 23, 2006 3:25 PM Subject: Re: [meteorite-list] Chondrule formation mechanism (Info Please) Hi Sterling, If the dates are right, the problem becomes how did that many identical atoms get together in one place so that the chondrules could form? Since this question has no good answer, one is forced to look at the dating and exactly what it is that that dating measured. No doubt the constituent components of our solar system date to that time, but does this mean that the formation of the condrules and their matrices date to that time? I still want to look at that Krasnojarsk - the mechanism for the olivine inclusions has to be interesting, whatever it was - its the best excuse I can come up with - what do you think about that one? Thanks, Ed === message truncated === __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Chondrule formation mechanism (Info Please)
I like this theory very much. (I particularly like it because it allows the structure to form the way i described it) Rob McC --- Mr EMan [EMAIL PROTECTED] wrote: I think crystal formation in a fluid preceded the choundrule formation. Seems standard mineralogy and crystalography answer the how. The proto planetary disk was a fluid. Molecules of a feather flock together even in low gravity fields. Each undefined circuit through time and space was another opportunity for like molecules to sort themselves onto a latice. Whatever duration this crystal formation epoch existed, it seemes to have been abruptly forclosed to subsequent growth.(e.g. Depletion of the stock of molecules by a sweeping solar megawind that sorted the natural abundance of the elements in the solar system based on atomic weight?) One current theory is that a period of intense mega-lightening 500 million miles long flash-melted the chondrules. If this were the case perhaps the vitrified spherical globs slowly restored the crystal lattice within the confines of the sphere. I think this is a part of the answer but not the whole story. Elton __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Chondrule formation mechanism (Info Please)
Hi Rob - molecules of a feather flock together? why? If they did, then say an initial detonation of our sun could have been the heat which fused them together. I think speculation on this kind of blast has been bandied about much recently. good hunting, Ed --- Rob McCafferty [EMAIL PROTECTED] wrote: I like this theory very much. (I particularly like it because it allows the structure to form the way i described it) Rob McC --- Mr EMan [EMAIL PROTECTED] wrote: I think crystal formation in a fluid preceded the choundrule formation. Seems standard mineralogy and crystalography answer the how. The proto planetary disk was a fluid. Molecules of a feather flock together even in low gravity fields. Each undefined circuit through time and space was another opportunity for like molecules to sort themselves onto a latice. Whatever duration this crystal formation epoch existed, it seemes to have been abruptly forclosed to subsequent growth.(e.g. Depletion of the stock of molecules by a sweeping solar megawind that sorted the natural abundance of the elements in the solar system based on atomic weight?) One current theory is that a period of intense mega-lightening 500 million miles long flash-melted the chondrules. If this were the case perhaps the vitrified spherical globs slowly restored the crystal lattice within the confines of the sphere. I think this is a part of the answer but not the whole story. Elton __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Chondrule formation mechanism (Info Please)
Hi, For those interested in follow-up to Sears' theories but reluctant to pop for the new book: Here's a nice (free) piece by Sears (cheaper than buying the $110 book...) http://www.lpi.usra.edu/meetings/lpsc97/pdf/1179.PDF A summary of some of Sears' views (by Bernd Pauli): http://www7.pair.com/arthur/meteor/archive/archive4/Feb98/temp/msg00213.html The best tests are experimental: Chondrules can be made in the laboratory: http://www.space.com/scienceastronomy/solarsystem/fiery_rain_000809.html Sterling K. Webb - - Original Message - From: Warin Roger To: Sterling K. Webb ; meteorite-list@meteoritecentral.com Cc: E.P. Grondine Sent: Tuesday, October 24, 2006 11:15 AM Subject: Re : [meteorite-list] Chondrule formation mechanism (Info Please) Hi, all, I am surprised that nobody evoked the theory following which chondrules were formed in relatively very few privileged zones of space. They would then form through one or more impacts of relatively large asteroids, onto the parent body covered with regoliths (and even with megaregoliths). The excellent book of Derek Sears, entitled “The origin of chondrules and chondrites” (Cambridge Planetary Science, 2004) supports this hypothesis. In corollary, ordinary chondrites (85% on Earth) would be quite rare in cosmos, and only few parent bodies would produce chondrites. Glad to hear some comments on the above assumptions. Thanks, Roger Warin - Message d'origine De : Sterling K. Webb [EMAIL PROTECTED] À : meteorite-list@meteoritecentral.com Cc : E.P. Grondine [EMAIL PROTECTED] Envoyé le : Dimanche, 22 Octobre 2006, 20h38mn 55s Objet : Re: [meteorite-list] Chondrule formation mechanism (Info Please) Hi, Ed, Rob, This scenario (Ed's) would require that we would find a chondrule with a formation age of 3.9 Gya, I think. As far as I know, that has never happened. All chondrites (so called because they contain chondrules) are the same age: about 4.555 Gya. Chondrules are the same age (2 to 5 million years variation among chondrules) as the chondrites they occur in. The about is because the dating methods have a limit to how precisely they can resolve small age differences. Dating by lead isotopes says the solar system is 4.560 +/- 0.005 Gya old. Other systems of isotope measurements (like 147Sm/143Nd) give 4.553 +/- 0.003, and so forth. Within the limits of measurement, all chondrites are the same age, a hair younger than the solar system itself, the Class of Zero, and so are their chondrules. Meteorites that do not (never did) contain chondrules have varying ages. Lunaites are the age of that portion of the lunar crust they came from, generally quite old compared to Martians which have the formation age of the basalt flow they were chipped off of for the long haul to Earth. Irons, which formed inside a differentiating body, have younger ages; some very much younger if the differentiation took a long time (Weekeroo Station IIe is 4.340 Gya, Kodaikanal IIe 3.800 Gya, many IAB irons the same). I'm thinking that before you need to develop a theory to explain a 3.9 Gya chondrule, you'd have to actually have a 3.9 Gya chondrule. As far as I know, none with discordant ages have ever been found. In certain solar circles it would be Big News. Oddly, if you Google for oldest chondrule, you get the oldest chondrules, and if you Google for youngest chondrule, you get the oldest chondrules... on the grounds that it is young as the solar system. If you Google for discordant chondrule age, you get arguments over 2 or 3 million years in the age of something 4-1/2 billion years old. Sterling K. Webb - Original Message - From: E.P. Grondine [EMAIL PROTECTED] To: meteorite-list@meteoritecentral.com Sent: Sunday, October 22, 2006 10:24 AM Subject: Re: [meteorite-list] Chondrule formation mechanism (Info Please) Hi Rob - You noticed the contradiction in cooling periods as well. What I am thinking is that there was at least one larger parent body which was disrupted about 3.9 Gya (at time of LPBE). When this larger parent body was disrupted, then the effervescent foaming that led to some chondrules occured - sudden cooling, as gravitation pressure had been released, and much lower local gravity. Local processes suddenly take over - a sharp gravitational and pressure transition, and a sudden cooling. Gross processes - perhaps sufficiently gross to overwhelm other small forces. Through collisions of the resulting fragments, we see some of the meteorite types we see today. good hunting, Ed __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list Découvrez une nouvelle façon d'obtenir des réponses à toutes vos questions ! Profitez des connaissances, des opinions et des
Re: [meteorite-list] Chondrule formation mechanism (Info Please)
Hi Sterling: Derek's book is only $107.50 on Amazon.com. I hope that Derek will be writing an article for the February issue of Meteorite magazine. Larry On Tue, October 24, 2006 11:28 am, Sterling K. Webb wrote: Hi, For those interested in follow-up to Sears' theories but reluctant to pop for the new book: Here's a nice (free) piece by Sears (cheaper than buying the $110 book...) http://www.lpi.usra.edu/meetings/lpsc97/pdf/1179.PDF A summary of some of Sears' views (by Bernd Pauli): http://www7.pair.com/arthur/meteor/archive/archive4/Feb98/temp/msg00213.ht ml The best tests are experimental: Chondrules can be made in the laboratory: http://www.space.com/scienceastronomy/solarsystem/fiery_rain_000809.html Sterling K. Webb - - Original Message - From: Warin Roger To: Sterling K. Webb ; meteorite-list@meteoritecentral.com Cc: E.P. Grondine Sent: Tuesday, October 24, 2006 11:15 AM Subject: Re : [meteorite-list] Chondrule formation mechanism (Info Please) Hi, all, I am surprised that nobody evoked the theory following which chondrules were formed in relatively very few privileged zones of space. They would then form through one or more impacts of relatively large asteroids, onto the parent body covered with regoliths (and even with megaregoliths). The excellent book of Derek Sears, entitled The origin of chondrules and chondrites (Cambridge Planetary Science, 2004) supports this hypothesis. In corollary, ordinary chondrites (85% on Earth) would be quite rare in cosmos, and only few parent bodies would produce chondrites. Glad to hear some comments on the above assumptions. Thanks, Roger Warin - Message d'origine De : Sterling K. Webb [EMAIL PROTECTED] À : meteorite-list@meteoritecentral.com Cc : E.P. Grondine [EMAIL PROTECTED] Envoyé le : Dimanche, 22 Octobre 2006, 20h38mn 55s Objet : Re: [meteorite-list] Chondrule formation mechanism (Info Please) Hi, Ed, Rob, This scenario (Ed's) would require that we would find a chondrule with a formation age of 3.9 Gya, I think. As far as I know, that has never happened. All chondrites (so called because they contain chondrules) are the same age: about 4.555 Gya. Chondrules are the same age (2 to 5 million years variation among chondrules) as the chondrites they occur in. The about is because the dating methods have a limit to how precisely they can resolve small age differences. Dating by lead isotopes says the solar system is 4.560 +/- 0.005 Gya old. Other systems of isotope measurements (like 147Sm/143Nd) give 4.553 +/- 0.003, and so forth. Within the limits of measurement, all chondrites are the same age, a hair younger than the solar system itself, the Class of Zero, and so are their chondrules. Meteorites that do not (never did) contain chondrules have varying ages. Lunaites are the age of that portion of the lunar crust they came from, generally quite old compared to Martians which have the formation age of the basalt flow they were chipped off of for the long haul to Earth. Irons, which formed inside a differentiating body, have younger ages; some very much younger if the differentiation took a long time (Weekeroo Station IIe is 4.340 Gya, Kodaikanal IIe 3.800 Gya, many IAB irons the same). I'm thinking that before you need to develop a theory to explain a 3.9 Gya chondrule, you'd have to actually have a 3.9 Gya chondrule. As far as I know, none with discordant ages have ever been found. In certain solar circles it would be Big News. Oddly, if you Google for oldest chondrule, you get the oldest chondrules, and if you Google for youngest chondrule, you get the oldest chondrules... on the grounds that it is young as the solar system. If you Google for discordant chondrule age, you get arguments over 2 or 3 million years in the age of something 4-1/2 billion years old. Sterling K. Webb - Original Message - From: E.P. Grondine [EMAIL PROTECTED] To: meteorite-list@meteoritecentral.com Sent: Sunday, October 22, 2006 10:24 AM Subject: Re: [meteorite-list] Chondrule formation mechanism (Info Please) Hi Rob - You noticed the contradiction in cooling periods as well. What I am thinking is that there was at least one larger parent body which was disrupted about 3.9 Gya (at time of LPBE). When this larger parent body was disrupted, then the effervescent foaming that led to some chondrules occured - sudden cooling, as gravitation pressure had been released, and much lower local gravity. Local processes suddenly take over - a sharp gravitational and pressure transition, and a sudden cooling. Gross processes - perhaps sufficiently gross to overwhelm other small forces. Through collisions of the resulting fragments, we see some of the meteorite types we see today. good hunting, Ed
Re: [meteorite-list] Chondrule formation mechanism (Info Please)
--- E.P. Grondine [EMAIL PROTECTED] wrote: Hi Rob - molecules of a feather flock together? why? This is the most blatant speculation on my part and I have not looked it up to check this (though to be fair, I didn't make the comment above, I just like it) but this is what I think and no more... Supernova are responsible for the synthesis of all the heavier elements. I suspect that large quantities of single elements are likely to be formed at the same place in the catastrophic destruction. I base this soley on the shell model of Supergiant stars and that the explosion is likely to apply the same temperature and energy to these regions making it likely that many fusion events in one place produce the same daughter element. These will inevitably spread in the explosion but are still going to travel in similar directions. This is obviously an off the cuff description and I've probably no justification for suggesting they head off in the same direction into space. This debris will eventually come together to form a protodisk. I am not sure that it is necessarily the case that elements or molecules of a feather -as it was put- may necessarily flock together. How homogenous the disk is I don't know but I cannot see any reason why it shouldn't be. Jupiter is essentially the same composition as the sun, after all but the sun also contains all the same elements as the earth, as observed spectrally. The structure of gas giants have rocky interiors and probably similar to terrestrial planets bulk composition. What it may be is that the minerals/elements which formed the chondrules condensed first. I believe this is what is currently believed. This being the case, it makes sense that they are mostly made of similar stuff as this is all there was to make them. I appreciate that different chondrules have different minerals, even in the same meteorite. I suppose this is where your question is most valid, why did they group together like that and why aren't they all a general mish-mash of all the available minerals? I suppose an answer to this is the chondrules may have initially formed at different distances. They can come together to form parent bodies interspersed by matrix at a later period. We've seen on this list in the last few months that planetary orbits are not nearly as fixed as we tend to think (the dancing rings video of the inner solar system and Neptune's migration spring immediately to mind). My difficulty with this is why would minerals form at different distances? Under gravity they'd all fall inward at the same rate during the earliest period of the disk formation. I need to have a bit of a think about it. It may be due to temperature in the protdisk at different distances. Not convinced I can bull my answer to that. Another contentious rambling I have is that the reason for the clumping of similar molecules is normal. If you think how crystals form in liquids, you need a nucleation point but once you begin to build up a structure there is a tendency for them to stick to their own type. This is true for liquid drops as well. I don't know if this is Van der Waal's forces or something else. VdW is a tiny force as I recal but in a low density environmet with a few thousand years, it may be enough. Dunno. I hope to one day have the mathematical ability and the time to work this out before someone else does...If only to prove I'm wrong. Sorry for the lengthy mail. I felt it needed it, even if it is all unsubstantiated. I just hope it's not twaddle. Rob McC __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Chondrule formation mechanism (Info Please)
Hi Sterling, I did not post my reply to you to the list, so they won't know what the extracts you cited came from - if you have a copy of that message please post it - The problem still remains what caused sufficient number of atoms of the same type to be in the same place at the same time to produce the crystals and glasses observed. If you have the gravity of a source proto-planet differentiating the components in an immiscible melt, then that problem is solved. I can't see any differentiating mechanism for an instellar melt, regardless of energy source. No doubt the dating techniques are accurate. And no doubt the elements were frozen in time in the chondrule glasses and crystals. But is what is being dated, the elements' formation date, or the chondrule's formation date? good hunting, Ed --- Sterling K. Webb [EMAIL PROTECTED] wrote: Hi, Ed, ...but does this mean that the formation of the condrules and their matrices date to that time? The formation date is when all the various materials can no longer be mixed with other material, be wetted, dried, migrate, be modified, interact chemically, be altered, or otherwise be messed with. The tiny packet of the chondrule is melted, fused, sealed -- ain't nothing going nowhere. From that point, the isotopes decay without any material being allowed to escape. The uranium turns slowly to a peculiar isotope of lead with a long halflife (billions of years). You count the uranium atoms; you count the odd lead atoms; calculate how long it took for some of the original uranium to that number of lead atoms. Since nothing can enter or leave the chondrule, it's pretty accurate (very accurate). No doubt the constituent components of our solar system date to that time, but does this mean that the formation of the condrules and their matrices date to that time? A solid rock, a melted lump (like a chondrule), a piece of glass (like a tektite) are all good dating candidates because atoms can't go waltzing in and out like it was a border bordello... Once a rock or any lump shows signs of being altered by the environment, partial melting or heating, aqueous modification, alarm flags go up. Sometimes, it's a good thing: a tektite's K/Ar date turns out to be when it either impacted or was impacted, but it's Rb/Sr shows (I think) its original formation date (curiously, about 480 mya). Many wouldn't agree with that, but they then have to explain why its original Rb/Sr ratio is radically different from ANY other rock, on Earth or off. (Mostly that detail's ignored.) At any rate, it's different from its K/Ar date (each tektite type has its own K/Ar date). If the dates are right, the problem becomes how did that many identical atoms get together in one place so that the chondrules could form? Not sure what you mean here. The chondrules have many elements in many compounds, just like the meteorites, many of the same ones. They were gas and dust before being flash melted, typical of the inner solar nebula -- the usual crap. Lots of argument about what melted them, and the details, of course, solar flare, electric currents in the disc, magnetic effects, shock waves? Your theory of pressure release isn't necessarily dead. What if a sudden short heating event (solar flare for example) melts them radiatively and heats the gas around that region. After the chondrule is flash fried, the hot gas (no longer being heated) expands rapidly and the heat and pressure around the chondrule drops as the gas expands and cools, letting them cool quickly by radiating their heat away quickly (?). I should shut up; that's dangerously close to being chemistry... Sterling --- My favorite two books on the formation of the solar system are John S. Lewis The Physics and Chemistry of the Solar System. The 2 Ed. is $75, $35 used. (I was lucky; I caught it when it was remaindered out of print and bought it for $8. The other is Stuart Ross Taylor, Solar System Evolution (1992) also very expensive. I bought a copy when 1st ed. was remaindered out of print for $4. However, the 2nd Ed. (1999), much bigger, is available used for $20: http://www.bookcloseouts.com/default.asp?R=0521641306B --- - Original Message - From: E.P. Grondine [EMAIL PROTECTED] To: Sterling K. Webb [EMAIL PROTECTED] Sent: Monday, October 23, 2006 3:25 PM Subject: Re: [meteorite-list] Chondrule formation mechanism (Info Please) Hi Sterling, If the dates are right, the problem becomes how did that many identical atoms get together in one place so that the chondrules could form? Since this question has no good answer, one is forced to look at the dating and exactly what it is that that dating measured. No doubt
Re: [meteorite-list] Chondrule formation mechanism (Info Please)
--- E.P. Grondine [EMAIL PROTECTED] wrote: The problem still remains what caused sufficient number of atoms of the same type to be in the same place at the same time to produce the crystals and glasses observed. I think crystal formation in a fluid preceded the choundrule formation. Seems standard mineralogy and crystalography answer the how. The proto planetary disk was a fluid. Molecules of a feather flock together even in low gravity fields. Each undefined circuit through time and space was another opportunity for like molecules to sort themselves onto a latice. Whatever duration this crystal formation epoch existed, it seemes to have been abruptly forclosed to subsequent growth.(e.g. Depletion of the stock of molecules by a sweeping solar megawind that sorted the natural abundance of the elements in the solar system based on atomic weight?) One current theory is that a period of intense mega-lightening 500 million miles long flash-melted the chondrules. If this were the case perhaps the vitrified spherical globs slowly restored the crystal lattice within the confines of the sphere. I think this is a part of the answer but not the whole story. Elton __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Chondrule formation mechanism (Info Please)
Ed Thanks for the reply. I'd really like to take a look at any data but to help be more specific on my requirements I'll give you an outline on my idea. The appearance of the unaltered chondrites seems to show that the outer rim of the chondrules are of a significantly diferent structure to the interior. Petrographic slides seem to show this as a dark boundary between the matrix and the chondrul and generally, the lower the petrographic type, the clearer this boundary is. 3.x it is impossible not to spot it. Now my understanding of this is that this is evidence of a rapid quenching period and the good internal structure is due to a much longer cooling period and this is where the current literature seems to stop. I do not believe that it need necessarily be evidence for rapid quenching and is instead a natural phenomena which occurs in true microgravity. A few months ago I was discussing Einstein's theories on Brownian Motion (as you do) with Canadian Astronaut, Bjarni Tryggvasson and he said that a few years ago he noticed Einstein missed a term for external energy and wanted to know what may happen if you removed external enegy sources (vibrations). Even on Mir and The Space Shuttle, the environment was not true microgravity (it's milligravity) you get minor accelerations due to vibrations in the spacecraft. So he developed a device to remove these vibrations and the environment in his equipment is of the order of 10^-6 g. He found that brownian motion is altered hugely by the lack of vibrations from an external source. Mixing is reduced by a factor of 3. A lot of what he was talking about was too abstract to fully comprehend at the time but it was fascinating so I read his paper and was astounded. Amazingly the temperature gradient at the surface of a liquid in microgravity is much steeper than on earth. Liquids are cooler at the surface because they lose heat outwards but by losing most of your brownian motion which would otherwise mix the outer and inner layers it increases the temp gradiaent massively. (convection is eliminated by microgravity and other forms of convection due to surface tension are removed in the experiment. These do not occur in small enough droplets anyway) Then I came accross one of his images of a glass bead forming in microgravity. It's about 0.5mm across (sound familiar?) and in thin section it has this beautiful outer rim that I instantly thought hmm! I've seen that before. I'm pretty convinced that nobody else has made this connection. Meteoritics and brownian motion in microgravity are pretty far apart in the library of knowledge I'd have thought. I wondered if I could be right. Over the last couple of months I've tried to contact this guy again with no sucess to ask for more details of his experiments. This is why I'm asking you lot for help on the chondrule issue. I'd like to see some proper analysis of the structure of the chondrule boundary. It's likely that the similarity is coincidental but I'd like to check anyway. It's why I want to know the theory on the solar nebula conditions. Too great a density would produce vibrations which prevent this happening but I suspect interplanetary vibrations, even that early on, at the distances these things formed at from a protostar is going to be unlikely to prevent chondritic glasses forming the boundary they exhibit. I personally think this is an elegant idea which does away with a lot of the messy heating, cooling stuff. The outer layer would form a nice insulating layer which would then allow the interior of chondrules to cool slowly and exhibit the structures we see. It neatly requires chondrules to form first. Other stuff would disrupt the pattern we see. The way I see it they needn't take too long to form either. But then, I'm probably not seeing it correctly. That's why I need information. I don't know enough yet about the birth of solar systems to even guess at the implications of my idea if it ever proved correct. I'd like to work on it and prove SOMETHING, anything. My mum always had aspirations of me becoming a doctor...ahem. Rob McCafferty --- E.P. Grondine [EMAIL PROTECTED] wrote: jeez Bob, and all I was trying to do was to come up with a good excuse to personally examine that Krasnojarsk RSPOD Oct 15. You're just about ready to handle some of my asteroid and comet impact correspondence. Ed --- Rob McCafferty [EMAIL PROTECTED] wrote: Hi list What I have ben able to find personally on chondrule formation is rather sketchy. Even the otherwise comprehensive Encyclopedia of Meteorites by O. Richard Norton seems to skim over the mechanism in a paragraph. It's almost as if there is something which defies explanation and scientists abhor that more than nature abhors a vacuum. The slow cooling followed by a rapid quenching period is that which interests me most. I would dearly like to know where to find the most up-to-date theories on
Re: [meteorite-list] Chondrule formation mechanism (Info Please)
Hi Rob - You noticed the contradiction in cooling periods as well. What I am thinking is that there was at least one larger parent body which was disrupted about 3.9 Gya (at time of LPBE). When this larger parent body was disrupted, then the effervescent foaming that led to some chondrules occured - sudden cooling, as gravitation pressure had been released, and much lower local gravity. Local processes suddenly take over - a sharp gravitational and pressure transition, and a sudden cooling. Gross processes - perhaps sufficiently gross to overwhelm other small forces. Through collisions of the resulting fragments, we see some of the meteorite types we see today. The problem here is that vibrations and accelerations from the disruption should show up in the chondrules. Getting enough cosmic dust particles of exactly the same type together to be melted together by some process into a chondrule of exactly the same composition all the way across does not seem too likely - but then there may have been some process to gather together cosmic dust particles of identical composition. The energy source for the dust melting should be seen in the chondrules - at least the melting energies can be calculated. Perhaps there is some non-euclidian solution for the composition problem, but id so it is well beyond me now, as is detailed measuring of chondrule boundaries. Oh well. Researching Krasnojarsk, I have at least discovered why some people become meteorite dealers - they do it so they can afford meteorites. good hunting, Ed --- Rob McCafferty [EMAIL PROTECTED] wrote: Ed Thanks for the reply. I'd really like to take a look at any data but to help be more specific on my requirements I'll give you an outline on my idea. The appearance of the unaltered chondrites seems to show that the outer rim of the chondrules are of a significantly diferent structure to the interior. Petrographic slides seem to show this as a dark boundary between the matrix and the chondrul and generally, the lower the petrographic type, the clearer this boundary is. 3.x it is impossible not to spot it. Now my understanding of this is that this is evidence of a rapid quenching period and the good internal structure is due to a much longer cooling period and this is where the current literature seems to stop. I do not believe that it need necessarily be evidence for rapid quenching and is instead a natural phenomena which occurs in true microgravity. A few months ago I was discussing Einstein's theories on Brownian Motion (as you do) with Canadian Astronaut, Bjarni Tryggvasson and he said that a few years ago he noticed Einstein missed a term for external energy and wanted to know what may happen if you removed external enegy sources (vibrations). Even on Mir and The Space Shuttle, the environment was not true microgravity (it's milligravity) you get minor accelerations due to vibrations in the spacecraft. So he developed a device to remove these vibrations and the environment in his equipment is of the order of 10^-6 g. He found that brownian motion is altered hugely by the lack of vibrations from an external source. Mixing is reduced by a factor of 3. A lot of what he was talking about was too abstract to fully comprehend at the time but it was fascinating so I read his paper and was astounded. Amazingly the temperature gradient at the surface of a liquid in microgravity is much steeper than on earth. Liquids are cooler at the surface because they lose heat outwards but by losing most of your brownian motion which would otherwise mix the outer and inner layers it increases the temp gradiaent massively. (convection is eliminated by microgravity and other forms of convection due to surface tension are removed in the experiment. These do not occur in small enough droplets anyway) Then I came accross one of his images of a glass bead forming in microgravity. It's about 0.5mm across (sound familiar?) and in thin section it has this beautiful outer rim that I instantly thought hmm! I've seen that before. I'm pretty convinced that nobody else has made this connection. Meteoritics and brownian motion in microgravity are pretty far apart in the library of knowledge I'd have thought. I wondered if I could be right. Over the last couple of months I've tried to contact this guy again with no sucess to ask for more details of his experiments. This is why I'm asking you lot for help on the chondrule issue. I'd like to see some proper analysis of the structure of the chondrule boundary. It's likely that the similarity is coincidental but I'd like to check anyway. It's why I want to know the theory on the solar nebula conditions. Too great a density would produce vibrations which prevent this happening but I suspect interplanetary vibrations, even that early on, at the distances these things formed at from a protostar is going to be
Re: [meteorite-list] Chondrule formation mechanism (Info Please)
Hi, Ed, Rob, This scenario (Ed's) would require that we would find a chondrule with a formation age of 3.9 Gya, I think. As far as I know, that has never happened. All chondrites (so called because they contain chondrules) are the same age: about 4.555 Gya. Chondrules are the same age (2 to 5 million years variation among chondrules) as the chondrites they occur in. The about is because the dating methods have a limit to how precisely they can resolve small age differences. Dating by lead isotopes says the solar system is 4.560 +/- 0.005 Gya old. Other systems of isotope measurements (like 147Sm/143Nd) give 4.553 +/- 0.003, and so forth. Within the limits of measurement, all chondrites are the same age, a hair younger than the solar system itself, the Class of Zero, and so are their chondrules. Meteorites that do not (never did) contain chondrules have varying ages. Lunaites are the age of that portion of the lunar crust they came from, generally quite old compared to Martians which have the formation age of the basalt flow they were chipped off of for the long haul to Earth. Irons, which formed inside a differentiating body, have younger ages; some very much younger if the differentiation took a long time (Weekeroo Station IIe is 4.340 Gya, Kodaikanal IIe 3.800 Gya, many IAB irons the same). I'm thinking that before you need to develop a theory to explain a 3.9 Gya chondrule, you'd have to actually have a 3.9 Gya chondrule. As far as I know, none with discordant ages have ever been found. In certain solar circles it would be Big News. Oddly, if you Google for oldest chondrule, you get the oldest chondrules, and if you Google for youngest chondrule, you get the oldest chondrules... on the grounds that it is young as the solar system. If you Google for discordant chondrule age, you get arguments over 2 or 3 million years in the age of something 4-1/2 billion years old. Sterling K. Webb - Original Message - From: E.P. Grondine [EMAIL PROTECTED] To: meteorite-list@meteoritecentral.com Sent: Sunday, October 22, 2006 10:24 AM Subject: Re: [meteorite-list] Chondrule formation mechanism (Info Please) Hi Rob - You noticed the contradiction in cooling periods as well. What I am thinking is that there was at least one larger parent body which was disrupted about 3.9 Gya (at time of LPBE). When this larger parent body was disrupted, then the effervescent foaming that led to some chondrules occured - sudden cooling, as gravitation pressure had been released, and much lower local gravity. Local processes suddenly take over - a sharp gravitational and pressure transition, and a sudden cooling. Gross processes - perhaps sufficiently gross to overwhelm other small forces. Through collisions of the resulting fragments, we see some of the meteorite types we see today. good hunting, Ed __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Chondrule formation mechanism (Info Please)
Hi list What I have ben able to find personally on chondrule formation is rather sketchy. Even the otherwise comprehensive Encyclopedia of Meteorites by O. Richard Norton seems to skim over the mechanism in a paragraph. It's almost as if there is something which defies explanation and scientists abhor that more than nature abhors a vacuum. The slow cooling followed by a rapid quenching period is that which interests me most. I would dearly like to know where to find the most up-to-date theories on chondrul formation. I know about the R-R Lyrae heating, timescales and frequecies for newly forming stars. I need theory of protostellar nebula. Maybe Nebula density/stellar distance formula. The conditions in which and the timescale in which these 0.1- 3mm chondules formed. Contact off list if you wish. I need this information to assist me with a theory I have, the information for which comes from branches of science so diverse, that their relevance has not been realised. It is only by serendipity that I make the connection. My thoughts will appear here first (though I will ruthlessly hunt down and murder anyone who tries to plagarise my theory, hehe) Rob McCafferty --- Darren Garrison [EMAIL PROTECTED] wrote: On Sat, 21 Oct 2006 16:41:48 -0700 (PDT), you wrote: Chondrule textures depend on the extent of melting of the chondrule precursor- material when cooling starts. Kind of begs the question - chodrules formed by collision, which causes melt - consider if one started from a steady molten state If viable nuclei I wonder what these viable nuclei are? viable cystal nuclei=Chondrules? How things appear to be (without trying to refer to chemical/minerological details that are beyond my level of knowledge) is that what became chondrules started out as fluff that slowly accumulated from the solar nebula, like you mentioned earlier. I imagine something like snowflakes, or dust-bunnies. Something fragile and irregular filled with empty spaces. Then, something (and there is no consensus on what that something was) heated those dust-bunnies/snowflakes up to the point where they melted-- and in a microgravity environment surface tension pulled them into little spheres. The viable nuclei means parts of that original fluff that didn't fully melt and became seeds for the new minerals to grow on. __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Chondrule formation mechanism (Info Please)
jeez Bob, and all I was trying to do was to come up with a good excuse to personally examine that Krasnojarsk RSPOD Oct 15. You're just about ready to handle some of my asteroid and comet impact correspondence. Ed --- Rob McCafferty [EMAIL PROTECTED] wrote: Hi list What I have ben able to find personally on chondrule formation is rather sketchy. Even the otherwise comprehensive Encyclopedia of Meteorites by O. Richard Norton seems to skim over the mechanism in a paragraph. It's almost as if there is something which defies explanation and scientists abhor that more than nature abhors a vacuum. The slow cooling followed by a rapid quenching period is that which interests me most. I would dearly like to know where to find the most up-to-date theories on chondrul formation. I know about the R-R Lyrae heating, timescales and frequecies for newly forming stars. I need theory of protostellar nebula. Maybe Nebula density/stellar distance formula. The conditions in which and the timescale in which these 0.1- 3mm chondules formed. Contact off list if you wish. I need this information to assist me with a theory I have, the information for which comes from branches of science so diverse, that their relevance has not been realised. It is only by serendipity that I make the connection. My thoughts will appear here first (though I will ruthlessly hunt down and murder anyone who tries to plagarise my theory, hehe) Rob McCafferty --- Darren Garrison [EMAIL PROTECTED] wrote: On Sat, 21 Oct 2006 16:41:48 -0700 (PDT), you wrote: Chondrule textures depend on the extent of melting of the chondrule precursor- material when cooling starts. Kind of begs the question - chodrules formed by collision, which causes melt - consider if one started from a steady molten state If viable nuclei I wonder what these viable nuclei are? viable cystal nuclei=Chondrules? How things appear to be (without trying to refer to chemical/minerological details that are beyond my level of knowledge) is that what became chondrules started out as fluff that slowly accumulated from the solar nebula, like you mentioned earlier. I imagine something like snowflakes, or dust-bunnies. Something fragile and irregular filled with empty spaces. Then, something (and there is no consensus on what that something was) heated those dust-bunnies/snowflakes up to the point where they melted-- and in a microgravity environment surface tension pulled them into little spheres. The viable nuclei means parts of that original fluff that didn't fully melt and became seeds for the new minerals to grow on. __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
