I've my own collection of ideas as to how chondrules developed but will save them for later. As to CAIs and their presence in carbonaceous meteorites. A list member and I had this discussion some time ago and the answer may lie in a process in the "T-Tauri" stage of stellar evolution.
When the T-Tauri protostar goes thermonuclear it loses a mass through a high solar wind output which sweeps a lot of the remaining unaccreted debris from the inner solar system--we believe. This is the foundation for our ability to develop isotopic curves of regions based on distance from the sun and explains the rocky inner planets and the gas giants much further out in the solar system. This probably is a player in chondrule formation. CAIs are dated to about 2 million years older. Prior to the hydrogen fuel-burning stage, there was an ongoing fission process which is the likely source for the short-lived isotopes such as 26Al. While I can't lay my hands on the link, I recall some diagrams of a particular phase of T-Tauri accretion where the dynamics were such that even though the solar disk was being spun into a flat, thin, rotating disk, the poles of the proto-sun were ejecting major mega streams of lighter, probably charged particles-- mainly such as calcium, aluminum, carbon, helium, etc. The particle streams resembled fountains spraying very high speed particles many many AUs up and out of the plane of the ecliptic into two giant hemispheres. If true, this tends to explain the Ort cloud formation and how CAIs were available for inclusion in cometary-like carbonaceous meteorites along with younger chondrules. It explains how CAIs predate the sun's fusion stage and how they were able to skip the mega solar winds generated when the sun kicked over to fusion from fission. Comets forming inside the Ort Cloud but outside the ecliptical plane my be devoid of chondrules (possible example: Tagish Lake) 1) supernova A super nova is theorized to be the catalyst for compressing enough dust close enough for gravity to take over and condense the early initial solar disk getting things spinning into a disk. > 2) few time later CAI formation Yes but a long time later, possibly explained under the T-Tauri pre-fusion stage during the collapse of the solar disk. 3) at the same time collapse of nebula Yes but probably well after the accretion stage was under way. 4) 2My later condrule formation. Yes again > 5) at the same time proto-sun and proto-planetary formation Probably in connection with the fusion to fusion change-over and during the interval before mega-solar wind swept out the lighter elements from the inner solar system and stopped chondrule formation. > 6) ... There were probably at least 6 additional Mars sized planets else planetary centers of accretion and some theorize 30 or more. One was accounted for by our moons formation, another knocked Uranus on its side one or more contributed to the asteroid belt. Someplace in the sequence comets formed outside the mainstream goings on in the solar disk/system it self. Elton --- On Wed, 9/30/09, Francesco Moser <[email protected]> wrote: > From: Francesco Moser <[email protected]> > Subject: [meteorite-list] CAI and chondrules > To: "ZZ ML Meteorite-List" <[email protected]> > Date: Wednesday, September 30, 2009, 5:37 PM > Hello! > I take a look on wikipedia about CAI and chondrules, but I > have still some doubt. > > http://en.wikipedia.org/wiki/Calcium-aluminium-rich_inclusion > http://en.wikipedia.org/wiki/Chondrule > > What prompted the formation of CAI? and what's caused the > formation of chondurles??? > The supernova gave the energy for the formation of CAI and > for the collapse of the solar nebula? > Some other energy source, still unknow, 2 million years > later molten the material which formed the chondrules? But > wich type of energy source? > > Is correct this time line? > > 1) supernova > 2) few time later CAI formation > 3) at the same time collapse of nebula > 4) 2My later condrule formation > 5) at the same time proto-sun and proto-planetary > formation > 6) ... > > Thanks a lot! > > Best regards! > > Francesco Moser > IMCA #1510 ______________________________________________ http://www.meteoritecentral.com Meteorite-list mailing list [email protected] http://six.pairlist.net/mailman/listinfo/meteorite-list
