[extropy-chat] stardust discovery

[Amara Graps]

Stardust's discovery of crystalline silicates in the dust of comet
Wild 2 implies either:  (1)

1) that the dust formed above glass temperature (>>1000K) in the inner
disk region around a hot young star, and was radially mixed in the
solar nebula from the inner regions a larger distance from the star

or

2) the dust particles condensed in the outflow of evolved red giants or
supergiants stars (for example AGB stars eject 15% of their silicates in
crystalline form)

Discovering which tells us alot of the early formation of the solar
system. Another complication is that crystalline silicates are rapidly
converted into amorphous silicates in the interstellar medium and
back to crystalline silicates in protoplanetary disks.

Next question: does it match solar?

Also, wasn't crystalline silicates was found in the spectra of
comet Hale-Bopp?  Then Stardust's discovery shouldn't be a surprise.

Also, I read that calcium-aluminum-inclusions (CAI) were found,
which are probably from the extremely early part of solar-system
formation (or from the molecular cloud before), which are known
to form quickly by a high temperature event (lightning, for example),
cooling in an hour or a few hours.

So the stardust comet samples indeed have 'hot' embedded in 'cold'...

Amara

(1)
Xander Tielens: Interstellar and Circumstellar Dust
http://presolar.wustl.edu/ref/Tielens2005c.pdf
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Amara Graps, PhD        www.amara.com
Istituto di Fisica dello Spazio Interplanetario, CNR - ARTOV,
Via del Fosso del Cavaliere, 100, I-00133 Roma, ITALIA
tel: +39-06-4993-4375      |  fax:  +39-06-4993-4383
Amara.Graps at ifsi-roma.inaf.it 
http://www.mpi-hd.mpg.de/dustgroup/~graps/                            
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"We came whirling out of Nothingness scattering stars like dust." --Rumi