[meteorite-list] Questions about accretion.

[GeoZay at aol.com]

>>How long does the formation of  meteoroid bodies and larger asteroids 
take?<<

I really don't know,  but gonna throw out a guess. I'm assuming that in the 
beginning of star and  planet formation, there is a lot of dust around. I 
recall an experiment aboard  one of the Shuttles or space station where a lot of 
fine material such as talcum  powder was floating around weightless in a 
container. I guess there was  amazement about how this material was clumping very 
fast due to electrostatic  charges. Based on that scenario, I'd have to guess 
that we can expect to see  fist sized clumps in about a month maybe? I'd imagine 
eventually gravity itself  will have to get into the picture as well. Overall, 
I wouldn't think it would  take too many years for asteroid sized bodies to 
form...as long as there are a  lot of raw material available.  

>>How does the iron migrate  to the core?<<

Again I don't really know, but will throw out a  guess for someone to work me 
over with. :O) I'm assuming that the iron will have  to melt in order for 
this differentiation to occur. I guess there will also have  to be a minimum 
sized asteroid in order for iron to melt so it can migrate.  Okay...what could 
melt the iron then? Things that comes to mind is the heat from  radioactive 
elements; Heat from compression; heat generated if the asteroid is  in a strong 
magnetic field around the sun (like the moon Io around Jupiter); and  heat from 
impacts as well. then it becomes sorta like gold in a pan...the  heavies at the 
bottom or middle and lighter material on top...but in this case  without the 
melting. 

>>Do all "large" asteroids consist of an iron  core surrounded by lighter 
materials further towards the asteroids  surface?<<

My guess...if there was some internal melting, I'd say  yes.


>> If a meteoroid is a small part of a larger asteroid,  wouldn't all 
asteroids 
once have been meteoroids by definition during their  formation within 
solar nebulae?<<

I'd say yes to those that  formed from dust. But if a solar nebula is the 
remnants of previous stars that  went supernova, I would imagine there could be a 
fair amount of asteroids left  over from that explosion as well. I don't 
really know. If that was right, I'd  expect to hear about a few meteorites that 
were older than our solar  system...unless our solar system formation began very 
fast after it's source of  material from a supernova occurred showing a near 
similar age.
GeoZay  

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