(meteorobs) Fw: Possible meteorite

MexicoDoug at aol.com MexicoDoug at aol.com
Thu May 19 20:06:46 EDT 2005

En un mensaje con fecha 05/19/2005 5:58:54 PM  Mexico Daylight Time, 
geert.barentsen at telenet.be escribe:
Hi  Doug,

(This is a slow reply on a mail you sent to the list 17 days ago,  sorry :-))

>If you work out the math based based  on a few  simplifying assumptions and
>reasonable, you will find that iron   meteorites that fall have a core
>temperature around 90 degrees C (194 F),  which  is rather hot to touch,

This interests me; how do you  calculate the (core) temperature of a (small) 
body in space? Can you or  anyone else give me some pointers on this topic?

Many thanks,
Hola Geert,

Here is a graph for the three main types of meteorites  vs. Solar distance in 
AU, and if you click on "detailed assumptions" you can see  how it is 
generated using a few assumptions.  The assumptions would not be  necessary if you 
knew the topography, mass, composition, and rotational  rates.  But the 
assumptions are probably very good if you just want a guide  for a sphere.  Please 
don't read too much into "Core temperature".   Probably a better description 
would have been "steady state radiative  equilibrium" or something like that 
regarding flux since the idea here is that  you are not looking at a surface in the 
night, nor in the shadow of another  planetoid (a la Dactyl, for example) for 
an extended time but a reasonably  barbequeed (skewered via rotation) 
meteoroid at an internal point principally  influenced by neighboring internal mass 
rather than where the stone or iron  meteoroid is at night-time, which requires 
"reasonable" rotation rates to avoid  having a cold spot or cold poles.  Even 
so, for a pretty small object, the  efficiency of heat conducting probably 
trumps emissivity...And for a large  object with a very long day, like Mercury, 
with no radioactive (warming)  activity and an otherwise dead core and no 
insulating atmosphere (like Venus and  Earth), the assumptions ought to be decent. 
 Note how well the OC  temperatures correspond with the Planet Mars for 
example, and the calculated  temperature ranges with rest of the planets, even, 
except Venus and to some  extent Earth.
Saludos, Doug  

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