(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,
Geert
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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