Re: conplaneteering
| From: | Jörg Rhiemeier <joerg_rhiemeier@...> |
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| Date: | Saturday, February 12, 2005, 14:47 |
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Hallo!
On Fri, 11 Feb 2005 16:02:29 -0500,
"Mark J. Reed" <markjreed@...> wrote:
> I'm trying to calculate the orbital period of an Earth-sized planet at
> 15 AUs out from a star that's about 7.5 times the mass of the Sun.
What are you going to do with that planet? If you want an Earthlike
planet with nitrogen-oxygen atmosphere and lots of life on it,
forget it! A star with about 7.5 times the mass of the Sun has
a very short lifespan (only a few million years), which means
that the planet doesn't have enough time to evolve an advanced
biosphere before the star goes bust. Your star would go supernova
before the planet has formed a solid crust.
And according to current theories, such huge stars don't have planets
at all. High-mass stars rotate rapidly (with periods of a few
*hours* as compared to the 20-something *days* of the Sun) and
have angular momenta comparable with that of the entire solar
system (where the *mass* is mostly in the Sun, but the *angular
momentum* mostly in the planets), which indicates that they
don't have planets to transfer their angular momentum to.
Greetings,
Jörg.
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