On Feb 11, 2:23=A0pm, Crown-Horned Snorkack <chornedsnork...@[EMAIL PROTECTED]
>
wrote:
> There are plenty of main sequence orange dwarfs in globular clusters.
Fair enough, if you have an old enough population of stars, you can
have old and coolish white dwarfs (although the metallicities in
globular might be low enough to make for some interesting planet
formation mechanics as well). It seems I overestimated the number of
cooler stars. Is there any hard data on the population density of
white dwarfs of various temperatures (corrected for observational
bias, as much as possible?)
> As for nearby "white" dwarfs, Procyon B is just about 7500 K, and it
> is considerably younger than Sun.
Yep. It should also have a BB UV emission about 100 times that of the
Sun, if I did my numbers right. Even for a star around 6000 K, you
expect a UV increase of twice that of the Sun, roughly speaking. The
question then becomes "how much UV can an early biosphere handle",
which is a tougher question.
> Simply drop the distance and central mass from the equation, and
> express the tidal locking limit in terms of orbital period.
>
> This leaves the variables of 2nd order Love #, Quality factor, initial
> rotational period and density of the planet.
OK, *if* I got my math right,
P_orbital =3D ( 0.104 {(k2/Q) / rho}^(1/6) T P_rotational )^(1/4)
I'm not sure that's a lot easier, but I think that's the form you were
implying (with very odd units: T in years, P_orbital in years, and
P_rotational in hours, ugh). The original I got out of Burn's
"Satellites", for comparison.
--
Brian Davis
|
