Re: [nbos] Stellar Radius - Mass - Luminosity Parameters.
Fri Feb 22nd, 2008
The information I had/have is based on main sequence stars rather than
giants, so I don't know how useful this will be...

>From ASTRONOMY: A SELF TEACHING GUIDE by Dinah L. Moche page 82:

Luminocity of Sun is approximately equal to mass to the 3.5 power.

Luminocity = 4 pi R^2 (5.67 EE -8) T^4

There are other books that you may find useful depending on whether you
want to buy them or not...

World-Building: A writer's guide to constructing star systems and
life-supporting planets by Stephen L. Gillet. That book contains formulas
out the whazoo including the apparent diameter of the star from any planet
at any distance from that star. In addition, it has formulas for
correcting for the bolometric luminocity as compared against the apparent
luminocity. I found it to be a very nicely explained book.

WORLD-BUILDING does differ from ASTRONOMY above in listing the mass
luminocity relation as being Luminocity is approximately equal to

mass ^ 3.8 (as opposed to 3.5).

It solves for the other side of the equation by saying that Mass
approximately equal to Luminocity^.2632

GURPS FIRST IN: while it is useful for role playing games, it does have one
feature that might be of interest - stellar masses for type III and type I
stars (Giants and Super Giants). You can use interpolation to determine
star masses and radii for those stars that fall between spectal types (ie a
G3 III won't be listed, but it will fall between G0 and G5 class stars.

For what it is worth, you can now pick up TRAVELLER 2300 as PDF documents
from FAR FUTURES. The ENTIRE collection of books printed for that game
system was made into PDF's and if I recall correctly, runs about $35 plus
s&h. 2300 AD has the math formulas for determing the spherical volume and
thus mass of any given star based on density and radius. Thus, if you know
for example, that the expected density of a star is expected to be 1.01 and
you know its radius - you can determine its mass by virtue of the volumn

I don't know how much help this is, and I apologize if it isn't what you're
looking for. :(

Good luck :)

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