Continuing the quest for a Standardized FT Campaign System (for which I
propose the name "Full Metal Admiral", by the way, although "Fleet Thrust" is
a contender as well).
Making the following assumptions: 1) I have my stellar mass data correct; 2)
the jump limit is 22 light minutes for a G0 star (per
Weber--Alderson drive gives you a jump distance much farther out);
3) jump limit is based on gravity and thus varies by the square root
of the mass--that is, I'm using 22 * (sqrt starmass / sqrt G0mass )
to find the distance;
4) we are using Schoon's "1 hex = 1/3 AU" scale;
then we come up with the following distances, in hexes, from the star to the
jump limit (if you want to place your star in the center of a
hex, remember to include the half-hex from the star to the border of
the center hex).
9.8 F0 9.5 F2 9.1 F5 8.4 F8 7.9 G0 7.7 G2 7.4 G5 7.1 G8 6.9 K0 6.8 K1 6.7 K2
6.5 K3 6.4 K4 6.3 K5 6.0 K7 5.5 M0 5.2 M1 4.9 M2 4.6 M3 4.2 M4 3.9 M5 3.5 M6
3.1 M7 2.7 M8 2.4 M9
I start with F0 because most of the local stars are there or below. Alarish
and OU probably contend for the title "occupant of the star
system with the smallest, puniest star"--I suspect I'm ahead as
Alarish itself orbits a brown dwarf companion to an M3, and Huy
Braseal is even feebler as a dwarf M4--so I went all the way through
the M's.
> Continuing the quest for a Standardized FT Campaign System (for which
There are some problems with assuming that stellar masses are directly related
to stellar types. In fact, there is no correlation at all. For example, you
can have an M0 star, but is it a dwarf, a giant, or a supergiant star? Each
will have a different mass value.
A more direct example: Alpha Orionis (Betelgeuse) is an M2 star. But it is
*huge* and massive. It is ~20x the mass of the sun, and has a volume of about
160 million times that of the sun (I am citing from an
out-dated copy of Burnham's Celestial Handbook because I just happen
to have it on hand:) more accurate numbers can be found in more recent
publications, but these numbers work fine for purposes of this
example :) ). Conversely, an M1/M2 star like GL 229 is much smaller,
and subsequently far less massive and takes up less volume than the sun. But
it's basically the same spectral type as Betelgeuse (~M2).
Another example: the sun, a G0 star, is a dwarf star. It's assumed to be an
'average' star. Rastaban, Beta Draconis, is a G2 star. It is a
supergiant, and out-masses the sun by A Lot (tm). (I don't have the
exact figure onhand). By basic spectral type they are not very different. Yet
their masses (and volume, and luminosity) are radically so.
So, muddying the waters, you need to start clarifying whether a given star is
a dwarf, giant, or supergiant, along with the spectral type, in order to
determine your jump limits. I agree that if you're going to have jump limits
imposed that they should be as a function of mass, but you cannot make a
direct correlation to a star's spectral type.
So, what does this mean? More research for youuuu!:):) If you need some
reference materials or something, lemme know and I'll see what I can dig up.
Mk
The next time you ask me a hypothetical question, the answer is 'no' wrote:
> There are some problems with assuming that stellar masses are directly
Mark is right. To really do jump limits right you should base it on the mass
of the star and then add spectral color and age as background. This background
will influence type of planets, etc., so it is useful. Also remember that most
stars are in multiple star systems, not counting brown dwarfs. Some
astronomers swear Jupiter is a brown dwarf, so Sol just might be a binary star
system too.
> Continuing the quest for a Standardized FT Campaign System (for which
I'd vote for Fleet Thrust.
> 3) jump limit is based on gravity and thus varies by the square root
Good.
[snipped data]
This all looks workable.
> Making the following assumptions:
Insert
1A) that all stars in question are main sequence size V (IIRC)--which
they aren't but the last time I whimpered for a source for more data, no one
responded.
> Indy said:
I hereby let you know. Please note that Nyrath's Star List for the
Official Unofficial GZG Canon, Non-Canon, and Auto-Canon Universe(s)
does not have stellar size, IIRC--at least the last version I
downloaded didn't have it for many/most of the stars in question.
I've written a solar system generator that generates a lot of star details.
One of which is mass. From looking at the code I wrote it seems that mass is
only affected by luminosity. I've included a segment of C++ code below.
If anyone wants it translated I'll be happy to do that but it should be mostly
self explanatory
This give very good figures though I'm not sure why. Certainly I think they'd
be good enough to calculate jump points
#include <math.h>
const double fudgeVal = 3.53155146; // =(6 / LOG10(50))
double Mass = pow(10,log10(Luminosity) / fudgeVal);
Dan
> I've written a solar system generator that generates a lot of star
Well, the other way around, and not entirely--luminosity depends on
temperature, temperature depends on mass and chemical composition. For Main
Sequence stars, if my memory is right, Luminosity is proportional to Mass^3.8,
approximately and leaving out a couple of factors.
> Well, the other way around, and not entirely--luminosity depends on
Ok that's fair. Not being an astronomer, I just picked the equations out of a
book and stuck them into code. The point is that once you have luminosity you
can calculate mass to a fair degree of accuracy (I mean they are only
estimates in the first place). Again looking at the code most of the details
rely on having a luminosity value to generate them. So whether luminosity is
the defining factor for these values or whether they are just proportionally
related it doesn't matter too much.
btw. The book I worked from was Kauffman's "Universe".
Dan
PS: Anyone know how to determine the colour of a star in RGB form given its
luminosity? I had to guess and something a little closer to reality would be
nice.
> Making the following assumptions:
Sorry, I musta missed the post. Been too danged busy around here lately
(lately?) to keep up with all the mail (see 'ps' below), even on this
relatively low-volume group. :-/
> Indy said:
You wouldn't happen to have a list of stars on hand you want mass info
for, would you? ;-)
Mk
(ps: laser-dude, thanks for the colorado/ouray mail)
> I've written a solar system generator that generates a lot of star
The best way to visualize things is to dig up a Hertzsprung-Russell
Diagram. Most astronomy textbooks will have this, and there are a few sources
on the web (although what I've found so far doesn't give a lot of detail; I
ought to generate one myself for my research group)
Mk
> PS: Anyone know how to determine the colour of a star in RGB
You can't tell the color of a star from luminosity. The color of a
star is temperature-dependent, not luminosity-dependent. I refer you
to a Hertzprung-Russell diagram for an illustration of this:
http://astrosun.tn.cornell.edu/courses/astro201/hrdiagram.htm
(though admittedly I've seen very few *green* stars in my time ;-)
Mk
> Daniel Cleyne wrote:
> > Well, the other way around, and not entirely--luminosity depends on
If those stars are part of a multiple star system (and the majority of stars
are), those estimates about mass tend to be very accurate, so they do matter.
The only place where estimates are questionable are distances. If you don't
know about stars, why not go down to the public library and check out a couple
of books about them. University libraries are usually much better, if one is
nearby.
> You can't tell the color of a star from luminosity. The color of a
Green stars appear white to the naked eye.
http://www.faqs.org/faqs/astronomy/faq/part7/