[TML] average stellar intervals

[Jerry W Barrington]

On 11/16/07 12:41 PM, Garry Ward wrote:

> All versions of Traveller have conviently used the notion that stars are at
> least 1 parsec apart.

I prefer 2300AD's 3D charts, positions accurate to .1 LY.  :) But that's me.

> Given how jump drives work, this makes sense.

Not in my view.  I think if hexes were about .5 LY, but the jump ranges and
star densities remained about the same, it would be more interesting.  You
would have a more "clustery" effect that would be very useful for a Pocket
Empires campaign.  (I'd also use true distance, not counted hexes.)

For that matter, instead of a simple (1, 2, 3, 4, 5, 6) progression of
ranges, I wonder what it would look like if they followed some other
progression.  Think of it like a quantum effect.  The energy of different
photons emitted by say, a hydrogen atom don't go in a nice arithmetic
progression.

R=6*N^(2/3) [LY]
1  6.0
2  9.5
3 12.5
4 15.1
5 17.5
6 19.8

That's a fairly tame progression, and reduces the gain at higher quanta.
You could go the other way and make higher quanta much better than each
previous one, but that would make ranges too big.  Unless you had fewer Jump
quanta...
R=1.82^(N+1) [LY]
1  3.3
2  6.0
3 11.0
4 20.0

> However, in the wonderful world of reality, is there an actual average
> distance between stars that has ever been calculated?
> 
> Or have I just not looked in the right place yet to find it?

There are a couple of problems coming up with this number.  You need a good
list of stars in an area to do some math on.

A) Distance measures are only approximate.  Old parallax measures were only
good out to about 150 LY.  Hipparcos has extended that to about 1600 LY, but
at the extremes the uncertainty of distance is pretty large.

B) It gets harder to find dim stars the further away they are.  Since the
majority of stars are dim M dwarfs, they are under-represented in catalogs,
especially the further you look from Earth.

Between these 2 problems, we don't have a real good catalog of stars beyond
really close to Earth.  Even 2300AD's catalog out to 50 LY (based on a 1969
star catalog) misses a lot of dim stars.  While they probably are no use for
colonies, they certain add a lot of systems to the map.  That would change
any system that uses a limit on how far you can jump!

Anthony's answer of 100 stars within 6.62 parsecs (21.6 LY) probably misses
some of the really small stars too.  And the smaller your sample the more
likely you have all the stars, but the less likely that it's a good
statistical representation.

Besides, I'm not sure the average distance to nearest star is even very
useful, considering reality is 3D and the Traveller map is 2D.  :P