Date: Fri, 25 Aug 1995 16:14:53 -0400 (EDT)
From: "Tony L. Hayes" <tlh@epsilon.com>
To: james vassilakos <jimv@cs.UCR.edu>
Subject: Re: stpbem & other stuff

On Wed, 23 Aug 1995, james vassilakos wrote:
>    Planetoid: Generally a very small world which is not part of
>       an asteroid belt. Not necessarily round. Could be a
>       captured planet. No atmosphere. Composed primarily of rock.

FYI - traditionally planetoids are larger then asteroids but not
near the size of planets.  Neither really need be part of a collection
of objects nor are either excluded - its a size/mass thing (with
some composition thrown in).

>    Desert World: Generally a non-breathable atmosphere, but there
>       may be water and oxygen tied up as ice crystals in the
>       soil. May be volcanically active. Probably on its way to
>       becoming a shallow world.

How do you separate this type of desert world from a true desert
world - ie low water, high temp - livable but just barely?

>    Exotic: Not an atmosphere you want to breath, maybe because it
>       contains poisonous gasses or even lethal micro-organisms,
>       but not a place you can't otherwise walk around, so long as
>       you have your own oxygen supply. Note that an alien
>       ecosystem may well be thriving. Many alien homeworlds will
>       be exotics.

Hmm...Exotic and Belch seem similar perhaps you could use Corrosive
and Toxic instead?  Then save Exotic for planets that are neither
corrisive nor toxic but merely...exotic?  Ie.  you can't breath
without aid because the oxy level is too low or there's no oxy
at all but its not corrosive nor are any of the gases actually
toxic (for example water isn't toxic or corrisive but you can't
breath it).

>    Shallow World: Has atmosphere but not enough to breath, at
>       least not without descending to a very deep altitude. Mars
>       could be an example.

Why not 'Thin'?  Shallow make me think 'no mountains' not 'thin
air'.  Just a thought.

>    Asteroid: Like a planetoid, only part of an asteroid belt.

See comment above re: membership in a collection of objects

>    Unusual: This world cannot be placed in any of the previously
>       defined categories. It may be an artificial planet or
>       perhaps a fluke of nature. GM's discretion advised.

As a thought, you might want to expand slightly the 'habitable'
range.  Have you seen the game Master of Orion by Microprose? 
Or the Avalon Hill board game (on which _I_ believe it is based)
Stellar Conquest?  You might consider, in addition to 'Garden',

Minimal - livable, breathable, but only just.  Perhaps it is a little
too rocky for massive vegitation or a little thin on air.  You can
live there without aid but its a hard life.

Standard - Earth

Garden - Earth only better - just _think_ about a plant and it grows -
super fertile and mineral rich.

At the risk of adding a second byte - you could also subclassify
with a quality level like - mineral rich or mineral poor.  Civilization
can't thrive (well) with out essential minerals and will do much better
if they exist in abundance.  (Using StarTrek as a tech background for
example) think of the planet that has dilithum in abundance?  How
did Earth ever discover Dilithum power if they had no dilithum?  They
had to manufacture dilithum crystals.  You see what I mean? That 
sort of thing.

Overall the idea and the system look good to me.  Naturally, my 
comments are only that - comments.  Use them or not as you see fit.


Date: Fri, 8 Sep 1995 15:31:56 -0400 (EDT)
From: "Tony L. Hayes" <tlh@epsilon.com>
To: james vassilakos <jimv@cs.UCR.edu>
Subject: Re: stpbem: update

I looked at your planet data.  I haven't had a chance to sit down and
really think about it but a few comments for your consideration - as
always, do what you want with them:

On star types and planet likelyhoods - there is a theory - about a decade
old - that postulate that A stars (which are unstable) frequently expell
upper atmosphere and can shift down the spectrum to G stars.  The theory
points to 'holes' in the stellar frequency distributions and to certain
local data.  They contend our star did this.  There is a lot of pieces
that point to it but one is Mercury which is believed to have been
fried back when good ole sol was a Type A.  Consequently, planets seem
to depend more on angular momentum and abundance of second and third
generation material (ie have stuff other then hydrogen and helium).

I think you need to up the chances of gas giants forming.  Current
thinking is binary systems (and bigger) are more likely then solitary
systems (angular momentum causes eddies during condensation and the
primordial cloud fractures).  However, most secondary 'stars' do not
reach ignition critereon because (among other things) when the larger
primary fires off, it blasts the system clean (relatively speaking)
preventing the smaller star from acreating enough material (ala Jupiter).

As for the distributions, I need to think more.  Most look ok.  I think
the greater range will occur within the Biozone as you have shown but 
beaware that Jupiter and Saturn both radiate thus causing their moons to 
be slightly warmer then would otherwise be expected.  Taking this a bit 
further, a Jupiter, say, 5 times ours in mass and it might produce a 
local biozone for its moons so I don't know that I would rule out
more traditional planets from that region.

Now, I was looking at the odds of a given star type having a planet.
Looks ok (who knows right?) but I would suggest that the M type stars
be lower and the G's be higher.  M type stars are often (but not
exclusively) Pop I stars ... or is it Pop II?...anyway, then tend
to be first generation stars comprised mostly of hydrogen with little
on no metals (non-hydrogen, non-helium) components.  Why?  They age
so slowly that most of the stars present in that range are _original_
or first generation whereas hotter stars burn, pop, burn out and spread
thier metals from which new stars form ala the Sun.  With out the metals
you can't have planets (other then gas giants).  

Again, only my thoughts.  I hope they are somewhat useful.  I don't
often get to put that Astro degree to use these days!


From: james vassilakos <jimv>
Subject: Re: stpbem: update
To: tlh@epsilon.com (Tony L. Hayes)
Date: Fri, 8 Sep 1995 15:39:19 -0700 (PDT)
 
> On star types and planet likelyhoods - there is a theory - about a decade
> old - that postulate that A stars (which are unstable) frequently expell
> upper atmosphere and can shift down the spectrum to G stars.  The theory
> points to 'holes' in the stellar frequency distributions and to certain
> local data.  They contend our star did this.  There is a lot of pieces
> that point to it but one is Mercury which is believed to have been
> fried back when good ole sol was a Type A.  Consequently, planets seem
> to depend more on angular momentum and abundance of second and third
> generation material (ie have stuff other then hydrogen and helium).

So what you're saying is that 2nd and later generation types F, G, K, and
M stars should have an equal chance of having planets? I'm not sure what
the angular momentum figures are for each stellar type&class.

> I think you need to up the chances of gas giants forming.  Current
> thinking is binary systems (and bigger) are more likely then solitary
> systems (angular momentum causes eddies during condensation and the
> primordial cloud fractures).  However, most secondary 'stars' do not
> reach ignition critereon because (among other things) when the larger
> primary fires off, it blasts the system clean (relatively speaking)
> preventing the smaller star from acreating enough material (ala Jupiter).

This makes sense, however, there are many binaries out there. So many,
in fact, that GURPS calls for a binary system on a roll of 10+ on 2d6 with
a +2 modifier if the system is in a star cluster or the galactic core.
And the near-star map which comes with Traveller 2300 shows many binary
systems. I've heard some people even say that the majority of stars in
the galaxy are members of multiple-star systems. Nonetheless, you're right
that in many of these systems, the hydrogen would have been pushed out
to the outer system where gas giants would form, which is apparently what
happened around Sol. Yeah, I think I'll definitely up the likelihood of
gas giants being present.

> As for the distributions, I need to think more.  Most look ok.  I think
> the greater range will occur within the Biozone as you have shown but 
> beaware that Jupiter and Saturn both radiate thus causing their moons to 
> be slightly warmer then would otherwise be expected.  Taking this a bit 
> further, a Jupiter, say, 5 times ours in mass and it might produce a 
> local biozone for its moons so I don't know that I would rule out
> more traditional planets from that region.

This may be possible, however, I think it is unlikely enough that I'll
allow GMs to invent such world on an ad hoc basis. Besides, my system
isn't intended to account for moons, so that throws the entire issue
out the window.
 
> Now, I was looking at the odds of a given star type having a planet.
> Looks ok (who knows right?) but I would suggest that the M type stars
> be lower and the G's be higher.  M type stars are often (but not
> exclusively) Pop I stars ... or is it Pop II?...anyway, then tend
> to be first generation stars comprised mostly of hydrogen with little
> on no metals (non-hydrogen, non-helium) components.  Why?  They age
> so slowly that most of the stars present in that range are _original_
> or first generation whereas hotter stars burn, pop, burn out and spread
> thier metals from which new stars form ala the Sun.  With out the metals
> you can't have planets (other then gas giants).  

I've wondered about this also. The type M stars have long lifetimes,
so one would think that they are 1st generation (population II) stars
most of the time. However, in GURPS:Space, it says that 1st generation
stars inhabit the core and the galactic "halo" almost exclusively and
are found in the galactic "disk" (which I assume is where Sol is
located) only rarely (1% of all disk-area stars). Well, there are lots
and lots of type M stars around Sol. The majority of stars around us
are type M stars. So, it would seem that according to GURPS, most
type M stars are 2nd or later generation (population I). Do you have
any reasonably reliable source which indicates that type M stars are
usually 1st generation?


Date: Fri, 8 Sep 1995 21:02:32 -0400 (EDT)
From: "Tony L. Hayes" <tlh@epsilon.com>
To: james vassilakos <jimv@cs.UCR.edu>
Subject: Re: stpbem: update

On Fri, 8 Sep 1995, james vassilakos wrote:
> So what you're saying is that 2nd and later generation types F, G, K, and
> M stars should have an equal chance of having planets? I'm not sure what
> the angular momentum figures are for each stellar type&class.

Well, I think nearly equal but not necessarily the same kinds of planets.
Two systems may have equal chances of having planets but nice earth-like
planets may generally only be found in certain types.  
 
> This may be possible, however, I think it is unlikely enough that I'll
> allow GMs to invent such world on an ad hoc basis. Besides, my system
> isn't intended to account for moons, so that throws the entire issue
> out the window.

Yeah, this would be an odd ball thing - but not that far out.  The
moon of Saturn - Titan - is _very_ much like a primordial earth only
too cold.  If it were moved inward, we could have had a very interesting
moon indeed!  Of course, the problem is the more inward you go the
higher the temp and the harder it is to keep your atmosphere.  Hitting
the right combination to make a life-friendly planet is pretty tough.
Habitable or usable is one thing (Mars nearly qualifies by some
definitions) but getting a planet to produce its _own_ life is hard.
  
> I've wondered about this also. The type M stars have long lifetimes,
> so one would think that they are 1st generation (population II) stars
> most of the time. However, in GURPS:Space, it says that 1st generation
> stars inhabit the core and the galactic "halo" almost exclusively and
> are found in the galactic "disk" (which I assume is where Sol is
> located) only rarely (1% of all disk-area stars). Well, there are lots
> and lots of type M stars around Sol. The majority of stars around us
> are type M stars. So, it would seem that according to GURPS, most
> type M stars are 2nd or later generation (population I). Do you have
> any reasonably reliable source which indicates that type M stars are
> usually 1st generation?
 
Yeah, somewhere around here.  I haven't unpacked my astrophysics books.
I have limited room just now and not a big need for them.  I'll try to
dig them out and find something useful.

What Gurps said is true to a degree.  Pop II (thanks for refreshing
my memory about which is which - backwards) do tend to be in the
core and the halo - as a rule because, the core is dense so the stars
'fought' for the material that was present thus most of the stars
were smaller plus the core is, on average, older.  Consequently the
hot stars are burned out already (repeately).  The halo is less dense
so again the hot stars are burned out already leaving only the old,
cool stars.

In the disk, things are more dynamic.  The material is more dense so
its easy for stars to form but not so dense that there is great contention
for material.  Plus as the galaxy rotates it creates a matter shock
wave in the galatic arms cause a 'strip' of star formation along the
leading edge.  The net result is that disk stars tend to be more mixed
with a fair number of new, young, hot stars.  Some of the new stars
naturally, are cool (not everyone can be a big star after all).  So on
straight percentages, yes the higher percentage of pop II stars are in
the core and halo but that shouldn't be construed to mean that the
number of pop II stars in the disk (especially in the M range) is
necessarily low.  Some smaller M class stars have lifespans that
exceed easily the age of the galaxy (maybe even the universe).  

I'll see if I can find a good source for some of this stuff this
weekend if I get a chance.

If you are interested, look for a text by George Abell called something
like 'Exploring our Universe'.  Its a freshmen level text that I used
to teach from (back in Grad school).  It is very introductory since
it was for general ed stuff but it was very good at explaining the
basic ideas and concepts.  You might find it a useful reference.
If you want something more meaty, I can get you some more intermediate
books as well.  The only problem with them is they spend too much
time on equations and theory - great if you care and facinating but
not real useful from the stand point of trying to get some basics
together for something like a game.  Overkill.

If you want to know more about the Type A shifting to Type G you will
have to read the journals, its still a new and disputed theory.  I
know of it because my advisor was one of the originators and so all
her students had to spend time working on it (you know profs, the
students do the work then the prof writes the paper and takes
the credit :-) ).


Date: Wed, 20 Sep 1995 15:00:12 -0400 (EDT)
From: "Tony L. Hayes" <tlh@epsilon.com>
To: james vassilakos <jimv@cs.UCR.edu>
Subject: Re: sf-rpg list
 
> Hey, I'm currently setting up some mailing lists. Of course you
> are going to be one the stpbem one. However, I'm also setting one
> up for the sfrpg I'm working on. Currently it consists of some
> hard-sf astrophysics types, and we'll probably be talking a
> little bit longer about starsystem generation, but eventually
> i hope to move things to the point where we're actually writing
> races and background info for use with the game setting. Let me
> know if you want me to add your address in there.
 
Yes, please do.  And thanks for the message from Carlos.  He wrote
me some time back - a one liner to let me know he was still there.
He never responded to any of my queries though so I didn't know what
had come about with his Father.  Too bad, he seems like a nice person.

Anyway, yes, put me on the list.  I'll try to chime in with comments
once in a while as time permits.  Being new I have days (like today)
which are packed and others (like yesterday) where I have almost
nothing to do!  Soon it'll migrate to constantly packed.  Such is
life though.

I haven't gotten around to finding the boxes with my astro books in them
yet (I know, I'm lazy...).  If I remember correctly, weren't you on the
Traveller mailing list a while back (when they reorganized, I dropped
as I was drifting off in other directions at that time).  Anyway, the
point is, there was some good 'handwaving' on several topics that
might be relevent.  One of which was my personal favorite pet theory
of anti-grav propulsion systems.  There was also some discussion of
system generation ideas.  While, the game systems may or may not be of
direct interest, the foundations might be.

Lastly, when the time comes, I have a few alien races that I developed
for Traveller that you might want to look at.  They might provide
some good ideas and I'll get some interesting feedback on them that
I can use regardless.


