Help! Notable locations for "local" space opera setting

[Phantasm]

Originally Posted by Brett

That is a volume that is general close enough to use real star catalogues (reasonably complete out to 35 light-years if you aren't interested in M-class junk), and there are some good maps available. Look at Winchell Chung's actual starmaps page. Winchell's HabHYG 50ly hab and HabHYG 20ly will probably be useful to you, and are free. It you are prepared to shell out a few bucks, Winchell has hard-copy poster maps available: the Nearest 100 Stars is close to your 20-lightyear sphere, but I recommend the 30 Light Years Map, which is much more legible as being printed on a white background. I got mine laminated, and store it flat, Blu-Tack®ed to the back of my study door. You might also like the Astrogator's Handbook: the standard edition goes out to 25 light-years, and the electronic version is a free download. (The De Luxe Edition goes out to 75 light-years, and hard-copy in a binder cost me only $30 plus postage.)

Thanks, those should come in handy.

Originally Posted by Brett

When you say "points of interest", do you mean to include points of scientific interest (such as, say, Sirius), or only what we might call "points of social interest", i.e. habitats and artifacts?

Looking mainly for points of social interest - places the PCs could get into (or cause) trouble rather than places that would be of scientific interest.

Originally Posted by Brett

1. I don't understand why Ocean planets (in the sense GURPS Space uses it, anyway) should not be found elsewhere, e.g. orbiting class A stars but doomed in a timespan too short to expect a [natural] oxygen catastrophe.
2. Are you not interested in planets that have come tantalisingly close to being settlement candidates? I understand that with an open frontier there is no economic justification for terraformation, but such worlds would be of scientific interest.

For the Ocean planets, I was looking mainly at planets that would be "Earth-like but with 95%-99.95% water coverage". I'd have to look to see whether those would be viable in the comfort zones of A-class stars. (Sirius is unlikely to have one, due to Sirius B's orbit, but Altair and Vega are possibilities.)

Planets that are settlement candidates on the frontier are also useful. Some of them could be uncharted settlements - pirate havens, refugee settlements, etc.

The time-frame of the setting is roughly the 2550s, with the medium progression as listed in GURPS Ultra-Tech (IDHMBWM, but I believe that's TL9 at 2040, TL10 at 2200, TL11 at 2400.)

[Agemegos]

Originally Posted by tbrock1031

Looking mainly for points of social interest - places the PCs could get into (or cause) trouble rather than places that would be of scientific interest.

Righto, I'll bend my thoughts that way.

For the Ocean planets, I was looking mainly at planets that would be "Earth-like but with 95%-99.95% water coverage".

Ah. That's different. GURPS Space uses the term "Ocean world" for a planet or moon that has oceans, but does not have free oxygen in its atmosphere. Those are mostly potential future Garden worlds that are simply too young to have undergone their oxygen catastrophe, and naturally the young A-type and F-type stars are prime places to find them.

The time-frame of the setting is roughly the 2550s, with the medium progression as listed in GURPS Ultra-Tech (IDHMBWM, but I believe that's TL9 at 2040, TL10 at 2200, TL11 at 2400.)

Whooshka! TL11.

What superscience?

If you don't mind my saying, 20–50 light-years seems a little small for 550 years and TL11. Human population growth could theoretically fill up 300,000 planets in that time. Perhaps you have huge populations in asteroid belts etc. Or a bottleneck on growth somewhere. I suppose that the medium progression without emergent superscience implies no interstellar travel until 2400, and only time for growth to fill 30-odd systems since then….

[Fred Brackin]

Originally Posted by tbrock1031

I'd have to look to see whether those would be viable in the comfort zones of A-class stars. (Sirius is unlikely to have one, due to Sirius B's orbit, but Altair and Vega are possibilities.)

Sirius is also unlikely due to Sirius B beign post main sequence. Due to the overwhelming role stellar mass has on stellar lifespan we can be relatively certain that Sirius B was once larger than Sirius A before it shed a lot of mass durign red giant/planetary nebula phases.

If A captured a significant portion of B's ejected mass B may not have been that much larger than A is now but it's highly likely to have shed more than the equivalent of our Sun's mass.

That's bad for the possibility of local planets. Stable, lasting orbits need to come after any large period of moving mass.

[tshiggins]

You may want to take a look at the system HD 69830. It likely has a gas giant located in its habitable zone, and an asteroid belt closer in that is about 20 times as large as the one in our solar system.

Put a moon around the gas giant, and you may have a habitable world. The presence of such a massive asteroid belt makes it a great location for an extensive mining effort, with which a habitable moon could trade and support.

The game, Halo 3, put an intelligent race of ETs on just such a moon, in that system.

http://en.wikipedia.org/wiki/HD_69830

[Fred Brackin]

Originally Posted by tshiggins

The presence of such a massive asteroid belt makes it a great location for an extensive mining effort,

I don't know if there is a known one in your target area but if you want to mine asteroids you find a young system that hasn't formed it's planets yet.

You not only have all the mass of the inner planets spread out where you can get at it more easily but there woud be more that either fell into the Sun or was kicked out beyond the outer esges in our Solar System.

This might even occur around a star that was too big to stay on the Main Sequence long enough to develop planets with significant lifw.

It still wouldn't be as thick as a cinematic asteroid belt but it should much much thicker than our belt.

[tshiggins]

Originally Posted by Fred Brackin

I don't know if there is a known one in your target area but if you want to mine asteroids you find a young system that hasn't formed it's planets yet.

You not only have all the mass of the inner planets spread out where you can get at it more easily but there woud be more that either fell into the Sun or was kicked out beyond the outer esges in our Solar System.

This might even occur around a star that was too big to stay on the Main Sequence long enough to develop planets with significant lifw.

It still wouldn't be as thick as a cinematic asteroid belt but it should much much thicker than our belt.

I looked for one of those, but I didn't find any within his defined area. However the large belt of HD 69830, combined with the possibility of a habitable moon in close proximity, made for a fairly cool possibility, I thought.

[Fred Brackin]

Originally Posted by tshiggins

I looked for one of those, but I didn't find any within his defined area. However the large belt of HD 69830, combined with the possibility of a habitable moon in close proximity, made for a fairly cool possibility, I thought.

<shrug>I'm not throwing rocks at your ideas. I'm just contributing things as they occur to me, frequently triggerred by other's ideas.

Speaking of that, if you melted Ganymede, Callisto or Europa and put it in the habitable zone (possibly while orbitng a gas giant) a "water world" (common meaning, not techical use in G:Space) is pretty much what you'd get.

[Astromancer]

Originally Posted by Brett

Also windy, dimly-lit, subject to pronounced (40%) variation in insolation owing to the sunspot cycle, and occasionally subject to intense solar wind from large coronal mass ejections. Any habitable planet of a red dwarf would certainly be an interesting place.

Before you settle on a red dwarf as primary for a habitable planet, make sure it is not a flare star or other variable!

Valid! But I was suggesting Red Dwarfs as interesting places to place truely exotic ecosystems. Which in a Space Opera would have exotic biological treasures for the medical ethnobotanist. Also good for exotic primitive alien cultures with strange insights/secrets!

[Agemegos]

Originally Posted by Fred Brackin

Speaking of that, if you melted Ganymede, Callisto or Europa and put it in the habitable zone (possibly while orbitng a gas giant) a "water world" (common meaning, not techical use in G:Space) is pretty much what you'd get.

Yes, but it wouldn't last very long in geological scales of time. If you warmed Ganymede up to a habitable-to-Man temperature its MMWR (minimum molecular weight retained) would rise to about 75 (see Space p. 86). Its water (molecular weight 18) would evaporate, drift off into space by Jeans escape, and in geological time leave a Tiny Rock world.

[Agemegos]

Originally Posted by tbrock1031

What I need now are some points of interest in the region.

Were you a subscriber to Old On-Line Pyramid? I had a 'Terra Incognita' called Nahal in the 27 March 2008 issue, which you could adapt fairly easily.