Subject:
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Re: The "geography" of local space
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Newsgroups:
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lugnet.space
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Date:
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Thu, 4 Nov 1999 23:34:22 GMT
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Viewed:
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561 times
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Hey John (and all)-
Astronomy is an armchair hobby? Well, I'm a historian (not done with the
PhD just yet, but give me just a couple more years) who started out as a
palaeontologist and astronomer--so I come at it from a different angle, but
I've had a long standing interest in the "demography" of the local
population of heavenly bodies (no snickering).
> I've been reading the proposal for an integrated space milieu. There
> is a question about what the geography (cosmography?) of this Legoverse
> should be. Some people have suggested that what we currently know about
> local space should be taken as a starting point. This makes sense --
> minifigs are rather human-looking, after all. It is only natural to
> assume that they call a Lego Earth their home.
That seems most logical. And if we presume that various unknowable factors
might affect human life (background radiation, tidal forces, etc), a point
here in the "seen" interstellar region, on a spiral arm, outside the dust
lanes, would probably be most plausible.
> [Tom McDonald:]
> > I also am not against someone wanting to do real research about "what's • real" though I
> > think that once we establish some sort of map, it should be "first come, • first served" so that
> > if someone finds out that IRL there's a huge black hole where we've • put a densely
> > populated set of solar systems, then the hole has to be relocated.
If you want a local map of the nearby stars, the best I've seen (aside from
processing the information in Sky Catalogue 2000.0--both volumes of which
I've got--and Burnham's, all three volumes of which I own) is in GDW's old
"Traveller 2300" game. You have to figure out what some of the stars really
were, but it's fairly accurate out to c.100ly. Burnham's gives you lots of
proper names for obscure stars and phenomena, however. ("No, it's not Alpha
Centauri, it's Rigel Kentaurus...*grumble grumble Visigoths*")
> Well, I've done a little of that research -- astronomy is one of my
> hobbies (I have too many of those!). I'll share what I know with you
> here.
>
> As for building models to add to the "Datsville universe" -- well, I'm
> not quite ready to do that! First, I have to negotiate with my son for
> the pieces. 8^) I'm also kind of a "hard" science fiction fan, and
> disinclined to accept FTL travel... but I'm not building anything, so
> you can ignore me! 8^) 8^)
Yes, but even "hard" sci-fi fans (like you and I) who dislike superluminal
travel can still deal with space-folding, wormholing, and the like--there
are ways around it. ;) But I believe that beyond 200ly you begin to get
"weird." See below.
> > ** If you all want to see it, I've got a map from which we could • possibly start. It's from an
> > old Star Trek Tech Manual which shows major stars (48 of them in fact) • in a sphere within
> > 7 pc, 22.82 ly, centered round our own star Sol (though the original • Federation was much
> > bigger than that, more along the lines of 4kpc+). And it does not • show any other objects,
> > such as nebulae, black holes, etc.
>
> I wouldn't expect to see any nebulae or black holes on the small-scale
> Star Trek map. It is well established that the nearest nebulae and
> black holes are much farther than 7 parsecs from the Sun! If such
> things were that nearby, life would probably be very different here.
> Life might not even exist here at all. We live in a pretty boring
> corner of the cosmos, and that's probably good for life. For example,
> black holes emit LOTS of X-rays, either through mangling the daylights
> out of matter thery're ingesting, or through a more subtle process known
> as Hawking radiation. X-rays are quite bad for living things.
Okay, Cygnus X-1 is out for the holiday vacation...next! (Then again, this
doesn't preclude races or entities that aren't subject to carbon-water
chemistry. Hal Clement wrote a nice essay about why H20-C (imagine
subscript) chemistry is most likely, but you never can be sure...though I
think silicon for all but artificial life is out.)
> Now, the Star Trek manual (Is this the original '70's Trek manual? I
> think I still have a copy of it myself somewhere) is likely to have been
> fairly accurate -- but it is clearly incomplete. There are about 100
> stars known within 7 parsecs of Sol. Most of those have been known for
> decades, so it is likely that Trek left off some minor, dim stars. Do
> you care about these dim, "red dwarf" stars? Well, they're actually the
> most numerous type of star! They're under 1/10 as bright as the sun,
> and they're unlikely to have planets where you can walk around on the
> surface in your shirtsleeves. One theory holds that they're unlikely to
> have any planets at all. But, it's your universe. What kinds of
> interesting things might you find in such places?
John's 100% right here. The Traveller manual included red stars, but
interestingly as you got nearer the edges of the map, there were fewer red
stars! That's because (drum roll) they're hard to see from here. How many
people know about the C component of Rigel Kentaurus? But what may be even
more numerous than red dwarves are *brown* dwarves--stars so small that they
"abort"--sort of super-Jupiters, like Van Biesebroeck 8B and the sort. They
give off heat, and can have habitable tidally locked moons, but they're
really too small to light up like a red star. Some of the life posited by
the GDW folks for such planets is really rather interesting. As a game it
may have been too technical, but I think it's the most scientifically sound
space-opera game ever created by far.
> In that 7 parsec-radius bubble of space, two red dwarf stars were found
> in just the past three years. It is estimated that, within this same
> radius, there are about 20 more stars waiting to be found. They will
> all be red dwarfs. The nearest 25 star *systems* can be found inside a
> sphere, centered on Sol, that is 4.01 parsecs in radius. Nine of these
> star systems are double or triple stars. There may be more, incredibly
> dim stars to be found, even in this close.
Double and multiple systems are probably the rule, not the exception. Many
astronomers (and not all "rogues" or weirdos) feel that the Sun may be or
may once have been part of a multiple system. They call the extant
iteration the "Nemesis Theory," for the name of this unseen, M5-or-fainter
companion. I wasn't aware about the new dwarves, though--I presume they're
M3 or less. Where are they?
> If you wanted to keep the Datsville universe this small, there will
> almost certainly be planets to explore. Some of them might even prove
> to be habitable. (If there is interest, I will be happy to discuss
> planets in more detail -- but I'll try to stick to stars in this post,
> it's getting long enough already.) But there won't be any exciting
> *stellar* objects. Where is the closest known black hole? Neutron
> star? Nebula? I can't answer these questions definitively, but I can
> state with confidence that you will find no such objects within 50
> parsecs of us. We wouldn't fail to notice them, if they were in so
> close. We would probably be able to see them by eye, and we would
> certainly spot them with even modest telescopes.
As you say in your message, Cygnus X-1 is probably the closest, between 1000
and 2500pc away (Burnham's, 2:793). Nebulae are usually the result of
supernova explosions, the home of star formation, in the dust lanes, or the
throes of novae (thrown off in shells by stars that have exhausted
hydrogen). The Pleiades (M45) and its Merope, Maia, and Taygeta Nebulae are
probably the closest, at about 125pc.
> The closest "interesting stellar object" is probably the star Vega.
Sure, it's a matter of opinion, but I've gotta disagree--I think it's
probably the white dwarf B component of Sirius, else the white dwarf B
component of Procyon. But Vega is indeed an interesting star. Arcturus is
interesting because it's a heavy-element-poor Pop II star--so probably no
planets except for maybe gas giants. If VB8B exists, that might be more
interesting still.
> The three nearest blue giant stars are all on the order of 100 parsecs
> away
> (it gets difficult to measure distances accurately, out that far) --
> Canopus, Spica, and Acrux. These are supernovae in the making -- and,
> mercifully, far from Earth.
I'm not sure 100pc is far enough to prevent a disaster here on the ol'
mudball. :(
> Cygnus X-1 has been called "the closest black hole to Earth." I found
> two distance estimates on the Web, and their disagreement shows just how
> bad we are at measuring the distance to far-away objects. Once source
> says 300 parsecs, another 1800 parsecs. Furthermore, I seem to recall
> that a somewhat closer candidate black hole had been located recently.
> Use your imagination, I guess!
Again, darnit. See above. I was trumped again! But they can't use direct
parallax to measure the distance--so you can be pretty sure it's not within
300pc.
> > Which reminds me: if we use faster than light (FTL) velocities, what • kind of velocity scale
> > do we want to adopt?
>
> This depends on where you want to go, and how quickly you want to get
> there. If your imagination tells you that you should be able to travel
> from Earth to the Crab Nebula in a week, parsecs per hour is a
> reasonable unit of measure.
If superluminality isn't based on linear spatial travel, it's always felt to
me that you should alter measurements to deal with the drive's physics. But
if we want realism we'll probably have to use such a unit, just for easy
convertibility. I've generated several "superluminality paradigms" for use
in universes of my own creation--either for my own amusement or for others'
request--but some are kind of rusty and (as might be suspected) based on
suspect chemistry/physics/geometries.
But what no sci-fi/space/Space system has done in my knowledge is utilize
*multiple* ways around the problem. The CW is that there can be only one
circumvention possible of the luminal speed limit. Why not more than one
method? Bubble-universes, superstring manipulation, space-folding, and warp
drives all--could such things all exist together?
> > Unless, maybe, someone wants to go to the trouble of staging an • emergency mass-exodus
> > of moving civilizations because a rogue black star is approaching! • That could be another
> > story :-)
>
> Sounds like fun! But realistically, you would have thousands of years'
> warning. The relative speeds of objects within the galaxy (and its
> attendant globular clusters) are pretty low -- no more than about 50
> kilometers per second, which works out to one parsec every 19,600
> years. An object moving much faster than this would have to come from
> far outside the local galactic group, and to my knowledge no such object
> has ever been found.
Thundarr the Barbarian? Never happen? I'm crushed! :( (Not really.)
This is interesting, and worth pursuing--I think a "Space datsville" would
be a lot of fun to populate, and I'm convinced we wouldn't be wanting for
planets.
best,
Lindsay Frederick Braun
---
Lindsay Frederick Braun (Mr)
Department of History
Rutgers, the State University of New Jersey
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Message has 2 Replies:
 | | Re: The "geography" of local space
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| (...) I remember a book called _The Dragon's Egg_ by Robert L. Forward. The ALFs in that book are residents of a neutron star -- totally different chemistries from H2O-C. (...) Would that be Jupiter? I've heard theories one way and the other -- some (...) (25 years ago, 4-Nov-99, to lugnet.space)
| | | Re: The "geography" of local space
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| Hello again, I''m glad I generated some interest here! I hope, however, that we do not stray too far from discussing LEGO -- I have noticed complaints in at least one other LUGNET newsgroup. (...) Both quite rewarding, but difficult fields in which (...) (25 years ago, 5-Nov-99, to lugnet.space)
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Message is in Reply To:
| | The "geography" of local space
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| Hi there! I have been lurking on LUGNET for a few months now. This is my first post to LUGNET, and I should probably introduce myself before jumping in to a discussion, but whatever... I will post a personal intro. over in lugnet.people under the (...) (25 years ago, 3-Nov-99, to lugnet.space)
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