OTU Only: A publication survey of 567-908

[robject]

I was fooling around with notation to "clarify" stars in star systems, and once again came across 567-908.

EXECUTIVE SUMMARY

The "right"(?) stellar data appears to be K5 III D


LONG DETAILS

ASSUME. The Shriekers and Adventure 10 as a whole require 567-908 to be in Orbit 8, and yet in the Habitable Zone. This is bizarre and paradoxical, but opens up interesting possibilities. I'll leave those possibilities for later rehashing.

1979. Supplement 3

567-908 0201 E532000-0 Poor.

1984. Adventure 10

The planet ... is 2,932 million kilometers from its central star. The local year is 42.5 standard years.

= 19 AU with a star massing about 4 sols. That's Orbit 8. Note the implications of a mainworld around a giant.

Going by CT Book 6: Scouts, and T5 world-gen charts, a K5-K9 III star allows a habitable zone in Orbit 8 (17 AU to 20 AU). It's also around 5 sols, which is close to the right mass.

M-class giants are far too massive. G-class giants are not massive enough (!).


1985. Module 3, The Spinward Marches Campaign
1987. MegaTraveller Imperial Encyclopedia
1995. Regency Sourcebook
2008. TNE 1248: The Spinward States

SMC generated this data for the world, and the stellar data stuck around until 2001.
1031 E532000-8 Lo Ba nIn Po. 310Na M9 V M1 D

Observations:

1. Three (humans) at TL8 suggests the informal presence of Scouts or some other factors.
2. The stars do not take AD10's text into account.
3. An M9 V has a habitable zone at 0.03 AU. I would say that this was not closely scrutinized.
4. 1248 used GURPS' name suggestion of Denuli, and gave a reasonable explanation for it. However, they used the old TNE stellar data.

2001. GURPS Planetary Survey 2: Denuli

I was prejudiced against this supplement for about 20 years. But -- they did it right. The star is promoted to a giant (M II), which acknowledges the problem and attempts to fix it, but it's too massive.

2014. Second Survey work

G5 V M9 V

T5 Second Survey work started from the original M9 V M1 D, acknowledging that an M9 V is just too close to the primary to make sense. They considered a main sequence versus a giant, and decided that (1) the star's mass would not affect the adventure and (2) a main sequence makes much more sense to allow evolution of NIL. I believe that there is reasonable doubt about point #1, and that GURPS' change was a step in the right direction.

 

[Spinward Flow]

It's also somewhat close to the right mass: about 5 sols, a bit high, but close.

A sol here, a sol there ... pretty soon we're talking about real stellar masses!

 

[mike wightman]

Just change it to what it should be.

 

[robject]

Just change it to what it should be.

Agreed. I tend to forget and flip-flop, so I also need to document the reasoning and assumptions.

 

[tjoneslo]

I recall the discussion with Don around the change for the star type. The problem with giant stars is their lifespan is too short to allow a planet form, cool, and generate life forms. So the decision was to change the type to something that would allow the planet to support life. I think an earlier discussion with you the idea was the world was not native to the system, but one of the deep space wanderers captured by the star and warmed to life.

 

[Spinward Flow]

I think an earlier discussion with you the idea was the world was not native to the system, but one of the deep space wanderers captured by the star and warmed to life.

Gravity capture of planetary wanderers is the best solution to stellar lifespan problems.

 

[mike wightman]

My suggestion was the Shriekers were natives of a world much closer to the star. As the star went through its life cycle the Shriekers were forced to move to colonies on worlds further from the star and space habitats. Eventually their civilization collapsed and what we find in the adventure is the last colony.

 

[HanleyTucks]

Gravity capture of planetary wanderers is the best solution to stellar lifespan problems.

"An interesting question. How will your character go about discovering the answer?" is the best solution to stellar lifespan problems, likewise to questions of what monsters in a dungeon eat, or what caused the global apocalypse, and so on.

The GM does not need an answer, the world simply is as it is. After all, the real universe has many unanswered questions, but we still manage to live in it, and could adventure in it if we were willing to risk our lives. The players do not need an answer either.

 

[whulorigan]

"An interesting question. How will your character go about discovering the answer?" is the best solution to stellar lifespan problems, likewise to questions of what monsters in a dungeon eat, or what caused the global apocalypse, and so on.

The GM does not need an answer, the world simply is as it is. After all, the real universe has many unanswered questions, but we still manage to live in it, and could adventure in it if we were willing to risk our lives. The players do not need an answer either.

Good answer. But I would suggest that at the very least the documentation for the adventure / setting / wiki-write-up "hang a lantern on it" and explicitly note the fact that there is an enigma here that no one quite understands, making clear that it is not simply an oversight of the authors.

 

[HanleyTucks]

That's a fair point.

 

[robject]

I recall the discussion with Don around the change for the star type. The problem with giant stars is their lifespan is too short to allow a planet form, cool, and generate life forms. So the decision was to change the type to something that would allow the planet to support life. I think an earlier discussion with you the idea was the world was not native to the system, but one of the deep space wanderers captured by the star and warmed to life.

I should reread GURPS to see if they took any particular stance.

...UPDATE: they don't.

 

[Grav_Moped]

Good answer. But I would suggest that at the very least the documentation for the adventure / setting / wiki-write-up "hang a lantern on it" and explicitly note the fact that there is an enigma here that no one quite understands, making clear that it is not simply an oversight of the authors.

This is a good principle. Granted, not every referee or author is an astronomer, so sometimes things like this get overlooked or handwaved.
That said, whenever possible it's good practice to at least have a general idea of where all the loose threads from your scenario will lead, even if they're not actually tied down to fully-developed background material at the far end.

 

[robject]

I recall the discussion with Don around the change for the star type. The problem with giant stars is their lifespan is too short to allow a planet form, cool, and generate life forms. So the decision was to change the type to something that would allow the planet to support life. I think an earlier discussion with you the idea was the world was not native to the system, but one of the deep space wanderers captured by the star and warmed to life.

GURPS' Planetary Survey doesn't even ask the question, so the question itself, as well as conjectures, is a useful addition to what's already out there (AD10, G:T PS2 et al).

 

[aramis]

Given

I recall the discussion with Don around the change for the star type. The problem with giant stars is their lifespan is too short to allow a planet form, cool, and generate life forms. So the decision was to change the type to something that would allow the planet to support life. I think an earlier discussion with you the idea was the world was not native to the system, but one of the deep space wanderers captured by the star and warmed to life.

Don felt that size III and up shouldn't have planets, as I recall. At the time, that was a defensible position. But it no longer is.

[1406.0884] The properties of planets around giant stars

arxiv.org

Their studied star is a K2 III... HIP 105854 ... and its superjovian-sized planet HIP105854b - some 5.4 Jupiter masses....

Planet HIP 105854 b

Detailed information about planet HIP 105854 b and its parameters.

exoplanet.eu

The largest star with an exoplanet known is also size III... HIP 114840 aka HD 240237, Also with a 5.something superjovian.

Moreover, both have orbist making them hot superjovians. Under the physics models from 15 years ago, hot jovians were unpredicted, and forcing changes in the theory.

It's entirely possible that a type III can have captured terrestrials, and/or pre-ignition coalesced rocky bodies; they're merely unlikely to have had time for life, not flat out impossible. And, given the OTU, it's entirely possible that busybody ancients may have terraformed them to cooler. Possibly with heat-sinks to extradimensional spaces.

 

[Krikkitone]

Except giant stars don’t “form”, instead they start as a normal V star (plenty of time to form planets) and then later expand (so some outer planets become the new hz planets). The issue is time to life in those newly habitable worlds. (giants can last ~1 billion years if they aren’t very massive, which could be argued either way)

 

[tjoneslo]

Don felt that size III and up shouldn't have planets, as I recall. At the time, that was a defensible position. But it no longer is.

There was a paper (which I can no longer find) I read about the rate of planetary formation. In the paper they were doing computer modeling of the formation of planets from the proto-planetary disk and initial dust cloud based upon the newer science. From their analysis systems would go from disk of dust and gas to a series of planets on the order of 10K years. An eye blinks in the geological time of most systems. The rocky planet's weren't habitable and there was still a large number of impacts from the smaller shards still floating around

 

[aramis]

Except giant stars don’t “form”, instead they start as a normal V star (plenty of time to form planets) and then later expand (so some outer planets become the new hz planets).

There are two kinds of giants - many are massive stars which may have formed as a binary then merged, being huge massive piles of mass doomed to become black holes, and cool giants, formed from the hydrogen burning stage of main sequence stars. Both exist.

A few (most notably Betelguese) are end-stage main sequence - with Betelgeuse having about 10 Mass☉ and a whopping 887 radii ☉... 6 million times less dense than Sol. (It's bright, but very cool. M2 color size Iab.) Most such are in the red. M_ I are burning hydrogen and have an envelope of low temperature hydrogen and helium...

Meanwhile, WBB2016 2 aka Westerhout 49-2, is estimated to be between 130 and 370 M☉, and 55 R☉, and is described as a "Young Stellar Object", color O2, size I, and being about 1/665 the density of Sol... but MUCH much hotter. And more than 12× the mass of Betelgeuse. These suckers are still burning hydrogen. And in the O and B colors and the I or II size classes. Betelgeuse may just outlive it...

 

[Spinward Flow]

Live fast. Fuse hot. Leave a gravity crushing corpse.

 

[Deldarius]

Live fast. Fuse hot. Leave a gravity crushing corpse.

Fusion is a hell of a drug!

 

[kilemall]

Live fast. Fuse hot. Leave a gravity crushing corpse.

Is that stars or Elvis?