Type T/ST variant planet types

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Re: Type T/ST variant planet types

Postby Crucis on Mon 10 Dec 2012 19:20

AlexeiTimoshenko wrote:From the calculations it looks like Red stars can't have habitable T worlds. Glacial ST's may in theory be possible as a larger planet should have more internal heat from radioactive decay along with a dense enough atmosphere to have a substantial greenhouse effect.


Oh, Red Stars can still have Type M planets (in this case, tidelocked planets). Just no regular T/ST's.


For Yellow, Green and White stars I would use the inner 20% of the HZ as warm, and the outer 20% as cold. Use the actual HZ's, no fuzzy versions. Orange would have a cold zone at 6 LM and no warm zone at it would be in the tidelock zone.


Well, 20% of most of these HZ's is basically just the border value, except perhaps for Green stars (i.e. old White stars).
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Re: Type T/ST variant planet types

Postby AlexeiTimoshenko on Mon 10 Dec 2012 19:50

I'm not used to the marginal planets yet. To me they are a bit more useful than barren, but not what I would call habitable.

On another note, I'm a bit concerned about the dividing line between mass 1 and 2 rocky worlds. I'm not sure that a worlds just over 0.1 Me would be able to hold it's atmosphere. A Mars sized world on the other hand could have an atmosphere and water for a significant amount of time.
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Re: Type T/ST variant planet types

Postby Crucis on Mon 10 Dec 2012 19:58

AlexeiTimoshenko wrote:I'm not used to the marginal planets yet. To me they are a bit more useful than barren, but not what I would call habitable.


Marginal planets are automatically Hostile and technically habitable ... barely.

Also, Type M is a catch-all for various different marginal situations. Tidelocked planets and worlds with immature ecospheres are the two primary situations.

On another note, I'm a bit concerned about the dividing line between mass 1 and 2 rocky worlds. I'm not sure that a worlds just over 0.1 Me would be able to hold it's atmosphere. A Mars sized world on the other hand could have an atmosphere and water for a significant amount of time.


:lol:

Alexei, Mars IS a world just over 0.1 Me!!! (0.11 Me to be exact.)
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Re: Type T/ST variant planet types

Postby AlexeiTimoshenko on Mon 10 Dec 2012 20:46

Ok, I'll concede the point on Mars.

Marginal planets being hostile environments makes sense. I was thinking that they were between hostile and barren.
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Re: Type T/ST variant planet types

Postby Crucis on Mon 10 Dec 2012 20:58

AlexeiTimoshenko wrote:Ok, I'll concede the point on Mars.


I actually did a double take on Mars myself the first time. I always thought of it as a Mass 1 planet, and was surprised to see that it slightly exceeded the minimum mass for Mass 2. But I suppose that Mars is a fine example of a very borderline mass 1/mass 2 planet.

Marginal planets being hostile environments makes sense. I was thinking that they were between hostile and barren.


In some cases they may be thought of as between hostile and desolate. But they are meant to be in the "habitable" group rather than the "non-habitable" group. They're meant to cover various difficult situations that each in its own way is about as bad as it can be and still technically be "habitable".
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Re: Type T/ST variant planet types

Postby Crucis on Mon 10 Dec 2012 21:24

AlexeiTimoshenko wrote:From the calculations it looks like Red stars can't have habitable T worlds.


This illustrates the difficulty in using an average for a star type, as opposed to just using all 50 spectral subtypes. Oh, it's not so bad for the A-K spectral classes. After all, G3 may differ a bit from G5, but not so much that it really matters. You'd still have a healthy inner rocky zone, HZ, and outer rocky zone.

But with Type M stars, their masses and luminosities are so low that their HZ's are minuscule and often inside of 1 LM. Of all the M subtypes, only M0 is really decent. M1 is half decent. And M2 and below have little to offer. M7's (ie. the spectral subclass on which the Red Dwarf type is based) are so lame that even their gas zones and overall planetary disks are tiny. Most of the real estate around an M7 is likely to be the mF moons of Type I planets ... which I suppose is better than nothing if you want to emplace an outpost to secure a claim to the star system.
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Re: Type T/ST variant planet types

Postby AlexeiTimoshenko on Tue 11 Dec 2012 22:33

With the proposed die roll modifier for the number of moons, there may not be all that many mF's to plant the flag on in red/red dwarf systems.

For a red (not red dwarf) star could you have a Gas Giant at 2-3 LM with a tidelocked moon and have the moon be better than a marginal environment? As the moon revolves around the planet it should have an effective day/night cycle. I doubt that it would be benign, but in a best case could it be a harsh environment.
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Re: Type T/ST variant planet types

Postby Crucis on Tue 11 Dec 2012 23:50

AlexeiTimoshenko wrote:With the proposed die roll modifier for the number of moons, there may not be all that many mF's to plant the flag on in red/red dwarf systems.


Did I miss something? What proposed modifier would mean that there were fewer mF moons in red/red dwarf systems?

EDIT: Ohhhhhhhhhh... Now I know what you're talking about (I think). You're talking about a proposal you made in the Continuing Sysgen Discussion thread:

AlexeiTimoshenko wrote:The moon table looks good. Would it be possible to add a modifier for stellar class? I'm thinking that larger stars would have more material to form moons, while smaller stars would have less.


As I said there ... "I've never read anything to that effect. If anything, I'd think that that sort of modifier would be more appropriate for planetary masses, rather than # of moons, since I *have* read where class M stars have fewer large gas giants than larger stars. (And if smaller stars had less massive planets, that would have a secondary effect on the # of moons table when those less massive planets rolled for moons.)"


Honestly, though, I'm a bit wary of getting into using star type modifiers for # of moons or planetary mass. Things are complicated enough already. But I won't rule it out entirely either.

It is worth noting that with the small gas Zones I'm currently envisioning for Red and Red Dwarfs, there won't be all that many gas giants around those stars.





For a red (not red dwarf) star could you have a Gas Giant at 2-3 LM with a tidelocked moon and have the moon be better than a marginal environment? As the moon revolves around the planet it should have an effective day/night cycle. I doubt that it would be benign, but in a best case could it be a harsh environment.



2-3 LM in a Red Star system is on the border of the Rocky/Gas zone. 1-2 LM is the Rocky Zone, 3-12 LM is the Gas Zone... 2-3 LM *was* the HZ I'd previous intended to use, though it was the HZ for an M0 rather than M2 star. Are you talking about a hot Jupiter potentially having a somewhat habitable moon? If so, that might be possible..."
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Re: Type T/ST variant planet types

Postby Vandervecken on Wed 12 Dec 2012 02:38

Just want to say that there will be very few true T worlds on any world with less than 0.6 earth masses. You can get small planets and even large moons with atmospheres as dense or more dense than Earth's own; but they will be exceedingly rare (or short lived) in the habitable zone with a Nitrogen - Oxygen combo atmosphere due to both gravity and steller energy interactions with the atmosphere envelope. Also, worlds smaller than 0.6 cool quicker and often lose their magnetosphere or most of it when the core or outer-core stops circulating. If Mars had a 'Golden' age, it was extremely short compared to the one Earth currently is in. Things get somewhat better after 0.5 and really look decent after 0.7 earth masses.

Of course, one problem with the ST worlds is that the higher gravity worlds tend to keep their primordial atmospheres much, much longer than Earth did. Many ST worlds that would have formed when Earth did would still have a lot of that lighter stuff still as a significal component of their atmosphere, and that stuff is kinda bad for life on Earth (except for a few bacteria types). Primordial ST's could be a variant I suppose but they, at best, would be type M and at that point they aren't really a ST anymore.
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Re: Type T/ST variant planet types

Postby Crucis on Wed 12 Dec 2012 02:52

Vandervecken wrote:Just want to say that there will be very few true T worlds on any world with less than 0.6 earth masses. You can get small planets and even large moons with atmospheres as dense or more dense than Earth's own; but they will be exceedingly rare (or short lived) in the habitable zone with a Nitrogen - Oxygen combo atmosphere due to both gravity and steller energy interactions with the atmosphere envelope. Also, worlds smaller than 0.6 cool quicker and often lose their magnetosphere or most of it when the core or outer-core stops circulating. If Mars had a 'Golden' age, it was extremely short compared to the one Earth currently is in. Things get somewhat better after 0.5 and really look decent after 0.7 earth masses.


Van, this may just be a residual of how mass 1, 2, and 3 were originally described back in 3rd edition.

Hmmm, looking back in the New Empires and ISF, I see no mention of a lower end to the gravity range for Type T worlds, which is how I determined the lower end for mass 2. Interesting. I could change the upper mass number for mass 1 to 0.5 Me and the lower value for mass 2 to 0.6 Me without messing with much of anything from what I can see at this moment. I'll give this serious consideration.

Thanks, Vandervecken.



Of course, one problem with the ST worlds is that the higher gravity worlds tend to keep their primordial atmospheres much, much longer than Earth did. Many ST worlds that would have formed when Earth did would still have a lot of that lighter stuff still as a significal component of their atmosphere, and that stuff is kinda bad for life on Earth (except for a few bacteria types). Primordial ST's could be a variant I suppose but they, at best, would be type M and at that point they aren't really a ST anymore.


Well, there's already some mention of immature ecosystem T/ST's in the sysgen oddities changing the planet from being T/ST to M... if I can get around to writing those darned sysgen oddites up, that is.
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