[Space] System Generator

[dscheidt]

Very cool, Brett. Thank you.

Has anyone gotten solver to work on this? I'm trying to create some mildly-habitable (5 or so) systems, by changing the system number, and solver gives an error that "error in model. Please verify all cells and constraints are valid." It does that with no constraints at all. Am I just an idiot here?

[Bandii]

Awesome work, as usual.

Every iteration this gets closer and closer to what I need.

Thanks for all the hard work.

One note, I am using it mostly to create systems for actual pre-existing real-life star systems and I've gotten a couple of weird results. I entered the known data for the star system Stein 2051 AB and got different results than real-life has; so I tinkered a bit until I got the numbers I needed, so its not a big problem.

Keep up the great work.

-Mike

[Infojunky]

Originally Posted by Agemegos

I don't have solver and don't know how it works. But perhaps you ought to have constraints. For example, System Number ought to be constrained to be positive.

Solver is an funtion of Excel I beleive it is part of the anaylsis pack that comes uninstalled with excel.

[Pomphis]

Luminosity is quite variable. Apparently rotation can affect it.

http://www.journals.uchicago.edu/AJ/...62/200462.html

A particularly notorious example is Vega, whose overluminosity (by about 0.7 mag) was hypothesized by Gray (1988) to be due to rapid rotation with a pole-on aspect, a hypothesis that was essentially confirmed by the work of Gulliver, Hill, & Adelman (1994).

Paper 2 comes to the conclusion that microturbulences are important as well.

Metallicity also seems to be a factor, at least the title seems to imply that.

http://aas.aanda.org/index.php?optio...51/aas:2000223

http://209.85.135.104/search?q=cache...&ct=clnk&cd=10

is about the link between luminosity and metallicity for galaxies.

http://www.blackwell-synergy.com/doi...ournalCode=mnr

shows a tight relationship between luminosity and metallicity for K dwarfs.

And sol is unusually metallic.

[MrId]

Originally Posted by Agemegos

It would not be easy to give them their own line in the system table. There are a lot of elaborate formulas, especially in the columns that do tidal braking, that depend on the fact that all the moons of any given planet are in adjacent rows delimited by things that are not moons. Besides, we know that any ring has to go between two shepherd moons/moonlets, but Space doesn't say where to put them. I guess I could squeeze a line in between the inner moonlets and the major moons, and treat them as asteroid belts for the purposes of filling in the table, presenting them if their row number is entered into the planet display, etc.

Would it be easier to have a field in the planet display and then change the type of gas giant in the system display from "Medium Gas Giant" to "Ringed Medium Gas Giant?" This would evade the problem of adding a line to the system display that could muck up tidal breaking calculations, and having to figure out the orbital radius of the rings. If that's not possible, then maybe just a field in the planet display (with values like None, Ring System, Large Ring System), and if people really want to know if a planet has rings, they can check there.

Rings are a pretty minor element of system construction, though, so if these solution are problematic, it's probably best to leave them out and concentrate on the more complicated elements of system design (which the spreadsheet handles quite nicely, as far as I can tell.)

[Bandii]

Originally Posted by Agemegos

Good. So what do you guess I'm going to do next?

No idea, but i look forward to it whatever it is. You've made the mind-numbing task of system and planet creation blissfully easy already; so the only guess I could have is that possibly you're teaching the spreadsheet to make cappuccinos.

I strive to please.


Luminosity is off for known mass and age?

I get that too. For example, Sol comes out 9% too bright. This doesn't seem to be a coding error on my part: I get the same result when I do the calculations manually.

Sorry, i should have been more clear. When I entered the data for Stein 2051's companion, a white dwarf, I got a result for a red dwarf instead. I don't think its an error in your work, but rather a peculiarity with the GURPS Space generation system.

But as I said, I fudged some numbers and my players wont know (or care).

[David Johnston]

Originally Posted by Agemegos

I get that too. For example, Sol comes out 9% too bright.

Is that including the adjustment in luminosity for distance of the Earth from the sun?

[Bandii]

Originally Posted by Agemegos

That will be because a white dwarf is a remnant of a much more massive star that threw off a lot of its mass at the end of its giant stage. The main-sequence, subgiant, and giant stages through which the star has already gone are those of a much more massive and correspondingly shorter-lived star.

The mass figure used by GURPS Space is the initial mass of the star, not the mass of the white dwarf.

And this is why I am not either an astronomer (despite a fascination with it) nor a mathematician. So how do i trick the program into giving me the results I need?

-Mike

[Pomphis]

Originally Posted by Agemegos

No. It is just taht if you put in mass=1 and age=4,5 billion years you get luminosity = 1.09, whereas the luminosity of the Sun ought to be 1.0.

Manually I get 1.094.

[Flyndaran]

Originally Posted by Agemegos

Check your inbox. I sent you 800K of PDFs.

Now to giggle publicly. Hee, hee, hee.

The RAW and your program list numerous M class stars with habitable planets. How likely is that when considering that the majority of their output will be in the infrared or lower range?
Habitable atmospheres are transparent to visible light and radio only. This makes any hypothetical life based on other forms of em radiation emitted by the star absurdly unlikely.

I say "emitted by the star", because I have heard of real world fungi capable of deriving useful energy from ionizing radiation. But those are definitely niche organisms not likely to form the basis of an ecosystem of any remotely habitable planet.