[SPACE] Star Generation

[whswhs]

Originally Posted by Noven

I started with the nearest starts to Sol and worked my way out, and currently have finished Barnard's Star.

Aren't Proxima and Alpha Centauri part of the same multiple-star system? I would have thought you'd stat them up as Alpha Centauri A having one distant companion and one near companion.

Bill Stoddard

[Agemegos]

Originally Posted by whswhs

Aren't Proxima and Alpha Centauri part of the same multiple-star system?

Probably: but not for certain. The combined mass of the A-B pair is well-known, but there is uncertainty in the distance of their barycentre from Proxima, and uncertainty in the space velocities of the A-B pair and of Proxima. The upshot is that Proxima could be a distant companion of A-B, or it could be an independent red dwarf on a slow close pass. It could go either way when more precise measurements come in.

[RyanW]

I know it isn't specified in the rules, but shouldn't the inner most planets of Sirius' white dwarf companion be cinders, assuming they survived at all?

[t@nya]

Originally Posted by RyanW

I know it isn't specified in the rules, but shouldn't the inner most planets of Sirius' white dwarf companion be cinders, assuming they survived at all?

Probably. In our own solar system, Mercury, Venus, and Earth are going to be disintegrated, whilst the other planets will end up on wider orbits.

[Agemegos]

Originally Posted by RyanW

I know it isn't specified in the rules, but shouldn't the inner most planets of Sirius' white dwarf companion be cinders, assuming they survived at all?

The rules really don't handle white dwarfs at all. They will tell you that a star has become a white dwarf, but not its mass and luminosity when it does, and things go downhill from there. The planets of white dwarfs ought perhaps to be generated first around the star at its maximum luminosity in giant stage, then have their orbital radii and orbital eccentricities increased, their atmospheric masses decreased, and be chilled down to the temperatures supported by the luminosity of the remnant white dwarf. The loss of mass of the star and the effect of the passing planetary nebula outflows on the planets is not estimated.

[t@nya]

Originally Posted by Agemegos

The rules really don't handle white dwarfs at all. They will tell you that a star has become a white dwarf, but not its mass and luminosity when it does, and things go downhill from there.

That's too bad. Sounds like it would make a good e23 book, maybe along with pages on pulsars, black holes and other "dead" stars. I even have a name for it: GURPS Space: Shadow of Dead Stars. :)

[whswhs]

Originally Posted by Agemegos

The rules really don't handle white dwarfs at all. They will tell you that a star has become a white dwarf, but not its mass and luminosity when it does, and things go downhill from there. The planets of white dwarfs ought perhaps to be generated first around the star at its maximum luminosity in giant stage, then have their orbital radii and orbital eccentricities increased, their atmospheric masses decreased, and be chilled down to the temperatures supported by the luminosity of the remnant white dwarf. The loss of mass of the star and the effect of the passing planetary nebula outflows on the planets is not estimated.

I didn't find it hard to do white dwarfs. I generated the planets as of the condition of the solar system when the star was on the main sequence; then I looked at its two giant phases, figuring the temperatures of the planets that weren't simply engulfed by it, and the planetary types that resulted, and then at the temperatures they fell to when it reached its white dwarf phase.

It was more of a challenge figuring the effect of a distant second star on the temperature of planets orbiting a white dwarf.

Bill Stoddard

[Agemegos]

Originally Posted by whswhs

I didn't find it hard to do white dwarfs. I generated the planets as of the condition of the solar system when the star was on the main sequence; then I looked at its two giant phases, figuring the temperatures of the planets that weren't simply engulfed by it, and the planetary types that resulted, and then at the temperatures they fell to when it reached its white dwarf phase.

How did you take account of the effect on the planet's orbits when the central star lost 10% to 60% of its mass in its supernova explosion?

[Noven]

Work has been ongoing on my wiki and I started thinking about something: is there some website that can tell me how far (lets say....) Kruger 60 is from Alpha Centauri? I know how far both are from Sol, but if someone was in a different system and was going to another, I am drawing a blank on how far they are from each other. Something cool like this is neat and tells me (but is rather useless since it only covers systems within 10 light-years from Sol) what I need to know, but not how to compare 2 distances from each other.

[t@nya]

Originally Posted by Agemegos

How did you take account of the effect on the planet's orbits when the central star lost 10% to 60% of its mass in its supernova explosion?

You meant the red giant phase, right? (since white dwarfs don't go supernova)