Yellow/Green/Blue/Black Zones

[tkdguy]

Does anyone know where the values of these zones in Star Hero came from? I'd like to look at the astrophysics of this.

[Ternaugh]

Re: Yellow/Green/Blue/Black Zones

 

These are zones in a star system where certain planet types are most likely to show up. SH p. 80 describes them. For those with a background in Traveller, they match up something like this:

 

Yellow: Inner zone. Planets are usually too hot to support (earth-like) life. Gas Giants should be extremely rare in this zone.

Green: Habitable Zone. Planets have a chance of developing an earth-like environment. In the Terran System, Venus is just on the edge of the inner habitable zone, Mars is just on the edge of the outer habitable zone, and Earth is "just right".

Blue Zone: Outer zone. Planets are usually too cold to support (earth-like) life. Gas Giants are more common in this zone.

Black Zone: Outer zone. As Blue zone, but the amount of material for planetary construction is lower. Gas Giants still common, but tend to be smaller than those in Blue Zone. At the far edge of the system, an Oort cloud usually forms from the various leftovers of planetary construction. From this cloud, comets and some meteors may arise.

 

Calculations for all of these zones are based upon the energy output of the star, and the range from the star. These raw numbers, shaped by things like albedo and atmospheric thickness (and many more), give an average surface temperature for any given planet.

 

JoeG

 

Now Playing: Alan Parsons, "The Time Machine"

[tkdguy]

Re: Yellow/Green/Blue/Black Zones

 

Thanks, Ternaugh. Do you know where I can find some equations for them?

[Ternaugh]

Re: Yellow/Green/Blue/Black Zones

 

Thanks' date=' Ternaugh. Do you know where I can find some equations for them?[/quote']

 

This is all based upon the Green zone, that is, the zone where liquid water can exist. The Yellow zone is then defined as being closer to the star, while the Blue zone is further from the star.

Try:

http://www.star.ucl.ac.uk/~idh/STROBEL/lifezone/lifezone.htm has the formulas needed (in relation to Sol's lifezone), and some great explanations.

 

The boundary distance is

 

rstar = rsun × Sqrt[Lstar/Lsun]

 

where the boundaries of the Sun rsun = 0.7 and 1.5 A.U., and Lstar/Lsun is the luminosity of the star compared to the Sun. For example the inner and outer bounds of the lifezone for a star like Vega (an A0-type main sequence star with LVega/Lsun = 53) are 5.1 - 10.9 A.U, respectively. For a cool star like Kapteyn's Star (a M0 main sequence star with LKapt/Lsun = 0.004), the lifezone stretches from only 0.044 - 0.095 A.U.

 

Hope it helps,

 

JoeG

 

Now Playing: Thomas Dolby, "The Golden Age of Wireless"

[tkdguy]

Re: Yellow/Green/Blue/Black Zones

 

That's exactly what I was looking for. Many thanks!