11.0 Solving The K Class Star While we said F-type stars are characteristic of copper-silver
civilizations because they have lower metallicities, this is not always true; it depends on the type
of F star. The older F-type stars have lower metallicity than G-type stars because they formed in
an environment that was not metal-rich because the environment has not been enriched by
previous generations of stars. Younger F-type stars (that formed more recently) formed in an
environment where previous stellar generations enriched the environment from which the F-
star formed. Also, F-type stars are more luminous meaning they have higher radiation pressure,
thus may be blowing the heavier metallic elements further out, perhaps beyond the habitable
zone of the planet. in general you can say F-type stars have lower metallicity than G-type stars.
In general, younger G-type stars like our Sun tend to have higher metallicities compared to older
stars, because they formed in a part of the galaxy that has undergone more stellar generations
enriching the interstellar medium. Also they have lower radiation pressure than F stars,
meaning the heavier elements needed to form terrestrial planets have not been so heavily blown
out beyond the habitable zone.
Like with F-stars and G stars, younger K stars have higher metallicities than older K stars
because they formed after other stars enriched the environment where they formed. Also, the
radiation pressure is lower in K-stars than in G stars, meaning perhaps not so much metal got
blown out beyond the habitable zone.
It in fact may be that we want to say that the stars of the silver-copper type civilizations are the
Population II stars which is to say they are older and did not form from gas clouds enriched by
earlier generations of stars, and that the the stars of the silver-gold type civilizations are the
Population I stars, like our Sun, which is to say they are younger and formed from clouds
enriched with heavier metals from pervious generations of stars. However we do have to say it
may depend on spectral class as well because the hotter F-stars have more radiation pressure
and whether they formed from metal-rich environments or not, they may blow more heavier
elements out of their habitable zones.
However, there is more to it. K-type stars are generally older than G-type stars, they have longer
life-spans, meaning they formed in environments that were less enriched by previous
generations of stars, that is to say they are usually Population II stars. Thus, they in general have
lower metallicities than G-type stars. F-stars, in general, do have lower metallicities than G-type
stars as well, because they are usually older than G-stars. Many F-type stars are part of the thick
disc or halo populations in our galaxy the Milky Way. G-type stars are generally found in the
thin disc region of our galaxy, which tend to have higher metallicities because they are younger
and closer to regions of recent star formation. Thus stars like the Sun, G-type stars, in general do
have higher metallicities than F or K stars, even thought they are in-between the two in spectral
class. So, we were right to make F-type stars copper-silver type civilizations, and G-type stars
silver-gold type civilizations because in general this would be true, though there can be
exceptions. We suggested G-star civilizations can become more sophisticated than F-star
civilizations because they have longer life-spans giving more time for intelligent life to evolve.
However, K stars have longer life-spans than G stars, so we suggested they can have more
sophisticated life than found around G-stars. However, we did not associate any metals in
particular with these stars because we started at F-type stars with copper and silver, went to G-
type stars with silver and gold, and after gold in this group of elements there is no suitable metal
left to utilize in this approach to the theory, Indeed most F-type stars would have copper-silver
type civilizations because they are in general older than G-type stars. So, as we begin to solve K-
type stars we will start with them as copper-silver civilizations as in general they have lower
metallicities.
However it may be, regardless of the metallicity of the star, if it is more luminous, having more
radiation pressure, it may blow more heavier elements out of its habitable zone. However, it may