Probabilities in the Galaxy
A Distribution Model for habitable Planets
Copyright © Klaus Piontzik

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12 – A General Approach

12.1 - Spectral Classes

Galaxiy In previous observations, star systems with a sun-like central star were examined. Assuming that other star systems, i.e. not solar-like systems, also have frequencies for technological civilizations, then the Drake-Seager equation 10.3.2 can be derived:
   
12.1.1 Equation NX = A FX Fph Fk FLiz


Equation 12.1.1 then applies to the star quantities formed by a solar type or spectral class[1], respectively.

Hertzsprung-Russel-Diagramm The suns of our galaxy are represented in the so-called Hertzsprung-Russel diagram[2], arranged according to colour and luminosity. A total of 13 spectral types exist.

The spectral types O, B, A, F, K, i.e. the blue, the blue-white, white, the white-yellow and the orange spectral colors make up about 1% of the total stars.

In addition, there are the brown dwarfs and the red giants, i.e. the spectral classes L, T, Y, R, N, S, which also make up 1% of the total stars.

Two classes have become known so far. This is the set of sun-like G stars, with a yellow spectral color and the probability Fs = 0.28 = 7:25.

As well as the number of red dwarfs, i.e. M stars with a red-orange spectral color and a probability FRZ = 0.7 = 7:10. Thus, the two spectral classes make up 98 % of the total stars in the galaxy.

 

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