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I doubt I'm the first person to ask this question, so if anyone knows of previous post of the same subject, point me that way. If by some magical means I am the first person to pose this question, perhaps someone would be kind enough to enlighten me.

How are the star classes ... calculated? For example, our sun (Sol) is a Class G2 V star. What exactly does this mean?

Thank you.

Hero wrote:I doubt I'm the first person to ask this question, so if anyone knows of previous post of the same subject, point me that way. If by some magical means I am the first person to pose this question, perhaps someone would be kind enough to enlighten me.

How are the star classes ... calculated? For example, our sun (Sol) is a Class G2 V star. What exactly does this mean?

Thank you.

After entering e.g. 'stellar type' or 'star colors' into Google there is a long list of explanatory pages popping up. E.g.

http://lheawww.gsfc.nasa.gov/users/allen/spectral_classification.html

So the standard color classes are nothing but a representation of the stars' effective surface temperature. The latter may be estimated theoretically by means of stellar models, various empirical correlations with other observables (e.g. Hertzsprung-Russel diagram: Luminosity vs. Temperature) or directly measured by means of spectroscopy.

Bye Fridger