Yellow dwarves are of particular interest - they are the ones most likely to support life as we know it.

The life span of a star is a function of its mass. The larger the star, the faster it burns its fuel and the shorter its life span. It is very unlikely for one of the giant blue stars (O, B, or A) to last long enough for planets to form life before they explode. The O type stars are 1,400,000 times the luminosity of the sun and pour out radiation on any planet that they few hundred thousand years before they explode.

On the flip side, the red and brown dwarves at one tenth the mass of the sun, while they can burn for 10 trillion years (our sun is expected to last for about 12 billion years). This is several thousand times the current age of the universe. In order for a planet to get even the same heat that Mars gets from the sun would either be tidally locked (always showing one face to the star) or within the Roche limit and crumble. Neither of these are good things for life.

The yellow dwarf star has an average surface temperature of about 5,000 K to 6,000 K, mass somewhere about 1.1 solar masses and 1.1 solar radii. This star would be about 1.2x the luminosity of our sun. Notable characteristics are absorption lines of neutral metallic atoms and ions (once-ionized calcium for example).

Our sun is a classic example of a G type dwarf star. The full classification of our sun is G2V. The 'G' refers to the surface temperature and color. The '2' is the subclass within 'G' which puts us closer to the F (hotter) than the K (colder). The 'V' is from the Yerkes Luminosity Classes indicating that the sun is a main sequence dwarf star.

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