A Class O star is the brightest type of star, sitting on the line between main sequence and giant. Traditionally, they are coloured blue. They are also the rarest type of main sequence star, making up only 0.00001% of luminous stars.

A typical class O star has a mass of 50 solar masses, a radius of 10 solar radii, a luminosity of 100,000 solar luminosities, a surface temperature of 40000 K and a lifespan of 10 million years.

The habitable zone of a typical O-Class star is on the order of 500 AU. This, coupled with their short lifespans, makes them poor candidates for having solar systems, especially those that support life.

Stellar Classes
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