Main Sequence Stars: The Cosmic Majority

Main sequence stars are the most common type of stars in the universe, making up about 90% of all stars.
They shine by fusing hydrogen into helium in their cores, releasing enormous amounts of energy.
A star’s position on the main sequence depends on its mass, temperature, and luminosity.
Hot, massive blue stars live fast and die young, burning out in just millions of years.
Smaller, cooler red dwarfs can remain on the main sequence for trillions of years.
Our Sun is a typical main sequence star, midway through its 10-billion-year lifespan.
The Hertzsprung–Russell diagram maps main sequence stars in a diagonal band across the chart.
Main sequence stars come in spectral types O, B, A, F, G, K, and M, from hottest to coolest.
Their color ranges from blue-white to red, reflecting their surface temperatures.
Once they run out of core hydrogen, stars leave the main sequence and evolve into red giants or other stellar remnants.