How Do Astronomers Identify a Main Sequence Star Using the Hertzsprung Russell Diagram?

A star’s age or maturity is marked by its location on the main sequence of the Hertzsprung-Russell diagram.

Where it first appears on the main sequence, however, depends on its mass.

A star with greater mass will be hotter, take less time to mature, and will appear on the upper part of the diagram.

A star with less mass will be cooler, take longer to show up, and will appear lower down on the main sequence.

It took the Sun about 30 million years to age from a protostar to a main sequence star. The average temperature of the Sun is approximately 6,000°K (10,000°F/ 6,000°C).

A star three times the size of the Sun will mature in about 1 million years, and will be more than twice as hot.

A star about one-tenth the mass of the Sun will take about 100 million years to appear on the main sequence and will be half as hot as the Sun.