Stars on the top left of the main sequence spend less time because they have a higher mass and therefore burn through their fuel at a faster rate. This causes them to have a shorter lifespan compared to stars with lower mass.
A star's mass is directly related to its lifespan. The more massive a star is, the shorter its lifespan will be. This is because the higher mass creates a stronger gravitational force, causing the star to burn through its fuel at a faster rate.
The main sequence is a diagonal band on the Hertzsprung-Russell diagram, which plots a star's luminosity (brightness) against its temperature. It represents the stage of a star's life when it is converting hydrogen into helium in its core.
The position of a star on the main sequence can give us an estimate of its age. Stars on the top left of the main sequence are younger because they are still burning through their fuel at a faster rate. As a star ages, it moves towards the lower right side of the main sequence.
Yes, stars can move off the main sequence as they age. As a star runs out of hydrogen fuel in its core, it will begin to expand and cool, moving towards the upper right of the Hertzsprung-Russell diagram. This marks the end of its main sequence stage and the beginning of its next stage in its life cycle.