Which of the following stars has the longest main sequence lifetime?
Group of answer choices
a star with a mass of 0.4 solar masses
a star with a mass of 1.2 solar masses
a star with a mass of 0.5 solar masses
a star with a mass of 3 solar masses
and why?
A star with a mass of 0.4 solar masses has the longest main sequence lifetime.
The main sequence lifetime of a star is determined primarily by its mass. Stars with lower masses have longer main sequence lifetimes because they burn their fuel (hydrogen) at a slower rate than stars with higher masses.
As the mass of a star increases, its main sequence lifetime decreases. This is because higher-mass stars have stronger gravitational forces that compress their cores more, leading to a higher temperature and pressure that accelerates nuclear fusion. Consequently, higher-mass stars burn through their hydrogen fuel faster and have shorter main sequence lifetimes.
Therefore, out of the given options, the star with a mass of 0.4 solar masses is expected to have the longest main sequence lifetime since it has the lowest mass.