Question

Using the relations between mass and radius and mass and luminosity for main sequence stars that we wrote down in class:

a. Determine the density of main sequence stars as a function of mass.

b.Using this relation compute the density of a 0.1 solar mass star relative to that of the Sun. Compute the density of a 10 solar mass star relative to that of the Sun.

c. Determine the surface gravity of main sequence stars as a function of mass.

d. What is the surface gravity of a 0.1 solar mass star relative to that of the sun ? What is the surface gravity of a 10 solar mass star relative to that of the sun?

e. Assume the total core hydrogen burning main sequence lifetime of the Sun is 10 billion years. Also assume the efficiency of hydrogen fusion into helium is 0.7% (i.e., 0.7% of the mass in fusing hydrogen into helium is converted to energy) . What is the total fraction of the Sun’s mass that it will fuse from hydrogen into helium in its main sequence lifetime?

f. Assuming tha t the total fraction of a star’s mass it converts from hydrogen to helium is the same across the main sequence, and that the efficiency of hydrogen fusion into helium is 0.7%, what is the main sequence lifetime of a 0.1 solar mass star? A 10 solar mass star

Answer 1