There are about \(10^{11}\) stars in the Galaxy with mass comparable to the Sun. Determine total mass \(M_{S}\) in the stars and the fraction of the Galaxy mass in the form of interstellar medium (ism). Use the value determined in the question 8 for the mass of the interstellar medium.

Question 8: 

The Galaxy can be schematized as a disk of radius 15 kpc and thickness 200 pc. Since we know that 1 pc=3.08 × 10¹⁶ m, determine the volume of the Galaxy and the total mass of gas in the interstellar medium. Use the data from the question 7.

Question 7:

The density of the interstellar medium in our Galaxy is measured to be 10^-21 kg m^-3
and consists mainly of hydrogen. Estimate how many hydrogen atoms per cm³ are present in the Galaxy.