(a) Estimate the mass of the luminous matter in the known universe, given there are 1011 galaxies, each containing 1011 stars of average mass 1.5 times that of our Sun. (b) How many protons (the most abundant nuclide) are there in this mass? (c) Estimate the total number of particles in the observable universe by multiplying the answer to (b) by two, since there is an electron for each proton, and then by 109 , since there are far more particles (such as photons and neutrinos) in space than in luminous matter.
(a) Estimate the mass of the luminous matter in the known universe, given there are 1011 galaxies, each containing 1011 stars of average mass 1.5 times that of our Sun.
(b) How many protons (the most abundant nuclide) are there in this mass? (c) Estimate the total number of particles in the observable universe by multiplying the answer to (b) by two, since there is an electron for each proton, and then by 109 , since there are far more particles (such as photons and neutrinos) in space than in luminous matter.
mass of one star, m = 1.5 ×mass of the sun
m = 1.5 ×1.989 × 1030 = 2.9835 × 1030 kg
number of stars in one galaxy = 1011
number of stars in 1011 galaxies, n = 1011 × 1011 = 1022
Mass of luminous matter, M = n × m
M = 2.9835 × 1030 × 1022
M = 2.9835 × 1052 kg
Step by step
Solved in 2 steps
