A star near the visible edge of a galaxy travels in a uniform circular orbit. It...

A star near the visible edge of a galaxy travels in a uniform circular orbit. It is 48,400 ly (light-years) from the galactic center and has a speed of 275 km/s.

a) Estimate the total mass of the galaxy (billion solar mass) based on the motion of the star. Gravitational constant is 6.674×10⁻¹¹ m³/(kg·s²) and mass of the Sun M_s=1.99 × 10³⁰ kg.

b) The total visible mass (i.e., matter we can detect via electromagnetic radiation) of the galaxy is 10¹¹ solar masses. What fraction of the total mass of the galaxy is visible, according to this estimate?

Expert Solution

genius_generous answered 1 year ago

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