If a giant molecular cloud is 73 pc in diameter and a shock wave can sweep  through it at 9 million years, how fast is the shock wave going in km per second?  1 pc = 3.1× 10^13 km; 1 yr = 3.2 × 10^ 7 s

If a giant molecular cloud is 38 pc in diameter and a shock wave can sweep through it in 6 million years, how fast is the shock wave going in kilometers per second? (Notes: 1 pc = 3.1  1013 km; 1 yr = 3.2  107 s.) answer in km/s

A supernova’s energy is often compared to the total energy output of the Sun over its lifetime. Using the Sun’s current luminosity, calculate the total solar energy output, assuming a 1010 year main-sequence lifetime. Using Einstein’s formula E=mc2 calculate the equivalent amount of mass, expressed in Earth masses. [Hint: The total energy output of the Sun over its lifetime is given by its current luminosity times the number of seconds in a year times its ten billion-year lifetime; ; mass of earth = 6×1024kg; c = 3×108m/s. Your answer should be 200-300 Earth masses.]

If a giant molecular cloud has a mass of 2.0 ✕ 1035 kg, and it converts 8 percent of its mass into stars during a single encounter with a shock wave, how many stars can it make? Assume the stars each contain 1 solar mass. (Hint: The mass of the Sun is 1.99 ✕ 1030 kg.)

If a standard passenger aircraft can fly at 0.32 km/s (716 mph), how long (in yr) would it take to reach the sun? ______ yr How long (In yr) would it take to reach the galactic center? (Note: 1 pc = 3.1 x 10^13 km. The radius of the suns orbit around the galactic center is approximately 8,300 pc.)  ______ yr

why do dark streaks appear in visible light images of the Trifid nebula, but appear bright in an infared image

if a protostellar disk is 260 au in radius and the disk plus the forming star together contain 7 solar masses what is the orbital speed at the outer edge of the disk in km per second. use the circular orbital velocity formula

What is the escape velocity (in km/s) from the surface of a 1.1 M neutron star? From a 3.0 M neutron star?

How many years? Thank you!

If a giant molecular cloud has a diameter of 56 pc and drifts relative to nearby objects at 19 km/s, how long (in yr) does it take to travel a distance equal to its own diameter?