What is a good estimate for the mass of a goat?

Suppose you observe a star orbiting the galactic center at a speed of 1400 in a circular orbit with a radius of 15.0 light-days. What would your estimate be for the mass of the object that the star is orbiting in M_sun?

Make an order-of-magnitude estimate of the power a car engine contributes to speeding the car up to highway speed. In your solution, state the physical quantities you take as data and the values you measure or estimate for them. The mass of a vehicle is often given in the owner’s manual.

Make an order-of-magnitude estimate of your power output as you climb stairs. In your solution, state the physical quantities you take as data and the values you measure or estimate for them. Do you consider your peak power or your sustainable power?