Calculating Schwarzschild Radius at Galaxy's Core

[mantillab]

Homework Statement

Astronomers have observed a small, massive object at the center of our Milky Way galaxy. A ring of material orbits this massive object; the ring has a diameter of about 15 light years and an orbital speed of about 200 km/s. Take the distance of one light year to be 9.461 X 10^15 m. Mass of object = 4.26 X 10^37 kg. Speed of light (c) = 3 X 10^8 m/s. G = 6.67 x 10^(-11).

Many astronomers believe that the massive object at the center of the Milky Way galaxy is a black hole. If so, what is its Schwarzschild radius R_S?

Homework Equations

From Wikipedia, I got the equation for the Schwarzschild radius to be R_S = [2Gm]/c^2.

The Attempt at a Solution

Using the above equation and the above constants, I got 1.89 x 10^19 m, which is wrong.

Other wrong answers: 1.90×10^19 and 1.89x10^35.

Any help would be appreciated! Thanks!

 

[nicksauce]

Well it looks like you divided by c instead of c^2.

 

[mantillab]

Doh! Thanks so much.