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oddjobmj
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Homework Statement
Astronomers believe that there is a massive black hole at the center of the Milky Way galaxy. What evidence is there for that?
A group of astronomers have observed a star "S2" in a 15.2-year orbit around the center of the galaxy. They measured the period of revolution T = 15.2 years, the eccentricity of the elliptical orbit ε = 0.87, and the semimajor axis of the orbit a = 4.62 mpc. [The unit: mpc = milli-parsec = 0.001 parsec.]
(A) Calculate the mass of the compact object about which S2 is revolving.
Homework Equations
sm=semi-minor axis
sM=semi-major axis
Eccentricity=[itex]\sqrt{1-(sm/sM)^2}[/itex]
Mass=[itex]\frac{4π^2r^3}{GT^2}[/itex]
The Attempt at a Solution
If I plug in my values to the eccentricity equation and solve for the semi-minor axis I get 7.031*1010 km. With that I can find r which is the average of the semi-major and semi-minor axis:
r=1.06455*1011 km
Plugging in my knows to the mass equation I get 3.11*10^36 kilograms which is incorrect. What am I doing wrong?
Thank you!