The Velocities of Stars

# The Velocities of Stars - physical units such as...

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The Velocities of Stars To get the tangential velocity, you need to first measure the angular velocity of the star across the sky ( d / dt ). This is how many degrees on the sky the star moves in a given amount of time and is called the proper motion by astronomers. If you determine the star's distance from its trigonometric parallax or the inverse square law method, you can convert the angular velocity (proper motion) to tangential velocity in
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Unformatted text preview: physical units such as kilometers/second. The tangential velocity = k × the star's distance × the proper motion, where k is a conversion factor that will take care of the conversion from arc seconds and parsecs and years to kilometers/second. Using the Pythagorean theorem for right triangles, you find that the star's total velocity = Sqrt [(radial velocity) 2 + (tangential velocity) 2 ]....
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## This note was uploaded on 12/15/2011 for the course AST AST1002 taught by Professor Emilyhoward during the Fall '10 term at Broward College.

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