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Unformatted text preview: Working with the ap parent brightness ? luminosity ? distance formula (inverse-square law) The amount of starlight reaching a telescope is proportional to the amount of power produced by the star and inversely proportional to the square of the distance to that star. or (flux is energy per square area received in 1 second) Results of calculations using this equation are hard to understand if we use absolute values. For example, let's say that a star has a luminosity of 3.826 x 10 26 watts, and is 1.495979 x 10 11 meters away. What is the flux per square centimeter on the Earth? This is for a very famous star, Sol (our star), and is known as the solar constant. Even this value seems hard to comprehend in everyday terms! Astronomers like to take ratios of relationships in order to compare unknown objects with known objects. For example, Sirius is the brightest star in the sky. How would the apparent brightness of another star having the identical luminosity as Sirius compare if the second star were 100 times...
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- Fall '10