PHYS 1600 Chapter Notes - Chapter 11: Apparent Magnitude, Stellar Classification, Main Sequence
21 Dec 2015
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Distance in ly 3 times distance in pc. Distance in pc 1/3 the distance in ly. A magnitude 1 star is 2. 5 times more luminous than a magnitude 2 star. A magnitude 2 star is 2. 5 times more luminous than a magnitude 3 star. Their absolute luminosity will be less than their apparent luminosity and because of the backward nature of the magnitude scale their absolute magnitude will be greater than their apparent magnitude. Nearer than 10 pc: lv < lv, and mv > mv: see if you can reason out the other and more usual case (since most stars are further away than 10 pc). If they were moved toward us they would appear brighter. Further than 10 pc: lv > lv, and mv < mv. 11-1 distances to nearby stars are found using stellar parallax. Closest star other than the sun is about 40 trillion km away. Light takes more than 4 years to get here from there.
