PHYS 190 Lecture Notes - Lecture 12: Absolute Magnitude, Main Sequence, Horse Length
24 Feb 2018
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Document Summary
Absolute magnitude - convenient way to compare star brightnesses, independent of distance, equivalent to luminosity. Absolute mag of object defined as apparent mag it would have at standard distance of. Every 5 magnitude is factor of about 100. Sun appears to be 100 billion times brighter than betelgeuse, but absolute magnitude: Betelgeuse is 25 00 times brighter than sun. For normal stars, there is tight r/s b/w properties. Correlation v/w car horsepower & weight makes sense. Similarly, stars exhibit correlation b/w luminosity & temperature. Luminosity factor of 1010 = 10 billion. Dying stars - in upper right of graph. Stars spend about 9% of time in stable adult phase. 90% of stars lie along main sequence. Spectral type - at top of diagram, another way of telling hot hot. O, b, a, f, g, k, m. When star starts to die, starts swelling & shrinking.
