ASTR 1020 1st Edition Lecture 9 Outline of Last Lecture I. Surveying the Stars, pt 2A. PropertiesB. RadiiC. MassD. Binary Star SystemsE. DiagramF. Cosmic Distance ScaleOutline of Current Lecture I. Stellar Properties ReviewA. EquationsB. Main Sequence Star SummaryCurrent LectureI. Stellar Properties ReviewA. Equations- Luminosity: from brightness and distance 10-4 LSun - 106 LSun - Temperature: from color and spectral type 3,000 K - 50,000 K - Mass: from period (p) and average separation (a) of binary-star orbit 0.08 MSun - 100 MSun- Lifetime: Stellar lifetime α stellar massstellar luminosity- Life expectancy of 10 MSun star: 10 times as much fuel, uses it 104 times as fast 10 billion years x 10 / 104 ~ 10 million years - Life expectancy of 0.1 MSun star: .1 times as much fuel, uses it 0.01 times as fast 10 billion years x 0.1 / 0.01 ~ 100 billion yearsB. Main Sequence Star Summary- High Mass: - High Luminosity - Short-Lived- Large Radius - Blue - Low Mass: - Low Luminosity - Long-Lived0- Small Radius - Red- Massive blue stars die first, followed by lower mass stars (white, yellow, orange, and red)- In HRD, stars die away first at the top end (massive stars) of main sequence. - Find cluster age by determining the turn-off point, the most massivestars still on main sequence.- Oldest globular clusters are 13 billion years
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