Lecture06

Lecture06 - Previous Lecture types of binary stars optical,...

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Previous Lecture types of binary stars optical, visual , astrometric, spectroscopic, eclipsing binary star light and velocity curves masses from binary stars mass-luminosity relation: L M 3 stellar sizes from eclipsing binaries Sun properties
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Basic Solar Properties Sphere of gas 71% H, 27% He, 2% “metals” (by mass) Mass: 1.99 x 10 30 kg (~300,000 x M earth ) Radius: 6.96 x 10 5 km (~100 x R earth ) Average density: 1.4 g/cm 3 Surface Temperature: 5800 K Luminosity: 3.86 x 10 26 W Rotation: ~25 day period, differential
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Solar Photosphere Visible “surface”of the Sun Temperature, density, and opacity all increase rapidly inward Photosphere is relatively thin (few 100 km) due to rapidly increasing opacity with depth apparent sharp edge to Sun’s disk
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Photosphere (continued) Sunspots cooler (~4500K) and hence darker regions 2,500 – 50,000 km size range contain strong magnetic fields Number of sunspots changes periodically maximum every 11 years 350 years of complete records Maunder minimum: 1640-1700 almost no sunspots observed possibly correlated with time of cold climate?
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Lecture06 - Previous Lecture types of binary stars optical,...

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