AST201H1 Lecture Notes - Lecture 3: Annie Jump Cannon, Stellar Classification

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST201H1
• Professor: Michael Reid

Document Summary

Ast201: spectral classification (chp 15. 1 spectral type & temperature) Note: video not in zero gravity, in free fall. Edward pickering and his associates grouped spectra into similar groups and labeled them alphabetically. Annie jump cannon finally made sense of the vast catalog of stellar spectra. Cannon realized that you could get rid of most of the spectral categories and kept only a few. We determine surface temperature of a star from either its color or its spectrum. Sun"s 5800 k surface temp. causes it to emit most strongly in the middle of the visible portion of the spectrum which is why sun looks yellow or white in color. Obafgkm (oh be a fine girl kiss me) Each spectral type is subdivided into numbered subcategories (b0, b1etc. ) The larger the number, the cooler the star. Sun is g2 = slightly hotter than a g3 star, cooler than a g1 star. Coolest stars are type m, surface temperatures as low as 3000k.