1123Spectra of different kinds of celestial objectsSpectra of different kinds of celestial objectsMakemake2410/17/1110/17/11SpectroscopySpectroscopyStellar Classification UsingStellar Classification UsingStrength of Absorption LinesStrength of Absorption Lines5SpectraSpectra in sections lookedin sections looked different different because emission tubesbecause emission tubescontained different elements. Stars have them all.contained different elements. Stars have them all.BUT, in general, stars to within afraction of a percentage, all havesimilar abundances of the elements!AbuAbundandancncees s iin n thethe S Sun un Element Abundance (% of total) number of atoms Hydrogen 91.2 (71% by mass) Helium 8.7 (27% by mass) Oxygen 0.078 Carbon 0.043 Iron 0.030 Sulfur 0.015 Nitrogen 0.0088 Silicon 0.0045 Magnesium 0.0038 Neon 0.0035 6Classification overview: TextbookClassification overview: Textbook37Understanding atomsUnderstanding atomsHeNaCaFe89Understanding the guidesUnderstanding the guides410Qualitative determination of line strengthQualitative determination of line strength1112513Identifying 3 lines + assigning element and line strengthIdentifying 3 lines + assigning element and line strength41 Cygni data in ExcelGoogle Spreadsheet (see instruction on a handout)389.1H8430.3“G” band540.7He II14Calculating a line strengthCalculating a line strength! Line strength =1 "flux line bottomflux continuum15Measuring the strength of 3 linesMeasuring the strength of 3 lines! 1 "0.450.73= 0.38! 1 "0.670.84= 0.2061617Determining Spectral Type and Surface TemperatureDetermining Spectral Type and Surface
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