PowerPoint PresentationSlide 2Spectra of different kinds of celestial objects10/17/11 Spectroscopy Stellar Classification Using Strength of Absorption LinesSpectra in sections looked different because emission tubes contained different elements. Stars have them all.Classification overview: TextbookUnderstanding atomsSlide 8Understanding the guidesQualitative determination of line strengthSlide 11Slide 12Identifying 3 lines + assigning element and line strengthCalculating a line strengthMeasuring the strength of 3 linesSlide 16Determining Spectral Type and Surface Temperature1QuickTime™ and a decompressorare needed to see this picture.2QuickTime™ and a decompressorare needed to see this picture.QuickTime™ and a decompressorare needed to see this picture.3Spectra of different kinds of celestial objectsSpectra of different kinds of celestial objectsQuickTime™ and a decompressorare needed to see this picture.QuickTime™ and a decompressorare needed to see this picture.QuickTime™ and a decompressorare needed to see this picture.Makemake410/17/11 10/17/11 SpectroscopySpectroscopyStellar Classification UsingStellar Classification UsingStrength of Absorption LinesStrength of Absorption Lines5Spectra in sections looked different because emission tubes Spectra in sections looked different because emission tubes contained different elements. Stars have them all.contained different elements. Stars have them all.BUT, in general, stars to within a fraction of a percentage, all have similar abundances of the elements!AAbubundndaanncceess iinn ththee SSunun 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 0.00356Classification overview: TextbookClassification overview: Textbook7QuickTime™ and a decompressorare needed to see this picture.Understanding atomsUnderstanding atomsQuickTime™ and a decompressorare needed to see this picture.QuickTime™ and a decompressorare needed to see this picture.QuickTime™ and a decompressorare needed to see this picture.HeNaCa FeQuickTime™ and a decompressorare needed to see this picture.8QuickTime™ and a decompressorare needed to see this picture.9Understanding the guidesUnderstanding the guides10Qualitative determination of line strengthQualitative determination of line strength11QuickTime™ and a decompressorare needed to see this picture.12QuickTime™ and a decompressorare needed to see this picture.13QuickTime™ and a decompressorare needed to see this picture.Identifying 3 lines + assigning element and line strengthIdentifying 3 lines + assigning element and line strengthQuickTime™ and a decompressorare needed to see this picture.41 Cygni data in ExcelGoogle Spreadsheet (see instruction on a handout)389.1H8430.3“G” band540.7He II14Calculating a line strengthCalculating a line strengthQuickTime™ and a decompressorare needed to see this picture.€ Line strength =1 −flux line bottomflux continuum15Measuring the strength of 3 linesMeasuring the strength of 3 linesQuickTime™ and a decompressorare needed to see this picture.€ 1 −0.450.73= 0.38€ 1 −0.670.84= 0.2016QuickTime™ and a decompressorare needed to see this picture.17Determining Spectral Type and Surface TemperatureDetermining Spectral Type and Surface TemperatureQuickTime™ and a decompressorare needed to see this
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