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print4 - Stellar Properties 1 COMIPOSITION What elements...

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Unformatted text preview: Stellar Properties 1. COMIPOSITION: What elements are present? 1. Take spectrum. 2. Compare spectral lines to lines of wavelengths measured for different elements in laboratory. . intensity Results: Stars are mainly hydrogen and helium, but contain other elements in small quantifies. 2. TEMPERATURE: HOW hot? 4000 5000 6000 7000 1. Take spectrum. Wavelength (7*) 2. Scan for most intense wavelength (peak 3»). A M AX 3. Use Wien’s law to calculate. x” 7 2.9 x 10 E Peakvisihle Visible peak is . TM "”4“ l wavelength is red yellow lmax = -——————u------ T in Kelvin g ‘ ‘ T 7mm in Angstroms S g I l 5 50010001541: noon son imisBom Huflennd- ,n-i—o lfldengrl ism—— Visible peak is blue From Ihe peak wavelength. the temperature is determined. Results: Stars range in surface temperature from 3000 K to 100,000K. : E E The Spectral Sequence Spectra reveal temperature _ ' Spectral class Color Temperature (K) Spectral lines and composmon O Blue-violet 30,000—30,000 Ionized atoms, especially helium 0 Analysis of spectral lines gives B Blue-white 1100040000 Neutral helium, some hydrogen sompos‘flo'? (Ii, He? but temperature A White 750041300 Strong hydrogen, some Influences line dominance (1) ionized murals . F Yll . h’ 5900—7500 H d d‘ ‘ d i * Wien’s law—“peak” wavelength of 5 W W ”8 sui,,‘§§:§;;,;‘;§;;g§m 5’ emission indicates temperature (2) G Yellow 5200-5900 Both neural and ionized metals, _ _ especially ionized calcium ' Spectral “3555193th system “’95 K Orange 3900—5200 Neutral metals developed in the early 19008 M Red-orange 2500—3900 Strung titanium oxide and some neutral calcium 3 ways energy is transferred Our Star = the Sun ’ 110 Earth diameters 33:23:? Grantham um 8cm 9 330,000 Earth masses MW” gas motion 0 Average density a 1.4 g/cm3 9 Composition: 73% H, 25% He, l 2% heavy elements (60 elements), . 20 different molecules detected 0 Temp = 10,000“7 = 5800 Kelvins via photons The outer regions are very different from the core. Pholnsphere Core 5800 K 15 million K Densig 2 x 10'7 glcm’ 150 g/cm3 Pressure 0.0001 aim 3 x 10’ arm 13% 1500 1520 1940 1960 hit ...
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