<p> SPECTRA</p><p>Gustav Kirchoff Three types of Spectra 1. Continuous Spectrum 2. Emission Spectrum 3. Absorption Spectrum</p><p>Radiation given off by luminous solids, liquids, and opaque gasses form a continuous spectrum Luminous Solid = Tungsten filament of an incandescent bulb Hot Liquid = Hot, moltant lava Opaque Gas = Gas you can’t see through</p><p>Radiation given off by transparent (thin or rarefied) excited gases form an emission spectrum (bright line spectrum) A transparent gas does not need to be hot to emit energy</p><p>The strength of a bright spectral line is determined by the peak size</p><p>When two or more gases are combined the relative intensities of the spectral lines tells us the relative quantity of the gasses. Formulas</p><p>0.0029   Wein’s Law  max is in meters, T is in Kelvin</p><p>2.9107    max in Angstroms, T is in Kelvin</p><p> So as temp increases the maximum wavelength decreases.  Very useful in determining the temp of stars. Don’t need to know how far away or the size of a star Just need to know the dominant wavelength</p><p>How much Energy The total amount of energy radiated by a blackbody depends on its temp and surface area.</p><p>Total emitted Energy E = T4 E is in Joules per m2, T is in Kelvin  = 5.67x108 W m-2k-4</p><p>We see the stars by the light they emit due to their high temps We see the planets and moons by the light they reflect</p><p>What would be the surface temp of a protostar if it emits the greatest amount of energy at 30,000 Angstroms? RESULTS</p><p>The Sun’s continuous spectrum tells us that light must come from a hot solid, hot liquid, or hot dense opaque gas</p><p>The Sun’s yellowish color indicates a peak emission energy of about 5000 angstroms</p><p>The Sun’s dark lines in its spectrum indicates There must be a relatively cool gas above the photosphere The temp of the Sun’s surface is about 4500 K</p><p>The Sun’s Flash Spectrum The moon progressively eclipses the sun The photosphere becomes blocked Only the Sun’s atmosphere is visible The spectrum then changes from a dark line to a bright line Happens quickly – therefore called Flash Spectrum Since the emission lines appear pinkish the emitting region is called the chromosphere Above the chromosphere is the corona ~ 2 million K</p><p>Ionized Gas Between the Stars Nebulae – means cloud Radiates UV energy captured from massive “O” type stars The resulting ionized hydrogen gas is called H II regions H I regions are are non ionized hydrogen gas clouds</p>