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Stellar Spectra

# Stellar Spectra - ii Examination of the graphs shows that...

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Stellar Spectra Kirchhoff’s Laws – Describes different types of stellar spectrum 1. Continuous Spectrum – a spectrum that contains neither emission or absorption lines 2. Emission Spectrum (emission lines) – a narrow bright region of the spectrum. Emission lines are produced when electrons in atoms jump from one energy level to a lower energy level spontaneously. 3. Absorption Spectrum (absorption lines) – a dark line superimposed on a continuous spectrum when a gas absorbs light from a continuous source that is hotter than the absorbing gas. In terms of spectra, the sun is nothing but a large ball of gas held together by gravity with the energy or shine created by fusion. The colors of the stars 1. By measuring the color of a star: i. We can determine the wavelength distribution. ii. From the wavelength distribution you can calculate the star’s temperature. 2. To determine a stars color: i. First pass light through spectrograph and measure the intensity at each wavelength.

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Unformatted text preview: ii. Examination of the graphs shows that radiation peaks in certain wavelengths and decreases in amount more slowly on the infrared side of the peak, than on the ultra violet end. From this graph color is determined What causes color (spectra)? 1. There is a set of physical laws that govern what happens to a material when it is heated. i. As a material is heated the peak of the radiation given off shifts to the blue end on the ultra violet end of the spectrum. ii. This shift is known as “Wien’s Displacement Law”. iii. As a material gets hotter, the amount of radiation given off grows quickly. iv. The energy follows the Stefan-Boltzman model. v. The Stefan-Boltzman model – the energy given off from a constant surface area of gas; the actual amount of energy a star gives off depends on how hot a star is, and how large the surface area is. Example 1 – energy is temperature is 300k Example 2 – Energy if temperature is 600k....
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Stellar Spectra - ii Examination of the graphs shows that...

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