AST210H1 Study Guide - Midterm Guide: Star System, Annie Jump Cannon, Absolute Magnitude
16 Apr 2017
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We feel the energy of the sun on our skin. Different wavelength perceived as different colors by our eyes. So color corresponds to temperature: blue is hotter, red is colder. Characteristic of wave motion: wavespeed = wavelength (lambda) x frequency (f) Light as a wave: 300 000m/s o. Light in a vacuum (interstellar space) is always the same speed: speed of light is the fastest possible speed in the universe, different wavelengths are perceived as different colors. 400nm = violet: c = wavelength x frequency, c is constant so different colors have different frequencies, describe stuff using wavelength or frequency instead of color. Spectrum peaks at different wavelengths for different temperature stars. Hotter is shorter: hot stars = white or violet, colder stars = red o, wien"s displacement law states that the spectral radiance of black body radiation per unit wavelength, peaks at the wavelength max given by:
