AST 111 Chapter Notes - Chapter 2: Very-Long-Baseline Interferometry, Light Curve, Spectroscopy
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Composition since different elements and molecules have different patterns of spectral lines. Motion because of doppler effects, lines are red-shifted and blue-shifted. Physical conditions (such as temperature and pressure) since these effects the relative strength and width of spectral lines. Another technique used by astronomers is to look at time variations in celestial objects. Record variations in brightness of variable stars. Results in a light curve a plot of brightness against time. All ground based telescopes have to contend with the effects of looking through the. Turbulence in the atmosphere blues images (seeing) To minimize effects, high altitude dry sites are favored. Substantial clusters of telescopes have been built at the world"s best sites. Observe the sky at radio wavelengths (cm to metre) Radio dish reflects radio waves in the same way as the mirror in a reflecting telescope reflects light. Sensitive radio receivers are mounted at the focus of the dish.