PHYS 1902 Chapter Notes - Chapter 12-18: Big Crunch, Gravitational Lens, Static Universe
1 May 2014
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Stars chapter 11: their bright surfaces send us the light that we see. As the temperature increases, the gas gives off more energy at every wavelength. Those of intermediate temperature (like the sun) appear white, despite having spectra around yellow or green wavelengths (physiological response of our eyes: classifying stars, all the spectral lines of normal stars are absorption lines which cause a star"s spectrum to deviate from that of a black body (not by much). B a f g k m even cooler objects ex. Astronomers use a modification of the magnitude scale known as absolute magnitude. To do so, have set a specific distance to compare stars. If something is intrinsically fainter, it has a higher absolute magnitude. Inverse-square law: for example, if a star"s distance is doubled, it appears four times fainter: you can determine how far away a star is by comparing how bright it looks with its intrinsic brightness, inverse square law.
