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Unformatted text preview: significant fraction of their light in the ultraviolet band and the coolest stars emit a significant fraction of their light in the infrared band. Regardless of the star, though, the spectrum of a star, and, hence, the spectrum of a normal galaxy, rises to a peak at some wavelength determined by the temperature (remember Wien's law ?) and drops off at wavelengths shorter or longer than the peak wavelength. Such a spectrum is called a thermal spectrum because it depends on just the temperature. Quasars have a decidedly non-thermal spectrum: they are luminous in the X-rays, ultraviolet, visible, infrared, and radio bands. They have about the same power at all of the wavelengths down to the microwave wavelengths (shortwave radio wavelengths). The spectrum looks like the synchrotron radiation from charged particles spiralling around magnetic field lines at nearly the speed of light (remember the emission from pulsars ?)....
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