What do stellar spectra look like (the light observed from stars)?
Stars have absorption line spectra. We can think of stars as a hot continuum source with a “cool” atmosphere of absorbing gas. The wavelengths that get absorbed depend on the chemical make up of the gas in the stellar atmosphere. • In the 1800’s the light from the Sun was dispersed and it looked more-or-less like a Planck spectrum (a blackbody curve) with some missing light, or absorption lines at certain wavelengths. [NMSU, N. Vogt] • Stellar blackbody spectra have a characteristic shape, with a steep rise, a peak in or near to the visual passband, and a slow decrease in the infrared. Hotter stars have higher peak amplitudes, and peak at shorter wavelengths. Blackbody curves are shown for three stars in the figure below, with temperatures ranging from 4,000 K (a cool, red star) to 7,500 K (a hot, violet-blue star). Small arrows mark the peak wavelength for each star. [NMSU, N. Vogt] • Emission spectrum: The wavelengths with missing light in a stellar spectrum turned out to be very int
