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An absorption spectrum is the combination of an emission spectrum on top of a continuous spectrum. Chemical Composition of a Star. Stellar spectral lines are caused by the interactions between photons and the atoms present in gaseous layers of stars.
Absorption lines are produced by atoms whose electrons absorb light at a specific wavelength, causing the electrons to move from a lower energy level to a higher one. This process removes some of the continuum being produced by the star and results in dark features in the spectrum.
This graph shows the strengths of absorption lines of different chemical species (atoms, ions, molecules) as we move from hot (left) to cool (right) stars. The sequence of spectral types is also shown.
SpectroWeb has been developed to provide users with a means to directly assess the quality of spectral line identifications by comparing high-quality observed spectra of bright stars with state-of-the-art computed spectra through an interactive on-line application.
Arcturus is the brightest star in the constellation of Boötes. With an apparent visual magnitude of −0.05, Arcturus is the brightest star in the northern celestial hemisphere and the fourth-brightest star in the night sky, [ 14 ] after Sirius (−1.46 apparent magnitude), Canopus (−0.72) and α Centauri (combined magnitude of −0.27).
The star emits continuous-spectrum white light, but some of the light is absorbed by the cloud. The figure shows the spectrum of light that the astronomer observes as well as the absorption spectra of several pure elements.
We investigate the infrared spectrum of Arcturus to clarify the nature of the cool component of its atmosphere, referred to as the CO-mosphere, and its relationship to the warm molecular envelope or the MOLsphere in cooler M (super)giant stars.
