CalciumIIHKLinien

CalciumIIHKLinien refers to specific spectral lines emitted or absorbed by singly ionized calcium atoms. These lines are found in the ultraviolet region of the electromagnetic spectrum, with prominent examples including the H line at 396.8 nanometers and the K line at 393.4 nanometers. These are often collectively referred to as the Ca II H and K lines. They are particularly important in astrophysics for several reasons. Their intensity allows them to be detected even in the spectra of distant stars and galaxies. The Ca II H and K lines are very sensitive to the temperature and density of the stellar atmosphere where they originate. Changes in their profile, width, and strength can indicate phenomena such as stellar rotation, stellar activity (like flares and prominences), and the presence of interstellar gas clouds. In the Sun, these lines are primarily produced in the chromosphere, a layer of the solar atmosphere above the photosphere. Studying the Ca II H and K lines has been crucial in understanding the structure and dynamics of stellar atmospheres and has contributed significantly to our understanding of stellar evolution and activity.