Answer:
Step-by-step explanation:
An absorption line spectrum occurs when light passes through a cloud of cool gas in space, such as an interstellar molecular cloud, a planetary atmosphere, or a circumstellar disk. The light from a star behind the cloud is absorbed by the atoms and molecules in the gas, which have a range of temperatures and densities.
When the light passes through the gas, the atoms and molecules in the gas absorb light at specific frequencies that correspond to the energy levels in the atoms. This results in missing or reduced light at those frequencies, which appears as dark lines against the otherwise continuous spectrum of the star.
The specific wavelengths of light that are absorbed depend on the chemical composition of the gas and its physical conditions, such as temperature and pressure. By analyzing the pattern of absorption lines in the spectrum, astronomers can learn about the composition, density, and temperature of the gas, as well as the velocity of the gas along the line of sight.
Absorption line spectra can also provide information about the physical conditions in the star itself, such as its temperature, surface gravity, and chemical composition, by analyzing the strength and shape of the lines. This information can help astronomers to better understand the processes occurring in stars, as well as in the interstellar medium, and the conditions necessary for the formation of stars and planetary systems.