Question

Could the spectral types of stars still be identified if there were no elements other than hydrogen in their atmospheres? Explain.

Answer 1

In research the spectra of stars plays a very important role. The astronomers have worked day and night for finding the answer. At the very first when the spectra of different stars are observed , they found that those are not matching with one another i.e they are not identical. Astronomers first thought that the spectral result of differnet stars are different because they all are not made of same chemical constituents. but this assumptions were found to be wrong. After that they found that the main reason of the stellar spectra look different because of their temperature difference.Hydrogen is mostly available in stars. They have nearly same compositions like sun but the lines of hydrogen are not seen in the spectra of the hottest and the coolest stars. for the hottest stars, hydrogen atoms are completely ionized and for the coolest stars, hydrogen atoms have their electrons attached and generates energy levels to produce lines. so the spectral lines of the steller stars are identified by the composition of hydrogen present in it.