They are characterized by the ionized lines of nitrogen, carbon or oxygen and typically show strong broad emission lines in their spectra, mostly with helium, nitrogen, carbon, silicon, and oxygen, but with hydrogen lines usually weak or absent.
They are characterized by the ionized lines of nitrogen, carbon or oxygen. This was mostly with helium, but with hydrogen lines usually weak or absent. They are typically show strong broad emission lines in their spectra with helium, but with hydrogen lines usually weak or absent. This is mostly. Helium is nitrogen. Helium is carbon. Helium is silicon. Helium is oxygen.