Helium abundances and its radial gradient from the spectra of HII regions and ring nebulae of the Milky Way

J. E. Méndez-Delgado, C. Esteban, J. García-Rojas +2

We determine the radial abundance gradient of helium in the disc of the Galaxy from published spectra of 19 $\text{H}\text{II}$ regions and ring nebulae surrounding mass…