Helium abundances and its radial gradient from the spectra of H II regions and ring nebulae of the Milky Way
We determine the radial abundance gradient of helium in the disc of the Galaxy from published spectra of 19 H II regions and ring nebulae surrounding massive O-type stars. We revise the Galactocentric distances of the objects considering Gaia DR2 parallaxes (Gaia Collaboration 2018) and determine the physical conditions and the ionic abundance of
Méndez-Delgado, J. E. et al.
Fecha de publicación:
6
2020