Revisiting the radial abundance gradients of nitrogen and oxygen of the Milky Way

Esteban, C.; García-Rojas, J.
Bibliographical reference

Monthly Notices of the Royal Astronomical Society, Volume 478, Issue 2, p.2315-2336

Advertised on:
8
2018
Number of authors
2
IAC number of authors
2
Citations
71
Refereed citations
58
Description
We present spectra obtained with the 10.4 m Gran Telescopio Canarias telescope of 13 Galactic H II regions, most of them of very low ionization degree. The objects are located along the Galactic disc, with RG from 5.7 to 16.1 kpc. We determine Te([N II]) for all of them. We obtain - for the first time - a radial abundance gradient of N that is independent on the ionization correction factor. The radial distribution of the N/O ratio is almost flat, indicating that the bulk of N is not formed by standard secondary processes. We have made a reassessment of the radial O abundance gradient combining our results with previous similar ones by Esteban et al. producing a homogeneous data set of 35 H II regions with direct determinations of the electron temperature. We report the possible presence of a flattening or drop of the O abundance in the inner part of the Galactic disc. This result confirms previous findings from metallicity distributions based on Cepheids and red giants. Finally, we find that the scatter of the N and O abundances of H II regions with respect to the gradient fittings is not substantially larger than the observational uncertainties, indicating that both chemical elements seem to be well mixed in the interstellar gas at a given distance along the Galactic disc
Related projects
Izquierda - Imagen RGB de la nebulosa de Orión y M43 obtenida filtros estrechos con la cámara WFC en el INT: H alfa (rojo), [S II] 6716+30 (verde), [O III] 5007 (azul). Derecha - Imagen en falso color de la nebulosa planetaria NGC 6778. En azul se ve la emisión en la línea de O II tomada con el filtro sintonizable azul del instrumento OSIRIS en el GTC; en verde imagen con el filtro estrecho de [O III] del Nordic Optical Telescope (NOT).
Physics of Ionized Nebulae
The research that is being carried out by the group can be condensed into two main lines: 1) Study of the structure, dynamics, physical conditions and chemical evolution of Galactic and extragalactic ionized nebulae through detailed analysis and modelization of their spectra. Investigation of chemical composition gradients along the disk of our
Jorge
García Rojas