Small-spatial-scale variations of nebular properties and the abundance discrepancy in three Galactic HII regions

Mesa-Delgado, A.; Esteban, C.
Bibliographical reference

Monthly Notices of the Royal Astronomical Society, Volume 405, Issue 4, pp. 2651-2667.

Advertised on:
7
2010
Number of authors
2
IAC number of authors
2
Citations
19
Refereed citations
18
Description
We present the results of long-slit spectroscopy in several slit positions that cover different morphological structures of the central parts of three bright Galactic HII regions: M8, M17 and NGC 7635. We study the spatial distributions of a large number of nebular parameters, such as the extinction coefficient, line fluxes, physical conditions and ionic abundances at the maximum spatial resolution attainable with our instrumentation. Particularly, our goal is to study the behaviour of the abundance discrepancy factor of O2+ [ADF(O2+)], defined as the logarithmic difference of the O2+ abundances derived from collisionally excited and recombination lines. We find that ADF(O2+) remains fairly constant along the slit positions of M8 and M17. For NGC 7635, we only detect the OII recombination lines in the integrated spectrum along the whole slit, where ADF(O2+) reaches a remarkably high value of about 0.59 dex. We compare our results with previous results obtained for the Orion Nebula. We find much evidence to suggest the presence of a candidate Herbig-Haro object in M8. Based on observations made with the 4.2-m William Herschel Telescope (WHT) operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. E-mail: amd [at] iac.es (amd[at]iac[dot]es)
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