Sign on

SAO/NASA ADS Astronomy Abstract Service

· Find Similar Abstracts (with default settings below)
· Electronic Refereed Journal Article (HTML)
· Full Refereed Journal Article (PDF/Postscript)
· Full Refereed Scanned Article (GIF)
· References in the article
· Citations to the Article (110) (Citation History)
· Refereed Citations to the Article
· SIMBAD Objects (74)
· Associated Articles
· Also-Read Articles (Reads History)
·
· Translate This Page
Title:
Oxygen and helium abundances in Galactic Hii regions - II. Abundance gradients
Authors:
Deharveng, L.; Peña, M.; Caplan, J.; Costero, R.
Affiliation:
AA(Observatoire de Marseille, 2 place Le Verrier, 13248 Marseille Cedex 4, France), AB(Instituto de Astronomía, UNAM, Apdo. Postal 70-264, Cd. Universitaria, 04510 México, D.F., México), AC(Observatoire de Marseille, 2 place Le Verrier, 13248 Marseille Cedex 4, France), AD(Instituto de Astronomía, UNAM, Apdo. Postal 70-264, Cd. Universitaria, 04510 México, D.F., México)
Publication:
Monthly Notices of the Royal Astronomical Society, Volume 311, Issue 2, pp. 329-345. (MNRAS Homepage)
Publication Date:
01/2000
Origin:
MNRAS
MNRAS Keywords:
ISM: ABUNDANCES, HII REGIONS, GALAXY: ABUNDANCES
DOI:
10.1046/j.1365-8711.2000.03030.x
Bibliographic Code:
2000MNRAS.311..329D

Abstract

The absolute integrated fluxes that we obtained (Paper I) for 34 Hii regions, with Galactocentric distances RG in the 6.6-17.7kpc range, in the emission lines [Oii] λλ3726 and 3729, [Oiii] λλ4363 and 5007, Hei λ5876, Hα and Hβ, are analysed to derive the extinctions, the electron densities and temperatures, the ionic abundances O+/H+, O++/H+ and He+/H+ and the O/H abundances. The electron temperature has been derived from the [Oiii] λ4363/λ5007 ratio in six Hii regions with RG between 6.6 and 14.8kpc. These new measurements of Te, which are in good agreement with those from radio recombination lines, widen the RG range for which reliable Te measurements exist. Combining our new Te([Oiii]) results with the radio values, we obtain the following temperature relationship: Te K]=(372+/-38)RG+4260+/-350. The O+/H+ and O++/H+ abundances have been obtained assuming a two-temperature Hii region model. Our O/H relationship for 5kpc<RG<15kpc is 12+logO/H= (-3.95+/-0.49)x10-2RG+(8.82+/-0.05). The slope is lower, by a factor of 2, than that previously obtained by Shaver et al. No significant flattening of this relation is obtained out to 15kpc. At the solar Galactocentric distance, 12+log(O/H)=8.48, in good agreement with the O/H abundance measured in the local interstellar medium by Meyer et al., and a factor of 2 lower than the solar abundance. Our helium observations show that even a region ionized by a star earlier than O6.5 may contain a significant amount of neutral helium. We confirm the high ΔY/Δ(O/H) value (>=180) measured in the Galaxy by Peimbert et al.

Associated Articles

Part 1     Part  2    

Printing Options

Print whole paper
Print Page(s) through

Return 600 dpi PDF to Acrobat/Browser. Different resolutions (200 or 600 dpi), formats (Postscript, PDF, etc), page sizes (US Letter, European A4, etc), and compression (gzip,compress,none) can be set through the Printing Preferences


More Article Retrieval Options

HELP for Article Retrieval
Bibtex entry for this abstract   Preferred format for this abstract (see Preferences)
   

Find Similar Abstracts:

Use: Authors
Title
Keywords (in text query field)
Abstract Text
Return: Query Results Return    items starting with number
Query Form
Database: Astronomy
Physics
arXiv e-prints