Chemical self-enrichment of HII regions by the Wolf-Rayet phase of an 85 M_☉ star

Autor(en)

Danica Kröger, Gerhard Hensler, Tim Freyer

Abstrakt

It is clear from stellar evolution and from observations of WR stars that massive stars are releasing metal-enriched gas through their stellar winds in the Wolf-Rayet phase. Although HII region spectra serve as diagnostics to determine the present-day chemical composition of the interstellar medium, it is far from being understood to what extent the HII gas is already contaminated by chemically processed stellar wind. Therefore, we analyzed our models of radiative and wind bubbles of an isolated 85 Mž star with solar metallicity (Krošger et al. 2006, A&A, in preparation) with respect to the chemical enrichment of the circumstellar HII region. Plausibly, the hot stellar wind bubble (SWB) is enriched with 14N during the WN phase and even much higher with 12C and 16O during the WC phase of the star. During the short period that the 85 Mž star spends in the WC stage enriched SWB material mixes with warm HII gas of solar abundances and thus enhances the metallicity in the HII region. However, at the end of the stellar lifetime the mass ratios of the traced elements N and O in the warm ionized gas are insignificantly higher than solar, whereas an enrichment of 22% above solar is found for C. Important issues from the presented study comprise a steeper radial gradient of C than O and a decreasing effect of self-enrichment for metal-poor galaxies. Œ ESO 2006.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

Christian-Albrechts-Universität zu Kiel

Journal

Astronomy & Astrophysics

Band

450

Seiten

5-8

Anzahl der Seiten

4

ISSN

0004-6361

DOI

https://doi.org/10.1051/0004-6361:200600020

Publikationsdatum

2006

Peer-reviewed

Ja

ÖFOS 2012

103003 Astronomie

Link zum Portal

https://ucris.univie.ac.at/portal/de/publications/chemical-selfenrichment-of-hii-regions-by-the-wolfrayet-phase-of-an-85-m-star(8affe327-e77c-45d3-952b-e4e80e7bf60f).html