Predictions of the extent of self-enrichment in oxygen of giant metal-poor HII regions

Abstract

In general, HII regions do not show clear signs of self-enrichment in products from massive stars (M > 8 M_sun). In order to explore why, I modeled the contamination with Wolf-Rayet star ejecta of metal-poor (Z=0.001) HII regions, ionised either by a 10^6 M_sun cluster of coeval stars (cluster 1), or a cluster resulting from continuous star formation at a rate of 1 M_sun yr^-1 (cluster 2). The clusters have Z=0.001 and a Salpeter initial mass function (IMF) from 0.1 to 120 M_sun. Independent one dimensional constant density simulations of the emission-line spectra of unenriched HII regions were computed at the discrete ages 1, 2, 3, 4, and 5 Myr, with the photoionisation code CLOUDY, using as input, radiative and mechanical stellar feedbacks predicted by the evolutionary synthesis code STARBURST99. Each HII region was placed at the outer radius of the adiabatically expanding superbubble of Mac Low and McCray (1988). For models with thermal and ionisation balance time-scales of less than 1 Myr, and with oxygen emission-line ratios in agreement with observations, the interior of the superbubble and the HII region were uniformly and instantaneously polluted with stellar ejecta predicted by STARBURST99. I obtained a maximum oxygen abundance enhancement of 0.025 dex, with cluster 1, at 4 Myr. It would be unobservable.

arXiv comment13 pages, 6 eps figures, MN Latex v2.2, accepted for publication in MNRAS

References in corpus (33)

• Starburst99: Synthesis Models for Galaxies with Active Star Formation
• A standard stellar library for evolutionary synthesis: I. Calibration of theoretical spectra
• Line formation in solar granulation: IV. [O I], OI and OH lines and the photospheric O abundance
• Optimization of Starburst99 for Intermediate-Age and Old Stellar Populations
• The Discordance of Mass-Loss Estimates for Galactic O-Type Stars
• Atomic data for astrophysics. I. Radiative recombination rates for H-like, He-like, Li-like and Na-like ions over a broad range of temperature
• Interstellar Turbulence II: Implications and Effects
• A reappraisal of the chemical composition of the Orion nebula based on VLT echelle spectrophotometry
• Line formation in solar granulation VI. [C I], C I, CH and C2 lines and the photospheric C abundance
• The evolution of the Milky Way from its earliest phases : constraints on stellar nucleosynthesis
• Ten Million Degree Gas in M 17 and the Rosette Nebula: X-ray Flows in Galactic H II Regions
• A strong case for fast stellar rotation at very low metallicities
• Mixing Time Scales in a Supernova-Driven Interstellar Medium
• The localized chemical pollution in NGC 5253 revisited: Results from deep echelle spectrophotometry
• Carbon Nitrogen, and Oxygen Galactic Gradients: A Solution to the Carbon Enrichment Problem
• Chemical abundances of the Galactic H II region NGC 3576 derived from VLT echelle spectrophotometry
• Modeling the emission line sequence of H II galaxies
• A photoionization modeling study of 30 Doradus: the case for small-scale chemical inhomogeneity
• On the Sensitivity of Massive Star Nucleosynthesis and Evolution to Solar Abundances and to Uncertainties in Helium Burning Reaction Rates
• The interplay between ionized gas and massive stars in the HII galaxy IIZw70: integral field spectroscopy with PMAS
• The Birth of a Super Star Cluster: NGC 5253
• On the Determination of N and O Abundances in Low Metallicity Systems
• Enrichment of the ISM by metal-rich droplets and the abundance bias in HII regions
• Evolution of the X-ray luminosity and metallicity of starburst blown superbubbles
• Metal Abundances of KISS Galaxies. II. Nebular Abundances of Twelve Low-Luminosity Emission-Line Galaxies
• The effects of spatially distributed ionisation sources on the temperature structure of HII region
• Exploring the Kinematics of the Oxygen-Rich Supernova Remnant G292.0+1.8: Ejecta Shells, Fast-Moving Knots and Shocked Circumstellar Material
• Can Ejecta-Dominated Supernova Remnants be Typed from their X-ray Spectra? The Case of G337.2-0.7
• Feedback from Multiple Supernova Explosions inside a Wind-Blown Bubble
• The N/O Plateau of Blue Compact Galaxies: Monte Carlo Simulations of the Observed Scatter
• Chemical Self-Enrichment of HII Regions by the Wolf-Rayet Phase of an 85 Msun star
• Bubbles and Superbubbles
• Mass loss and very low-metallicity stars

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