The physical structure of Magellanic Cloud HII regions

Vermeij, R; Damour, F; Hulst, J. M. van der; Baluteau, J. P.

doi:10.1051/0004-6361:20020424

Cited by 38 publications

(55 citation statements)

References 46 publications

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“…The sample of low-metallicity H  regions in blue compact dwarf galaxies observed by Izotov with colleagues (Fricke et al 2001;Guseva et al 2001Guseva et al , 2003aIzotov & Thuan 1998Izotov et al 1994Izotov et al , 1997Izotov et al , 2001Noeske et al 2000;Thuan et al 1995Thuan et al , 1999 Kennicutt et al (2003); Lee et al (2003); ; ; Peimbert (2003); Tsamis et al (2003); Vermeij et al (2002);Vílchez & Iglesias-Páramo (2003). The spectroscopic data so assembled form the basis of the present study.…”

Section: Observational Data: Line Fluxesmentioning

confidence: 76%

On the relationship between auroral and nebular oxygen line intensities in spectra of H II regions

Pilyugin¹

2005

A&A

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Abstract. We investigate relationships between observed auroral and nebular oxygen line fluxes in spectra of H  regions. We find a relation that is metallicity-dependent at low metallicities, but becomes independent of metallicity (within the uncertainties of the available data) above 12+logO/H ∼ 8.25, i.e. there is one-to-one correspondence (the ff-relation) between auroral and nebular oxygen line fluxes in spectra of high-metallicity H  regions. The ff-relation allows one to estimate the flux in the auroral line from strong oxygen line measurements only. This solves the problem of the electron temperature (and, consequently, abundance) determination in high-metallicity H  regions. The ff-relation confirms the basic idea of the "empirical" method, proposed by Pagel et al. (1979, MNRAS, 189, 95) a quarter of a century ago, that the oxygen abundance in H  region can be esimated from the strong oxygen lines measurements only.

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Section: Observational Data: Line Fluxesmentioning

confidence: 76%

On the relationship between auroral and nebular oxygen line intensities in spectra of H II regions

Pilyugin¹

2005

A&A

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“…Using a new data base of infrared and optical spectroscopical data described in Vermeij et al (2001) (Paper I), we reexamine the elemental abundances of a sample of H  regions in the Magellanic Clouds. We use the H  regions in our sample primarily in their role as probe of the local gas-phase abundances, but we also address their large-scale temperature stratification.…”

Section: Introductionmentioning

confidence: 99%

“…Based on a new data set of optical and infrared spectra described in Vermeij et al (2001), we analyse the gasphase elemental abundances of a sample of H  regions in the Large and Small Magellanic Cloud. The combined optical and infrared data set gives us access to all the ionization stages of astrophysically important elements such as sulfur and oxygen.…”

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confidence: 99%

The physical structure of Magellanic Cloud HII regions

Vermeij¹,

Hulst²

2002

A&A

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Abstract. Based on a new data set of optical and infrared spectra described in Vermeij et al. (2001), we analyse the gasphase elemental abundances of a sample of H  regions in the Large and Small Magellanic Cloud. The combined optical and infrared data set gives us access to all the ionization stages of astrophysically important elements such as sulfur and oxygen. We self-consistently determine the electron temperatures and densities for the O + , S ++ and O ++ ionization zones, and use these parameters in the derivation of the ionic fractions. We discuss the uncertainties on these ionic fractions. The different relations between the electron temperatures as proposed by Garnett (1992) and Thuan et al. (1995) are confronted with our results. We find our electron temperatures to be consistent with these relations, although the relation between T e [S ] and T e [O ] might be slightly steeper than predicted. We investigate the reliability of the Ionization Correction Factors (ICFs) used in the derivation of the full elemental abundances of sulfur and neon. We conclude that the prescription for the ICF used to derive the sulfur abundance as given by Stasińska (1978) for α = 3 is accurate for O + /O > 0.20. No conclusions could be drawn for neon. Avoiding the use of ICFs as much as possible, we then proceed to derive the full elemental abundances. We calculate a grid of general photoionization models to compare our results with the "bright-line" abundance diagnostics for oxygen (R23) and sulfur (S23(4)). The reliability of the newly proposed S234 parameter (Oey & Shields 2000) which includes emission lines from S + , S ++ and S +3 is checked. We find a very good agreement between the S234 models and our analysis results. Finally, we compare the heavy element-to-oxygen ratios of our sample objects to those of giant H  regions in a large sample of lowmetallicity blue dwarf galaxies (Izotov & Thuan 1999) and with the results from Kobulnicky & Skillman (1996 for the irregular galaxies NGC 1569 and NGC 4214.

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“…Vermeij et al, 2002a;) and M33 (Willner & Nelson-Patel, 2002). H ii regions in the Magellanic Clouds are characterised by low metallicities and high excitation (see e.g.…”

Section: H II Regionsmentioning

confidence: 99%

“…The lines present the results of detailed model calculations for a range in densities and incident FUV fields (Kaufman et al, 1999). The data are taken from LWS observations of a sample of H ii regions 2005;Vermeij et al 2002a). …”

Section: The Photodissociation Regionmentioning

confidence: 99%