A comprehensive study of reported high-metallicity giant H ii regions — II. Ionizing stellar populations

Castellanos, M.; Díaz, Ángeles I.; Terlevich, Elena

doi:10.1046/j.1365-8711.2002.05934.x

Cited by 13 publications

(9 citation statements)

References 35 publications

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“…Kennicutt 1992). It is worth noting that the high metallicity H II regions within which optical Wolf-Rayet features have been detected (Bresolin & Kennicutt 2002;Castellanos et al 2002;Pindao et al 2002) are located within the disks of their host galaxies, and may suffer less extinction (and dilution) than our deeply obscured infrared star forming regions.…”

Section: Wolf-rayet Galaxiesmentioning

confidence: 98%

“…Recent surveys of a large number of H II regions (Bresolin & Kennicutt 2002;Castellanos et al 2002;Pindao et al 2002) located in the disks of local high metallicity galaxies have revealed the presence of weak Wolf-Rayet-like features in ∼30% of the surveyed regions, which implies that Wolf-Rayet stars do in fact exist in high metallicity environments. This result confirms previous work on smaller samples Schaerer et al 2000) and high metallicity systems included in other Wolf-Rayet samples (e.g.…”

Section: Wolf-rayet Galaxiesmentioning

confidence: 99%

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A mid-infrared spectroscopic survey of starburst galaxies: Excitation and abundances

Verma¹,

Lutz²,

Sturm³

et al. 2003

A&A

133

236

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Abstract. We present spectroscopy of mid-infrared emission lines in twelve starburst regions, located in eleven starburst galaxies, for which a significant number of lines between 2.38 and 45 µm were observed with the ISO Short Wavelength Spectrometer, with the intention of providing a reference resource for mid-infrared spectra of starburst galaxies. The observation apertures were centred on actively star forming regions, including those which are inaccessible at optical wavelengths due to high levels of obscuration. We use this data set, which includes fine structure and hydrogen recombination lines, to investigate excitation and to derive gas phase abundances of neon, argon, and sulphur of the starburst galaxies. The derived Ne abundances span approximately an order of magnitude, up to values of ∼3 times solar. The excitation ratios measured from the Ne and Ar lines correlate well with each other (positively) and with abundances (negatively). Both in excitation and abundance, a separation of objects with visible Wolf-Rayet features (high excitation, low abundance) is noted from those without (low excitation, high abundance). For a given abundance, the starbursts are of relatively lower excitation than a comparative sample of H II regions, possibly due to ageing stellar populations. By considering the abundance ratios of S with Ne and Ar we find that, in our higher metallicity systems, S is relatively underabundant by a factor of ∼3. We discuss the origin of this deficit and favour depletion of S onto dust grains as a likely explanation. This weakness of the mid-infrared fine structure lines of sulphur has ramifications for future infrared missions such as SIRTF and Herschel since it indicates that the S lines are less favourable tracers of star formation than is suggested by nebular models which do not consider this effect. In a related paper (Sturm et al. 2002), we combine our results with spectra of Seyfert galaxies in order to derive diagnostic diagrams which can effectively discriminate between the two types of activity in obscured regions on the basis of excitation derived from detected mid-infrared lines.

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Section: Wolf-rayet Galaxiesmentioning

confidence: 98%

Section: Wolf-rayet Galaxiesmentioning

confidence: 99%

A mid-infrared spectroscopic survey of starburst galaxies: Excitation and abundances

Verma¹,

Lutz²,

Sturm³

et al. 2003

A&A

133

236

View full text Add to dashboard Cite

show abstract

“…The statistical error associated with the observed emission lines is calculated using the expression σ 1 = σ c N 1/2 [1 + EW/(N∆)] 1/2 (Gonzalez-Delgado et al 1994;Castellanos et al 2002;Pérez-Montero & Díaz 2003), where σ 1 is the error in the observed line flux, σ c corresponds to the noise in the continuum near the measured emission line, N is the number of pixels used in the measurement of the line flux, EW is the line equivalent width, and ∆ is the wavelength dispersion.…”

Section: Technique To Derive the Physical Properties And Chemical Abumentioning

confidence: 99%

On the Use of the Index N2 to Derive the Metallicity in Metal-Poor Galaxies

Morales-Luis

Montero

Alméida

et al. 2014

ApJ

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The N2 index ([Nii]λ6584/Hα) is used to determine emission line galaxy metallicities at all redshifts, including high redshift, where galaxies tend to be metal-poor. The initial aim of the work was to improve the calibrations used to infer oxygen abundance from N2 employing updated low-metallicity galaxy databases. We compare N2 and the metallicity determined using the direct method for the set of extremely metal-poor galaxies compiled by Morales-Luis et al. (2011). To our surprise, the oxygen abundance presents a tendency to be constant with N2, with a very large scatter. Consequently, we find that the existing N2 calibrators overstimate the oxygen abundance for most low metallicity galaxies, and then they can be used only to set upper limits to the true metallicity in low-metallicity galaxies. An explicit expression for this limit is given. In addition, we try to explain the observed scatter using photoionization models. It is mostly due to the different evolutionary state of the Hii regions producing the emission lines, but it also arises due to differences of N/O among the galaxies.

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“…Crowther et al 2006;Fernández-Martín et al 2012;Shara et al 2012;Smith et al 2012;Kanarek et al 2015) and in nearby galaxies (e.g. Massey & Johnson 1998;Castellanos, Díaz & Terlevich 2002;Massey 2003;Eldridge & Relaño 2011;Neugent & Massey 2011;Bibby & Crowther 2012;Howarth & Walborn 2012;Neugent, Massey & Georgy 2012;Neugent, Massey & Morrell 2012;Kehrig et al 2013;Shara et al 2013;Gvaramadze et al 2014a;Massey, Neugent & Morrell 2015;Sokal et al 2015). The presence of WRs close to the nucleus of NGC 1313 was detected by Hadfield & Crowther (2007), in an H II region identified by the authors as 37.…”

Section: The Wr(s) In Regionmentioning

confidence: 90%

The emission-line regions in the nucleus of NGC 1313 probed with GMOS-IFU: a supergiant/hypergiant candidate and a kinematically cold nucleus

Menezes

Steiner

2016

Mon. Not. R. Astron. Soc.

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NGC 1313 is a bulgeless nearby galaxy, classified as SB(s)d. Its proximity allows high spatial resolution observations. We performed the first detailed analysis of the emission-line properties in the nuclear region of NGC 1313, using an optical data cube obtained with the Gemini Multi-object Spectrograph. We detected four main emitting areas, three of them (regions 1, 2 and 3) having spectra typical of H II regions. Region 1 is located very close to the stellar nucleus and shows broad spectral features characteristic of Wolf-Rayet stars. Our analysis revealed the presence of one or two WC4-5 stars in this region, which is compatible with results obtained by previous studies. Region 4 shows spectral features (as a strong Hα emission line, with a broad component) typical of a massive emission-line star, such as a luminous blue variable, a B[e] supergiant or a B hypergiant. The radial velocity map of the ionized gas shows a pattern consistent with rotation. A significant drop in the values of the gas velocity dispersion was detected very close to region 1, which suggests that the young stars there were formed from this cold gas, possibly keeping low values of velocity dispersion. Therefore, although detailed measurements of the stellar kinematics were not possible (due to the weak stellar absorption spectrum of this galaxy), we predict that NGC 1313 may also show a drop in the values of the stellar velocity dispersion in its nuclear region.

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A comprehensive study of reported high-metallicity giant H ii regions — II. Ionizing stellar populations

Cited by 13 publications

References 35 publications

A mid-infrared spectroscopic survey of starburst galaxies: Excitation and abundances

A mid-infrared spectroscopic survey of starburst galaxies: Excitation and abundances

On the Use of the Index N2 to Derive the Metallicity in Metal-Poor Galaxies

The emission-line regions in the nucleus of NGC 1313 probed with GMOS-IFU: a supergiant/hypergiant candidate and a kinematically cold nucleus

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