Collision Strengths for Electron Collision Excitation of Fine‐Structure Levels in S<scp>iii</scp>

Tayal, S. S.; Gupta, Govind P.

doi:10.1086/307971

Cited by 107 publications

(93 citation statements)

References 20 publications

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“…S iii New collisional data for S iii have been calculated with the R-matrix suite of codes by Hudson et al (2012), and have been included. They replace the previous R-matrix calculations from Tayal & Gupta (1999). We have retained the A-values for the allowed and forbidden transitions we had in the previous CHIANTI version, calculated by Froese Fischer et al (2006) with the ab initio MHCF method, and the Tayal & Gupta (1999) A-values for the decays from the 4d levels.…”

Section: Na-like Ionsmentioning

confidence: 99%

“…They replace the previous R-matrix calculations from Tayal & Gupta (1999). We have retained the A-values for the allowed and forbidden transitions we had in the previous CHIANTI version, calculated by Froese Fischer et al (2006) with the ab initio MHCF method, and the Tayal & Gupta (1999) A-values for the decays from the 4d levels. Observed energies have been taken from NIST (Kramida et al 2013).…”

Section: Na-like Ionsmentioning

confidence: 99%

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CHIANTI – An atomic database for emission lines. Version 8

Zanna

Dere

Young

et al. 2015

A&A

436

407

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We present version 8 of the CHIANTI database. This version includes a large amount of new data and ions, which represent a significant improvement in the soft X-ray, extreme UV (EUV) and UV spectral regions, which several space missions currently cover. New data for neutrals and low charge states are also added. The data are assessed, but to improve the modelling of low-temperature plasma the effective collision strengths for most of the new datasets are not spline-fitted as previously, but are retained as calculated. This required a change of the format of the CHIANTI electron excitation files. The format of the energy files has also been changed. Excitation rates between all the levels are retained for most of the new datasets, so the data can in principle be used to model highdensity plasma. In addition, the method for computing the differential emission measure used in the CHIANTI software has been changed.

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Section: Na-like Ionsmentioning

confidence: 99%

Section: Na-like Ionsmentioning

confidence: 99%

CHIANTI – An atomic database for emission lines. Version 8

Zanna

Dere

Young

et al. 2015

A&A

436

407

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“…4.1.2 for more details on the MA 1 nebula); we therefore derive the chemical abundances of the different elements assuming a single, observed temperature. Garnett (1992), mostly due to the introduction of the new atomic coefficients for S 2+ from Tayal & Gupta (1999).…”

Section: Nebular Propertiesmentioning

confidence: 99%

Gemini GMOS spectroscopy of HeII nebulae in M 33

Kehrig

Oey

Crowther

et al. 2011

A&A

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We have carried out a narrow-band survey of the Local Group galaxy, M 33, in the HeII λ4686 emission line, to identify HeII nebulae in this galaxy. With spectroscopic follow-up observations, we confirm three of seven candidate objects, including identification of two new HeII nebulae, BCLMP651, HBW673. We also obtain spectra of associated ionizing stars for all the HII regions, identifying two new WN stars. We demonstrate that the ionizing source for the known HeII nebula, MA 1, is consistent with being the earlytype WN star MC8 (M 33-WR14), by carrying out a combined stellar and nebular analysis of MC8 and MA 1. We were unable to identify the helium ionizing sources for HBW 673 and BCLMP 651, which do not appear to be Wolf-Rayet stars. According to the [OIII]λ5007/Hβ vs.[NII]λ6584/Hα diagnostic diagram, excitation mechanisms apart from hot stellar continuum are needed to account for the nebular emission in HBW 673, which appears to have no stellar source at all.

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“…However, we have used the most recently determined collision strengths for both doubly and triply ionised S from Tayal & Gupta (1999) and Saraph & Storey (1999), respectively. These papers use improved and more complex methods to determine accurate collision strengths than previous, commonly used studies (e.g.…”

Section: Weak Sulphur Lines and The Origin Of Low Sulphur Abundancementioning

confidence: 99%

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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Collision Strengths for Electron Collision Excitation of Fine‐Structure Levels in Siii

Cited by 107 publications

References 20 publications

CHIANTI – An atomic database for emission lines. Version 8

CHIANTI – An atomic database for emission lines. Version 8

Gemini GMOS spectroscopy of HeII nebulae in M 33

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

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