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Article: A reexamination of electron density diagnostics for ionized gaseous nebulae

TitleA reexamination of electron density diagnostics for ionized gaseous nebulae
Authors
KeywordsAtomic Data
Ism: Lines And Bands
Ism: Planetary Nebulae: General
Issue Date2004
PublisherE D P Sciences. The Journal's web site is located at http://www.aanda.org
Citation
Astronomy And Astrophysics, 2004, v. 427 n. 3, p. 873-886 How to Cite?
AbstractWe present a comparison of electron densities derived from optical forbidden line diagnostic ratios for a sample of over a hundred nebulae. We consider four density indicators, the [O II] λ3729/λ3726, [S II] λ6716/λ6731, [Cl III] λ5517/λ5537 and [Ar IV] λ4711/λ4740 doublet ratios. Except for a few H II regions for which data from the literature were used, diagnostic line ratios were derived from our own high quality spectra. For the [O II] λ3729/λ3726 doublet ratio, we find that our default atomic data set, consisting of transition probabilities from Zeippen (1982) and collision strengths from Pradhan (1976), fit the observations well, although at high electron densities, the [O II] doublet ratio yields densities systematically lower than those given by the [S II] λ6716/λ6731 doublet ratio, suggesting that the ratio of transition probabilities of the [O II] doublet, A(λ3729)/ A(λ3726), given by Zeippen (1982) may need to be revised upwards by approximately 6 per cent. Our analysis also shows that the more recent calculations of [O II] transition probabilities by Zeippen (1987) and collision strengths by McLaughlin & Bell (1998) are inconsistent with the observations at the high and low density limits, respectively, and can therefore be ruled out. We confirm the earlier result of Copetti & Writzl (2002) that the [O II] transition probabilities calculated by Wiese et al. (1996) yield electron densities systematically lower than those deduced from the [S II] λ6716/λ6731 doublet ratio and that the discrepancy is most likely caused by errors in the transition probabilities calculated by Wiese et al. (1996). Using our default atomic data set for [O II], we find that N e([O II]) ≲ N e([S II]) ≈ N e([Cl III]) < N e([Ar IV]).
Persistent Identifierhttp://hdl.handle.net/10722/174895
ISSN
2014 Impact Factor: 4.378
2015 SCImago Journal Rankings: 2.446
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorWang, Wen_US
dc.contributor.authorLiu, XWen_US
dc.contributor.authorZhang, Yen_US
dc.contributor.authorBarlow, MJen_US
dc.date.accessioned2012-11-26T08:48:01Z-
dc.date.available2012-11-26T08:48:01Z-
dc.date.issued2004en_US
dc.identifier.citationAstronomy And Astrophysics, 2004, v. 427 n. 3, p. 873-886en_US
dc.identifier.issn0004-6361en_US
dc.identifier.urihttp://hdl.handle.net/10722/174895-
dc.description.abstractWe present a comparison of electron densities derived from optical forbidden line diagnostic ratios for a sample of over a hundred nebulae. We consider four density indicators, the [O II] λ3729/λ3726, [S II] λ6716/λ6731, [Cl III] λ5517/λ5537 and [Ar IV] λ4711/λ4740 doublet ratios. Except for a few H II regions for which data from the literature were used, diagnostic line ratios were derived from our own high quality spectra. For the [O II] λ3729/λ3726 doublet ratio, we find that our default atomic data set, consisting of transition probabilities from Zeippen (1982) and collision strengths from Pradhan (1976), fit the observations well, although at high electron densities, the [O II] doublet ratio yields densities systematically lower than those given by the [S II] λ6716/λ6731 doublet ratio, suggesting that the ratio of transition probabilities of the [O II] doublet, A(λ3729)/ A(λ3726), given by Zeippen (1982) may need to be revised upwards by approximately 6 per cent. Our analysis also shows that the more recent calculations of [O II] transition probabilities by Zeippen (1987) and collision strengths by McLaughlin & Bell (1998) are inconsistent with the observations at the high and low density limits, respectively, and can therefore be ruled out. We confirm the earlier result of Copetti & Writzl (2002) that the [O II] transition probabilities calculated by Wiese et al. (1996) yield electron densities systematically lower than those deduced from the [S II] λ6716/λ6731 doublet ratio and that the discrepancy is most likely caused by errors in the transition probabilities calculated by Wiese et al. (1996). Using our default atomic data set for [O II], we find that N e([O II]) ≲ N e([S II]) ≈ N e([Cl III]) < N e([Ar IV]).en_US
dc.languageengen_US
dc.publisherE D P Sciences. The Journal's web site is located at http://www.aanda.orgen_US
dc.relation.ispartofAstronomy and Astrophysicsen_US
dc.subjectAtomic Dataen_US
dc.subjectIsm: Lines And Bandsen_US
dc.subjectIsm: Planetary Nebulae: Generalen_US
dc.titleA reexamination of electron density diagnostics for ionized gaseous nebulaeen_US
dc.typeArticleen_US
dc.identifier.emailZhang, Y: zhangy96@hku.hken_US
dc.identifier.authorityZhang, Y=rp00841en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1051/0004-6361:20041470en_US
dc.identifier.scopuseid_2-s2.0-10044241877en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-10044241877&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume427en_US
dc.identifier.issue3en_US
dc.identifier.spage873en_US
dc.identifier.epage886en_US
dc.identifier.isiWOS:000225197500013-
dc.publisher.placeFranceen_US
dc.identifier.scopusauthoridWang, W=14626931700en_US
dc.identifier.scopusauthoridLiu, XW=7409287288en_US
dc.identifier.scopusauthoridZhang, Y=23768446500en_US
dc.identifier.scopusauthoridBarlow, MJ=18041819500en_US

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