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Article: Helium recombination spectra as temperature diagnostics for planetary nebulae

TitleHelium recombination spectra as temperature diagnostics for planetary nebulae
Authors
KeywordsIsm: General
Planetary Nebulae: General
Issue Date2005
PublisherBlackwell Publishing Ltd. The Journal's web site is located at http://www.blackwellpublishing.com/journals/MNR
Citation
Monthly Notices Of The Royal Astronomical Society, 2005, v. 358 n. 2, p. 457-467 How to Cite?
AbstractElectron temperatures derived from the He I recombination line ratios, designated T e(He I), are presented for 48 planetary nebulae (PNe). We study the effect that temperature fluctuations inside nebulae have on the T e(He I) value. We show that a comparison between T e(He I) and the electron temperature derived from the Balmer jump of the H I recombination spectrum, designated T e(H I), provides an opportunity to discriminate between the paradigms of a chemically homogeneous plasma with temperature and density variations, and a two-abundance nebular model with hydrogen-deficient material embedded in diffuse gas of a 'normal' chemical composition (i.e. ∼solar), as the possible causes of the dichotomy between the abundances that are deduced from collisionally excited lines and those deduced from recombination lines. We find that T e(He I) values are significantly lower than T e(H I) values, with an average difference of = 4000 K. The result is consistent with the expectation of the two-abundance nebular model but is opposite to the prediction of the scenarios of temperature fluctuations and/or density inhomogeneities. From the observed difference between T e(He I) and T e(H I), we estimate that the filling factor of hydrogen-deficient components has a typical value of 10 -4. In spite of its small mass, the existence of hydrogen-deficient inclusions may potentially have a profound effect in enhancing the intensities of He I recombination lines and thereby lead to apparently overestimated helium abundances for PNe. © 2005 RAS.
Persistent Identifierhttp://hdl.handle.net/10722/174937
ISSN
2015 Impact Factor: 4.952
2015 SCImago Journal Rankings: 2.806
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorZhang, Yen_US
dc.contributor.authorLiu, XWen_US
dc.contributor.authorLiu, Yen_US
dc.contributor.authorRubin, RHen_US
dc.date.accessioned2012-11-26T08:48:15Z-
dc.date.available2012-11-26T08:48:15Z-
dc.date.issued2005en_US
dc.identifier.citationMonthly Notices Of The Royal Astronomical Society, 2005, v. 358 n. 2, p. 457-467en_US
dc.identifier.issn0035-8711en_US
dc.identifier.urihttp://hdl.handle.net/10722/174937-
dc.description.abstractElectron temperatures derived from the He I recombination line ratios, designated T e(He I), are presented for 48 planetary nebulae (PNe). We study the effect that temperature fluctuations inside nebulae have on the T e(He I) value. We show that a comparison between T e(He I) and the electron temperature derived from the Balmer jump of the H I recombination spectrum, designated T e(H I), provides an opportunity to discriminate between the paradigms of a chemically homogeneous plasma with temperature and density variations, and a two-abundance nebular model with hydrogen-deficient material embedded in diffuse gas of a 'normal' chemical composition (i.e. ∼solar), as the possible causes of the dichotomy between the abundances that are deduced from collisionally excited lines and those deduced from recombination lines. We find that T e(He I) values are significantly lower than T e(H I) values, with an average difference of <T e(H I) - T e(He I)> = 4000 K. The result is consistent with the expectation of the two-abundance nebular model but is opposite to the prediction of the scenarios of temperature fluctuations and/or density inhomogeneities. From the observed difference between T e(He I) and T e(H I), we estimate that the filling factor of hydrogen-deficient components has a typical value of 10 -4. In spite of its small mass, the existence of hydrogen-deficient inclusions may potentially have a profound effect in enhancing the intensities of He I recombination lines and thereby lead to apparently overestimated helium abundances for PNe. © 2005 RAS.en_US
dc.languageengen_US
dc.publisherBlackwell Publishing Ltd. The Journal's web site is located at http://www.blackwellpublishing.com/journals/MNRen_US
dc.relation.ispartofMonthly Notices of the Royal Astronomical Societyen_US
dc.subjectIsm: Generalen_US
dc.subjectPlanetary Nebulae: Generalen_US
dc.titleHelium recombination spectra as temperature diagnostics for planetary 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.doi10.1111/j.1365-2966.2005.08810.xen_US
dc.identifier.scopuseid_2-s2.0-17044405447en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-17044405447&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume358en_US
dc.identifier.issue2en_US
dc.identifier.spage457en_US
dc.identifier.epage467en_US
dc.identifier.isiWOS:000227673700012-
dc.publisher.placeUnited Kingdomen_US
dc.identifier.scopusauthoridZhang, Y=23768446500en_US
dc.identifier.scopusauthoridLiu, XW=7409287288en_US
dc.identifier.scopusauthoridLiu, Y=36064406700en_US
dc.identifier.scopusauthoridRubin, RH=14024741900en_US
dc.identifier.citeulike130567-

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