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Neon and CNO Abundances for Extreme Helium Stars—A Non-LTE Analysis

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dc.contributor.author Pandey, G
dc.contributor.author Lambert, D. L
dc.date.accessioned 2011-02-01T10:04:39Z
dc.date.available 2011-02-01T10:04:39Z
dc.date.issued 2011-02
dc.identifier.citation The Astrophysical Journal , Vol. 727, No. 2, 122 (15pp) en
dc.identifier.uri http://hdl.handle.net/2248/5330
dc.description Open Access en
dc.description.abstract A non-LTE (NLTE) abundance analysis was carried out for three extreme helium stars (EHes): BD+10° 2179, BD–9° 4395, and LS IV+6° 002, from their optical spectra with NLTE model atmospheres. NLTE TLUSTY model atmospheres were computed with H, He, C, N, O, and Ne treated in NLTE. Model atmosphere parameters were chosen from consideration of fits to observed He I line profiles and ionization equilibria of C and N ions. The program SYNSPEC was then used to determine the NLTE abundances for Ne as well as H, He, C, N, and O. LTE neon abundances from Ne I lines in the EHes: LSE 78, V1920 Cyg, HD 124448, and PV Tel, are derived from published models and an estimate of the NLTE correction applied to obtain the NLTE Ne abundance. We show that the derived abundances of these key elements, including Ne, are well matched with semi-quantitative predictions for the EHe resulting from a cold merger (i.e., no nucleosynthesis during the merger) of an He white dwarf with a C-O white dwarf. en
dc.language.iso en en
dc.publisher IOP Publishing en
dc.relation.uri http://dx.doi.org/10.1088/0004-637X/727/2/122 en
dc.rights © IOP Publishing en
dc.subject Stars: abundances en
dc.subject Stars: atmospheres en
dc.subject Stars: chemically peculiar en
dc.subject Stars: evolution en
dc.subject stars: fundamental parameters en
dc.title Neon and CNO Abundances for Extreme Helium Stars—A Non-LTE Analysis en
dc.type Article en

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