Lines of O IV and S IV in the Goddard High-Resolution Spectrograph spectrum of RR Tel: constraints on atomic data

Summary, in English

High signal-to-noise ratio spectra of RR Tel obtained at medium resolution with the Goddard High-Resolution Spectrograph (GHRS) on the Hubble Space Telescope (HST) are used to test available atomic data for the O IV 2s(2)2p P-2-2s2p(2) P-4 multiplet (UV 0.01). The fine-structure intervals of the 2s2p(2) P-4 term given by Moore (1983) appear to need revision. The flux ratios of lines within multiplet UV (0.01), which have a common upper level, depend only on transition probabilities. The observed flux ratio of lines from the P-4(3/2) level differs from that predicted by theory, but this difference cannot be attributed to a blend with a line of S IV]. At the electron densities in the RR Tel nebula, other flux ratios give information on the relative electron excitation rates between the P-2 and P-4 fine-structure levels. Using the collision strengths calculated by Zhang, Graziani & Pradhan, the rate to the P-4(5/2) level, relative to the rates to the other J states, appears to be underestimated by similar to 10 per cent, which is within the expected uncertainty of 20 per cent. We also discuss the S IV 3s(2)3p P-2-3s3p(2) P-4 multiplet.

• Författare: GM Harper; C Jordan; PG Judge; RD Robinson; KG Carpenter; Tomas Brage
• Avdelning/ar: Fysiska institutionen
• Publiceringsår: 1999
• Språk: Engelska
• Sidor: 41-46
• Publikation/Tidskrift/Serie: Monthly Notices of the Royal Astronomical Society
• Volym: 303
• Issue: 3
• Länkar: http://dx.doi.org/10.1046/j.1365-8711.1999.02392.x
• Dokumenttyp: Artikel i tidskrift
• Förlag: Oxford University Press
• Ämne: Physical Sciences
• Nyckelord: RR Tel; individual; ultraviolet; stars; atomic data; symbiotic; binaries
• Status: Published
• ISBN/ISSN/Övrigt: ISSN: 1365-2966