UV spectral analysis of very hot H-deficient [WCE]-type central stars of planetary nebulae: NGC 2867, NGC 5189, NGC 6905, Pb 6 and Sand 3

Autor(es)

Keller, Graziela R. ^{[1, 2]} ; Bianchi, Luciana ^[2] ; Maciel, Walter J. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, BR-05508090 Sao Paulo - Brazil

^[2] Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 - USA

• Tipo de documento: Artigo Científico
• Fonte: Monthly Notices of the Royal Astronomical Society; v. 442, n. 2, p. 1379-1395, AUG 1 2014.
• Citações Web of Science: 7

Resumo

We analysed ultraviolet Far Ultraviolet Spectroscopic Explorer, International Ultraviolet Explorer, and Hubble Space Telescope/Space Telescope Imaging Spectrograph spectra of five of the hottest {[}WCE]-type central stars of planetary nebulae: NGC 2867, NGC 5189, NGC 6905, Pb 6, and Sand 3. The analysis leveraged on our grid of cmfgen synthetic spectra, which covers the parameter regime of hydrogen-deficient central stars of planetary nebulae and allows a uniform and systematic study of the stellar spectra. The stellar atmosphere models calculated by us include many elements and ionic species neglected in previous analyses, which allowed us to improve the fits to the observed spectra considerably and provided an additional diagnostic line: the Ne vii lambda 973 angstrom, which had not been modelled in {[}WCE] spectra and which presents, in these stars, a strong P-Cygni profile. We report newly derived photospheric and wind parameters and elemental abundances. The central stars of NGC 2867, NGC 5189, and Pb 6 had their temperatures revised upward in comparison with previous investigations and we found the carbon to helium mass ratio of the sample objects to span a wide range of values, 0.42 < C : He < 1.96. Modelling of the Ne vii lambda 973 angstrom P-Cygni profile indicated strong neon overabundances for the central stars of NGC 2867, NGC 5189, NGC 6905, and Pb 6, with Ne mass fractions between 0.01 and 0.04. Nitrogen abundances derived by us for the central stars of NGC 5189, Pb 6, and Sand 3 are higher than previous determinations by factors of 3, 10, and 14, respectively. (AU)

• Processo FAPESP: 09/54006-4 - Um cluster de computadores para o Departamento de Astronomia do IAG-USP e para o Núcleo de Astrofísica da UNICSUL
• Beneficiário: Elisabete Maria de Gouveia Dal Pino
• Modalidade de apoio: Auxílio à Pesquisa - Programa Equipamentos Multiusuários
• Processo FAPESP: 12/03479-2 - Espectros Sintéticos para a Análise de Estrelas Centrais de Nebulosas Planetárias Deficientes em Hidrogênio
• Beneficiário: Graziela Roswitha Keller Rodrigues
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 06/58240-3 - Nebulosas planetárias e estrelas centrais: ventos estelares e metalicidades
• Beneficiário: Graziela Roswitha Keller Rodrigues
• Modalidade de apoio: Bolsas no Brasil - Doutorado