Spectral analysis of the hybrid PG 1159-type central stars of the planetary nebulae Abell 43 and NGC7094
- Stellar post asymptotic giant branch (post-AGB) evolution can be completely altered by a final thermal pulse (FTP) which may occur when the star is still leaving the AGB (AFTP), at the departure from the AGB at still constant luminosity (late TP, LTP) or after the entry to the white-dwarf cooling sequence (very late TP, VLTP). Then convection mixes the Herich material with the H-rich envelope. According to stellar evolution models the result is a star with a surface composition of H approximate to 20 per cent by mass (AFTP), approximate to 1 per cent (LTP), or (almost) no H (VLTP). Since FTP stars exhibit intershell material at their surface, spectral analyses establish constraints for AGB nucleosynthesis and stellar evolution. We performed a spectral analysis of the so-called hybrid PG 1159-type central stars (CS) of the planetary nebulae Abell 43 and NGC7094 by means of non-local thermodynamical equilibrium models. We confirm the previously determined effective temperatures of T-eff = 115 000 +/- 5 000K and determine surfaceStellar post asymptotic giant branch (post-AGB) evolution can be completely altered by a final thermal pulse (FTP) which may occur when the star is still leaving the AGB (AFTP), at the departure from the AGB at still constant luminosity (late TP, LTP) or after the entry to the white-dwarf cooling sequence (very late TP, VLTP). Then convection mixes the Herich material with the H-rich envelope. According to stellar evolution models the result is a star with a surface composition of H approximate to 20 per cent by mass (AFTP), approximate to 1 per cent (LTP), or (almost) no H (VLTP). Since FTP stars exhibit intershell material at their surface, spectral analyses establish constraints for AGB nucleosynthesis and stellar evolution. We performed a spectral analysis of the so-called hybrid PG 1159-type central stars (CS) of the planetary nebulae Abell 43 and NGC7094 by means of non-local thermodynamical equilibrium models. We confirm the previously determined effective temperatures of T-eff = 115 000 +/- 5 000K and determine surface gravities of log (g /(cm s(-2))) = 5.6 +/- 0.1 for both. From a comparison with AFTP evolutionary tracks, we derive stellar masses of 0.57(-0.04)(+0.07)M(circle dot) and determine the abundances of H, He, and metals up to Xe. Both CS are likely AFTP stars with a surface H mass fraction of 0.25 +/- 0.03 and 0.15 +/- 0.03, respectively, and an Fe deficiency indicating subsolar initial metallicities. The light metals show typical PG 1159-type abundances and the elemental composition is in good agreement with predictions from AFTP evolutionary models. However, the expansion ages do not agree with evolution time-scales expected from the AFTP scenario and alternatives should be explored.…
Author details: | Lisa LöblingORCiDGND, Thomas RauchORCiDGND, Marcelo Miguel Bertolami MillerORCiD, Helge Tobias TodtORCiD, F. Friederich, M. Ziegler, Klaus WernerORCiD, J. W. Kruk |
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DOI: | https://doi.org/10.1093/mnras/stz1994 |
ISSN: | 0035-8711 |
ISSN: | 1365-2966 |
Title of parent work (English): | Monthly notices of the Royal Astronomical Society |
Publisher: | Oxford Univ. Press |
Place of publishing: | Oxford |
Publication type: | Article |
Language: | English |
Date of first publication: | 2019/07/25 |
Publication year: | 2019 |
Release date: | 2020/11/02 |
Tag: | stars: AGB and post-AGB; stars: abundances; stars: atmospheres; stars: evolution; stars: individual: WD1751+106; stars: individual: WD2134+125 |
Volume: | 489 |
Issue: | 1 |
Number of pages: | 18 |
First page: | 1054 |
Last Page: | 1071 |
Funding institution: | German Research Foundation (DFG)German Research Foundation (DFG) [WE 1312/49-1]; Agencia National de Promotion Cientifica e Tecnologica (ANPCyT), Argentina [PICT 2016-0053]; German Academic Exchange Service - Ministerio de Ciencia, Tecnologia e Innovacion Productiva (DAAD-MinCyT) bilateral cooperation program [DA/16/07]; NASANational Aeronautics & Space Administration (NASA) [NAS5-26666, NAS5-26555]; La Silla Paranal Observatory [167.D-0407]; High Performance and Cloud Computing Group at the Zentrum fur Datenverarbeitung of the University of Tubingen; DFGGerman Research Foundation (DFG) [INST 37/935-1 FUGG]; Federal Ministry of Education and Research (BMBF) at TubingenFederal Ministry of Education & Research (BMBF) [05AC 6VTB, 05AC 11 VTB]; NASA Office of Space ScienceNational Aeronautics & Space Administration (NASA) [NNX09AF08G]; state of Baden-Wurttemberg through bwHPC |
Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie |
DDC classification: | 5 Naturwissenschaften und Mathematik / 52 Astronomie / 520 Astronomie und zugeordnete Wissenschaften |
Peer review: | Referiert |
Publishing method: | Open Access |
Open Access / Green Open-Access |