Free Access
Issue
A&A
Volume 538, February 2012
Article Number A48
Number of page(s) 15
Section Stellar structure and evolution
DOI https://doi.org/10.1051/0004-6361/201117398
Published online 31 January 2012

Online material

Table 2

Observed Fe i and Fe ii lines.

Table 4

Other lines studied.

Appendix A: Supplementary material

A.1. GLMP 334 and IRAS 15482–5741

We provide an additional set of figures for both post-AGB stars in this section. We aim to shown the behavior of theoretical predictions by changing the AGB initial mass and 13C-pocket efficiency. The discrepancy between predicted and observed [C, N/Fe] may be improved by increasing the metallicity by 0.2 dex in both stars. This would reduce the predicted [C/Fe] by 0.3 dex with respect to Figs. 3 and 4, while leaving [ls/Fe] and [hs/Fe] unchanged. Indeed, 12C is primarily produced during partial He burning in the convective thermal pulse (independently of the metallicity) and is then dredged-up in the envelope after each TDU. In Figs. A.13 and A.14 we present two special cases modelled for both post-AGB stars. We present a summary of the theoretical interpretations of the two post-AGB stars discussed here compared with other post-AGB stars found in the literature in Sect. A.2.

thumbnail Fig. A.1

GLMP 334: the same as Fig. 3, but showing an additional 13C-pocket (case ST, thin solid line). This figure shows as by further decreasing the s-process efficiency, the observed [hs/Fe] is underestimated by the theoretical prediction.

Open with DEXTER

thumbnail Fig. A.2

GLMP 334: the same as Fig. 3, but for = 3 M models. Three 13C-pocket efficiencies are shown: cases ST × 2 (solid line), ST × 1.3 (dotted thin line) and ST (dotted thick line). The first two 13C-pockets provide solutions similar to = 2 M models.

Open with DEXTER

thumbnail Fig. A.3

GLMP 334: the same as Fig. A.2, but for = 1.5 M models. Owing to the lower number of thermal pulses with TDU (19th), none of the 13C-pockets reach the observed [ls/Fe] value. These solutions were discarded.

Open with DEXTER

thumbnail Fig. A.4

GLMP 334: the same as Fig. A.2, but for = 1.4 M models (11 TDUs). None of the 13C-pockets reach the observed ls and hs peaks. These solutions were discarded.

Open with DEXTER

thumbnail Fig. A.5

GLMP 334: the same as Fig. A.2, but for = 1.3 M models (5 TDUs). Even if these solutions perfectly agree with the observed [C/Fe], the low s-process distribution strongly underestimates the observed ls and hs peaks.

Open with DEXTER

thumbnail Fig. A.6

Theoretical interpretation of the post-AGB stars GLMP 334 ([Fe/H] =  − 0.4; Teff = 7400 K; log g = 1.4) with = 5 M models. Three 13C-pocket efficiencies are shown: cases ST-IMS × 4 (solid line), ST-IMS × 2 (dotted thin line) and ST-IMS (dotted thick line). Note that a different 13C-pocket notation is adopted for IMS stars, because they have a smaller He-intershell than low-mass AGBs, with a smaller 13C-pocket (see Bisterzo et al. 2010). None of these solutions agrees with the observations.

Open with DEXTER

thumbnail Fig. A.7

IRAS 15482–5741: the same as Fig. 4, but showing a different range of 13C-pockets: cases ST × 2 (solid line), ST (dotted thin line) and ST/3 (dotted thick line). This figure shows the behavior of the s-process elements if the 13C-pocket is changed.

Open with DEXTER

thumbnail Fig. A.8

IRAS 15482–5741: the same as Fig. 4, but for = 1.3 M models. The theoretical [ls/Fe] is about 0.6 dex lower than observed. Even if the predicted [C/Fe] is closer to the low observed value, we discarded this solution.

Open with DEXTER

thumbnail Fig. A.9

IRAS 15482–5741: the same as Fig. 4, but for = 1.5 M models. These models do not provide good theoretical interpretations for two reasons: first of all, with respect to Fig. 4, a further increase of about 0.2 dex is predicted for [C/Fe], because higher initial masses more TDUs (specifically, 19 instead of 11). Second, no good match is obtained of both ls and hs peaks: [ls/Fe] is perfectly interpreted by a case ST × 2, but [hs/Fe] is too high with respect the observed value. But, case ST/1.3 predicts a [ls/Fe] slightly higher than observed, even if the theoretical [hs/Fe] still lies within the errorbars.

Open with DEXTER

thumbnail Fig. A.10

IRAS 15482–5741: the same as Fig. A.9, but for = 2 M models. Owing to [C/Fe], [ls/Fe] and [hs/Fe], these solutions were discarded.

Open with DEXTER

thumbnail Fig. A.11

IRAS 15482–5741: the same as Fig. A.9, but for = 3 M models. Owing to [C/Fe], [ls/Fe] and [hs/Fe], these solutions were discarded.

Open with DEXTER

thumbnail Fig. A.12

Theoretical interpretation of the post-AGB star IRAS 15482–5741 ([Fe/H] =  − 0.5; Teff = 7400 K; log g = 1.1) with = 5 M models. Three 13C-pocket efficiencies are shown: cases ST-IMS × 4 (solid line), ST-IMS × 2 (dotted thin line) and ST-IMS (dotted thick line). None of these solutions agree with the observations.

Open with DEXTER

thumbnail Fig. A.13

Theoretical interpretation of the post-AGB star GLMP 334 ([Fe/H] =  − 0.4; Teff = 7400 K; log g = 1.4) by assuming a metallicity 0.2 dex higher than that observed. AGB models of initial mass of 1.5 M (19 TDUs), cases ST × 2 (solid line), ST × 1.7 (dotted thin line) and ST × 1.3 (dotted thick line) are shown. Note that the mass of the pocket was multiplied by a plausible factor of two to obtain 0.2 dex higher abundances in both [ls/Fe] and [hs/Fe]. We modelled these special cases to decrease [C/Fe] predictions with respect to Fig. 3, leaving [ls/Fe] and [hs/Fe] unchanged.

Open with DEXTER

thumbnail Fig. A.14

Theoretical interpretation of the post-AGB star IRAS 154825741 ([Fe/H] =  − 0.5; Teff = 7400 K; log g = 1.1) by assuming a metallicity 0.2 dex higher than that observed. AGB models of initial mass of 1.4 M (10 TDU), cases ST × 2 (solid line), ST × 1.7 (dotted thin line) and ST × 1.3 (dotted thick line) are shown. Note that the mass of the pocket was multiplied by a plausible factor of two to obtain 0.2 dex higher abundances in both [ls/Fe] and [hs/Fe]. We modelled these special cases to decrease the [C/Fe] predictions with respect to Fig. 4, leaving [ls/Fe] and [hs/Fe] unchanged.

Open with DEXTER

A.2. Comparison with other post-AGB stars presented in the literature.

We provide in Table A.1 a summary of the theoretical interpretations of the post-AGB stars discussed in the literature. Solutions are found within the mass range = 1.4 to 3 M. The choice of the 13C-pocket efficiency is peaked at ST/1.5, with a spread between ST/3 and ST × 2 (see also Gallino et al. 2008).

Table A.1

Summary of the stellar parameters, metallicities, [ls/Fe], [hs/Fe] and theoretical interpretations of the two post-AGB stars studied in this paper compared with the post-AGB stars discussed in the literature.


© ESO, 2012

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.