thesis - IRS, The Infrared Spectrograph

Table 5.4–. Assumptions adopted in the TP-AGB synthetic calculations discussed in the paper.3 rd D-up efficiency Inter-shell composition Initial oxygen abundanceModels (ref.) Z Opacity 1 λ 2 X csh ( 12 C) X csh ( 16 O) X csh ( 4 He) X 0 (O) 3A) Figs. 5.3, 5.9 0.019 κ fix const. 0.50 0.220 0.020 0.760 O ⊙ HighB) Fig. 5.6 0.019 κ var const. 0.50 0.220 0.020 0.760 O ⊙ HighC) Fig. 5.6 0.019 κ var var. 0.457 0.220 0.020 0.760 O ⊙ HighD) Fig. 5.6, 5.11, 5.12 0.019 κ var var. 0.457 0.220 0.020 0.760 O ⊙ LowE) Fig. 5.6, 5.11, 5.12 0.019 κ var var. 0.30 0.220 0.020 0.760 O ⊙ LowF) Figs. 5.9, 5.11, 5.12 0.019 κ var var. 0.88, 0.96 0.050 0.005 0.945 O ⊙ LowG) Fig. 5.10 0.008 κ fix const. 0.50 0.220 0.020 0.760 (Z/Z ⊙ )× (O ⊙ High)H) Fig. 5.10 0.008 κ fix const. 0.90 0.220 0.020 0.760 (Z/Z ⊙ )× (O ⊙ High)I) Fig. 5.10 0.008 κ var const. 0.90 0.220 0.020 0.760 (Z/Z ⊙ )× (O ⊙ High)J) Figs. 5.10, 5.11, 5.12 0.008 κ var const. 0.90 0.030 0.001 0.969 (Z/Z ⊙ )× (O ⊙ High)K) Figs. 5.10, 5.11, 5.12 0.008 κ var const. 0.90 0.010 0.001 0.999 (Z/Z ⊙ )× (O ⊙ High)1 “κ fix ” corresponds to solar-scaled molecular opacities by Alexander & Ferguson (1994);“κ var” denotes the variable molecular opacities as calculated according to Marigo (2002).2 “const. value” means that the same constant value of λ is adopted at each dredge-up episode;“var. value” means that λ is made vary up to a maximum value, according to the analytic recipe by Karakas et al. (2002, their equation 7)3 “O ⊙ High” refers the determination of the oxygen abundance for the Sun by Anders & Grevesse (1989);“O ⊙ Low” refers to the recent determination of the oxygen abundance for the Sun by Allende Prieto et al. (2001).Other assumptions common to all TP-AGB models are:– log Tb dred = 6.4 following Marigo et al. (1999);– Mixing-length parameter α = Λ/H p = 1.68 (where H p denotes the pressure-scale height, and Λ is the mixing-length) following Girardi et al. (2000),unless otherwise specified;–Nuclear reaction rates from Caughlan & Fowler (1988).80 CHAPTER 5: Probing AGB nucleosynthesis via accurate Planetary Nebula abundances