J/ApJ/797/44 Evolution and nucleosynthesis of AGB stars (Fishlock+, 2014)
Evolution and nucleosynthesis of asymptotic giant branch stellar models
of low metallicity.
Fishlock C.K., Karakas A.I., Lugaro M., Yong D.
<Astrophys. J., 797, 44 (2014)>
=2014ApJ...797...44F 2014ApJ...797...44F (SIMBAD/NED BibCode)
ADC_Keywords: Stars, giant ; Stars, masses ; Effective temperatures ;
Abundances ; Models, evolutionary
Keywords: nuclear reactions, nucleosynthesis, abundances - stars: abundances -
stars: AGB and post-AGB
Abstract:
We present stellar evolutionary tracks and nucleosynthetic predictions
for a grid of stellar models of low- and intermediate-mass asymptotic
giant branch (AGB) stars at Z=0.001 ([Fe/H]=-1.2). The models cover
an initial mass range from 1 M☉ to 7 M☉. Final surface
abundances and stellar yields are calculated for all elements from
hydrogen to bismuth as well as isotopes up to the iron group. We present
the first study of neutron-capture nucleosynthesis in
intermediate-mass AGB models, including a super-AGB model, of [Fe/H]=-1.2.
We examine in detail a low-mass AGB model of 2 M☉ where the
13C(α,n)16O reaction is the main source of neutrons. We also
examine an intermediate-mass AGB model of 5 M☉ where intershell
temperatures are high enough to activate the 22Ne neutron source,
which produces high neutron densities up to ∼1014 n/cm3. Hot bottom
burning is activated in models with M≥3 M☉. With the 3 M☉
model, we investigate the effect of varying the extent in mass of the
region where protons are mixed from the envelope into the intershell
at the deepest extent of each third dredge-up. We compare the results
of the low-mass models to three post-AGB stars with a metallicity of
[Fe/H]~-1.2. The composition is a good match to the predicted
neutron-capture abundances except for Pb and we confirm that the
observed Pb abundances are lower than what is calculated by AGB models.
Description:
We calculate AGB stellar models for a range of initial masses from
1 M☉ to 7 M☉ with a metallicity of Z=0.001 ([Fe/H]=-1.2)
and a helium abundance of Y=0.25. For the purposes of this study, we
define the low-mass models to be those with an initial mass up to and
including 3 M☉, and the intermediate-mass models, 3.25 M☉
and above. Each stellar model is evolved from the zero-age main
sequence to near the end of the AGB phase when the majority of the
convective envelope is lost by stellar winds. A two-step procedure is
performed to calculate the structure and detailed nucleosynthesis for
each stellar model.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 174 772 Model structural properties for each thermal
pulse
table8.dat 104 1840 The isotopic yields
table9.dat 104 1328 The elemental yields
table10.dat 199 114 The final surface abundances for each isotope
table11.dat 62 1344 The final surface abundance of each element
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See also:
J/ApJ/696/797 : Evolution and yields of low-mass AGB stars
(Cristallo+, 2009)
J/MNRAS/403/1413 : Updated stellar yields from AGB models (Karakas, 2010)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 F4.2 Msun Mass [1.0/7.0] Initial model mass (G1)
6- 8 I3 --- Pulse [1/135] Pulse number
10- 19 E10.4 Msun Mcore Core mass
21- 30 E10.4 Msun Mcsh Maximum mass of intershell convection zone
32- 41 E10.4 yr tcsh Duration of intershell convection
43- 52 E10.4 Msun MDred Mass dredged into envelope
54- 63 E10.4 --- lamb Third dredge-up efficiency
65- 74 E10.4 K THesh Maximum He-shell temperature
76- 85 E10.4 K Tbce Maximum temperature at base of convective
envelope (2)
87- 96 E10.4 K THsh Maximum H-shell temperature (2)
98-107 E10.4 yr tip Interpulse period
109-118 E10.4 Msun Mtot Total mass
120-129 E10.4 Lsun Lmax Maximum radiated luminosity (2)
131-140 E10.4 Lsun LHemax Maximum He-luminosity during a thermal pulse
142-151 E10.4 Rsun Rmax Maximum radius (2)
153-163 E11.4 mag mBol Bolometric magnitude
165-174 E10.4 K Teff Effective temperature at maximum radius
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Note (2): During previous interpulse period.
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Byte-by-byte Description of file: table8.dat table9.dat
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Bytes Format Units Label Explanations
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1- 4 F4.2 Msun Mass [1.0/7.0] Initial model mass (G1)
6- 7 A2 --- El ? Element identifier
9- 10 I2 --- Z [0/84]? Atomic number
12- 15 A4 --- Species ? Species identifier
17- 18 I2 --- A [1/70]? Atomic mass number
20- 33 E14.7 Msun M Net stellar yield (2)
35- 47 E13.7 Msun Mlost Amount lost from stellar wind
49- 61 E13.7 Msun M0 Total mass expelled (3)
63- 75 E13.7 --- Average mass fraction in the wind
77- 89 E13.7 --- X0 Initial mass fraction
91-104 E14.7 [-] f Production factor (4)
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Note (2): As defined in Equation 4.
Note (3): During the stellar lifetime multiplied by the initial mass fraction.
Note (4): Defined as log10[/X0].
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Byte-by-byte Description of file: table10.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Species Species identifier
6- 7 I2 --- A [1/70] Atomic mass number
9- 19 E11.5 --- Abd-1 Surface abundance in 1 solar mass model (1)
21- 31 E11.5 --- Abd-1.25 Surface abundance in 1.25 solar mass model (1)
33- 43 E11.5 --- Abd-1.5 Surface abundance in 1.5 solar mass model (1)
45- 55 E11.5 --- Abd-2 Surface abundance in 2 solar mass model (1)
57- 67 E11.5 --- Abd-2.25 Surface abundance in 2.25 solar mass model (1)
69- 79 E11.5 --- Abd-2.5 Surface abundance in 2.5 solar mass model (1)
81- 91 E11.5 --- Abd-2.75 Surface abundance in 2.75 solar mass model (1)
93-103 E11.5 --- Abd-3 Surface abundance in 3 solar mass model (1)
105-115 E11.5 --- Abd-3.25 Surface abundance in 3.25 solar mass model (1)
117-127 E11.5 --- Abd-3.5 Surface abundance in 3.5 solar mass model (1)
129-139 E11.5 --- Abd-4 Surface abundance in 4 solar mass model (1)
141-151 E11.5 --- Abd-4.5 Surface abundance in 4.5 solar mass model (1)
153-163 E11.5 --- Abd-5 Surface abundance in 5 solar mass model (1)
165-175 E11.5 --- Abd-5.5 Surface abundance in 5.5 solar mass model (1)
177-187 E11.5 --- Abd-6 Surface abundance in 6 solar mass model (1)
189-199 E11.5 --- Abd-7 Surface abundance in 7 solar mass model (1)
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Note (1): In Y where Y=X/A and X is the mass fraction and A is the atomic mass.
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Byte-by-byte Description of file: table11.dat
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Bytes Format Units Label Explanations
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1- 4 F4.2 Msun Mass [1.0/7.0] Initial model mass (G1)
6- 7 A2 --- El Element identifier
9- 10 I2 --- Z [1/84] Atomic number
12- 20 F9.6 [-] loge Log abundance (2)
22- 30 F9.6 [-] [X/H] Log abundance relative to hydrogen (3)
32- 40 F9.6 [-] [X/Fe] Log abundance relative to iron (3)
42- 50 F9.6 [-] [X/O] Log abundance relative to oxygen (3)
52- 62 E11.5 --- X Mass fraction
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Note (2): Where loge=log10(NA/NH)+12 and NA and NH are abundances
of element A and H.
Note (3): Where [X/Y]=log10(NX/NY)-log10(NX/NY)solar and
NX/NY are the abundances of elements X and Y.
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Global notes:
Note (G1): All models have Z=0.001.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 16-Aug-2017