Exploring mass-loss in M-type AGB stars · 2014. 9. 1. · Exploring mass-loss in M-type AGB stars...
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Exploring mass-loss in M-type AGB stars Sara Bladh, Uppsala University Collaborators: Susanne Höfner, Kjell Eriksson, Bernhard Aringer and Walter Nowotny
Transcript of Exploring mass-loss in M-type AGB stars · 2014. 9. 1. · Exploring mass-loss in M-type AGB stars...
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Exploring mass-loss in M-type AGB stars
Sara Bladh, Uppsala University
Collaborators: Susanne Höfner, Kjell Eriksson,
Bernhard Aringer and Walter Nowotny
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RHD model atmospheres
(W. Nowotny)
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Wind models of M-type AGB stars
(Bladh et al. 2014, in prep.) a < b < c < d
M=1M!
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Dynamical properties
(Bladh et al. 2014, in prep.) 0 5 10 15 20
u [km/s]
-8
-7
-6
-5
-4
log
(dM
/dt [
Msu
n/yr
])
Observations (Olofsson et al. 2002, Delgado et al. 2003)Wind models (M-type)
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Photometric properties in near-IR
(Bladh et al. 2014, in prep.)
4 6 8 10 12 14(V-K)0
1.0
1.5
2.0
2.5
3.0
3.5
(J-K
) 0
Bulge Miras (Groenewegen & Blommaert 2005)Field C-type LPVs (Bergeat 2001)Field M-type LPVs (Mendoza 1967)Wind models (M-type)
Model values shown are means over the
pulsation period.
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4 6 8 10 12 14(V-K)0
1
2
3
4
5
(J-K
) 0
RR ScoR CarR HyaR OctR VirT ColT HorRU Vir (C-type)
4 6 8 10 12 14(V-K)0
1
2
3
4
5
(J-K
) 0
Model A2Model A3Model B1Model B2Model B3Model C1
4 6 8 10 12(V-K)
1.1
1.3
1.5
1.7
(J-K
) 0
4 6 8 10 12(V-K)
1.1
1.3
1.5
1.7
(J-K
) 0
(Bladh et al. 2013)
The photometric variations are characterised by large variations in (V-K) and small variations in (J-K)
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4 6 8 10 12 14(V-K)0
1
2
3
4
5
(J-K
) 0
RR ScoR CarR HyaR OctR VirT ColT HorRU Vir (C-type)
4 6 8 10 12 14(V-K)0
1
2
3
4
5
(J-K
) 0
Model A2Model A3Model B1Model B2Model B3Model C1
4 6 8 10 12(V-K)
1.1
1.3
1.5
1.7
(J-K
) 0
4 6 8 10 12(V-K)
1.1
1.3
1.5
1.7
(J-K
) 0
4 6 8 10 12 14(V-K)0
1
2
3
4
5
(J-K
) 0
RR ScoR CarR HyaR OctR VirT ColT HorRU Vir (C-type)
4 6 8 10 12 14(V-K)0
1
2
3
4
5
(J-K
) 0
Model A2Model A3Model B1Model B2Model B3Model C1
4 6 8 10 12(V-K)
1.1
1.3
1.5
1.7
(J-K
) 0
4 6 8 10 12(V-K)
1.1
1.3
1.5
1.7
(J-K
) 0
(Bladh et al. 2013)
The photometric variations are characterised by large variations in (V-K) and small variations in (J-K)
The variations in (V-K) are due to molecular changes during the pulsation cycle, not changes in the dust
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Spectra in the mid-IR
1 10 [µm]
1032
1033
1034
1035
1036
1037
1038
L [e
rg/s
]
V I J H K L M
Missing silicate features!
(Bladh et al. 2013)
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1 10λ [µm]
1032
1033
1034
1035
1036
1037
1038
νL
ν [
erg
/s]
V I J H K L M
Freezing of dust temp at 800KFreezing of dust temp at 500K
No freezing of dust temp
Spectra in the mid-IR
(Bladh et al. 2014, in prep)
Keeping the grain temperature constant from ~3R* outwards shows that the missing features are not due to low abundance of silicates, but too cool grains.
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1 10λ [µm]
1032
1033
1034
1035
1036
1037
1038
νL
ν [
erg
/s]
V I J H K L M
Freezing of dust temp at 800KFreezing of dust temp at 500K
No freezing of dust temp
1 10 [µm]
1032
1033
1034
1035
1036
1037
1038
L [e
rg/s
]
V I J H K L M
Mg2SiO4 core, MgFeSiO4 mantel (10% of the radius)Mg2SiO4 cor, MgFeSiO4 mantel (5% of the radius)
Mg2SiO4 core, MgFeSiO4 mantel (1% of the radius)Pure Mg2SiO4 grains
Spectra in the mid-IR
Keeping the grain temperature constant from ~3R* outwards shows that the missing features are not due to low abundance of silicates, but too cool grains.
(Bladh et al. 2014, in prep)
Adding a thin mantel of MgFeSiO4 when this material is thermally stable will also heat up the grains, resulting in silicate features.
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0.1
1.0
10.0
Norm
alize
d flu
x [J
y]
R Aqr (Kramer 2002, Sloan 2003)
Model A3, 10% MgFeSiO4 mantelModel A3, 5% MgFeSiO4 mantelModel A3, 1% MgFeSiO4 mantelModel A3, pure Mg2SiO4 grains
10 [µm]
0.1
1.0
10.0
Norm
alize
d flu
x [J
y]
R Cas (Kramer 2002, Sloan 2003)
Qualitative comparison
(Bladh et al. 2014, in prep)
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Summary
• We present the first extensive set of time-dependent wind models for M-type AGB stars.
• These wind models reproduce well both observed dynamic properties and photometry, especially the large photometric variation in the visual band during a pulsation cycle.
• The current wind models of M-type AGB stars
(with pure forsterite grains) do not reproduce the characteristic silicate features. “Dirty” grains may solve this problem.
