Injection of Supernova Dust Grains Into Protoplanetary Disks
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Transcript of Injection of Supernova Dust Grains Into Protoplanetary Disks
Injection of Supernova Dust Grains Into Protoplanetary
Disks
N. Ouellette
S. J. Desch & J. J. Hester
Arizona State University
Motivation• Many SLRs have been shown to be present
during the formation of the Solar System, and their origin remains a mystery.
• The one-time presence of 60Fe demands the Solar System formed near a supernova.– Irradiation and inheritance do not yield enough 60Fe
(Leya et al. 2003; Gounelle et al. 2006).– AGB stars are not naturally associated with star
forming regions (Kastner & Myers 1994).
• Most low-mass stars form in close proximity to massive stars.– More than 50% of all low-mass stars form in
association with a supernova (Hester & Desch 2005).
Aerogel Model
Hester & Desch (2005)
0.4 pc
Aerogel Model
• SLRs are injected from a supernova into an already formed protoplanetary disk a few tenths of a parsec away (Ouellette et al. 2005).
• Hydrodynamics simulations by Ouellette et al. (2007) have shown that:– Disks survive being hit by supernova ejecta– Very little gas (~ 1% of the gas that is intercepted
by the disk) is injected.
Supernova Ejecta
Hwang et al. 2004
Si/S jet
Supernova Dust
• Refractory elements in the ejecta begin to condense within few years.– Tdust < 640 K, 2 years after explosion (Wooden et
al 1993).– Fe/FeS and/or graphite formed within 2 years of
SN 1987A (Colgan et al. 1994, Wooden 1997).– SiC X grains and LD presolar graphite contained
49V (t1/2 = 330 days) (Meyer & Zinner 2006).
Dust Size
Type Size
SiC 0.1-20 m
Graphite 1-20 m
Silicates 0.1-1 m
Al2O3 0.1-3 m
Nanodiamond 1-5 nmMeyer & Zinner (2006)
• From the meteoritic record:
Method of Calculation• Snapshots (sampled once a year for 1000
years) from Ouellette et al. (2007) are used for the gas density and velocity.
• 2 forces acting on the dust: gravity and gas drag (Gombosi et al. 1986).
• The dust trajectories are followed until:– The dust “burns up” (Tdust > 1500 K).– The dust “stops” (|vdust-vgas| < 0.1 x gas sound
speed).– The dust leaves the computational domain.
• Dust is considered injected if it reaches a depth in the disk where disk processes dominate. gas > 10-16 g cm-3 (Z < 3H).
Injected Dust (D=1 m)
Deflected Dust (D=0.01 m)
Injection Efficiency
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0.01 um 0.1 um 1 um 10 um
injected intact injected but burned up miss
Discussion
Ratio Measured Predicted26Al/27Al 4.5 × 10−5 4.1 × 10−5
36Cl/35Cl 1.4 − 3.0 × 10−6 3.3 × 10−6 41Ca/40Ca 1.5 × 10−8 1.5 × 10−8
53Mn/55Mn 2.0 × 10−5 2.0 × 10−5 60Fe/56Fe 3 − 10 × 10−7 9.3 × 10−7
• Large grains (D > 0.1 m) are injected efficiently ( > 90 % of the mass).
• Predicted ratios in 30 AU radius disk 0.2 pc from a 21 M supernova (0.8 Myr delay; using Rauscher et al. 2002). See poster by Ellinger et al. for details.
Discussion
• SLRs condense into different presolar supernova grains with different densities and sizes.
• Grains with different sizes are injected slightly differently and reach different peak temperatures. This could lead to some elemental fractionation.
• E.g., almost no nanodiamonds produced in this supernova would be injected.
Discussion
• Work by Bizzarro et al. (2007) suggests that that 60Fe was injected into the Solar System a fraction of 1 Myr after 26Al was.
• This scenario is compatible with the aerogel model.– 26Al, 36Cl and 41Ca are injected via Wolf-Rayet winds.– The remainder of the SLRs (especially 60Fe) are
injected during the supernova explosion.
• The aerogel model is a robust model framework for understanding the SLRs abundances observed in meteorites.