Injection of Supernova Dust Grains Into Protoplanetary Disks

1
Injection of Supernova Dust Grains Into
Protoplanetary Disks

• N. Ouellette
• S. J. Desch J. J. Hester
• Arizona State University

2
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).

3
Aerogel Model
0.4 pc
Hester Desch (2005)
4
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.

5
Supernova Ejecta
Si/S jet
Hwang et al. 2004
6
Supernova Dust

• Refractory elements in the ejecta begin to
  condense within few years.
• Tdust lt 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).

7
Dust Size

• From the meteoritic record

Meyer Zinner (2006)
8
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 gt 1500 K).
• The dust stops (vdust-vgas lt 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 gt 10-16 g cm-3 (Z lt 3H).

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Injected Dust (D1 ?m)
10
Deflected Dust (D0.01 ?m)
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Injection Efficiency
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Discussion

• Large grains (D gt 0.1 ?m) are injected
  efficiently ( gt 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.

13
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.

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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.