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.