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 < 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 > 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).

9. Injected Dust(D=1 m)

10. Deflected Dust(D=0.01 m)

11. Injection Efficiency

12. Discussion • 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.

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.

14. 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.