The Aerogel Model for the Origin of the ShortLived Radionuclides in the Early Solar System

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The Aerogel Model for the Origin of the
Short-Lived Radionuclides in the Early Solar
System

• Steve Desch, Nicolas Ouellette, Jeff Hester and
  Laurie Leshin
• Arizona State University

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The Early Solar System held Short-Lived
Radionuclides
41Ca (t1/2 0.1 Myr) 36Cl (t1/2 0.3 Myr) 26Al
(t1/2 0.7 Myr) 10Be (t1/2 1.5 Myr) 60Fe
(t1/2 1.5 Myr) 53Mn (t1/2 3.7 Myr) 107Pd
(t1/2 6.5 Myr) 182Hf (t1/2 9 Myr) 129I
(t1/2 16 Myr)
60Ni 61Ni
Tachibana Huss (2003) ApJ 588,L41
56Fe 61Ni
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Only Plausible Explanation for the 60Fe A Nearby
Supernova
60Fe / 56Fe 5 x 10-7 (Tachibana Huss 2003
Huss Tachibana 2004)

• Background levels of 60Fe 60Fe/56Fe ltlt 10-9
  (Harper 1996)
• Nuclear reactions caused by proto-solar flares lt
  10-9 (Lee et al 1998 Leya et al 2003)
• Passing AGB star 60Fe / 56Fe 10-7, but highly
  improbable P ltlt 10-6 (Kastner Myers 1994)
• Nearby Supernova 60Fe / 56Fe 10-6 (Wasserburg
  et al. 1998 Meyer Clayton 2000)

Sun HAD to be born within a few parsecs of a
supernova!
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Supernova Probably lt 1 pc Away
Radionuclides in supernova ejecta carried by dust
grains that implant themselves in Suns
protoplanetary disk like aerogel (but also
evaporate)
0.2pc
disks
?1Ori C imminent supernova
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Summary

• Meteorites show early solar system definitely had
  live 60Fe
• Only plausible source of the 60Fe is a nearby
  supernova
• Sun therefore formed in association with massive
  stars / H II region
• Early Solar System probably just like disks in
  Orion Nebula (and was greatly affected by the
  environment)

• Radionuclides in supernova grains probably lodged
  in our disk like aerogel explains radionuclide
  abundances well if lt 0.3 pc away (Desch
  Ouellette, in preparation)
• Disks can probably survive supernova if gt 0.1 -
  0.3 pc away (Chevalier 2000 Desch Ouellette,
  in preparation)