Late Injection of Radionuclides into

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Late Injection of Radionuclides into Solar
Nebula Analogs in Orion
Steve Desch and Nicolas Ouellette collaborator
s Jeff Hester and Laurie Leshin Arizona State
University
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Outline

• A supernova injected radionuclides into solar
  system.
• Injection occurred after the disk had formed.
• The Sun is typical most stars form near a
  supernova.
• Supernova shock probably doesnt destroy disk
• Radionuclides are injected promptly and close to
  disk

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The solar system possessed short-lived
radionuclides
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Short-lived radionuclides were injected by a
supernova

• 10Be uniquely attributable to 10Be cosmic rays
  trapped before solar system formed (Desch et al
  2004)
• 41Ca, 36Cl, 26Al, 60Fe produced in meteoritic
  proportions in supernovae (Meyer Clayton 2000)
• 60Fe not made by irradiation (Lee et al 1998
  Leya et al 2003), 60Fe must be from
  supernova

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Supernova injection happened after solar system
had formed

• Many inclusions never had 26Al, 41Ca
• Many even contained 10Be
  (Marhas et al 2002 Desch et al 2004)
• Late Injection of 26Al, 41Ca argued
  (Sahijpal Goswami 1998)

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Most stars born near massive O stars that will
supernova

• 50-90 of all stars form in massive clusters
  (Lada Lada 2003)
• Almost all clusters with gt 2000 stars have an O
  star (Adams Laughlin 2001)
• Most stars born lt a few pc from an O star

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Star Formation Near O Stars

• O stars probably trigger formation of solar-type
  stars (references)
• Solar systems emerge into region as EGGs, then as
  proplyds,

finally disks
Evaporating Gaseous Globules new solar systems
Hester et al (1996)
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Protoplanetary Disks Near Supernovae

• Proplyds Disks with gas cocoons around them
  from photoevaporative outflows
• Sizes gt 100 AU
• Lasts 104 years
• Protoplanetary Disks Disks with no loosely bound
  gas
• Sizes lt 30 AU
• Lasts until O stars supernova

?1 Ori C Massive Star (40 M?) will supernova in
3 Myr
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Effect of Supernova on Disk

• Supernova shock will plow into disk until
  critical isobar reached
• Shock stalls when disk pressure gt pressure behind
  shock
• Pressure behind shock depends on distance to
  supernova
• Disk inside 30 AU will survive shock!

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Penetration depth of shock

• Supernova ejecta reaches disk in lt 103 yr
• Ejecta penetrates to about 0.5 AU above midplane

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Radionuclides mixed in

• Ejecta gas stops where shock stalls
• Ejecta dust evaporates where shock stalls...
• ...unless they were already slowed down in
  proplyd outflow (1 chance)
• Radionuclides then mixed with disk gas

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Conclusions

• Short-lived radionuclides 26Al, 41Ca, 36Cl, and
  especially 60Fe, injected by a supernova, after
  disk formed
• This is the exact sequence of events we expect if
  Sun formed like most stars, in clusters
• Injection is prompt and rapid (lt 103 yr but
  solids may take longer to form), and happens
  throughout disk
• Upcoming numerical calculations will test this
  hypothesis