Transcript LPSC 2004 - Arizona State University

Late Injection of Radionuclides
into
Solar Nebula Analogs in Orion
Steve Desch and Nicolas Ouellette
collaborators: Jeff Hester and Laurie Leshin
Arizona State University
Outline
1. A supernova injected radionuclides into solar system.
2. Injection occurred after the disk had formed.
3. The Sun is typical: most stars form near a supernova.
4. Supernova shock probably doesn’t destroy disk
5. Radionuclides are injected promptly and close to disk
The solar system possessed
short-lived radionuclides
41Ca
0.10 Myr
41Ca/40Ca
= 1.5 x 10-8
Srinivasan et al
(1994)
36Cl
0.30 Myr
36Cl/35Cl
= 5-10 x 10-6
Lin et al (2004),
this conference
26Al
0.71 Myr
26Al/27Al
= 5 x 10-5
MacPherson et al
(1995)
10Be
1.5 Myr
10Be/9Be
= 9 x 10-4
McKeegan et al
(2000)
60Fe
1.5 Myr
60Fe/56Fe
= 5 x 10-7
Huss & Tachibana
(2004) this conference
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
•
60Fe
produced in meteoritic
proportions in supernovae (Meyer & Clayton 2000)
not made by irradiation (Lee et al 1998; Leya et al 2003),
60Fe must be from supernova
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)
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 > 2000 stars have
an O star (Adams & Laughlin 2001)
• Most stars born < a few pc from an O star
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)
Protoplanetary Disks Near Supernovae
• Proplyds: Disks with gas
“cocoons” around them from
photoevaporative outflows
• Sizes > 100 AU
• Lasts ~ 104 years
• Protoplanetary Disks: Disks
with no loosely bound gas
• Sizes < 30 AU
• Lasts until O stars supernova
1 Ori C: Massive Star (40 M)
will supernova in ~ 3 Myr
Effect of Supernova on Disk
•Supernova shock will
plow into disk until
critical isobar reached
•Shock stalls when
disk pressure >
pressure behind shock
•Pressure behind
shock depends on
distance to supernova
•Disk inside 30 AU
will survive shock!
Penetration depth of shock
•Supernova ejecta
reaches disk in < 103 yr
•Ejecta penetrates to
about 0.5 AU above
midplane
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
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 (< 103 yr; but
solids may take longer to form), and happens
throughout disk
• Upcoming numerical calculations will test this
hypothesis