J/ApJ/733/L31 Distribution of ^26^Al in the solar system (Makide+, 2011) ================================================================================ Heterogeneous distribution of ^26^Al at the birth of the solar system. Makide K., Nagashima K., Krot A.N., Huss G.R., Ciesla F.J., Hellebrand E., Gaidos E., Yang L. =2011ApJ...733L..31M ================================================================================ ADC_Keywords: Solar system ; Atomic physics ; Comets Keywords: meteorites, meteors, meteoroids - protoplanetary disks - stars: Wolf-Rayet - Sun: evolution - supernovae: general Abstract: It is believed that ^26^Al, a short-lived (t_1/2_=0.73Ma) and now extinct radionuclide, was uniformly distributed in the nascent solar system (SS) with the initial ^26^Al/^27^Al ratio of ~5.2x10^-5^, suggesting an external, stellar origin rather than local, solar source. However, the stellar source of ^26^Al and the manner in which it was injected into the SS remain controversial: the ^26^Al could have been produced by an asymptotic giant branch star, a supernova, or a Wolf-Rayet star and injected either into the protosolar molecular cloud, protosolar cloud core, or protoplanetary disk. Corundum (Al_2_O_3_) is predicted to be the first condensate from a cooling gas of solar composition. Here we show that micron-sized corundum condensates from ^16^O-rich ({Delta}^17^O~-25%) gas of solar composition recorded heterogeneous distribution of ^26^Al at the birth of the SS: the inferred initial ^26^Al/^27^Al ratio ranges from ~6.5x10^-5^ to <2x10^-6^; 52% of corundum grains measured are ^26^Al-poor. Abundant ^26^Al-poor, ^16^O-rich refractory objects include grossite- and hibonite-rich calcium-aluminum-rich inclusions (CAIs) in CH (high metal abundance and high iron concentration) chondrites, platy hibonite crystals in CM (Mighei-like) chondrites, and CAIs with fractionation and unidentified nuclear effects CAIs chondrites. Considering the apparently early and short duration (<0.3Ma) of condensation of refractory ^16^O-rich solids in the SS, we infer that ^26^Al was injected into the collapsing protosolar molecular cloud and later homogenized in the protoplanetary disk. The apparent lack of correlation between ^26^Al abundance and O-isotope composition of corundum grains constrains the stellar source of ^26^Al in the SS. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 86 116 Oxygen-isotope compositions and the inferred (^26^Al/^27^Al)_0_ ratios from individual micron-sized corundum grain in unequilibrated ordinary chondrites (UOCs) and unmetamorphosed CM carbonaceous chondrites (CCs) -------------------------------------------------------------------------------- Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 23 A23 --- Type chondrite type (Carbonaceus or Ordinary) 25- 38 A14 --- Grain Grain (1) 40- 44 F5.1 10-3 d18O Excess {delta}^18^O of ^18^O isotope 46- 48 F3.1 10-3 e_d18O The 2{sigma} error in d180 50- 54 F5.1 10-3 d17O Excess {delta}^18^O of ^17^O isotope 56- 59 F4.1 10-3 e_d17O The 2{sigma} error in d170 61- 65 F5.1 10-3 D17O {Delta}^17^O composition (D17O=d17O-0.52*d18O) 67- 70 F4.1 10-3 e_D17O The 2{sigma} error in D17O 72- 77 F6.3 10-5 Al.r ? Inferred (^26^Al/^27^Al)_0_ ratio (2) 79- 80 A2 --- f_Al.r [ND] ND: indicates Al.r not determined (2) 82- 86 F5.3 10-5 e_Al.r ? The 2{sigma} error in Al.r -------------------------------------------------------------------------------- Note (1): Abbreviations are: Sem = Semarkona (LL3.0 UOC [unequilibrated ordinary chondrite]) Bis = Bishunpur (LL3.15 UOC [unequilibrated ordinary chondrite]) RC = Roosevelt County 075 (H3.10 UOC [unequilibrated ordinary chondrite]) ALHA = Alan Hills A77307 (CO3.0 CC [unmetamorphosed carbonaceous chondrite]) Mur = Murray (CM2 CC [unmetamorphosed carbonaceous chondrite]) Org = Orgueil (CI1 CC [unmetamorphosed carbonaceous chondrite]) Ren = Renazzo (CR2 CC [unmetamorphosed carbonaceous chondrite]) *P = presolar corundum grains; *U = isotopically unusual corundum grains, possibly an analytical artifact. "^" = grains with O-isotope compositions previously reported by Makide et al. (2009GeCoA..73.5018M). The *P and *U grains are not plotted in Figure 1 and not discussed in the text. Note (2): ^26^Al/^27^Al ratio could not be determined due to either the presence of Mg-rich grains attached to corundum grains, or loss of grains during oxygen isotopic measurements. -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 19-Nov-2012