Heterogeneous distribution of Al-26 at the birth of the Solar System

Details Heterogeneous distribution of Al-26 at the birth of the Solar System Heterogeneous distribution of Al-26 at the birth of the Solar System

2011-05-13

arxiv.org/abs/1105.2620v1

Astronomy and Astrophysics

Astrophysics

Earth and Planetary Astrophysics

Astrophysical Journal Letters 733, L31

Scientific paper

It is believed that Al-26, a short-lived (t1/2 = 0.73 Ma) and now extinct radionuclide, was uniformly distributed in the nascent Solar System with the initial Al-26/Al-27 ratio of ~5.2\times10-5, suggesting its external stellar origin. However, the stellar source of Al-26 and the manner in which it was injected into the solar system remain controversial: the Al-26 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 or protoplanetary disk. Corundum (Al2O3) is thermodynamically predicted to be the first condensate from a cooling gas of solar composition. Here we show that micron-sized corundum condensates from O-16-rich gas (Big Delta O-17 ~ -25%) of solar composition recorded heterogeneous distribution of Al-26 at the birth of the solar system: the inferred initial Al-26/Al-27 ratio ranges from ~6.5x10-5 to <2x10-6; ~50% of the corundum grains measured are Al-26-poor. Other Al-26-poor, O-16-rich refractory objects include grossite (CaAl4O7)- and hibonite(CaAl12O19)-rich calcium-aluminum-rich inclusions (CAIs) in CH chondrites, platy hibonite crystals in CM chondrites, and FUN (fractionation and unidentified nuclear isotopic anomalies) CAIs in CV, CO, and CR chondrites. Considering the apparently early and short duration (<0.3 Ma) of condensation of refractory O-16-rich solids in the solar system, we infer that Al-26 was injected into the collapsing protosolar molecular cloud and later homogenized in the protoplanetary disk. The apparent lack of correlation between Al-26 abundance and O-isotope compositions of corundum grains put important constraints on the stellar source of Al-26 in the solar system.

Affiliated with

Also associated with

No associations

Rating

Heterogeneous distribution of Al-26 at the birth of the Solar System does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Heterogeneous distribution of Al-26 at the birth of the Solar System, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Heterogeneous distribution of Al-26 at the birth of the Solar System will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-26781