Type II Supernova Matter in a Silicon Carbide Grain from the Murchison Meteorite
The circumstellar silicon carbide (SiC) grain X57 from the Murchison meteorite contains large amounts of radiogenic calcium-44 (20 times its solar system abundance) and has an anomalous silicon isotopic composition, different from other circumstellar SiC grains. Its inferred initial 44Ti/Si and 44Ti/48Ti ratios are 1.6 x 10(-4) and 0.37. In addition, it contains radiogenic magnesium-26; the inferred initial 26Al/27Al ratio is 0.11. The isotopic and elemental data of X57 can be explained by selective mixing of matter from different zones of a typical type II supernova of 25 solar masses during its explosion. The high 44Ti/Si ratio requires contributions from the innermost nickel zone of the supernova to the SiC condensation site, as similarly suggested by astronomical observations.
Hoppe
P
P. Hoppe, R. Strebel, P. Eberhardt, Physikalisches Institut, Universitat Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. S. Amari and R. S. Lewis, Enrico Fermi Institute, University of Chicago, Chicago, IL 60637, USA.
Strebel
R
Eberhardt
P
Amari
S
Lewis
RS