AAS 206th Meeting, 29 May - 2 June 2005
Session 6 Formation and Fate of Stardust
Poster, Monday, 9:20am-6:30pm, Tuesday, 10:00am-7:00pm, May 30, 2005, Ballroom A

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[6.07] Are presolar dust grains from novae actually from supernovae?

L. R. Nittler (Carnegie Instituion of Washington), P. Hoppe (Max Planck Institute for Chemistry, Mainz, Germany)

Meteorites contain presolar stardust grains that formed in prior generations of stars and exhibit large isotopic anomalies reflecting the nuclear processes that occurred in their individual parent stars. RGB and AGB stars and supernovae are well established as sources of many of these grains. Novae have been proposed as sources for a few SiC and graphite grains with low 12C/13C and 14N/15N ratios and unusual Si isotopic ratios (Amari et al., ApJ, 551, 1065). We have found three SiC grains from the Murchison meteorite with C and N isotopic ratios similar to the previously-reported putative nova grains. However, the isotopic signatures of Si, Ca, Al and Ti in one of the grains (334-2) clearly indicate a supernova origin, especially excess 28Si correlated with excess 44Ca. The latter signature is attributable to in situ decay of (half-life=50yr) 44Ti. Another 13C- and 15N-rich grain (151-4) has a large 47Ti enrichment. This signature is not expected for nova nucleosynthesis. Thus, the new isotopic data raise the possibility that the grains previously reported to have formed in novae actually formed in supernovae, and that novae have not left a record in the presolar grain populations that have been so far studied. Moreover, the results in grain 334-2 indicate that supernovae contain regions highly enriched in both 13C and 15N. This is not predicted by current models but may bear on the cosmic origin of 15N.

This work was funded in part by NASA.

The author(s) of this abstract have provided an email address for comments about the abstract: lrn@dtm.ciw.edu

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Bulletin of the American Astronomical Society, 37 #2
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