The Origins of Boron
Abstract
The Orion OB1 association comprises four subgroups of differing ages. The youngest stars show higher oxygen abundances than the oldest stars. This enrichment has been shown to be due to contamination of the original gas in Orion by oxygen-rich ejecta from supernovae. Boron abundances will be derived from the B I 2497 Angstrom line in four lower-mass stars in the Orion association having different oxygen and lithium abundances. Two of the target stars have undepleted Li abundances, as determined by us based upon ground-based optical spectra, which indicates that the boron observed in these stars will be untouched by internal stellar astration, and will thus represent an unambiguous measurement of the current boron abundance in young Galactic gas. The target stars also exhibit a real variation in their oxygen abundances, such that a positive correlation of the boron and oxygen abundances will, if present, indicate that boron, as ^11B, is synthesized by the supernovae responsible for the oxygen abundances. The boron abundances derived from the HST spectra, in conjunction with oxygen, iron, and especially lithium abundances derived from the ground-based spectra, will yield our clearest look at the current behavior of boron in the Milky Way.
- Publication:
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HST Proposal
- Pub Date:
- July 1997
- Bibcode:
- 1997hst..prop.7748S