Apparent Lithium Isotope Ratios in F5-G8 Main Sequence Stars.

Abstract

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Apparent Lithium Isotope Ratios in F5-G8 Main Sequence Stars. Herbig, G. H. Abstract The isotopic splitting of the N6707 resonance line of Li I between Li6 and Li7 is 0.16 A, or 7 km/sec. Although the line is somewhat more diffuse than lines of heavier elements (due to unresolved doublet structure and larger thermal broadening) in the spectra of Li-rich F5 to G8 dwarfs, the isotopic shift is well above the uncertainty of measurement (0.3 to 0.5 km/sec) on 120-inch coude' spectrograms of dispersion 4 A/mm. Since the structure of X6707 is intrinsically blended in these stars, this first attempt to evaluate the contribution of Li6 was based on its effect on the center of gravity of the Li7 line. The Li6/Li7 ratio determined in this way from visual settings on photographic spectrograms is here called the apparent isotope ratio because of the approximations implicit in this approach. The results for 14 bright stars show clearly that Li7 is the preponderant isotope in these objects (as in the sun, earth, and stone meteorites), but that there is evidence for apparent Li6/Li7 ratios near 0.3 in several stars. Publication: The Astronomical Journal Pub Date: 1964 DOI: 10.1086/109371 Bibcode: 1964AJ.....69Q.141H full text sources ADS |