Astronomy and Astrophysics – Astrophysics
Scientific paper
Jun 1994
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994apj...428l..25h&link_type=abstract
The Astrophysical Journal, vol. 428, no. 1, pt. 1, p. L25-L28
Astronomy and Astrophysics
Astrophysics
102
Dwarf Stars, Galactic Halos, Lithium Isotopes, Metallicity, Star Formation, Abundance, Astronomical Photometry, Cosmic Rays, Echelle Gratings
Scientific paper
Echelle spectra of six halo stars with -2.9 less than or equal to (Fe/H) less than or equal to -1.4 and Te approximately greater than 5650 K were recorded in the region of the Li I lambda 6707 line, at S/N ratios 230 less than or equal to S/N less than or equal to 500 and a resolving power of 120,000. Similar spectra were also obtained at the Ca I lambda 6162 line, in order to determine the various contributions to the stellar line widths. Theoretical Li I line profiles were then calculated for several Li-6/Li-7 ratios and were compared to the observed profiles. The lighter isotope is detected in HD 201891 and HD 84937, at abundance ratios Li-6/Li-7 = 0.05 plus or minus 0.02 and 0.07 plus or minus 0.03, respectively. Upper limits on Li-6/Li-7 ranging from less than or equal to 0.03 to less than or equal to 0.10 are found for BD + 3 deg 740, BD + 26 deg 3578, HD 19445, and HD 140283. Our results for HD 84937 and HD 19445 agree with those of Smith, Lambert, & Nissen. The observed Li-6 fractions are discussed in terms of stellar evolutionary models and the primordial lithium abundance.
Hobbs Lew M.
Thorburn Julie A.
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