Bibcode
DOI
Mathieu, R. D.; Martin, E. L.; Lee, C. W.
Bibliographical reference
The Astronomical Journal, vol. 108, no. 4, p. 1445-1455
Advertised on:
10
1994
Citations
25
Refereed citations
23
Description
We present a study of the lithium abundance of five pre-main sequence
(PMS) double-lined binaries. These binaries are composed of weak-lined T
Tauri stars having spectral types ranging from K3 to K7. For each
binary, Lee (1992) has determined domains of spectral type and
luminosity for the binary componenets. Lithium abundances in Local
Thermodynamic Equilibrium (LTE) and non-LTE are then derived from the Li
I lambda 6707 resonance line. Considering the entire range of spectral
type and luminosity available to each binary component, we place an
upper limit on lithium abundance differences between binary components
of 1.0 dex. However, within the more limited range of spectral type and
luminosity where a binary's component have theoretical mass ratios
consistent with their dynamical mass ratios we find smaller abundance
differences. For such pairs of components the lithium abundance
differences are less than 0.4 dex for four of the binaries; for the
binary 162814-2427 the upper limit remains 1.0 dex. We conclude that for
each binary the components formed from similar material, and that the
formation and early evolution of the binaries did not alter their
relative lithium abundances. These results are also consistent with
previous suggestions that effective temperature uncertainties are the
origin of observed ranges of lithium abundances as large as 1 dex in
star-forming regions. The mean non-LTE lithium abundance of the five
binaries is log N(Li) = 3.1 +/- 0.4, very near the present cosmic
abundance, although we find a higher lithium abundance of 3.8 +/- 0.3
for the binary P1540.