We derive lithium abundances for a sample of 25 late F to early G dwarfs in the direction of the Orion association from spectra obtained with the McDonald Observatory's 2.1 m telescope plus a Cassegrain crossdispersed echelle spectrometer at a spectral resolution of 60,000. Iron abundances are also derived for the slowly rotating stars. A kinematical discussion, combined with information on rotation and X-ray emission for the stars, led us to conclude that 10 stars in our sample are members of the Ic and Id subgroups of Orion, while two are probable members of the Ib subgroup, with the remaining stars being field stars in the direction of Orion. The Li abundances obtained for the seven members of the Ic subgroup with v sin i > 20 km s~(-1) show a small scatter, comparable to our uncertainties in the abundance determinations themselves. The mean non-LTE Li abundance for the rapidly rotating Ic members is log ε(Li) = 3.2 ± 0.1—very close to the solar system meteoritic value of 3.3. If the Orion interstellar gas is representative of local Galactic gas, there is apparently little evidence of an increase in the Li abundance over the last 5 Gyr.
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机译：我们从麦当劳天文台的2.1 m望远镜和卡塞格伦交叉分散的埃谢尔光谱仪以60,000的光谱分辨率获得的光谱中，得出了Orion关联方向上25个F晚期至G早期侏儒样品中锂的丰度。缓慢旋转的恒星也具有铁丰度。运动学的讨论，结合有关恒星自转和X射线发射的信息，使我们得出结论，样本中的10个恒星是猎户座Ic和Id子组的成员，而两个可能是Ib子组的可能的成员，其余的恒星是猎户座方向的野外恒星。对于v sin i> 20 km s〜（-1）的Ic子组的七个成员，其Li丰度表现出较小的分散性，与丰度确定本身的不确定性相当。快速旋转的Ic成员的平均非LTE Li丰度为logε（Li）= 3.2±0.1，非常接近太阳系的气象值3.3。如果猎户座星际气体代表局部银河气体，则几乎没有证据表明最近5个Gyr中锂的丰度增加。
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