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LITHIUM ABUNDANCES IN δ SCUTI STARS AND THEIR RELATIONSHIP WITH THE LITHIUM DIP

机译:δ矮星中的锂丰度及其与锂倾角的关系

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摘要

Several years ago it was suggested that mass loss from δ Scuti stars may transform them into the lithium "dip" stars seen in open clusters like Coma Berenices and the Hyades. Although there is evidence to indicate that this is unlikely, there has never been a study made of the lithium abundances in δ Scuti stars themselves. This paper reports the results of a survey of lithium in these stars. Lithium was detected in about half of the stars studied, with only upper limits being determined for the others. For those stars with measurable lithium there is evidence for a moderate depletion at the cooler temperatures. For those stars with no measurable lithium, the upper limits are consistent with only moderate depletion in all except one or two cases. There is no correlation between lithium depletion and a star's rotational velocity, mass, gravity, period of pulsation, or metallicity. There is, therefore, no support for the suggestion that mass loss on the main sequence due to δ Scuti pulsation may be responsible for the lithium dip stars. However, the data cannot exclude the possibility that mass loss may be responsible for a degree of lithium depletion in δ Scuti stars. Interestingly, though most elements are in solar ratio to iron, there is evidence for a pronounced carbon abundance deficiency in all of the stars with measurable carbon.
机译:几年前,有人提出δScuti恒星的质量损失可能会将它们转变成在像Coma Berenices和Hyades这样的开放星团中看到的锂“浸”星。尽管有证据表明这不太可能,但从未对δScuti恒星本身中的锂丰度进行过研究。本文报告了这些恒星中锂的调查结果。在大约一半被研究的恒星中都检测到了锂,仅对其他恒星确定了上限。对于那些锂含量可测量的恒星,有证据表明在较低温度下会适度消耗。对于那些没有可测量的锂的恒星,其上限与除一种或两种情况以外的所有其他条件中的仅中等消耗量一致。锂的消耗与恒星的旋转速度,质量,重力,脉动周期或金属性之间没有关联。因此,没有证据表明锂浸星会由于δScuti脉动而导致主序列质量损失。然而,数据不能排除质量损失可能是造成δScuti星中锂耗尽程度的原因。有趣的是,尽管大多数元素与铁的日光比率都很高,但有证据表明,所有含碳量可测量的恒星中都存在明显的碳丰度不足。

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