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首页> 外文期刊>The Astrophysical journal >RAPID ROTATION OF ULTRA-Li-DEPLETED HALO STARS AND THEIR ASSOCIATION WITH BLUE STRAGGLERS
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RAPID ROTATION OF ULTRA-Li-DEPLETED HALO STARS AND THEIR ASSOCIATION WITH BLUE STRAGGLERS

机译：贫锂晕星的快速旋转及其与蓝散光的联系

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摘要

Observations of 18 halo main-sequence turnoff stars, four of which are extremely deficient in Li, show that three of the Li-poor ones have substantial line broadening. We attribute this to stellar rotation. Despite the great ages of halo stars, for G202-65, BD +51°1817, and Wolf 550 we infer v sin i = 8.3 +- 0.4, 7.6 +- 0.3, and 5.5 +- 0.6 km s~(-1), respectively. The stated errors are 3σ. For CD -31°19466 we derive a 3σ upper limit v sin i < 2.2 km s~(-1). The three rotating stars are known spectroscopic binaries. We explain the high rotation velocities in terms of mass,and angular momentum transfer onto the surface of the turnoff star from an initially more massive donor. Estimates of the specific angular momentum of accreted material indicate that quite small transfer masses could have been involved, although the unknown subsequent spin-down of the accretor prevents us from assigning definitive values for each star. The accretor is now seen as an ultra-Li-deficient star whose origin makes it a low-mass counterpart of field blue stragglers. The Li could have been destroyed before or during the mass transfer episode. Such objects must be avoided in studies of the primordial Li abundance and in investigations into the way normal single stars process their initial Li.
机译：观测到18个晕圈主序熄灭恒星，其中4个极度缺乏锂，这表明贫锂的3个恒星线变宽。我们将其归因于恒星旋转。尽管光晕星的年龄很长，但对于G202-65，BD + 51°1817和Wolf 550，我们推断v sin i = 8.3 +-0.4、7.6 +-0.3和5.5 +-0.6 km s〜（-1） ， 分别。规定的误差为3σ。对于CD -31°19466，我们得出3σ上限v sin i <2.2 km s〜（-1）。三颗旋转的恒星是已知的光谱双星。我们从质量上解释了高自转速度，并且角动量从最初更大的供体转移到了熄火星表面。吸积物质的特定角动量的估计表明，可能涉及到很小的传递质量，尽管随后未知的吸积体的下旋使我们无法为每颗恒星指定确定的值。现在，该累累星被视为一颗超锂不足的恒星，其起源使其成为野外蓝散流星的低质量对应物。黎族可能在大规模入侵事件发生之前或之中被摧毁。在研究原始Li丰度和研究正常单颗星处理其初始Li的方式时，必须避免此类物体。

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