We have determined the oxygen abundance of HE 0107-5240 from UV-OH lines detected in VLT/UVES spectra. Using a plane-parallel LTE model atmosphere, we derive [O/Fe] = +2.3, and a similar analysis of CD -38°245 yields [O/Fe] = +0.9. We estimate systematic errors due to three-dimensional effects to be on the order of 0.3-0.4 dex. That is, our derived O abundances are likely overestimates: effects from thermal inhomogeneities due to convection may require that the abundances should be reduced by 0.3-0.4 dex or even more. Radial velocity data for HE 0107-5240 based on high-resolution spectra show that over a time span of 373 days, the radial velocity was constant at 44.5 km s~(-1), with a 1 σ scatter of the measurements of 0.5 km s~(-1). However, it cannot yet he ruled out that HE 0107—5240 is a very long period and/or low amplitude binary. These results provide new constraints on scenarios for the origin of the abundance pattern of HE 0107-5240. In particular, it seems unlikely that the large overabundances of CNO have been produced in a medium-mass asymptotic giant branch star that later evolved into a white dwarf. The oxygen abundance of HE 0107-5240 is significantly smaller than the prediction of Umeda & Nomoto from calculated yields of an ～25 solar mass Population Ⅲ star exploding as a supernova of low explosion energy (E_(exp) = 3 x 10~(50) ergs) with mixing and fallback. The scenario of Limongi et al., involving two Population Ⅲ supernovae, predicts an oxygen abundance of [O/Fe] = +4.1 for HE 0107—5240, in strong contradiction to the observed value. In conclusion, none of the above-mentioned scenarios, in their present realizations, can satisfactorily explain the abundance pattern of HE 0107-5240.
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机译：我们已经从在VLT / UVES光谱中检测到的UV-OH线确定了HE 0107-5240的氧丰度。使用平面平行LTE模型大气，我们得出[O / Fe] = +2.3，对CD -38°245的相似分析得出[O / Fe] = +0.9。我们估计由于三维效应而导致的系统误差约为0.3-0.4 dex。就是说，我们得出的O丰度可能被高估了：由于对流引起的热不均匀性的影响可能要求将丰度降低0.3-0.4 dex甚至更多。基于高分辨率光谱的HE 0107-5240的径向速度数据显示，在373天的时间跨度内，径向速度恒定在44.5 km s〜（-1），测量值的1σ散射为0.5 km s〜（-1）。但是，他还不能排除HE 0107-5240是一个很长的周期和/或低振幅的二进制文件。这些结果为HE 0107-5240的丰度模式的起源提供了新的场景约束。特别是，似乎不太可能在中等质量的渐近巨型分支恒星中产生大量的CNO，该恒星后来演变成白矮星。 HE 0107-5240的氧丰度显着小于Umeda和Nomoto的预测值，该值是通过计算〜25太阳质量Ⅲ类恒星作为低爆炸能量的超新星爆炸而产生的（E_（exp）= 3 x 10〜（50 ）ergs）以及混合和后备广告。 Limongi等人的情景涉及两个Ⅲ类超新星，它预测HE 0107-5240的氧丰度[O / Fe] = +4.1，与观测值强烈矛盾。综上所述，在目前的情况下，上述方案均无法令人满意地解释HE 0107-5240的丰度模式。
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