An eclipsing-binary distance to the Large Magellanic Cloud accurate to two per cent

摘要

“食双星”体系中恒星的物理性质因两个天体rn之间的密切相互作用而可以被准确确定，而且rn通过监测来自这种体系的波动的光，有可能对rn银河系外的距离做出准确测量。这一方法现被rn用来确定对离我们最近的星系“大麦哲伦云”rn(LMC)的迄今最为准确的距离估计值。来自rn特别适合这种校准方法的8个长周期、晚期型rn(late-type)“食双星”体系的数据表明，LMCrn距我们在49．97千秒差距左右，这个数字的准rn确度为2．2％。LMC的距离在确定“哈勃常数”rn(宇宙膨胀速度的一个重要度量)中是一个关rn键要素。%In the era of precision cosmology, it is essential to determine the Hubble constant to an accuracy of three per cent or better. At present, its uncertainty is dominated by the uncertainty in the distance to the Large Magellanic Cloud (LMC), which, being our second-closest galaxy, serves as the best anchor point for the cosmic distance scale. Observations of eclipsing binaries offer a unique opportunity to measure stellar parameters and distances precisely and accurately. The eclipsing-binary method was previously applied to the LMC, but the accuracy of the distance results was lessened by the need to model the bright, early-type systems used in those studies. Here we report determinations of the distances to eight long-period, late-type eclipsing systems in the LMC, composed of cool, giant stars. For these systems, we can accurately measure both the linear and the angular sizes of their components and avoid the most important problems related to the hot, early-type systems. The LMC distance that we derive from these systems (49.97 ± 0.19 (statistical) ± 1.11 (systematic) kiloparsecs) is accurate to 2.2 per cent and provides a firm base for a 3-per-cent determination of the Hubble constant, with prospects for improvement to 2 per cent in the future.