标题： 超新星环 revisited II: LMC 的距离 显示英文标题

标题： The Supernova Ring Revisited II: Distance to the LMC

摘要： 我得出超新星 1987A 的距离上限为$\dsn<46.77\pm 0.76\,\kpc$，或者距离模数为$\mu_\sn<18.350\pm 0.035$。 如果超新星 1987A 位于大麦哲伦云（LMC）的平面内，并且因此位于 LMC 中心前方 500 秒差距处，则这表明$\mu_\lmc<18.37\pm 0.04$。 该测定基于对电离辐射光曲线中焦散现象的新测量，分别为$t_-=75.0\pm 2.6\,$天和$t_+=390.0\pm 1.8\,$天。 该估计假设环是圆形的。 已证明此假设与现有数据一致，并且可以接受未来的精确检验。 此外，我之前已经表明，适度的非圆形性（偏心率$e<0.4$）对结果的影响为$<1\%$。 M31 的距离模数上限为$\mu_{\rm M31} < 24.43\pm 0.06$。 如果超新星-环状气体的响应函数是即时的，那么这些上限将成为等式。 显示英文摘要

摘要： I derive an upper limit to the distance to SN 1987A of $\dsn<46.77\pm 0.76\,\kpc$, or a distance modulus $\mu_\sn<18.350\pm 0.035$. If SN 1987A lies in the plane of the Large Magellanic Cloud (LMC) and hence 500 pc in front of the LMC center, this implies $\mu_\lmc<18.37\pm 0.04$. The determination rests on a new measurement of the caustics in the ionized-emission light curves of $t_-=75.0\pm 2.6\,$days and $t_+=390.0\pm 1.8\,$days. The estimate assumes that the ring is circular. This assumption is shown to be consistent with the available data and can be subjected to a future precise test. Moreover, I have previously shown that modest deviations from circularity (eccentricities $e<0.4$) affect the result by $<1\%$. The upper limit to the distance modulus to M31 is $\mu_{\rm M31} < 24.43\pm 0.06$. If the response function of the supernova-ring gas is prompt, then these upper limits become equalities.