标题： 从sosie星系和HIPPARCOS几何校准中的哈勃常数 显示英文标题

标题： Hubble constant from sosie galaxies and HIPPARCOS geometrical calibration

摘要： 基于HIPPARCOS卫星提供的造父变星周期-光度关系的几何零点，得到了比以前更大的M 31和M 81的距离。通过将它们与独立测定的结果相结合，我们确定了这些重要校准星系的距离合理范围。在此基础上，我们通过相似星系（look-alike galaxies）的方法确定了哈勃常数，这些星系具有与校准器相同的特征。该方法非常可靠，因为它完全是差分的，并且不依赖于任何假设（除了两个相似星系具有相似的绝对光度这一自然假设）。然而，必须考虑马尔奎斯特偏差。观测结果完全符合该偏差的解析公式预测的行为。因此，排除受马尔奎斯特偏差影响的星系后，我们推导出哈勃常数： H_o = 60 +- 10 (external) km.s^{-1}.Mpc^{-1}如果我们严格使用HIPPARCOS获得的校准，并且考虑周期-光度关系中发现的偏差，则哈勃常数小于这个值（$\approx 55 km.s^{-1}.Mpc^{-1}$）。这为长距离尺度提供了支持。我们简要讨论了可能的改进措施，旨在进一步减少不确定性。 显示英文摘要

摘要： New distances, larger than previous ones, have been obtained for M 31 and M 81 based on the geometrical zero-point of the Cepheid Period-luminosity relation provided by the HIPPARCOS satellite. By combining them with independent determinations we define reasonable ranges for the distances of these important calibrating galaxies. On this basis, we determine the Hubble constant from the method of sosies (look-alike) galaxies, galaxies having the same characteristics than the calibrators. The method is quite secure because it is purely differential and it does not depend on any assumption (apart from the natural one that two sosies galaxies have similar absolute luminosities). Nevertheless, the Malmquist bias has to be taken into account. The observations behave exactly as predicted from the analytical formulation of the bias. Thus, rejecting galaxies which are affected by the Malmquist bias we derive the Hubble constant: H_o = 60 +- 10 (external) km.s^{-1}.Mpc^{-1} If we strictly use the calibration obtained with HIPPARCOS and if the bias found in the Period-Luminosity Relation is considered, the Hubble constant is smaller than this ($\approx 55 km.s^{-1}.Mpc^{-1}$). This gives arguments in favour of the long-distance scale. We briefly discuss possible improvements aiming at still reducing the uncertainty.