Hipparcos后的昴星团距离

Post-Hipparcos Distance of the Pleiades Cluster

详细介绍了Hipparcos测定的昴星团距离与以往地面测定结果比较所出现的差异、近年来对昴星团距离新的测定和对Hipparcos数据作的重新处理以及对造成不一致的原因所进行的探讨，最后对有关进展加以评述。

An unexpected discrepancy is exhibited in comparison between the distances of the Pleiades cluster obtained from the Hipparcos data and previous ground-based data. In recent years, new distance determinations for the cluster were discussed with various methods by a number of authors. A re-process for the Hipparcos raw data is performed on a set of software by Dr. Floor van Leeuwen. In view of these progresses, some comments would be found. In a Hertzsprung-Russel diagram of nearby open clusters on the old Hipparcos distances, the main sequence of some young clusters, represented by the Pleiades, locates 0.5 mag fainter than that of the other old clusters. This may be, at least for the Pleiades, due to two facts： （1） the Hipparcos-based parallax of the cluster could be about 1 mas larger than the true value, which could reduce its distance module about 0.3 mag; （2） the abundance of young flare stars with the violent chromospherical activity in the cluster could induce the faint mean sequence stars with Mv 〉 6 mag to shift towards the bluer side which has a displacement down to about 0.2 mag.