Resolving the Pleiades Distance Problem
The Pleiades are an impressive sight with
any or no optical aid. Photo: Akira Fujii.
any or no optical aid. Photo: Akira Fujii.
AnnOpen star clusters like the Pleiades and Hyades are perfect proving grounds for models of stellar evolution because their stars all have the same age and composition yet exhibit a wide range of masses. But for these models to work, it's critical that astronomers know the clusters' distances precisely.
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As detailed in a pair of articles here and here, ground-based methods had consistently shown that the Pleiades lie about 435 light-years (133 parsecs) away. However, according to Hipparcos, the cluster has a distance of just 392 light-years (120.2 parsecs), supposedly with an error of less than 1%.
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Now Carl Melis (University of California, San Diego) and others have seemingly put the matter to rest. In the August 29th issue of Science, they report distance results derived with a different and powerful method: very-long-baseline radio interferometry. They have seemingly nailed the distance at 444.0 light-years (136.2 parsecs), likewise accurate to within 1%.
