The Pleiades have for long been the astronomers' favourite cluster for honing their theories, but Hipparcos now reveals that the stars of the Pleiades are far from typical. The results are puzzling. On the other hand Hipparcos brings the Pleiades substantially nearer than astronomers had supposed them to be, and as a result the stars are less luminous than they should be according to previous theories. As leader of the Input Catalogue Consortium she has been an outstanding figure in the Hipparcos mission, and is now well-placed to judge where the early results may be leading. Another and more intriguing possibility is that the Pleiades, and perhaps some other star clusters, represent a zone of the Galaxy which is chemically different from most of the disk, and younger in an evolutionary sense.
Astronomers speculate that the dust nearer to the star has been largely consumed in making planets.
By fixing the distance of Beta Pictoris at a much more reliable figure of 63 light-years, the Hipparcos correction sharpens astronomers' knowledge of the star and its dust. The dust-ring is almost 20 per cent wider than they previously supposed. Technical uncertainties about the character of the star and the density of the dust are eliminated. But the star is no infant and may be up to 100 million years old. That aspect of the results lends support to the idea that, if Beta Pictoris is a planet-making star, its work may be largely complete.