High Proper Motion Stars II - Hipparcos

High Proper Motion Stars: Interesting Areas

The Hyades (at RA=66.5, Dec=15.5): this is a cluster of stars at a distance of about 40 parsecs (about 150 light years). It is the nearest moderately rich star cluster, and at the limit of visibility of the naked eye. Try the animation first with the tails switched off, and see whether you can pick out the highest moving stars. Then switch the tails on, and let the animation run for a few thousand years. Already by the year 3000 AD you will see that half a dozen of the highest proper motion stars have moved significantly from their present positions. By the year 8000 AD or so, notice that the motions of most of the stars in this region are concentrated in the same direction. This is how the sky will really appear to our descendents in thousands of years from now! The brightest star, Aldebaran (HIP 21421) does not participate in this common motion - it is much closer to us than the rest of the Hyades members. By the year 20000 AD or so, you will start to see that the motions are showing "convergence" towards a particular point on the sky. This is a consequence of the geometry of the stars which move with a common motion through space. It is the basis of the methods used to estimate the distance of this important cluster from the ground before the Hipparcos parallaxes became available.

The Pleiades (at RA=56.7, Dec=24.2): this is another important cluster, at a distance of about 110 parcsecs. As the animation evolves, the high proper motion stars in this region show up quickly. Let the animation run for a few thousand years, with the tails on, and see again that the central cluster objects move with a common proper motion on the sky.

The following objects are the nine highest proper motion stars contained in the Hipparcos Catalogue (the 61 Cygni binary is seen at this resolution only as a single object).