|Date:||25.1.00||Time:||20:16 UT||Exposure:||30 min|
|Field of View:||14.7o x 10.0o||Emulsion:||Kodak Royal Gold 400 Select||Filter:||none|
|Instrument:||f=135mm 1/2.8||Place:||Lichtenhagen||Observer:||T. Credner|
© Copyright by the observers
The Hyades play a quite major role in astrophysics.
The rich star cluster is so close that the distance can be measured
by geometrical methods, i.e. classical parallaxes of the individual
stars or the so called "convergent-point" method which gives a
distance to the cluster center. Getting this distance gives a
fundamental step of the distance ladder to our galaxy and even
further out to extragalactic objects.
Based on observations by the astrometric Hipparcos satellite trigonometric parallaxes to the individual stars could be measured with high accuracy. This parallax is the apparent annual motion of a star caused by our change of perspective when the earth orbits around the sun. The closer the star, the bigger is its parallax motion. The measurements yield a distance of 46.34 ± 0.27 pc to the clusters center.