NGC 3766 is a highly
concentrated open star cluster in the constellation Centaurus. The apparent
magnitude is 5.3 magnitudes, the apparent diameter is 12 arc minutes. In
amateur telescopes about 100 stars between 8th and 13th magnitude become
visible. The distance to the solar system is about 5,700 light years. The stars
in the cluster are extremely young, estimated to be only 20 million years old.
According to Trumpler, the star cluster is assigned to class I 1 p. It was
discovered in 1751 by Nicolas Louis de Lacaille.
In recent years, nearly 3,000 stars of the cluster
have been observed with the highest precision over a period of 7 years by a
team of astronomers from the Swiss Observatoire de Genève. In the
process a new class of variable stars was discovered.
There are 36 of the stars in the cluster that followed an unexpected
pattern. They show a small but regular brightness variation in the order of
0.1% of the stars' normal brightness. These fluctuations have periods of
between about two to 20 hours. The stars are slightly hotter and brighter than
the Sun, but otherwise do not appear to be very noticeable. This new class of
variable stars has not yet been given a name.