|Description of object:
The open star cluster NGC 4755 in the constellation Crux (Southern
Cross), is one of the most beautiful star clusters on the sky. The brightest
stars in the cluster are blue super giants, which shine a 1000 times brighter
than our sun. The highlight of the cluster is a single red super giant, which
likely caused Sir John Herschel to call this cluster "a box of differently
colored precious stones".
NGC 4755 has a distance of
7000 light years. The brightest stars are located in a spatial volume of 25
light years diameter, which is equivalent to 10 arc minutes in the sky. This
star cluster is roughly 10 million years old and therefore one of the youngest
open star clusters. The area on the picture is roughly equivalent to the size
of the moon.