Open cluster Haffner 18

Open stellar cluster Haffner 18, perfectly illustrating three different stages of this process of star formation : in the centre of the picture, Haffner 18, a group of mature stars that have already dispersed their birth nebulae, represents the completed product or immediate past of the star formation process. Located at the bottom left of this cluster, a very young star, just come into existence and, still surrounded by its birth cocoon of gas, provides insight into the very present of star birth. Finally, the dust clouds towards the right corner of the image are active stellar nurseries that will produce more new stars in the future. Haffner 18 contains about 50 stars, among which several short lived, massive ones. The massive star still surrounded by a small, dense shell of hydrogen, has the rather cryptic name of FM3060a. The shell is about 2.5 light-years wide and expands at a speed of 20 km/s. It must have been created some 40,000 years ago. The cluster is between 25,000 and 30,000 light-years away from us.