Astrometry of the Open Cluster M25

The young open star cluster M25 (IC 4725) is located in the direction of the galactic center, near much irregular absorption features on Sagittarius arm. This system is found to be at a distance of 600 pc, with a median age of 9.45 × 10⁷ years and a distance from the galactic plane of –52.82 pc The mass data available in the literature has been gathered and many statistical methods have been applied for this cluster. Depending only on these methods, the stellar density, the distribution of dark matter, the luminosity and the mass functions have been estimated. The center of the cluster has been defined, it is shifted by 45 arc sec in the northeast direction. The radius of the cluster is found to be 4 pc. More than 220 stars with mean reddening of 0.50 mag and absorption of 1.62mag are found inside this aria. The total mass of the cluster has been estimated with the mass of the interstellar matter (gas and dust). It is found to be 1937 M _⊙, whereas about 24% of the material mass of the cluster has remained as interstellar matter after the processes of formation. This revised version was published online in July 2006 with corrections to the Cover Date.