NGC 6520 explained

NGC 6520
Appmag V:7.6
Age:178 Myr
Names:Cr 361, Mel 187

NGC 6520 is an open cluster of stars in the southern constellation of Sagittarius, about 4° to the east of the Galactic Center. With an apparent visual magnitude of 7.6 and an angular size of, it can be viewed with binoculars or a small telescope. Just to the west of this cluster is the dark nebula Barnard 86, dubbed the Ink Spot. Both features are viewed against the dense stary background of the Large Sagittarius Star Cloud. This cluster is located at a distance of approximately 1605disp=outNaNdisp=out from the Sun.

This is a young open cluster of stars with age estimates yielding a values of  million years. However, the presence of stars with a spectral class of B4 and B5 suggest a much younger age of 60 million years. The estimated mass of this cluster is . The cluster and the nearby dark nebula Barnard 86 have radial velocities that differ by, and hence may be unrelated.

Two type 2 chemically peculiar stars and two Lambda Bootis candidates have been found among the members. Polarization measurements of the cluster members suggests that there are three closer dust layers partially obscuring the view from the perspective of the Earth.