NGC 6193

NGC 6193 is an open cluster of 27 stars in the constellation of Ara. It is about 3,765 light-years away, and it can be seen by eye from Earth. 
NGC 6193 lies at the centre of the Ara OB1 association. The cluster radiates energy to the nearby regions of the nebulosity NGC 6188.
At its centre are two O class multiple star systems within 10" of each other, and a probable binary B0 giant. These are very hot large stars. They are part of the multiple star system HD 150136. There are four stars which are each 36 to 63 times more massive than the Sun, 6 to ten times hotter, and each is more than 10,000 times as bright (luminosity) as the Sun.