NGC 1846 is about 1.7 billion years old. Its estimated mass is 5.7×104M☉, and its total luminosity is 1.68×105L☉, leading to a mass-to-luminosity ratio of 0.34 M☉/L☉.[2] All else equal, older star clusters have higher mass-to-luminosity ratios; that is, they have lower luminosities for the same mass.[2]
In an image taken by the Hubble Space Telescope in 2006 (see picture), astronomers spotted a green planetary nebula towards the bottom of the image. It is uncertain whether NGC 1846 contains this planetary nebula or if it just happened to be on the same line of sight; however, measurements of the motion of the cluster's stars along with the nebula's central star lead to the conclusion that it is a member of the cluster.[3]