Open cluster M46 and planetary nebula NGC 2438
author: R.Gendler/Novapix
reference: a-aou24-37003
Image Size 300 DPI: 36 * 32 cm
M46 (NGC 2437) is a rich open star cluster in the constellation Puppis. Within a diameter of 28 arc minutes, or about 30 light-years at its distance of 5400 light-years, M46 contains over 150 bright stars and a total population perhaps over 500. M46 is probably around 300 million years old. It is also noteworthy for the presence of the planetary nebula NGC 2438 on its northern edge (right of center). NGC 2438 is almost certainly not physically associated with M46 due to is probable evolutionary history, its significantly diffferent velocity, and a distance estimate only a little more than half the distance to M46.