The Planetary Nebula in the 500 Myr Old Open Cluster M37

Abstract

Abstract We report confirmation of a large, evolved, bipolar planetary nebula and its blue, white dwarf central star as a member of the ∼500 Myr old Galactic open star cluster M37 (NGC 2099). This is only the third known example of a planetary nebula in a Galactic open cluster and was found via our ongoing program of identifying and studying planetary nebulae—open cluster associations. High confidence in the association comes from the consistent radial velocities and proper motions for the confirmed central star and cluster stars from Gaia, reddening agreement, and location of the planetary nebula well within the tidal cluster boundary. Interestingly, all three Galactic examples have bipolar morphology and likely Type-I chemistry, both characteristics of higher mass progenitors. In this case the progenitor star mass is in the midrange of ∼2.8 M ☉. It provides a valuable, additional point on the key stellar initial-to-final mass relation independent of cluster white dwarf estimates and also falls in a gap in the poorly sampled mass region. This planetary nebula also appears to have the largest kinematical age ever determined and implies increased visibility lifetimes when they are located in clusters.