PHR~J1724-3859: A Bipolar Planetary Nebula in Open Cluster Trumpler 25

TL;DR

This study reports the discovery and analysis of a planetary nebula in open cluster Trumpler 25, providing insights into stellar evolution, progenitor mass, and nebular properties through spectral and photometric data.

Contribution

It adds a new confirmed OC-PN pair, detailed characterization of the CSPN and nebula, and supports trends in progenitor and final star masses relevant to stellar evolution models.

Findings

The PN is likely associated with Trumpler 25 based on velocity and distance.

The CSPN has an effective temperature of around 250,000 K.

The nebular age is approximately 23,000 years.

Abstract

Planetary nebulae (PNe) studies are essential for understanding late stellar evolution of low-to-intermediate mass stars. PNe in open clusters (OC) are rare but valuable since their study directly links their properties to those of their progenitors, something that cannot be achieved for field PNe. Here, we report the identification of one more OC-PN association to add to the small sample of, now, five pairs. The physical properties of the host cluster, PN and its central star (CSPN) have been explored using high and intermediate-resolution spectral and deep photometric data. The close agreement of the radial velocities of the PN and host cluster, together with concordance of reddening and distance, show that the PN PHR~J1724-3859 is highly likely to be physically associated with the OC Trumpler~25. Deep photometric data allowed clear identification of the CSPN. We find a CSPN effective temperature of around 250 kK and a nebular kinematic age of 23 kyrs, both at the extreme end, like the other members of this small class. The progenitor and final CSPN masses have been estimated to be 5.12$_{-0.15}^{+0.16}$ $M_\odot$ and 0.95$\pm$0.12 $M_\odot$ respectively. These latest results agree with the emerging trend for our other OC-PNe, falling below, but approximately parallel to, the latest initial-to-final-mass relation estimates derived from cluster white dwarfs and has important implications for stellar evolution models. All OC-PNe also possess some other common properties (e.g. all are Type-I PNe and bipolars) to be explored in future studies.