Serendipitous Chandra X-ray Detection of a Hot Bubble within the Planetary Nebula NGC 5315

TL;DR

This paper reports the serendipitous detection of a hot X-ray emitting bubble within the planetary nebula NGC 5315, highlighting the characteristics and implications of hot bubbles in young planetary nebulae with Wolf-Rayet central stars.

Contribution

It presents the first detailed X-ray analysis of NGC 5315, demonstrating that hot bubbles are common in young PNe with WR stars and exploring the physical processes governing their properties.

Findings

NGC 5315 hosts a hot plasma with T_X ~ 2.5 million K.

The nebula's X-ray luminosity is among the highest for PNe.

Hot bubbles are characteristic of young PNe with large stellar wind energies.

Abstract

We report the serendipitous detection of the planetary nebula NGC 5315 by the Chandra X-ray Observatory. The Chandra imaging spectroscopy results indicate that the X-rays from this PN, which harbors a Wolf-Rayet (WR) central star, emanate from a T_X ~ 2.5x10^6 K plasma generated via the same wind-wind collisions that have cleared a compact (~8000 AU radius) central cavity within the nebula. The inferred X-ray luminosity of NGC 5315 is ~2.5x10^{32} erg s^{-1} (0.3-2.0 keV), placing this object among the most luminous such ``hot bubble'' X-ray sources yet detected within PNe. With the X-ray detection of NGC 5315, objects with WR-type central stars now constitute a clear majority of known examples of diffuse X-ray sources among PNe; all such ``hot bubble'' PN X-ray sources display well-defined, quasi-continuous optical rims. We therefore assert that X-ray-luminous hot bubbles are characteristic of young PNe with large central star wind kinetic energies and closed bubble morphologies. However, the evidence at hand also suggests that processes such as wind and bubble temporal evolution, as well as heat conduction and/or mixing of hot bubble and nebular gas, ultimately govern the luminosity and temperature of superheated plasma within PNe.