A carbon-rich hot bubble in the planetary nebula NGC 5189

TL;DR

This paper reports the discovery of extended, carbon-rich X-ray emission in the planetary nebula NGC 5189, revealing insights into its composition, temperature, and the born-again evolutionary scenario of its central star.

Contribution

It provides the first detailed X-ray spectral analysis of NGC 5189, showing high carbon and neon abundances and supporting the born-again scenario for its evolution.

Findings

X-ray emission is dominated by C VI Lyα line at 0.37 keV.

Carbon and neon abundances are 38 and 6 times solar.

Plasma temperature is approximately 1.6 million Kelvin.

Abstract

We present the discovery of extended X-ray emission from the planetary nebula (PN) NGC 5189 around the [WO1]-type WD 1330-657 with XMM-Newton. The X-ray-emitting gas fills the cavities detected in the Hubble Space Telescope [O III] narrow-band image and presents a limb-brightened morphology towards the outer edges of the east and west lobes. The bulk of the X-ray emission is detected in the soft (0.3 - 0.7 keV) band with the XMM-Newton EPIC spectra dominated by the C VI Ly$\alpha$ line at 0.37 keV (=33.7 \AA). Spectral analysis resulted in carbon and neon abundances 38 and 6 times their solar values, with a plasma temperature of $kT=0.14\pm0.01$ keV ($T=1.6\times10^{6}$ K) and X-ray luminosity of $L_\mathrm{X}=(2.8\pm0.8)\times10^{32}$ erg s$^{-1}$. NGC 5189 is an evolved and extended PN ($\lesssim$0.70 pc in radius), thus, we suggest that the origin of its X-ray emission is consistent with the born-again scenario in which the central star becomes carbon-rich through an eruptive very late thermal pulse, subsequently developing a fast, carbon-rich wind powering the X-ray emission as suggested for A30 and A78.