X-ray observations of the nova shell IPHASX J210204.7+471015

TL;DR

This paper analyzes XMM-Newton X-ray observations of the nova shell IPHASX J210204.7+471015, revealing properties of the progenitor binary star, its X-ray emission, and potential white dwarf spin and orbital periods, with implications for nova explosion models.

Contribution

First detailed X-ray analysis of this nova shell, identifying binary star properties and challenging symmetric explosion assumptions.

Findings

Detected X-ray emission consistent with underluminous intermediate polars.

Identified two periodicities likely related to white dwarf spin and binary orbit.

No extended X-ray emission observed, possibly due to age or asymmetric explosion morphology.

Abstract

We present the analysis of XMM-Newton European Photon Imaging Camera (EPIC) observations of the nova shell IPHASX J210204.7$+$471015. We detect X-ray emission from the progenitor binary star with properties that resemble those of underluminous intermediate polars such as DQ Her: an X-ray-emitting plasma with temperature of $T_\mathrm{X}=(6.4\pm3.1)\times10^{6}$ K, a non-thermal X-ray component, and an estimated X-ray luminosity of $L_\mathrm{X}=10^{30}$ erg s$^{-1}$. Time series analyses unveil the presence of two periods, the dominant with a period of $2.9\pm0.2$ hr, which might be attributed to the spin of the white dwarf, and a secondary of $4.5\pm0.6$ hr that is in line with the orbital period of the binary system derived from optical observations. We do not detect extended X-ray emission as in other nova shells probably due to its relatively old age (130-170 yr) or to its asymmetric disrupted morphology which is suggestive of explosion scenarios different to the symmetric ones assumed in available numerical simulations of nova explosions.