X-Ray Spectroscopy of the Classical Nova V458 Vulpeculae with Suzaku

TL;DR

This study presents Suzaku X-ray observations of nova V458 Vulpeculae, revealing hard X-ray emission from ejecta shocks, with spectral analysis indicating an ONe-type nova origin and elemental abundance anomalies.

Contribution

First detailed Suzaku X-ray spectral analysis of V458 Vulpeculae, identifying shock emission and elemental abundance patterns indicative of an ONe-type nova.

Findings

Detected hard X-ray emission 88 days post-explosion.

Spectral analysis shows a 0.64 keV thermal plasma with specific elemental features.

Evidence suggests ejecta shocks from an ONe-type nova.

Abstract

We conducted a target of opportunity X-ray observation of the classical nova V458 Vulpeculae 88 days after the explosion using the Suzaku satellite. With a 20 ks exposure, the X-ray Imaging Spectrometer detected X-ray emission significantly harder than typical super-soft source emission. The X-ray spectrum shows K lines from N, Ne, Mg, Si, and S, and L-series emission from Fe in highly ionized states. The spectrum can be described by a single temperature (0.64 keV) thin thermal plasma model in collisional equilibrium with a hydrogen-equivalent extinction column density of ~3e21/cm2, a flux of ~1e-12 erg/s/cm2, and a luminosity of ~6e34 erg/s in the 0.3-3.0 keV band at an assumed distance of 13 kpc. We found a hint of an enhancement of N and deficiencies of O and Fe relative to other metals. The observed X-ray properties can be interpreted as the emission arising from shocks of ejecta from an ONe-type nova.