X-ray spectroscopy of the classical nova V458 Vulpeculae with Suzaku

Abstract

We conducted a target of opportunity X-ray observation of the classical nova V458 Vulpeculae 88 d 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 Kα 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 (̃0.64keV) thin thermal plasma model in collisional equilibrium with a hydrogen-equivalent extinction column density of ̃3 × 10 21cm-2, a flux of ̃ 10-12ergs -1cm-2, and a luminosity of ̃6 × 10 34ergs-1 in the 0.3-3.0keV 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. © 2009 Astronomical Society of Japan.