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 88d after the explosion using the Suzaku satellite. With a ∼20ks 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 ×10²¹cm^-2, a flux of ∼10^-12erg s^-1cm^-2, and a luminosity of ∼6 × 10³⁴erg s^-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.