Physical and chemical inhomogeneities inside the Vela SNR shell. Indications of ejecta shrapnels

TL;DR

This study uses high-resolution X-ray observations to reveal significant chemical inhomogeneities and potential ejecta shrapnels within the Vela supernova remnant, indicating complex plasma composition and structure.

Contribution

It provides detailed spatially resolved analysis of plasma properties and identifies possible stellar fragment remnants inside the Vela SNR.

Findings

Large variations in O, Ne, Mg, and Fe abundances

Detection of bright knots with enhanced Ne and Mg

Evidence supporting the presence of ejecta shrapnels

Abstract

We present the results of the combined analysis of three XMM-Newton EPIC observations of the northern rim of the Vela SNR. The three pointings cover an area of ~10 pc^2 (at 250 pc) behind the main shock front and we aim at studying with high resolution the spatial distribution of the physical and chemical properties of the X-ray emitting plasma on this large scale. We produce count-rate images and equivalent width maps of the Ne IX and Mg XI emission blends. We also perform a spatially resolved spectral analysis of a set of physically homogeneous regions. We reveal physical and chemical inhomogeneities in the X-ray emitting plasma. In particular, we find large variations of the O, Ne, Mg, and Fe abundances. In some bright knots we also find unexpectedly enhanced Ne and Mg abundances, with values significantly larger than solar. Our results support a possible association of a few X-ray emitting knots with previously undetected residuals of stellar fragments (i. e. shrapnels) observed, in projection, inside the Vela shell.