ChandraHigh‐Resolution X‐Ray Spectrum of Supernova Remnant 1E 0102.2−7219

Abstract

Chandra High Energy Transmission Grating Spectrometer observations of the supernova remnant (SNR) 1E 0102.2-7219 in the Small Magellanic Cloud reveal a spectrum dominated by X-ray emission lines from hydrogen-like and helium-like ions of oxygen, neon, magnesium, and silicon, with little iron. The dispersed spectrum shows a series of monochromatic images of the source in the light of individual spectral lines. Detailed examination of these dispersed images reveals Doppler shifts within the SNR, indicating bulk matter velocities on the order of 1000 km s-1. These bulk velocities suggest an expanding ringlike structure with additional substructure, inclined to the line of sight. A two-dimensional spatial/velocity map of the SNR shows a striking spatial separation of redshifted and blueshifted regions and indicates a need for further investigation before an adequate three-dimensional model can be found. The radii of the ringlike images of the dispersed spectrum vary with ionization stage, supporting an interpretation of progressive ionization due to passage of the reverse shock through the ejecta. Plasma diagnostics with individual emission lines of oxygen are consistent with an ionizing plasma in the low-density limit and provide temperature and ionization constraints on the plasma. Assuming a pure metal plasma, the mass of oxygen is estimated at ~6 M☉, consistent with a massive progenitor.