M ay 2 00 1 Spectral Line Imaging Observations of 1 E 0102 . 2 - 7219

E0102-72 is the second brightest X-ray source in the Small Magellanic Cloud and the brightest supernova remnant in the SMC. We observed this SNR for ∼140 ksec with the High Energy Transmission Gratings (HETG) aboard the Chandra X-ray Observatory. The small angular size and high surface brightness make this an excellent target for HETG and we resolve the remnant into individual lines. We observe fluxes from several lines which include O VIII Lyα, Lyβ, and O VII along with several lines from Ne X, Ne IX and Mg XII. These line ratios provide powerful constraints on the electron temperature and the ionization age of the remnant. 1E0102.2-7219 (hereinafter E0102-72) is the brightest X-ray SNR in the Small Magellanic Cloud (SMC) and was discovered with the Einstein Observatory's IPC [1]. Higher resolution observations showed that this SNR exhibits a shell-like structure [2]. Optical emission from E0102-72 was detected revealing that this is an oxygen-rich SNR [3] and thus the result of the explosion of a massive progenitor. A moderate resolution CCD spectrum of this remnant was obtained with ASCA which observed this object for ∼35 ksec. The X-ray spectrum shows clear lines of oxygen, neon, and magnesium [4]. Hayashi et al. use the NEI modeling code of Hughes & Helfand [5] and find that the data require at least two NEI plasmas. The assumption that each observed element has an independent nt and temperature lead them to the conclusion that the elements are not well mixed. Hayashi et al. find the NEI parameters for oxygen are log(nt) = 10.31 s cm −3 and log(T) = 7.03 • K (0.93 keV) and those for Ne are log(nt)=11.37 s cm −3 and log(T) = 6.78 • K (0.52 keV). The fact that the neon has a lower temperature and higher nt relative to oxygen leads them to the conclusion that the oxygen emission is related to the forward shock and the neon to the reverse shock. Our analysis below assumes that the emission is from a single τ plasma model.