Chuan-Jui Li 李傳睿 (ASIAA), You-Hua Chu 朱有花 (ASIAA)
Supernova remnants (SNRs) are commonly identified by diffuse X-ray emission, nonthermal radio emission, and strong [S II] λλ6716, 6731 lines, which are characteristics produced by high-velocity shocks. However, some SNRs exhibit optical spectra that are dominated by hydrogen Balmer lines with no or very weak forbidden lines. Such “Balmer-dominated” spectra can be explained by collisionless shocks advancing into a partially neutral medium. Surprisingly, in some Balmer-dominated Type Ia SNRs, forbidden line emission is detected at a significant level. In the cases of Kepler and N103B, bright forbidden-line emission is detected from dense knots in a circumstellar medium (CSM) ejected by the SN progenitor before its explosion, indicating that the progenitor white dwarf must have accreted material from a normal star companion. In this poster, we have used Hubble Space Telescope (HST) Hα images to examine the shell structure and to search for dense nebular knots within five LMC Balmer-dominated Type Ia SNRs: 0509−67.5, 0519−69.0, N103B, DEM L71, and 0548−70.4. We have also used the VLT MUSE and ATT WiFeS observations of these five SNRs to extract continuum-subtracted line images. These superb imaging and spectroscopic data make it possible to discover faint forbidden line emission and resolve dense knots. We discuss the implication of the results on the nature of the SN progenitors and the evolutionary status of the SNRs.