High Resolution Spectroscopy of Balmer - Dominated Shocks in the RCW 86 , Kepler and SN 1006 Supernova Remnants ⋆

We report results from high resolution optical spectroscopy of three non-radiative galactic supernova remnants, RCW 86, Kepler’s supernova remnant and SN 1006. We have measured the narrow component Hα line widths in Balmer-dominated filaments in RCW 86 and SN 1006, as well as the narrow component width in a Balmer-dominated knot in Kepler’s SNR. The narrow component line widths measured in RCW 86 and Kepler’s SNR show FWHM of 30 − 40 km s, similar to what has been seen in other Balmer-dominated remnants. Of the remnants in our sample, SN 1006 is the fastest shock (∼3000 km s). The narrow component Hα and Hβ lines in this remnant have a FWHM of merely 21 km s. Comparing the narrow component widths measured in our sample with those measured in other remnants shows that the width of the narrow component does not correlate in a simple way with the shock velocity. The implications for the pre-heating mechanism responsible for the observed line widths are discussed.