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 Halpha 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(-1), similar to what has been seen in other Balmer-dominated remnants. Of the remnants in our sample, SN 1006 is the fastest shock (similar to3000 km s(-1)). The narrow component Halpha and Hbeta lines in this remnant have a FWHM of merely 21 km s(-1). 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.