Published in: AJ, 106, 1566
We have reobserved the remnant of SN 1006 AD with the VLA at 1370 and 1665 MHz. We compare the resulting images with those reconstructed from observations made in 1983-1984 by Reynolds and Gilmore and find that expansion has occurred in the 8 intervening years. The mean expansion in this period is 3.5 +/- 1 arcsec, implying an expansion rate of 0.049 percent/yr, or R varying as t exp 0.48 +/- 0.13, consistent with Sedov expansion, or with a forward/reverse shock pair moving into constant-density material. There is some evidence that the expansion rate is not uniform around the shell, being slightly smaller in the southwest quadrant. Our mean value, based on the remnant periphery as a whole, is somewhat higher than that found for an optical filament in the NW quadrant by Long et al. (1988). Our value is marginally consistent with a prediction of an expansion rate, R varies as t exp 0.60, by Hamilton et al. (1986) based on fitting the X-ray data. We discuss the significance of these observations for the dynamics of young SNRs.