RECENT X-RAY OBSERVATIONS OF SN 1986J WITH ASCA AND ROSAT

We present ASCA and ROSAT observations of SN 1986J covering the period 1991 August to 1996 January. From observations with the ROSAT HRI and PSPC, we find that the 0.5-2.5 keV flux decreased proportional to t(- 2) during this period; the ASCA data are consistent with this result a nd extend it to the 2-10 keV band. ASCA spectra from 1994 January and 1996 January are consistent with thermal emission from a solar metalli city plasma at an equilibrium temperature kT = 5-7.5 keV, somewhat hot ter than that observed from other X-ray supernovae. These spectra also show a clear Fe K emission line at 6.7 keV with FWHM < 20,000 km s(-1 ) (90% confidence). This limit on the line width is consistent with th e reverse shock model of Chevalier & Fransson but does not rule out th e clumpy wind model of Chugai.