Recent X‐Ray Observations of SN 1986J withASCAandROSAT

We present ASCA and ROSAT observations of SN 1986J covering the period 1991August to 1996 January. From observations with the ROSAT HRI and PSPC, we findthat the 0.5-2.5 keV flux decreased proportional to $t^{-2}$ during thisperiod; the ASCA data are consistent with this result and extend it to the 2-10keV band. ASCA spectra from 1994 January and 1996 January are consistent withthermal emission from a solar metallicity plasma at an equilibrium temperaturekT = 5-7.5 keV, somewhat hotter 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 (90% confidence). This limit on the line width is consistent withthe reverse shock model of Chevalier & Fransson (1994), but does not rule outthe clumpy wind model of Chugai (1993).Comment: 20 pages, 9 postscript figures, latex, uses aastex4.0, submitted to The Astrophysical Journa