The X‐ray spectrum and light curve of Supernova 1995N

ABSTRACT We report on multi-epoch X-ray observations of the Type IIn (narrow emissionline) supernova SN 1995N with the ROSAT and ASCA satellites. The January 1998ASCA X-ray spectrum is well fitted by a thermal bremsstrahlung (kT ∼ 10 keV,N H ∼ 6 × 10 20 cm −2 ) or power-law (α ∼ 1.7, N H ∼ 10 21 cm −2 ) model. The X-raylight curve shows evidence for significant flux evolution between August 1996 and Jan-uary 1998: the count rate from the source decreased by 30% between our August 1996and August 1997 ROSAT observations, and the X-ray luminosity most likely increasedby a factor of ∼2 between our August 1997 ROSAT and January 1998 ASCA obser-vations, although evolution of the spectral shape over this interval is not ruled out.The high X-ray luminosity, L X ∼ 10 41 ergs s −1 , places SN 1995N in a small groupof Type IIn supernovae with strong circumstellar interaction, and the evolving X-rayluminosity suggests that the circumstellar medium is distributed inhomogeneously.Key words: supernovae: individual: SN 1995N – X–rays: stars – stars: circumstel-lar matter