We present the late-time optical photometry of supernova (SN) 1993J in M81 from 1995 February to 2003 January. The observations were performed in a set of intermediate-band filters that have the advantage of tracing the strength variations of some spectral features. SN 1993J was found to fade very slowly at late times, declining only by 0.05 ± 0.02 mag (100 days)-1 in most of the filters from 2 to nearly 10 yr after discovery. Our data suggest that the circumstellar interaction provides most of the energy that powers the late-time optical emission of SN 1993J. This is manifested by several flux peaks seen in the rough spectral energy distributions constructed from the multicolor light curves. The flux peaks near 6600, 5800, and 4900 ? may correspond to the emission lines of Hα, Na D + He λ5876, and [O III] λλ4959, 5007, respectively. The evolution of these emission lines suggest a power-law SN density model, as proposed by Chevalier & Fransson.
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机译：我们介绍了1995年2月至2003年1月在M81中超新星（SN）1993J的最新光学测光。观察是在一组中频滤波器中进行的，这些滤波器具有跟踪某些频谱特征的强度变化的优势。发现SN 1993J的衰减非常缓慢，从发现后的2年到近10年，大多数过滤器仅下降了0.05±0.02 mag（100天）-1。我们的数据表明，星际相互作用提供了为SN 1993J的后期光学发射提供动力的大部分能量。这由从多色光曲线构造的粗糙光谱能量分布中看到的几个通量峰来证明。通量在6600、5800和4900？附近达到峰值。可以分别对应于Hα，Na D + Heλ5876和[O III] λλ4959、5007的发射线。这些发射线的演变表明，如Chevalier＆Fransson提出的幂律SN密度模型。
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