Light curves of 4 supernovae

In all known supernovae, this radiation comes from internal energy deposited in the outflowing ejecta by one or more of the following processes: radioactive decay of freshly synthesized elements (typically ^56^Ni), the explosion shock in the envelope of a supergiant star, and interaction between the debris and slowly moving, hydrogen-rich circumstellar material.

Here we report observations of a class of luminous supernovae whose properties cannot be explained by any of these processes. The class includes four new supernovae that we have discovered and two previously unexplained events (SN 2005ap and SCP 06F6) that we can now identify as members of the same class.