Is the line-like optical afterglow SED of GRB 050709 due to a flare?
  Recently Jin et al. (2016) reanalyzed the optical observation data of GRB
050709 and reported a line-like spectral energy distribution (SED) component
observed by the Very Large Telescope at $t\sim 2.5$ days after the trigger of
the burst, which had been interpreted as a broadened line signal arising from a
macronova dominated by iron group. In this work we show that an optical flare
origin of such a peculiar optical SED is still possible. Interestingly, even in
such a model, an "unusual" origin of the late-time long-lasting Hubble Space
Telescope F814W-band emission is still needed and a macronova/kilonova is the
natural interpretation.
