An Optical/Infrared Outburst in the Exciting Source of HH 7–11
We report on an outburst of SVS 13, the exciting source of the HH 7–11 outflow, in the optical and near-infrared wavelength region (see also Eislöffel et al., 1991). CCD images from our archives and recently obtained ones show that the brightness of this source at 6740 Å increased by around 2.5 magnitudes sometime between December 1988 and September 1990 (Fig. la). Since then until July 1991, our last measurement so far, the source has been constantly brightening by 0.06 mag per month. A similar outburst was observed in the V, R and I bands. Photometry at K (Fig. lb) shows that the IR flux of SVS 13 apparently was slightly variable (up to 0.5 mag) already during the decade before the outburst. During the outburst it also increased, albeit the amplitude is only ΔK ~ 1.2 mag, i.e. much smaller than in the optical (see also Liseau et al., 1992, who noted the brightness increase in the infrared too).
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