1997A&A...321..523C

We present high-resolution imaging of the region around the Herbig Ae/Be star LkHα 234 in the 10µm and 17µm atmospheric windows and in the H₂ v=1-0 S(1) line and adjacent continuum. LkHα 234 is unresolved at mid-infrared wavelengths (FWHM<1.3") and has a decreasing spectrum compatible with an accretion disk. A cold mid-infrared companion is revealed 2.7" to the north-west of the optical star, corresponding well to the polarization centre identified in the K-band by Weintraub et al. (1994). The companion illuminates an arc-shaped reflection nebula with very red colours, and is associated with a radio continuum source, H₂O masers, and a bright extended H₂ emission knot, indicating that it is deeply embedded and has strong outflow activity. However, its role in driving the optical jet near LkHα 234 is not clear. Our high-resolution H₂ image reveals that the jet has a complex structure, with an inner part at PA 226° emitting brightly in H₂, and an outer part at PA 252° seen only in [SII]. The inner H₂ jet does not point back exactly toward the infrared companion, indicating either that it is deflected after leaving that object, or that it is driven by a yet unidentified source. Available long-slit spectra favor the idea that the outer jet emitting in [SII] could be powered by the 10µm companion rather than by LkHα 234. High-resolution [SII] imaging is required to test this hypothesis.