Radio observations of the planetary nebula around the OHIR star OH 354.88-0.54 (V1018 Sco)

Abstract

We present radio observations of the unique, recently formed, planetary nebula (PN) associated with a very long-period OHIR variable star V1018 Sco that is unequivocally still in its asymptotic giant branch phase. Two regions within the optical nebula are clearly detected in non-thermal radio continuum emission, with radio spectral indices comparable to those seen in colliding-wind Wolf-Rayet binaries. We suggest that these represent shocked interactions between the hot, fast stellar wind and the cold nebular shell that represents the PN's slow wind moving away from the central star. This same interface produces both synchrotron radio continuum and the optical PN emission. The fast wind is neither spherical in geometry nor aligned with any obvious optical or radio axis. We also report the detection of transient H 2O maser emission in this nebula. © 2006 RAS.