Recent images of the BL Lac object ON231 (W Com, 1219+285) show remarkable new features in the source structure if compared to those previously published. The images were obtained from observations made with the European VLBI Network plus MERLIN at 1.6 GHz and 5 GHz after the exceptional optical outburst occurred in Spring 1998. The iamges we made, allowed us to identify the source core with the brightest flat spectrum component. We suggest the existence of a (possible) counter-jet in ON231. An additional new feature found in the source, is a large bend in the jet at about 10 mas from the core. The emission extends for about 20 mas after the bend. We suggest some possible interpretations to relate the changes in the source structure with the optical and radio flux density variation in the frame of the unification model.
VLBI observations of ON231 (W Com, 1219+285) after the 1998 optical outburst
TOSTI, Gino;
2001
Abstract
Recent images of the BL Lac object ON231 (W Com, 1219+285) show remarkable new features in the source structure if compared to those previously published. The images were obtained from observations made with the European VLBI Network plus MERLIN at 1.6 GHz and 5 GHz after the exceptional optical outburst occurred in Spring 1998. The iamges we made, allowed us to identify the source core with the brightest flat spectrum component. We suggest the existence of a (possible) counter-jet in ON231. An additional new feature found in the source, is a large bend in the jet at about 10 mas from the core. The emission extends for about 20 mas after the bend. We suggest some possible interpretations to relate the changes in the source structure with the optical and radio flux density variation in the frame of the unification model.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
