Recent images of the BL Lac object ON 231, obtained from observations made with the European VLBI Network plus MERLIN at 1.6 GHz and 5 GHz after the exceptional optical outburst of Spring 1998, show remarkable new features in the source structure if compared to those previously published. Identifying the source core with the brightest flat spectrum component, we detected the existence of a (possible) counter-jet. We also found a new low brightness feature, 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 variations in the frame of the unification model.
EVN and MERLIN observations of ON 231 after the great optical flare of spring 1998
TOSTI, Gino;
2000
Abstract
Recent images of the BL Lac object ON 231, obtained from observations made with the European VLBI Network plus MERLIN at 1.6 GHz and 5 GHz after the exceptional optical outburst of Spring 1998, show remarkable new features in the source structure if compared to those previously published. Identifying the source core with the brightest flat spectrum component, we detected the existence of a (possible) counter-jet. We also found a new low brightness feature, 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 variations in the frame of the unification model.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
