百秒差距尺度上的4C39.25

通过主要在短厘米波长的全球VLBI观测,已经发现强射电类星体4C39.25在十秒差距尺度结构中的视超光速运动,其运动学图景表明该源是一个很特殊的视超光速源.近几年已提出了若干模型,试图解释这特殊的运动图景.报道不多的百秒差距尺度的VLBI观测,很可能有助于检验提出的模型.本文介绍用欧洲网及上海25m天线,在18cm波长对4C39.25所作的VLBI 成象观测的初步结果,显示百秒差距尺度复杂结构及可能存在的视超光速运动.

The Quasar 4C39.25 on the Scale of Hundreds of Parsecs

The superluminal motion on ten-parsec scale has been revealed in the powerful radio quasar 4C39.25 by a series of global VLBI observa tions at short centimetre wavelengths. The source is one of very peculiar superluminal radio sources that is indicated by its special kinematic scene. In the past few years, quite a few scenarios have been proposed to interpret the special scene. The VLBI observations on the scale of hundreds of parsecs, which has unfortunatly been reported rarely so far, would be helpful to shed new light on the nature of this unusual superluminal source. The preliminary results of an EVN-SHANGHAI VLBI observation of 4C39.25 at 18 cm are presented in this paper. They show complicated morphology of the source on a scale of hundreds of parsecs and the possible existence of superluminal motion on this scale. A model of an uncoplanar and undulating jet is implied by the results.