English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We present the results of 5 GHz VLBI observations of a compact steep spectrumsource 3C 138. The data are consistent with the western end being the locationof the central activity. The observed offset between different frequencies inthe central region of 3C 138 can be accounted for by a frequency dependentshift of the synchrotron self-absorbed core. Our new measurements confirm theexistence of a superluminal motion, but its apparent velocity of 3.3c is threetimes slower than the reported one. This value is consistent with the absenceof parsec-scale counter-jet emission in the inner region, but seems still toohigh to allow the overall counter-jet to be seen in terms of Doppler boostingof an intrinsically identical jet. Either an interaction of jet with centraldense medium, or an intrinsically asymmetrical jet must be invoked to reconcilethe detected superluminal speed with the observed large scale asymmetry in 3C138.Comment: 5 pages including 3 ps figures and 1 table, LaTex2e, accepted for  publication in Astronomy and Astrophysic

Superluminal motion in a compact steep spectrum radio source 3C 138