Proposal code

w508

Proposal title

Probing the center of activity in a CSS superluminal quasar 3C 138

The

Investigators and their

Affiliations

P.I. Zhi-Qiang Shen ISAS, Japan
Hisashi Hirabayashi, Philip G. Edwards ISAS, Japan
Seiji Kameno NAOJ, Japan
D.-R. Jiang, Y.-J. Chen Shanghai Observatory, China
Xiang Liu Urumqi Observatory, China

Proposal Abstract

We propose the first space VLBI observations of a CSS superluminal quasar 3C 138 at both 1.6 and 5 GHz to probe the fine structure within its central 10 mas. We aim to clearly separate the two compact knots for the first time at 1.6 GHz. This will enable us to obtain the spectral index for each component and then to determine the location of the central activity. These new data will also be used to refine the measurement of the superluminal speed, which has implications for models attempting to explain the observed large-scale asymmetrical lobes. We also hope to confirm the core position offset in 3C 138 that can be well accounted for by a frequency dependent shift of the synchrotron self-absorbed core. The fact that superluminal motion is not common in CSS sources makes it further interesting to compare 3C 138 with other two superluminal CSS quasars (3C 216 and 3C 446) that have already been imaged with VSOP.

The full Cover Sheets (compressed post-script, typically 50kbytes) can be retrieved. Note that some proposals were reduced in extent by the Scientific Review Committee (e.g. by reducing the number of experiments), however the Cover Sheets contain the full proposal as submitted. Also note that AO5 proposals were submitted in February 2001, and information such as affiliations and contact details has changed for some proposers since that time.