ON THE CONNECTION OF THE APPARENT PROPER MOTION AND THE VLBI STRUCTURE OF COMPACT RADIO SOURCES
- FOeMI Satellite Geodetic Observatory, P.O. Box 585, H-1592 Budapest (Hungary)
- Observatoire de Paris, Departement Systemes de Reference Temps Espace (SYRTE), CNRS/UMR8630, 75014 Paris (France)
- Geoscience Australia, P.O. Box 378, Canberra 2601 (Australia)
- Instituto de Astrofisica de Canarias, E-38205 La Laguna, Tenerife (Spain)
Many of the compact extragalactic radio sources that are used as fiducial points to define the celestial reference frame are known to have proper motions detectable with long-term geodetic/astrometric very long baseline interferometry (VLBI) measurements. These changes can be as high as several hundred microarcseconds per year for certain objects. When imaged with VLBI at milliarcsecond (mas) angular resolution, these sources (radio-loud active galactic nuclei) typically show structures dominated by a compact, often unresolved 'core' and a one-sided 'jet'. The positional instability of compact radio sources is believed to be connected with changes in their brightness distribution structure. For the first time, we test this assumption in a statistical sense on a large sample rather than on only individual objects. We investigate a sample of 62 radio sources for which reliable long-term time series of astrometric positions as well as detailed 8 GHz VLBI brightness distribution models are available. We compare the characteristic direction of their extended jet structure and the direction of their apparent proper motion. We present our data and analysis method, and conclude that there is indeed a correlation between the two characteristic directions. However, there are cases where the {approx}1-10 mas scale VLBI jet directions are significantly misaligned with respect to the apparent proper motion direction.
- OSTI ID:
- 21583117
- Journal Information:
- Astronomical Journal (New York, N.Y. Online), Vol. 141, Issue 6; Other Information: DOI: 10.1088/0004-6256/141/6/178; ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
Similar Records
VLBI FOR GRAVITY PROBE B. III. A LIMIT ON THE PROPER MOTION OF THE 'CORE' OF THE QUASAR 3C 454.3
VLBI FOR GRAVITY PROBE B. V. PROPER MOTION AND PARALLAX OF THE GUIDE STAR, IM PEGASI