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Published December 5, 1995 | Published
Journal Article Open

Bidirectional motion observed in the compact symmetric object 1946+708


We present the first direct measurements of bidirectional motions in an extragalactic radio jet. The radio source 1946+708 is a compact symmetric object with striking S-symmetry identified with a galaxy at a redshift of 0.101. From observations 2 years apart we have determined the velocities of four compact components in the jet, the fastest of which has an apparent velocity of 1.09 h^(-1)c. By pairing up the components, assuming they were simultaneously ejected in opposite directions, we derive a 1 lower limit on the Hubble constant, H_0 > 42 km•s^(-1)•Mpc^(-1).

Additional Information

© 1995 National Academy of Sciences. We thank the staffs at the observatories and the staff of the Jet Propulsion Laboratory/California Institute of Technology Block II Correlator for their assistance. This work was supported by the National Science Foundation under Grants AST-9117100 and AST-9420018. This paper was presented at a colloquium entitled "Quasars and Active Galactic Nuclei: High Resolution Radio Imaging," organized by a committe chaired by Marshall Cohen and Kenneth Kellermann, held March 24 and 25, 1995, at the National Academy of Sciences Beckman Center, Irvine, CA. The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

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Published - PNAS-1995-Taylor-11381-4.pdf


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