Astron. Astrophys. 336, L37-L40 (1998)

1. Introduction

There exists a class of powerful radio sources consisting of high luminosity radio emission regions separated by less than 1 kpc and situated symmetrically about the centre of activity. Objects of this type were first described as `Compact Doubles' by Phillips & Mutel (1982), but the more generic name of Compact Symmetric Objects (CSOs) was given by Wilkinson et al. (1994).

Three possible evolutionary scenarios of CSOs have been proposed: 1) they are old `frustrated' sources, in which a dense environment doesn't allow them to grow (van Breugel et al. 1984); 2) they are young sources which will `fizzle out' after a short lifetime (Readhead et al. 1994) or 3) they represent a very young stage in the evolution of large-sized classical radio sources (e.g. Fanti et al.1995, Readhead et al. 1996b, Begelman 1996, Owsianik & Conway 1998).

One archetypical CSO is the radio source 0108+388. This radio object is identified with a galaxy of m_V=22.0 mag at redshift z =0.669 (Lawrence et al. 1996). The radio flux density is weakly polarised ( at 4.8 GHz) and does not show significant variations (Aller et al. 1992). 0108+388 has a spectral turnover around 5 GHz, with spectral indices and (, Baum et al. 1990).

© European Southern Observatory (ESO) 1998

Online publication: July 20, 1998
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