SIMBAD references

High-resolution observations, made with the Very Large Array (VLA) at 330MHz, 1.4GHz and 8.4GHz and with the Ryle Telescope at 15GHz, are presented of a sample of 23 sources which are variable at 151MHz, concluding the observations of an unbiased sample of 40 such sources. The 8.4GHz emission of almost all of the sources is dominated by structure on a scale ≲0.1arcsec - the spectra of these compact components are such that they will also dominate the emission at 151MHz; the number of sources for which this is not the case is consistent with the number of spurious variables expected to be found in the sample. About two-thirds of the sources have the self-absorbed, or flat, spectra expected from their size. The majority (∼75per cent) of the sources belong to the compact steep-spectrum (CSS) class, but are generally more compact than other CSS sources; the CSS variables also appear to exhibit more spectral ageing than typical CSS sources, which may indicate a difference in the nature of the sources.