Open AccessCompact radio sources variable at 151 MHz – II. High‐resolution observations of an unbiased sample
Author(s) -
Minns A. R.,
Riley J. M.
Publication year - 2000
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2000.03802.x
Subject(s) - physics , spurious relationship , astrophysics , sample (material) , spectral line , telescope , resolution (logic) , radio telescope , spectral resolution , variable (mathematics) , astronomy , statistics , mathematical analysis , mathematics , artificial intelligence , computer science , thermodynamics
High‐resolution observations, made with the Very Large Array (VLA) at 330 MHz, 1.4 GHz and 8.4 GHz and with the Ryle Telescope at 15 GHz, are presented of a sample of 23 sources which are variable at 151 MHz, concluding the observations of an unbiased sample of 40 such sources. The 8.4 GHz emission of almost all of the sources is dominated by structure on a scale ≲0.1 arcsec – the spectra of these compact components are such that they will also dominate the emission at 151 MHz; 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 (∼75 per 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.