Open AccessVariability investigation of quasars 4C 38.41 and 3C 345 at 92 cm: additional 14 observations
Author(s) -
Peng B.
Publication year - 2002
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.1365-8711.2002.05102.x
Subject(s) - quasar , physics , astrophysics , radio telescope , brightness , sky , doppler effect , brightness temperature , astronomy , very long baseline interferometry , telescope , proper motion , spectral index , spectral line , galaxy , stars
This paper provides additional evidence for the variability of the quasar 4C 38.41 based on 14 short observations at 92 cm using the Westerbork Synthesis Radio Telescope (WSRT). A fractional variability of 11.6 per cent was observed during the periods of 1989 May and from 1992 December to 1993 May. A brightness temperature of T B ∼2.6 or 5.2×10 18 δ −3 K in 4C 38.41 can be estimated in the comoving frame, far in excess of the inverse Compton limit 10 12 K. A Doppler factor of δ 138 would be required by invoking the relativistic bulk motion. Combining the published six Westerbork North Sky Survey (WENSS) mosaic data at 92 cm, we conclude that 4C 38.41 has significant variability, which is unlikely to be caused by propagation effects. No variability was found for the quasar 3C 345.