Time variations of interstellar water masers: strong sources in HII regions

Little, L.T.; White, G. J. and Riley, P.W. (1977). Time variations of interstellar water masers: strong sources in HII regions. Monthly Notices of the Royal Astronomical Society, 180 pp. 639–656.

URL: http://adsabs.harvard.edu/full/1977MNRAS.180..639L

Abstract

The strong water-line sources W3OH, Orion A, W49N and W51S have been monitored over the period 1974 September - 1976 October. Variations on a variety of timescales from years to days have been observed. W49 and W51S exhibit more rapid variations than W30H or Orion A. A comparison of the present results with those of Sullivan during 1969-70 suggests that the flux from the main components of W49 has systematically decreased, whereas that from W51 has systematically in creased in the 5-yr interval between the two sets of observations. This fact is best explained if there are changes in the flux of radiation from a common exciting object, incident on all of the masing components. High-velocity features in W49 have on two occasions been brighter than any of the main components, supporting a Doppler shift rather than scattering explanation for their origin.

Viewing alternatives

Item Actions

Export

About

Recommendations