Possible Model for a Rapidly Pulsating Radio Source

Abstract

Recently, the Cambridge radio astronomy group has described observations of a rapidly pulsating radio source¹. Their observations can be summarized as follows. (a) The signal observed at 81·5 MHz has a period of 1·337 s, the phase being constant to one part in 10⁷. The amplitude, however, varies irregularly, the signal appearing and disappearing for periods of a few minutes. Each pulse has a length of ~0·3 s. (6) From the absence of proper motion and a consideration of the dispersive effects of transmission through the interstellar plasma the distance to the source is limited to the range 10³ au < d < 65 pc. (c) Variations of phase can be accounted for by the Earth’s orbital motion without the need for additional correction for the motion of the source. (d) No visible object brighter than twelfth magnitude is apparent in the radio error rectangle. (e) From the signal width and rate of sweep the source size must be smaller than 4·8 × 10⁸ cm.