An interesting article in Nature Online http://www.nature.com/
“Stuttering stars found; Unpredictable cousins of pulsars baffle astronomers”.
It concerns a new type of radio star that sends out irregular signals. To quote from the piece “Astronomers have so far seen 11 examples of the objects, which they call Rotating Radio Transients or RRATs" (- worth the price of admission just for the acronym). "The stars send out bursts of radio waves that last between 2 and 30 milliseconds, with a time interval between bursts varying unpredictably from 4 minutes to 3 hours”
One possibility the article raises is that this may be an intermediate stage between a pulsar and a magnetar. An alternative explanation that is also put forward is that pulsars often emit ‘extra strong” signals, if the RRATs are doing this but their normal signals are too weak to detect the effect would be an unpredictable burst of radio signals.

Andrew