AAS 205th Meeting, 9-13 January 2005
Session 111 Radio Pulsars
Poster, Wednesday, January 12, 2005, 9:20am-6:30pm, Exhibit Hall

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[111.09] Q- to B-Mode Transition Recovery Dynamics in Pulsar B0943+10

J. M. Rankin (Univ. of Vermont), S. A. Suleymanova (PRAO, Lebedev Inst., Russia)

Pulsar B0943+10 is well known for its `B' mode, characterized by accurately drifting subpulses, in contrast to its chaotic `Q' mode. Six new Arecibo observations using nearly the full 2+ hours available have shed considerable light on the modal dynamics in this pulsar. Of these, three were found to be exclusively `B' mode, and three were discovered to exhibit transitions from the `Q' to the `B' mode. One of these observations has permitted us to determine the circulation time of the subbeam ``carousel'' in the `Q' mode for the first time, at some 35.5 stellar rotation periods. The onset of the `B' mode is then observed to commence similarly in all three observations. The initial circular time is around 35.5 periods and relaxes to perhaps 38 periods in an near exponential [1-\exp (-t/\tau)] fashion with a characteristic time of some 54 minutes. Moreover, just after the `B'-mode onset the pulsar exhibits a resolved double profile form with a somewhat larger trailing component, but this trailing component slowly dies away leaving the usual single `B'-mode profile with the longitude of the magnetic axis falling at about its trailing half power point. Additional longer observations are still needed to learn how long `B'-mode sequences can persist and what factors determine how the modal alternation occurs.

Portions of this work were carried out with support from NSF Grants AST 99-87654 and 00-98685. Arecibo Observatory is operated by Cornell University under contract to the US NSF.

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