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

## [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.

Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.