A search for magnetic fields on central stars in planetary nebulae

Departamento de Astrofisica, Universidad de La Laguna, E-38205 La Laguna, Tenerife, SpainReceived To be inserted later, accepted To be inserted laterABSTRACTContext.One of the possible mechanisms responsible for the panoply of shapes in planetary nebulae is the presence of magnetic fiel dsthat drive the ejection of ionized material during the proto-planetary nebula phase.Aims. Therefore, detecting magnetic fields in such objects is of ke y importance for understanding their dynamics. Still, magneticfields have not been detected using polarimetry in the centra l stars of planetary nebulae.Methods. Circularly polarized light spectra have been obtained with the Focal Reducer and Low Dispersion Spectrograph at theVery Large Telescope of the European Southern Observatory and the Intermediate dispersion Spectrograph and Imaging System atthe William Herschel Telescope. Nineteen planetary nebulae spanning very different morphology and evolutionary stages have beenselected. Most of central stars have been observed at different rotation phases to point out evidence of magnetic variability.Results.In this paper, we present the result of two observational campaigns aimed to detect and measure the magnetic field in thecentral stars of planetary nebulae on the basis of low resolution spectropolarimetry. In the limit of the adopted method, we can statethat large scale fields of kG order are not hosted on the centra l star of planetary nebulae.Key words. planetary nebulae: general – magnetic fields – techniques: p olarimetric