LSD profiles of Aldebaran as observed with Narval on 14–15 March 2010 (upper panel), 5 October 2010 (middle panel) and 16 January 2011 (lower panel). For each graph, from top to bottom are Stokes V, null polarisation N, and Stokes I profiles. For display purposes, the profiles are shifted vertically, and the Stokes V and diagnostic N profiles are expanded by a factor of 5000. The dashed lines illustrate the zero level for the Stokes V and diagnostic null profiles. The Stokes V profiles illustrate a non detection (ND) on 14–15 March 2010, then definite detections (DD) with a change of polarity of the magnetic field between the two later dates.