We report in this paper phase-resolved spectropolarimetric observations of the rapidly-rotating fully-convective M4 dwarf V374 Peg , on which a strong , mainly axisymmetric , large-scale poloidal magnetic field was recently detected .
In addition to the original data set secured in 2005 August , we present here new data collected in 2005 September and 2006 August .

From the rotational modulation of unpolarised line profiles , we conclude that starspots are present at the surface of the star , but their contrast and fractional coverage are much lower than those of non-fully convective active stars with similar rotation rate .
Applying tomographic imaging on each set of circularly polarised profiles separately , we find that the large-scale magnetic topology is remarkably stable on a timescale of 1 yr ; repeating the analysis on the complete data set suggests that the magnetic configuration is sheared by very weak differential rotation ( about 1/10th of the solar surface shear ) and only slightly distorted by intrinsic variability .

This result is at odds with various theoretical predictions , suggesting that dynamo fields of fully-convective stars should be mostly non-axisymmetric unless they succeed at triggering significant differential rotation .