The electron heat flux in the polar solar wind: Ulysses observations

Ulysses measurements of the solar wind electron heat flux as a function of heliographic latitude are presented. Contamination from a light leak at the highest latitudes has been removed from the data by interpolating between uncontaminated pixels. After normalization by the radial gradient in the electron heat flux obtained during the inecliptic phase of the Ulysses mission, the electron heat flux is essentially constant from −80° to 80° of heliographic latitude. During brief periods of the fast latitude scan, both uncorrelated and anti‐correlated modulations of the electron heat flux and the solar wind velocity are observed. The implications of the observations with regards to different models of electron heat flux regulation are discussed.