SIMBAD references

An excellent Doppler image of the surface of ε UMa shows a strong, sharply defined belt at the magnetic equator with oxygen abundance five orders of magnitude greater than the abundance in the magnetic polar regions. The centre of abundance-symmetry for oxygen is located quite precisely at latitude +28° and longitude 349°. A secondary belt of oxygen abundance is observed tilted at 60° to 70° to the primary belt. In this secondary belt the abundance is only enhanced about two orders of magnitude above that of the surrounding abundance plateau in the polar regions. The relative depletion of Cr by about three orders of magnitude in a belt around the magnetic equator is confirmed. It is noted that, qualitatively, the location of the primary belt of oxygen enhancement, its extreme abundance difference compared to the polar plateau and the existence of the secondary oxygen belt, might suggest a chemically separated wind as a likely mechanism for producing the oxygen abundance pattern even though the radiative forces should not be sufficient to selectively expel oxygen in a wind.