Oxygen flux in the solar wind: Ulysses observations

We use the complete set of Ulysses solar wind data to conduct a comprehensive determination of the oxygen flux in relation to the proton flux in the solar wind during a wide range of solar activity levels. The data cover the heliosphere between 1.3 and 5.4 AU and, due to the unique orbit of Ulysses, all of the heliographic latitudes within 80. We find log-normal distributions for O and H daily flux values, but with significant differences between slow and fast wind. Coronal hole-associated fast wind has a distribution that is approximately three times narrower than the one of slow wind associated with streamers. Finally, we derive the solar oxygen abundance, finding a value of 8.82 0.08, and discuss this value in comparison with the results of spectroscopic determinations.