HR: 14:40h
AN: SH43A-03 INVITED     [Abstracts]
TI: The High-Latitude Heliosphere at Solar Minimum: Recent Results From Ulysses
AU: * Marsden, R G
EM: Richard.Marsden@esa.int
AF: Research & Scientific Support Department, ESA, Keplerlaan 1, Noordwijk, Z-H 2201AZ, Netherlands
AB: Launched in October 1990, Ulysses is the first spacecraft ever to fly over the poles of the Sun. From this unique perspective, it has literally changed the way we view the Sun's environment, the heliosphere. The primary goal of the Ulysses mission is to explore the heliosphere in four dimensions: three spatial dimensions, and time. The scientific instruments on board Ulysses that help accomplish this goal measure the solar wind, the heliospheric magnetic field, natural radio emission and plasma waves, energetic particles and cosmic rays, interplanetary and interstellar dust, neutral interstellar helium atoms, and cosmic gamma-ray bursts. Ulysses first visited the Sun's poles in 1994 (in the south) and 1995 (north), as the solar activity approached a minimum. The measurements showed the heliosphere to be dominated by high-speed solar wind flowing from the Sun's polar caps, filling a large fraction of the heliosphere. Surprises included the presence of energetic particles at high latitudes, and the lack of an increase in cosmic radiation towards the poles. Following its path around the Sun, Ulysses arrived over the southern and northern poles for a second time in November 2000 and October 2001, this time near solar maximum. The environment over the poles was very different from that found by Ulysses during the first high- latitude passes. Nevertheless, equally compelling evidence was found for large-scale latitudinal transport of energetic charged particles. As Ulysses returns to the polar regions for the third time, again near solar minimum, a number of important questions remain: will the polarity reversal of the Sun's magnetic field that occurred in 2000-01 lead to the expected changes in the latitudinal gradients of positively and negatively charged particles? Will the north-south asymmetry found in 1994-95 be present, and if so, will the offset still be to the south of the solar equator? In this paper, we will review the recent observations from Ulysses in the light of some of these questions.
DE: 2104 Cosmic rays
DE: 2114 Energetic particles (7514)
DE: 2124 Heliopause and solar wind termination
DE: 2134 Interplanetary magnetic fields
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2007 Joint Assembly