HR: 0830h
AN: SH11D-1136    [PDF]
TI: Relating Interplanetary Helium Variation to Coronal Magnetic Fields and Solar Wind Formation
AU: * Kasper, J C
EM: jck@space.mit.edu
AF: MIT Center for Space Research, 77 Massachusetts Avenue, Cambridge, MA 02139 United States
AU: Lazarus, A J
EM: ajl@space.mit.edu
AF: MIT Center for Space Research, 77 Massachusetts Avenue, Cambridge, MA 02139 United States
AU: Steinberg, J T
EM: jsteinberg@lanl.gov
AF: Los Alamos National Laboratory, P.O. Box 1663, MS D466 Los Alamos National Laboratory, Los Alamos, NM 87545 United States
AU: Riley, P
EM: pete.riley@saic.com
AF: Science Applications International Corporation, 10260 Campus Point Drive, San Diego, CA 92121 United States
AU: Sheeley, N
EM: sheeley@spruce.nrl.navy.mil
AF: Naval Research Laboratory, Code 7672, Washington, DC 20375 United States
AU: Wang, Y
EM: ywang@pinoak.nrl.navy.mil
AF: Naval Research Laboratory, Code 7672, Washington, DC 20375 United States
AB: We have recently identified two new features in the variation of the relative abundance of helium in the solar wind relative to hydrogen as observed by the Wind spacecraft. First, the {\it He/H} ratio is a linear function of speed for solar wind speeds ranging from 250-550 km/s. This signal is most evident during the previous solar minimum from 1995 through 1997. Secondly, during that same quiet interval we have identified a six-month periodic modulation of the {\it He/H} ratio which can be seen at all solar wind speeds. This modulation is in phase with the orbit of the Earth about the Sun, and maxima in {\it He/H} occur at the times when Earth is most distant from the heliographic equator. As we shall demonstrate, these effects are partly in agreement with theoretical models of the magnetic topology of the corona and of the formation of the solar wind. However, these features present challenges to the currently accepted paradigm of solar wind, with helium-poor wind emerging from coronal streamers and fast, helium-rich wind emerging from coronal holes. The abundance of helium is a sensitive test of models of solar wind formation and of the connection between photospheric, coronal, and interplanetary magnetic fields. The observed variations of {\it He/H} will be discussed in terms of existing models of coronal magnetic field topology and solar wind acceleration. This research is supported by the NSF/SHINE grant ATM-0327723.
DE: 2162 Solar cycle variations (7536)
DE: 2164 Solar wind plasma
DE: 2169 Sources of the solar wind
DE: 7509 Corona
SC: SPA - Solar and Heliospheric Physics [SH]
MN: 2003 Fall Meeting