Observations of the solar wind on by SWAN/SOHO

Jean-Loup Bertaux

Service d'Aéronomie du CNRS, BP. 3,
91371 Verrières-le-Buisson, France


In the motion of the Sun through the ISM, the flow of interstellar H atoms in the solar system is carved by their destruction during ionization charge-exchange with solar wind protons .The atoms not yet destroyed are illuminated by solar Lyman-alpha photons and maps of sky L-alpha emission recorded with SWAN instrument on SOHO reflect the latitude distibution of the solar wind. Some results of this remote sensing solar wind mapper will be presented and compared with Ulysses in-situ measurements. In the region of maximum emission , located in the upwind hemisphere, a depression aligned with the solar equatorial plane called the L alpha groove is the direct imprint on the sky of the enhanced carving by the slow solar wind, at this time of solar minimum.

The interaction of the heliosphere with the ISM will be discussed, with new results allowing to predict the distance of the heliopause to the sun.In particular, theory predicts the presence of a wall of neutral H at 150 AU in the upwind direction, supported by several observations.The local structure of interstellar clouds around the sun will be described, allowing to make predictions on the future behavior of our heliosphere.Finally, the possibility to detect the astrospheres of other stars will be discussed briefly.


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