Solar Physics

, Volume 161, Issue 2, pp 383–392 | Cite as

Recalculation of H-Lα sky surveys: No need for anisotropic solar wind mass outflows?

  • Horst Scherer
  • Hans J. Fahr


The variation with position and view direction of heliospheric H-Lα scattered intensity seen by a Lα detector in the heliosphere is re-examined. Here, a frequency- and angle-dependent multiscattering calculation (Scherer, 1994; Scherer and Fahr, 1995) is used that takes into account the local thermodynamical conditions of the scattering agent, such as temperature, density and bulk velocity of the neutral interplanetary hydrogen, as given in a recent model by Osterbart and Fahr (1992). The calculated intensity patterns show strongly pronounced dependencies of the direction of the line of sight which are explained by effects of the Doppler shift in the resonance absorption and the dipole-phase function used in the multiscattering calculation. The theoretical results obtained with these computations nicely fit the intensities measured byPrognoz 5/6 probe (Lallement, Bertaux, and Dalaudier, 1985; Bertauxet al., 1985) without, however, assuming a latitude dependence of the solar wind mass outflow. This expresses the fact that, using an adequate radiation transport calculation, it is possible to explain thePrognoz andGalileo data without the need to specify anisotropic solar wind mass outflow from the corona preferred by several authors (Lallement, Bertaux, and Dalaudier, 1985; Lallement, 1989; Broadfoot and Kumar, 1978; Bertauxet al., 1985; Ajelloet al., 1994). In view of forthcomingUlysses solar wind measurements at polar latitudes this might be of importance to know.


Solar Wind Scattered Intensity Calculated Intensity Resonance Absorption Bulk Velocity 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Kluwer Academic Publishers 1995

Authors and Affiliations

  • Horst Scherer
    • 1
  • Hans J. Fahr
    • 1
  1. 1.Institut für Astrophysik und Extraterrestrische Forschung der Universität BonnBonnGermany

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