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Elastic collisions of interstellar helium atoms with solar wind protons
Author(s) -
Gruntman Mike
Publication year - 2013
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/jgra.50199
Subject(s) - heliosphere , helium , physics , solar wind , atomic physics , energetic neutral atom , helium atom , interstellar medium , flux (metallurgy) , halo , elastic collision , atom (system on chip) , ion , astrophysics , plasma , electron , nuclear physics , galaxy , chemistry , organic chemistry , quantum mechanics , computer science , embedded system
Relative motion of the Sun with respect to the surrounding local interstellar medium results in entering of interstellar helium atoms into the heliosphere. Current models of helium flowing into the solar system do not include elastic collisions of atoms with solar wind ions. It was predicted in 1986, without quantitative elaboration, that such collisions would enhance wings of directional distributions of helium atom fluxes. This paper focuses on a theoretical treatment of elastic collisions of interstellar He atoms with the solar wind protons resulting in increased wing intensities, called the helium flux halo in contradistinction to the flux core. We concentrate on directional distributions of He atom intensities at 1 AU from the Sun for observers at rest and moving with the Earth and confirm the formation of the flux halo. We show that the collision‐produced halo would often dominate He atom intensities at angles larger than 30°–35° from the maximum intensity direction in the flux core. A comparison with direct measurements of interstellar helium atom fluxes is beyond the scope of this paper.