Premium
The solar wind alpha‐particle content as a clue for the origin of slow flows
Author(s) -
Bavassano B.,
Bruno R.,
Pietropaolo E.
Publication year - 1998
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/98gl02182
Subject(s) - solar wind , middle latitudes , equator , latitude , physics , atmospheric sciences , environmental science , astrophysics , plasma , astronomy , quantum mechanics
Some aspects of the variation of the alpha‐particle abundance in the solar wind are studied using Ulysses data. We focus on the first mid‐latitude phase of the mission, when the spacecraft intermittently enters the fast high‐latitude wind, and on the region around the first perihelion passage, when low‐latitude wind in conditions of low solar activity is observed. In particular, we look for the existence of a relationship between the alpha‐particle abundance and the solar wind velocity. No evidence of correlation is found for the midlatitude wind, while at low latitudes a positive correlation emerges. This difference may be indicative of a different relevance, in the two regions, of the processes that can be at the origin of low‐speed solar wind. At mid latitudes the low velocity of the wind would be mainly due to the topology of the solar magnetic field, with a large expansion factor. Near the equator this effect would become weaker and a dominant role would be played by source region features related to the alpha‐particle content.