HELIUM ION ANISOTROPIES IN COROTATING INTERACTION REGIONS AT 1 AU

Journal Article · Wed Aug 01 04:00:00 EDT 2012 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/754/2/L30· OSTI ID:22047640

Ebert, R W; Desai, M I; Dayeh, M A ^[1]; Mason, G M ^[2]

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1. Southwest Research Institute, San Antonio, TX (United States)
2. Applied Physics Laboratory, Johns Hopkins University, Laurel, MD (United States)

We investigated the first-order flow anisotropies in the solar wind frame of {approx}0.06-0.95 MeV nucleon{sup -1} He ions during three corotating interaction region (CIR)-associated particle intensity enhancements observed at 1 AU by Wind, examining CIRs with (1) a reverse shock, (2) a well-formed compression region, and (3) a weak compression region. We identified anti-sunward flows in the compression region downstream of the CIR trailing edge in the events with a reverse shock and well-formed compression that transitioned to sunward flows across and upstream of this boundary. These observations suggest that the trailing edge is organizing the He ion flows and is a local source for the particles in these events, this source being inside 1 AU prior to the trailing edge arrival and beyond 1 AU after its passage. The event with the weak compression region had predominantly sunward flows throughout, indicating that the source of the He ions was beyond 1 AU. These observations provide compelling evidence that He ions at 1 AU can be accelerated to suprathermal energies at the CIR trailing edge in events where the compression region is well formed.

• OSTI ID: 22047640
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 2 Vol. 754; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ANISOTROPY
ASTRONOMY
ASTROPHYSICS
HELIOSPHERE
HELIUM IONS
MEV RANGE
SHOCK WAVES
SOLAR WIND
SUN