Plasmoid Releases in the Heliospheric Current Sheet and Associated Coronal Hole Boundary Layer Evolution

Abstract

As the heliospheric current sheet (HCS) is corotating past STEREO-B, near-Earth spacecraft ACE, Wind and Cluster, and STEREO-A over more than three days between 2008 January 10 and 14, we observe various sections of (near-pressure-balanced) flux-rope-and magnetic-island-type plasmoids in the associated heliospheric plasma sheet (HPS). The plasmoids can qualify as slow interplanetary coronal mass ejections and are relatively low proton beta (<0.5) structures, with small length scales (an order of magnitude lower than typical magnetic cloud values) and low magnetic field strengths (2-8 nT). One of them, in particular, detected at STEREO-B, corresponds to the first reported evidence of a detached plasmoid in the HPS. The in situ signatures near Earth are associated with a long-decay X-ray flare and a slow small-scale streamer ejecta, observed remotely with white-light coronagraphs aboard STEREO-B and SOHO and tracked by triangulation. Before the arrival of the HPS, a coronal hole boundary layer (CHBL) is detected in situ. The multi-spacecraft observations indicate a CHBL stream corotating with the HCS but with a decreasing speed distribution suggestive of a localized or transient nature. While we may reasonably assume that an interaction between ejecta and CHBL provides the source of momentum for the slow ejecta's acceleration, the outstanding composition properties of the CHBL near Earth provide here circumstantial evidence that this interaction or possibly an earlier one, taking place during streamer swelling when the ejecta rises slowly, results in additional mixing processes.

Reconstruction and Prediction of Variations in the Open Solar Magnetic Flux and Interplanetary Conditions

“…These unambiguously reveal "folded flux" (in which source toward/away field is folded so it points away from/toward the Sun at greater (e.g., . Folded flux revealed by the suprathermal electron flows is often found in the vicinity of sector boundaries (Kahler et al, 1998;Crooker et al, 2004) along with seemingly plasmoidal structures (Foullon et al, 2011) (which may, in some cases, actually be folded flux that has latitudinal structure). In addition, have recently shown folded flux is also associated with pseudostreamers embedded within IMF polarity sectors.…”

“…Like the fixed-T (modulus) methods it has the advantage of being repeatable without implementing a catalogue of source sector boundary crossings. However, it should be noted that disconnected and folded flux is often well-aligned with the Parker spiral (Crooker et al, 2004;Foullon et al, 2011; and that the authors used an averaging interval of T = 6 h to match the open solar flux estimates derived from the satellite to those from the PFSS values, and hence there is an element of fixed-T averaging in this method also. …”

The proton and electron radiation belts at geosynchronous orbit: Statistics and behavior during high‐speed stream‐driven storms

“…Then (4) the magnetic field, proton temperature, and electron strahl structure of the solar wind data are examined to ensure that the CIR is not dominated by a magnetic cloud. Magnetic clouds are usually ejected from the magnetic sector reversals of helmet streamers [ Foullon et al , ] or from the double sector reversals of pseudostreamers [ Liu , ], both of which appear at 1 AU on the leading edges of CIRs; if a magnetic cloud is prevalent in the CIR, the event is rejected as a storm of “mixed origin.” Unfortunately, prior to 1995 solar wind measurements are sparse. In the OMNI2 multisatellite data base [ King and Papitashvili , ] for 1976–1994, solar wind velocity measurements are only available 55% of the time.…”

Tracking Solar Active Region Outflow Plasma from Its Source to the Near-Earth Environment

“…These authors found evidence from the Advanced Composition Explorer (ACE) in-situ data for the presence of active-region material in the slow solar wind that was associated with the passage of the two active regions across the disc in January 2008. Presence of (additional) ejected plasmoid material in the heliospheric plasma sheet (HPS) was suggested by Foullon et al (2011).…”