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STEREO Observations of Interplanetary Coronal Mass Ejections in 2007–2016
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| Zeitschriftentitel: | The Astrophysical Journal |
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| Personen und Körperschaften: | , , , |
| In: | The Astrophysical Journal, 855, 2018, 2, S. 114 |
| Format: | E-Article |
| Sprache: | Unbestimmt |
| veröffentlicht: |
American Astronomical Society
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| Schlagwörter: |
| Zusammenfassung: | <jats:title>Abstract</jats:title> <jats:p>We have conducted a survey of 341 interplanetary coronal mass ejections (ICMEs) using <jats:italic>STEREO A/B</jats:italic> data, analyzing their properties while extending a Level 3 product through 2016. Among the 192 ICMEs with distinguishable sheath region and magnetic obstacle, the magnetic field maxima in the two regions are comparable, and the dynamic pressure peaks mostly in the sheath. The north/south direction of the magnetic field does not present any clear relationship between the sheath region and the magnetic obstacle. About 71% of ICMEs are expanding at 1 au, and their expansion speed varies roughly linearly with their maximum speed except for ICMEs faster than 700 km s<jats:sup>−1</jats:sup>. The total pressure generally peaks near the middle of the well-defined magnetic cloud (MC) passage, while it often declines along with the non-MC ICME passage, consistent with our previous interpretation concerning the effects of sampling geometry on what is observed. The hourly average iron charge state reaches above 12+ ∼31% of the time for MCs, ∼16% of the time for non-MC ICMEs, and ∼1% of the time for non-ICME solar wind. In four ICMEs abrupt deviations of the magnetic field from the nominal field rotations occur in the magnetic obstacles, coincident with a brief drop or increase in field strength—features could be related to the interaction with dust. In comparison with the similar phases of solar cycle 23, the <jats:italic>STEREO</jats:italic> ICMEs in this cycle occur less often and are generally weaker and slower, although their field and pressure compressions weaken less than the background solar wind.</jats:p> |
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| Umfang: | 114 |
| ISSN: |
0004-637X
1538-4357 |
| DOI: | 10.3847/1538-4357/aab189 |