JETS IN POLAR CORONAL HOLES
| Autor: | John Gerard Doyle, Eamon Scullion, Robert Erdélyi, M. D. Popescu, Dipankar Banerjee |
|---|---|
| Rok vydání: | 2009 |
| Předmět: |
Physics
Astrophysics::High Energy Astrophysical Phenomena Stellar atmosphere Astronomy Coronal hole Astronomy and Astrophysics Astrophysics Corona Solar prominence Blueshift Space and Planetary Science Physics::Space Physics Astrophysics::Solar and Stellar Astrophysics Chromosphere Main sequence Line (formation) |
| Zdroj: | The Astrophysical Journal. 704:1385-1395 |
| ISSN: | 1538-4357 0004-637X |
| DOI: | 10.1088/0004-637x/704/2/1385 |
| Popis: | Here, we explore the nature of small-scale jet-like structures and their possible relation to explosive events and other known transient features, like spicules and macrospicules, using high-resolution spectroscopy obtained with the Solar and Heliospheric Observatory/Solar Ultraviolet Measurements of Emitted Radiation instrument. We present a highly resolved spectroscopic analysis and line parameter study of time-series data for jets occurring on-disk and off-limb in both a northern and a southern coronal hole. The analysis reveals many small-scale transients which rapidly propagate between the mid-transition region (N IV 765 A line formation: 140,000 K) and the lower corona (Ne VIII 770 A line formation: 630,000 K). In one example, a strong jet-like event is associated with a cool feature not present in the Ne VIII 770 A line radiance or Doppler velocity maps. Another similar event is observed, but with a hot component, which could be perceived as a blinker. Our data reveal fast, repetitive plasma outflows with blueshift velocities of 145 km s–1 in the lower solar atmosphere. The data suggest a strong role for smaller jets (spicules), as a precursor to macrospicule formation, which may have a common origin with explosive events. |
| Databáze: | OpenAIRE |
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