Mass upflows and magnetic-field dynamics in a forming sunspot penumbra
| Autor: | L. V. Ermakova, V. M. Grigor’ev |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Physics
Brightness Sunspot Photosphere 010504 meteorology & atmospheric sciences Meteorology Penumbra Astronomy and Astrophysics Astrophysics 01 natural sciences Magnetic tube Magnetic field Space and Planetary Science Evershed effect 0103 physical sciences Upwelling 010303 astronomy & astrophysics 0105 earth and related environmental sciences |
| Zdroj: | Astronomy Reports. 60:280-286 |
| ISSN: | 1562-6881 1063-7729 |
| DOI: | 10.1134/s1063772916020025 |
| Popis: | The formation of the penumbra of the leading spot of the active region NOAA 11117 has been studied using data fromthe Solar DynamicObservatory (SDO). HMI data on longitudinal magnetic fields, line-of-sight velocities, and continuum images were used. The appearance of localized upflows between the umbra and undisturbed photosphere precedes the penumbra formation. The sizes of them reach 1.5″–2″ and the velocity increases to 1 km/s over several minutes. These localized upflows change themselves to a region of material flowing horizontally from the penumbra (the Evershed effect). The formation of individual spine namely fine radial element of the penumbra magnetic field with higher strength and lower inclination than in the surrounding is traced for the first time. The formation of the spine manifests itself as appearance of region of 2″–3″ in size with enhanced upflow near the sunspot umbra, protrusion in longitudinal-field contours on one side of the upwelling center, and the subsequent appearance of magnetic pole of opposite polarity on the other side of the upwelling. This process is accompanied by a bending of the contour marking the boundary of the undisturbed photosphere, which puts the upwelling center in a zone of higher brightness. One possible explanation for this is the emergence of hot magnetic tube. The appearance and growth of the sunspot spines results in the formation of the penumbra. |
| Databáze: | OpenAIRE |
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