Spectro-imagery of an active tornado-like prominence: formation and evolution
| Autor: | Nicole Mein, Brigitte Schmieder, Nicolas Labrosse, Krzysztof Barczynski, Aaron W. Peat, Pierre Mein |
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| Rok vydání: | 2021 |
| Předmět: |
Physics
Electron density 010504 meteorology & atmospheric sciences Flux FOS: Physical sciences Astronomy and Astrophysics Plasma Astrophysics Rotation 01 natural sciences Solar prominence Magnetic field Astrophysics - Solar and Stellar Astrophysics Space and Planetary Science 0103 physical sciences Plasma diagnostics 010303 astronomy & astrophysics Solar and Stellar Astrophysics (astro-ph.SR) 0105 earth and related environmental sciences Line (formation) |
| ISSN: | 0004-6361 |
| DOI: | 10.48550/arxiv.2106.04259 |
| Popis: | The nature of flows in tornado-prominences is an open issue. While the AIA imager aboard the Solar Dynamics Observatory (SDO) allowed us to follow the global structure of a tornado-like prominence during five hours, the Interface Region Imaging Spectrograph (IRIS), and the Multi subtractive Double pass spectrograph (MSDP) permitted to obtain plasma diagnostics of its fine structures. We aim to address two questions. Is the observed plasma rotation conceptually acceptable in a flux rope magnetic support configuration with dips? How is the plasma density distributed in the tornado-like prominence? We calculated line-of-sight velocities and non-thermal line widths using Gaussian fitting for Mg II lines and bisector method for H-alpha line. We determined the electron density from Mg II line integrated intensities and profile fitting methods using 1D NLTE radiative transfer theory models. The global structure of the prominence observed in H-alpha, and Mg II h and k lines fits with a magnetic field structure configuration with dips. Coherent Dopplershifts in red- and blue-shifted areas observed in both lines were detected along rapidly-changing vertical and horizontal structures. However, the tornado at the top of the prominence consists of multiple-fine threads with opposite flows suggesting counter streaming flows rather than rotation. Surprisingly we found that the electron density at the top of the prominence could be larger (10^11 cm^{-3}) than in the inner part of the prominence. We suggest that the tornado is in a formation state with cooling of hot plasma in a first phase, and following that, a phase of leakage of the formed blobs with large transverse flows of material along long loops extended away of the UV prominence top. The existence of such long magnetic field lines on both sides of the prominence would avoid the tornado-like prominence to really turn around its axis. Comment: 30 pages, 23 figures, accepted for publication in A&A |
| Databáze: | OpenAIRE |
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