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Catalogue POP – Notice individuelle de publication

Rondi S., Roudier Thierry, Molodij Guillaume, Bommier Véronique, Keil Steve, Sütterlin P., Malherbe Jean-Marie, Meunier Nadège, Schmieder Brigitte, Maloney P.

Photospheric flows around a quiescent filament

Astronomy and Astrophysics, 2007, vol. 467, pp. 1289-1298

Référence DOI : 10.1051/0004-6361:20066649
Référence ADS : 2007A&A...467.1289R

Résumé :

Context: The horizontal photospheric flows below and around a filament are one of the components in the formation and evolution of filaments. Few studies exist because they require multiwalength time sequences at high spatial resolution. <BR />Aims: Our objective is to measure the horizontal photospheric flows associated with the evolution and eruption of a filament. <BR />Methods: We present observations obtained in 2004 during the international JOP 178 campaign which involved eleven instruments both in space and at ground based observatories. We use TRACE WL, DOT and DST observation to derive flow maps which are then coaligned with intensity images and with the vector magnetic field map obtained with THEMIS/MTR. <BR />Results: Several supergranulation cells cross the Polarity Inversion Line (PIL) and can transport magnetic flux through the PIL, in particular parasitic polarities. We present a detailed example of the formation of a secondary magnetic dip at the location of a filament footpoint. Large-scale converging flows, which could exist along the filament channel and contribute to its formation, are not observed. Before the filament's eruptive phase, we observe both parasitic and normal polarities being swept by a continuously diverging horizontal flow located in the filament gap. The disappearance of the filament initiates in this gap. Such purely horizontal motions could lead to destabilization of the filament and could trigger the sudden filament disappearance.

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