EMERGENCE OF HELICAL FLUX AND THE FORMATION OF AN ACTIVE REGION FILAMENT CHANNEL
- High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307 (United States)
- Lockheed Martin Solar and Astrophysics Lab, 3251 Hanover Street, Organization ADBS, Building 252, Palo Alto, CA 94304 (United States)
- National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
- Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan)
We present comprehensive observations of the formation and evolution of a filament channel within NOAA Active Region (AR) 10978 from Hinode/Solar Optical Telescope and TRACE. We employ sequences of Hinode spectro-polarimeter maps of the AR, accompanying Hinode Narrowband Filter Instrument magnetograms in the Na I D1 line, Hinode Broadband Filter Instrument filtergrams in the Ca II H line and G-band, Hinode X-ray telescope X-ray images, and TRACE Fe IX 171 A image sequences. The development of the channel resembles qualitatively that presented by Okamoto et al. in that many indicators point to the emergence of a pre-existing sub-surface magnetic flux rope. The consolidation of the filament channel into a coherent structure takes place rapidly during the course of a few hours, and the filament form then gradually shrinks in width over the following two days. Particular to this filament channel is the observation of a segment along its length of horizontal, weak (500 G) flux that, unlike the rest of the filament channel, is not immediately flanked by strong vertical plage fields of opposite polarity on each side of the filament. Because this isolated horizontal field is observed in photospheric lines, we infer that it is unlikely that the channel formed as a result of reconnection in the corona, but the low values of inferred magnetic fill fraction along the entire length of the filament channel suggest that the bulk of the field resides somewhat above the low photosphere. Correlation tracking of granulation in the G band presents no evidence for either systematic flows toward the channel or systematic shear flows along it. The absence of these flows, along with other indications of these data from multiple sources, reinforces (but does not conclusively demonstrate) the picture of an emerging flux rope as the origin of this AR filament channel.
- OSTI ID:
- 21455125
- Journal Information:
- Astrophysical Journal, Vol. 718, Issue 1; Other Information: DOI: 10.1088/0004-637X/718/1/474; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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