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CSI 769-001/PHYS 590-001 Solar Atmosphere Fall 2004 Lecture 12 Nov. 17, 2004. Filament/Prominence Eruption Corona Mass Ejection (CME). Filament/Prominence. Meudon (France) H α. Filament/Prominence. BBSO H α.
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CSI 769-001/PHYS 590-001 Solar Atmosphere Fall 2004 Lecture 12 Nov. 17, 2004 Filament/Prominence Eruption Corona Mass Ejection (CME)
Filament/Prominence Meudon (France) Hα
Filament/Prominence BBSO Hα
Filament/Prominence • Filament/Prominence: dense clouds of chromospheric-temperature material suspended in the corona • The filament material is either from cooling of coronal plasma or direct injection of chromospheric material • A filament can remain in a quiet or quiescent state for days or weeks • A filament can erupt and rise of the Sun over the course of a few minutes or hours
Filament in different regions • Active Region Filament • in active region • small in size • shortly lived in time (e.g., day) • Quiescent Filament • in quiet Sun region • long in size • relatively long lived (e.g., week) • Polar Crown Filament • close to polar coronal hole region • very long, e.g., circling the whole Sun at high latitude • very long lived (e.g., month)
Filament in different regions (cont’d) • Exp., Polar Crown Filament
Filament Configuration BBSO Hα Mt. Wilson Magnetogram
Filament Configuration • A filament always sits along the magnetic inversion line (magnetic neutral line) that separates regions of different magnetic polarity • A filament is supported by coronal magnetic field in a supporting configuration • Magnetic dip at the top of loop arcade (2-D) • Magnetic flux rope (3-D) • Helical or twisted magnetic structure is seen within filament
Filament Configuration • One of filament models: filament is supported by twisted magnetic flux rope
Filament Eruption BBSO Hα on 2003/08/05 BBSO Hα on 2004/03/24 BBSO Hα on 2002/11/24
Filament Eruption TRACE 195 Å, 1999/10/20 Filament eruption and loop arcade TRACE 195 Å, 2002/05/27 A failed filament eruption TRACE 195 Å, 1998/07/27 Filament internal motion
Filament Eruption Model • One model • by Martens & Kuin • A unified model of • Filament and • Flare
Filament Channel • A filament channel refers to the envisioned magnetic structure surrounding a filament. It may be larger than the filament itself.
CME (Coronal Mass Ejection) • A CME is a large scale coronal structure of plasma (and associated magnetic field) that is being ejected from the Sun, as seen by a coronagraph
Coronagraph • Coronagraph • A telescope equipped with an occulting disk that blocks out light from the disk of the Sun, in order to observe faint light from the corona • A coronagraph makes artificial solar eclipse • CMEs are observed by coronagraphs • The earliest CME observation was made in early 1970s
White light seen in Corona • Textbook P. 135-142 • K (continuum) corona, caused by scattering of photospheric light of rapidly-moving coronal electrion (so called Thomson scattering); the major component of white-light corona • F (Fraunhofer corona), caused by scattering of photospheric light off dust in interplanetary space between the orbits of Mercury and Earth • E (Emission corona), caused by emission of radiation by highly-ionized species in the actual corona, so called forbidden emission lines, e.g., at 5302 Å from Fe XIV (coronal green line)
White light from Corona (cont’d) • K corona: continuum (what a solar physicist wants) • F corona: continuum plus absorption (do not want) • E corona: emission lines (textbook P. 139, Fig. 5.9)
White light from Corona (cont’d) • K corona brightness is less than 10-5 that of disk • The instrument design is to reduce scattering of light (Textbook P.5, Figure 1.3)
LASCO Coronagraphs • C1: 1.1 – 3.0 Rs (E corona) (1996 to 1998, then died) • C2: 2.0 – 6.0 Rs (white light) (1996 up to today) • C3: 4.0 – 30.0 Rs (white light) (1996 up to today) C1 C2 C3 • LASCO uses a set of three overlapping coronagraphs to maximum the total effective field of view. A single coronagraph’s field of view is limited by the instrumental dynamic range.
Streamer Several streamers in a typical coronagraph image
Streamer (cont’d) • A streamer is a stable large-scale structure in the white-light corona. • It has an appearance of extending away from the Sun along the radial direction • It is often associated with active regions and filaments/filament channels underneath. • It overlies the magnetic inversion line in the solar photospheric magnetic fields. • When a CME occurs underneath a streamer, the associated streamer will be blown away • When a CME occurs nearby a streamer, the streamer may be disturbed, but not necessarily disrupted.