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

Filament Eruption

BBSO Hα on 2003/08/05

BBSO Hα on 2002/11/24

BBSO Hα on 2004/03/24

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 ofFilament andFlare

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.