Filament Doppler Shifts at Multiple Temperatures
T.Kucera, A.I. Poland,
Received October 29, 1999
SUMER observations of Doppler shifts in filament channels in
lines in a wide range of temperatures with CDS context images.
Introduction and Background
Prominences consist of large amounts of cool (10,000 K), dense material which
hangs suspended in long channels in the corona. These channels form in between
areas of opposite polarity and are visible as long dark features in emission
produced at coronal temperatures. The channels often exist without any
prominence material in them at all. They are crossed by arcades of hot (>1e6
K) loops. The filament itself forms beneath the arcade. It is still not known
what causes the actual filament material to collect in the filament channel,
or what causes the flows and motions observed in the plasma once it is there.
Although by far the bulk of filament material is relatively cool, filaments
are connected to their hotter surroundings by plasmas at hotter temperatures.
Using UV and EUV spectral lines formed at 2e4< T< 1e6 K and even higher can
provide valuable information on the origin, structure and dynamics of
filaments and their environments.
Many models seek to explain the presence of material in filaments via heating
and cooling of material from areas connected to the prominence via magnetic
fields. Such models predict various signatures which should be visible in
spectral lines produced at chromospheric and transition region temperatures.
Other models postulate that the material is lifted into the corona directly by
the magnetic field, also yielding distinctive spectral line signatures.
Furthermore, although the material is generally cool, prominence emission can
regularly be seen in lines formed at up to 6e5 K. Analysis of such data can
reveal important information about the structure of the prominence-corona
interface, which in turn can help us understand the complex motions observed
in prominence material.
We are attempting to measure the Doppler shifts in and around filament
channels are a function of temperature by observing these feature in a wide
range of lines with relatively long (5 min) exposure times.
In order to best remove the effect of detector distortion from the Doppler
shift measurements, the SUMER programs cycle through a series of grating
settings - pointing both at the filament and 120" to the south.
1859 KUC NS_SHFTA1 - Observes in 13 wavebands for Detector A. (2h49m12s)
Was used in campaign 5620. A Detector B version exists,
but has not been run.
1860 KUC HEI_RAS_A_NP - He I context raster (16m2s)
1 run of FILOBS2/v59 (which lasts about 70 min)
and then as many runs as is reasonable of
FILOBS1/v4 (which takes about 22 min/raster)