CORE VERSION OF JOP9 (as of May 1995)
-----------------------------

SOHO observations programs

1) Prominence diagnostics and dynamics

Contributors: J. Fontenla, J.-C. Vial, F. Paletou

The purpose of this project is to understand the structure of
prominences from the standpoint of the physics involved in the energy and force
balance processes that make them form, endure and dissapear. For this we need to
evaluate the importance, effects, and quantitative description of basic
physical processes, and then combine them into a full, consistent,
physical picture. These processes involve at least the following:

 a) particle transport along and accross the magnetic field, basically
    mass and energy exchange through the prominence-corona interface (or
    prominence- corona transition region);
 b) optically thin radiative losses, both in the prominence-corona
    interface and in the core of a forming condensation illuminated by solar
    radiation;
 c) radiative transfer between prominence and solar atmosphere (mainly
    the chromosphere where the incident radiation forms), and between various
    parts of the prominence, this involves interactions between prominence
    threads, Doppler shifts of incident with respect to local profile,
    and multidimensional radiative transfer;
 d) MHD processes that determine the force balance in both the local and

global scale, these involve considering the background magnetic field
configuration, the local electric current distribution, and the
magnetic interactions between various parts of the prominence.
These points are critical to all phases of prominences, but the detailed
treatement depends on which phase is studied. Many of these processes
have been studied in other contexts and few of them have been studied for
prominences (e.g., the prominence-corona interface was recently studied by FRVG
(Fontenla, Rovira, Vial and Gouttebroze), the radiative transfer was investigated
by HVG (Heinzel, Vial and Gouttebroze), the multidimensional radiative transfer
was investigated by PAV (Paletou, Auer and Vial)). These results will be
used and extended with quantitative evaluations of particular prominences that
will be observed to determine particular aspects in individual cases.
The basic scheme of the project is to set important questions, develop
observational sequences, and interpret quantitatively the results and
how they answer the questions. Few examples in which we want to concentrate
follow:

*) Formation: Observations have revealed that cold and warm dynamic material seen in
   Lyman alpha and C IV, respectively, is abundant on the corona apart
   from prominences, specially at heights below 10 arcsec above the
   chromosphere.

   - How much of this material is at each temperature and density range, and
     how this distribution relates to the photospheric magnetic fields?
   - How the distribution and shapes of the often observed loops relate to
     the network (are the footpointS in the cells or lanes, in high field)?
   - Why is this material in motion and whether and how it becomes almost
     homogeneous in temperature?
   - What is the actual size and geometry of such features, are they loops,
     what about plasmoids, are there both?
   - What is the footpoint signature of the dynamic loops, if any?
   - What is the interface between the dynamic loops and the corona (on the
     sides), are there current sheets?
   - If there are current sheets, how are they formed and maintained, are
     they in equilibrium, do they produce significant heating?
   - Where is gas and magnetic pressure lower: inside or outside the loops,
     do the two pressures balance or is there significant tension force?
   - Can the dynamic material be caught into magnetic traps and be the
     inital core of a prominence?
   - Once the initial core is formed, would it be stable, could it
     accumulate more mass, under which conditions?
   - As the initial core fills with mass, would the temperature drop or not,
     if it drops how fast and to which value, which are the net radiative
     losses?
   - How does the prominence formation relate to the cavity above, is there
     a relationship between prominence mass and cavity depletion or size?
   - Which electric currents develop as the prominence mass increases,
   - How does a prominence growth affect the background magnetic field, does
     a prominence change the background field (e.g., produces image current)
     in a particular way?

*) maintenance

   - Are prominences thermally stable or is the material being refilled
     through the corona, if so is it by coronal condensation or syphon from the
     chromosphere?
   - If there is refill, how are prominences loosing and gaining mass by
     ejections, by slow or fast drift, along or accross the fieldlines, does ambipolar
     diffusion transport accross the field play a role?
   - Why the prominences have fine structure, what size does this structure
     have, is it fixed or changing, dynamic or static, homogenoeus or varies with
     altitude or at the edges?
   - How does this structure affect the support and energy balance?
   - What is the interface between the prominences and the corona, are there
     current sheets, what are the roles of diffusion and heat conduction?
   - Which are the differences in density and temperature at the greater
     height and edges of prominence slabs? Why are there such differences?
   - How does a prominence maintain its temperature and density, are they
     constant vary slowly or fluctuate in time?
   - Why all prominences have similar parameters, are they really similar,
     or what is the variability?
   - Are the temperature and pressure almost homogeneous or vary a lot, if
     so in which temporal and spatial scale, is this related to the fine structure
     or not (the fine structure is just density variation), how does this
     relate to the field, does the magnetic field vary a lot or is it mostly
     homogeneous, and what about the electric currents?

*)DISAPPEARANCE

   - How prominences heat up and disapear, what is the difference that makes
     them stable or unstable to heating?
   - How are prominences being ejected, are there changes in the internal
     structure, how these changes relate to electric current changes, are there changes
     in the background field, how is the external field changed and how
     external changes affect the prominence structure?
   - Why some changes of the field may trigger prominence eruptions, others
     give heating and others don't affect them, are there specific type of
     changes, do they relate to specific prominence temperature and or density
     changes?
   - Are there strong incoming waves when prominences disappear, or is the
     prominence source of waves when disappearing?

This long list is just a summary of basic things we need to answer for
claiming we understand prominences. Many more questions can be posed too. To date
few observations have addressed these points, mainly because ground-based
optical data are not good enough to answer most of them.
Next we will ellaborate on experiments that can provide answers to many
of these questions. Of course, the answers from some experiments will
change others and inspire new ones. Some specific experiments we propose are
as follows:

 *) Use magnetograms (e.g., Kitt Peak) from previous days to compute
    potential fields (vector fields are better and we will coordinate with ground
    based observations of such), determine locations at the West limb with a few
    typical configurations (also look for non-potentiality as a configuration
    parameter).

    We will also coordinate with priminence polarization measurements.
    Use the strong  available lines, preferable temperature sensitive,
    covering the whole temperature range from coronal to as low as possible, idealy:
    Si XII 499, Mg X 625, O VI 1038, O V 630, Ne VIII 770, Ly c 912, C III
    977, C IV 1548,  Si IV 1394, C III 977, Si III 1206, He I 584, Si II 1265
    and 1197, Si I 1257, Ly beta 1026, and Ly alpha 1216.
 
    Infer the amount of material, at each temperature range, as function of
    position and field configuration (both local and global).

 *) The same as before but using density sensitive pairs of lines,
    initially:

    N III 772,989,1752,989, O IV 625,790,1401,1404,1407, Ne VI 562,999,1006,1010.
    (See Vernazza and Mason 1978, ApJ 226, 720).

    Infer the electron density at each temperature range and then the
    pressure as function of position and magnetic configuration.We will try to
    combine this with optical measurements of 10830, He I 5876, Na D, Mg b, Balmer and
    Ca lines.

 *) Observe cool material in the filament channels where no H alpha
    filament is observed. Look at sequences of line profiles in Ly alpha and beta,
    and He I 584, and  compare with neighboring regions find whether there is, and
    how much, cool absorbing material in the channeLs, whether the profiles are
    static or have any typical velocities and widths, find out if there is
    dynamic material only or if there is evidence of trapping. Compare channels
    that are mostly potential with others that are highly sheared. Some line
    modeling will be needed here.

 *) Similar to previous but carried on near disk center neutral lines
    where H alpha filament is observed, and where the field is apparently
    changing as seen in H alpha and idealLy magnetograms, find relation between changes
    and line asymmetry and or broadening. This will also require line modeling.

 *) On the limb, use the brightest previous lines, together with highest
    spatial and  temporal resolution, find fluctuations in profiles
    (intensities, shapes, widths and shifts), relate to position in prominence and
    magnetic configuration as inferred from potential field from previous or
    posterior magnetograms. Look also for inclined profiles where rotation may occur.

 *) As many of the above for comparing active region with quiet Sun
    prominences.  Here the field may evolve faster, and filaments are easy targets.

 *) Select few quiescent prominences to compare two or more pairs of
    density sensitive lines, formed in the same temperature range, between two
    isoelectronic sequences, one pair should be highly sensitive to temperature and the
    other insensitive, e.g., B and Li seqs. The comparison would show departures
    from local ionization equilibria. Also look for correlations between velocity and
    density variations. One can evaluate the diffusion or flow accross that
    temperature range, in relation to the temperature gradient and density. We are
    working on the theory of these effects, and will study several species to
    compareinferred mass flows and diffusion velocities form them. Check for ionization
    degree dependence, this gives relationship with electric field and with
    classical Coulomb collision processes.

I.A PROMINENCE EMISSION MEASURE
Operational Sequence

Initial pointing                selected limb position at the slit
center
Slit                    1x120 arcsec^2
Scan Area               120 arcsec^2
Step Size               0.76 arcsec; 4 STEPS OVER 2S
Resulting Number of Scan Locations      160 ELEMENTARY steps; 40
EXPOSURES
Dwell Time              10 s
Duration of Scan        6 MIN 40 S
Number of Scans         2
Number of Scan Mirror Settings  3
Repointing              none
Total Duration          8 MIN
Line Selection          1/ CIV (1548A AND 1550A), NE VIII (770 & 780)
                        2/ SI IV (1394 & 1401), O IV (1401 & 1404)
                        3/ NV (1238 & 1242), MG X(625), O V (630)

Bins Accross Line       25
Estimated Reduction Factor
        * Selection     1/ 4x25x24 ((AVERAGE OVER 5 SPATIAL PIXELS))
                        2/ 4x25x24 ((AVERAGE OVER 5 SPATIAL PIXELS))
                        3/ 4x25x24 ((AVERAGE OVER 5 SPATIAL PIXELS))

        * Compression   BYTESCALE 1
        * Reduction
Co-operation Requirements       CDS (SEE THE CME PROGRAM JOP3)

I. B LYMAN ALPHA EMISSION IN LIMB PROMINENCE
Operational Sequence

Initial pointing                selected limb position at the slit
center (SAME AS ABOVE)
Slit                    1x120 arcsec^2
Scan Area               120 arcsec^2
Step Size               0.76 arcsec; 4 STEPS OVER 2S
Resulting Number of Scan Locations      160 ELEMENTARY steps; 40
EXPOSURES
Dwell Time              4 s
Duration of Scan        2 MIN 40 S
Number of Scans         2
Number of Scan Mirror Settings          1
Repointing              none
Total Duration          2 MIN 40S
Line Selection          Ly alpha (1216.7A) (ON THE BARE MCP)
Bins Accross Line       50 pixelS
Estimated Reduction Factor
        * Selection     1x50x24 (AVERAGE OVER 5 SPATIAL PIXELS)
        * Compression   NONE
        * Reduction
Co-operation Requirements       CDS (SEE THE CME PROGRAM JOP3)

I. C PROMINENCE EMISSION MEASURE
Operational Sequence

Initial pointing                selected limb position at the slit
center (SAME AS ABOVE)
Slit                    1x120 arcsec^2
Scan Area               120 arcsec^2
Step Size               0.76 arcsec; 4 STEPS OVER 2S
Resulting Number of Scan Locations      160 ELEMENTARY steps; 40
EXPOSURES
Dwell Time              10 s
Duration of Scan        6 MIN 40 S
Number of Scans         2
Number of Scan Mirror Settings          4
Repointing              none
Total Duration          11 min
Line Selection          1/ Ly beta (1026A), O VI (1032 & 1036)
                        2/ SI XII (499), N III (992), C III (977), LY
GAMMA (973)
                        3/ LY DELTA, LY EPSILON, LY 6, LY 7 (926)
                        4/ LY CONT (912), C II (904), NE VII (895), LY
CONT (880)
Bins Accross Line       25 pixelS
Estimated Reduction Factor
        * Selection     1/ 4x25x24 ((AVERAGE OVER 5 SPATIAL PIXELS))
                        2/ 4x25x24 ((AVERAGE OVER 5 SPATIAL PIXELS))
                        3/ 4x25x24 ((AVERAGE OVER 5 SPATIAL PIXELS))
                        4/ 4x25x24 ((AVERAGE OVER 5 SPATIAL PIXELS))
        * Compression   BYTESCALE 1
        * Reduction
Co-operation Requirements       CDS (SEE THE CME PROGRAM JOP3)

II. DENSITY IN PROMINENCE
NOTE THAT PROGRAM I.A. (SCAN 2) ALLOWS A DENSITY MEASUREMENT  AT
O IV TEMPERATURE (1.7 E5)
IT IS DIFFICULT TO BUILD AN EFFICIENT PROGRAM ALLOWING FOR
 SIMULTANEOUS  MEAUREMENTS IN THE TWO LINES INVOLVED.
IF THIS SIMULTANEITY IS NOT CRITICAL, ONE CAN RECORD THE LINES WHICH
ARE NEEDED FOR DENSITY DIAGNOSTIC DURING THE SPECTRAL SCAN ABOVE
(TOTAL DURATION: 21 MINUTES

III. FILAMENT CHANNELS AND
IV FILAMENTS:
 Operational Sequence

Initial pointing                selected FILAMENT OR FILAMENT CHANNEL at
the slit center
Slit                    0.3x120 arcsec^2
Scan Area               120 arcsec^2
Step Size               0.38 arcsec; 8 STEPS OVER 2S
Resulting Number of Scan Locations      320 ELEMENTARY steps; 40
EXPOSURES
Dwell Time              8 s
Duration of Scan        5 MIN 20 S
Number of Scans         2
Number of Scan Mirror Settings  3
Repointing              SOLAR CORRECTION
Total Duration          8 MIN
Line Selection          1/ Ly alpha (1216.7A) (ON THE BARE MCP)
                        2/ HE I (584)
                        3/ LY BETA (1025)
Bins Accross Line       50 pixelS
Estimated Reduction Factor
        * Selection     1/ 1x50x24 (AVERAGE OVER 5 SPATIAL PIXELS)
                        2/ 1x50x24 (AVERAGE OVER 5 SPATIAL PIXELS)
                        3/ 1x50x24 (AVERAGE OVER 5 SPATIAL PIXELS)
        * Compression   NONE
        * Reduction
Co-operation Requirements       CDS (SEE THE CME EARTH-ORIENTED PROGRAM)

V. HIGH RESOLUTION QUIET PROMINENCE
THE PROGRAM IS IDENTICAL TO PROGRAM IV EXCEPT THAT ONE NEEDS NOW
A VERY HIGH COMPRESSION RATE AND/OR DATA SELECTION
Operational Sequence

Initial pointing                selected PROMINENCE at the slit center
Slit                    0.3x120 arcsec^2
Scan Area               120 arcsec^2
Step Size               0.38 arcsec (2 STEPS FOR ONE EXPOSURE)
Resulting Number of Scan Locations      320 ELEMENTARY steps; 160
EXPOSURES
Dwell Time              2 s
Duration of Scan        5 MIN 20 S
Number of Scans         2
Number of Scan Mirror Settings  3
Repointing              SOLAR CORRECTION
Total Duration          16 MIN
Line Selection          1/ Ly alpha (1216.7A) (ON THE BARE MCP)
                        2/ HE I (584)
                        3/ LY BETA (1025)
Bins Accross Line       50 pixelS
Estimated Reduction Factor
        * Selection     1/ 1x50x120
                        2/ 1x25x120
                        3/ 1x25x120
        ACCUMULATION OF DATA DURING SCANS  AND TRANSMISSION OF
EXCESS DATA (ABOUT 4 MBYTES) LATER ON.
        * Compression BYTESCALE 1
        * Reduction
Co-operation Requirements       CDS

VI SAME AS ABOVE FOR ACTIVE REGION PROMINENCE

VI DEPARTURES FROM LOCAL IONIZATION EQUILIBRIA
IF TIME IS NOT CRITICAL, WE CAN USE SEQUENCES I.A AND I.C ABOVE
FOR LINES OF O IV (B LIKE), O VI (LI LIKE): IN THIS CASE IT IS NECESSARY

THAT CDS RECORDS O VI (173 A).
___________________________________________________________________________

2) The composition of the dynamic low-altitude layers above the limb.

Contributors: J. Fontenla, J.-C. Vial, K. Bocchialini

Scientific Justification

Material above the limb has been observed in various wavelengths and the
observations are not explained by traditional sphericAlly symmetric
chromosphere-transition region models. Early observations showed
spicules at about 10^4 K (e.g. Beckers ), UVSP data showed a "cloud layer" of
dynamic material in the range of heights <~10,000 km (Fontenla et al 1987),
other UV data showed macro-spicules, and recently X-ray data from NIXT showed an
absorption rim.
The range in temperatures where this material is seen covers 10^4-10^5
K, and the velocities are tens of km/s. The Lyman alpha data showed a very
different profile as soon as the limb is crossed, and the central
reversal disAPPEARs. Also, the N V and C IV showed THAT this material is above
the bright rim in these lines. The can /SUPPRESSnSUPPRESS: onical X-ray absorption,
and the UV interpretation  advanced BY by Orrall and Schmall (19..), invoke neutral Hydrogen and
Helium  at or below 10^4 K and points that spicules are not enough, but
these data cannot determine which is the temperature and the source of
absorption. The observation so far indicateS that this material is very
dynamic and may represent the byproduct of MHD waves that were almost Alfven
type at the base of the chromosphere but brake into complex non-linear motions
at the top of the chromosphere and above. Therefore, these motions can be
closely associated with the magnetic energy and momentum transport through the
chromosphere into the corona. The diagnostics can make possible to
estimate the electric currents associated to these features, and thus the energy
flow.

SUMER provides the unique means for determining the height structure,
and composition of these dynamic layer, and its dependence with the
underlying solar features. We plan to observe the composition of this layer in
coronal holes, quiet Sun, and two types of active regions (simple bipolar and
complex polarity). For this we plan to observe various lines around Ly alpha,
NV, Si III, CIV and , and Si IV and. The slit 1x120 or 0.3x120 arcsec^2 will
be used and only a few rastering positions will be taken. Through
coordination with CDS we will try to secure an image of the position observed
so that we can determine the EUV morphology of the region observed.
With these data we will model the statistical distribution of
multi-thermal and multi-velocity material that can explain the observed profiles.
Strong departures from ionization equilibrium are expected and also a
distribution of densities is expected. For these regions we will analyze as many
lines as possible, including allowed and intercombination lines, and a few
continuum wavelengths to determine the reference height. The observations timing
is not crucial, and a number of these, at least 8 will be necessary to sample
the coronal hole and quiet Sun features, and another 8 to sample the two
types of active regions. However, the active region program would be dependent on
locating an adequate active region at the limb, and thus  has scheduling
constraints.


I.A LIMB EMISSION MEASURE
Operational Sequence

Initial pointing                selected limb position at the slit
center
Slit                    1x120 arcsec^2
Scan Area               10 arcsec
Step Size               0.76 arcsec
Resulting Number of Scan Locations      14 steps
Dwell Time              60 s
Duration of Scan        14 MIN
Number of Scans         2
Number of Scan Mirror Settings  3
Repointing              none
Total Duration          14 MIN
Line Selection          1/ CIV (1548A AND 1550A), NE VIII (770 & 780)
                        2/ SI IV (1394 & 1401), O IV (1401 & 1404)
                        3/ NV (1238 & 1242), MG X(625), O V (630)

Bins Accross Line       25
Estimated Reduction Factor
        * Selection     1/ 4x25x120
                        2/ 4x25x120
                        3/ 4x25x120

        * Compression   BYTESCALE 1
        * Reduction
Co-operation Requirements       NONE

I. B LYMAN ALPHA EMISSION AT LIMB
Operational Sequence

Initial pointing                selected limb position at the slit
center (SAME AS ABOVE)
Slit                    1x120 arcsec^2
Scan Area               10 arcsec
Step Size               0.76 arcsec
Resulting Number of Scan Locations      14 steps
Dwell Time              10 s
Duration of Scan        2 MIN 20 S
Number of Scans         2
Number of Scan Mirror Settings          1
Repointing              none
Total Duration          4 MIN 40S
Line Selection          Ly alpha (1216.7A) (ON THE BARE MCP)
Bins Accross Line       50 pixelS
Estimated Reduction Factor
        * Selection     1x50x120
        * Compression   NONE
        * Reduction
Co-operation Requirements       NONE

I. C LIMB EMISSION MEASURE
Operational Sequence

Initial pointing                selected limb position at the slit
center (AS ABOVE)
Slit                    1x120 arcsec^2
Scan Area               10 arcsec
Step Size               0.76 arcsec
Resulting Number of Scan Locations      14 steps
Dwell Time              60 s
Duration of Scan        14 MIN
Number of Scans         2
Number of Scan Mirror Settings          4
Repointing              none
Total Duration          19 min
Line Selection          1/ Ly beta (1026A), O VI (1032 & 1036)
                        2/ SI XII (499), N III (992), C III (977), LY
GAMMA (973)
                        3/ LY DELTA, LY EPSILON, LY 6, LY 7 (926)
                        4/ LY CONT (912), C II (904), NE VII (895), LY
CONT (880)
Bins Accross Line       25 pixelS
Estimated Reduction Factor
        * Selection     1/ 4x25x120
                        2/ 4x25x120
                        3/ 4x25x120
                        4/ 4x25x120
        * Compression   BYTESCALE 1
        * Reduction
Co-operation Requirements       NONE

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