JOP160 Emergence and Evolution of Young Active Regions

Received: Wednesday 19 June 2002

Participants: SOHO/MDI, SOHO/EIT, TRACE, THEMIS

Observation Period: July 27 - August 1, 2002

Contacts:
    THEMIS: Daniele Spadaro, INAF-Osservatorio Astrofisico di
                Catania, dspadaro@ct.astro.it 
                - PI of this JOP
            Francesca Zuccarello, Department of Physics and Astronomy,
                University of Catania, fzucca@ct.astro.it
    MDI: Alexander Kosovichev, Stanford University,
            sasha@quake.stanford.edu
    TRACE: Karel Schrijver, LMSAL, schryver@lmsal.com


SCIENCE OBJECTIVES:

We want to investigate the initial evolutionary phases of active
regions by using observations with the THEMIS IPM instrument in
several wavelength bands, including FeI and H-alpha, SOHO/MDI and
TRACE. Our emphasis will given to the dynamics of magnetic
elements (pores, sunspots), their emergence and temporal
evolution. We want to detect and study the motions of magnetic
flux tubes footpoints in order to deduce their characteristics
during different stages of the active region evolution. 


TARGET SELECTION:

The observing program requires that the target selection
is done as close as possible to the observing run.
We plan to do this 1 day in advance, and hope that this
will be acceptable for both TRACE and MDI. If the target
is in the MDI hi-res field of view then the high-res mode
with Dopplergrams and magnetograms is strongly preferred.



THEMIS OBSERVATIONS:

This will be accomplished by taking take images in several bands including
Fe lines. The IPM filter bandpass will be cyclically varied in
order to obtain the information about motions along the line of
sight. The footpoint motions are believed to shear magnetic field
lines which extend up to the chromospheric and coronal levels
above the active regions and produce dips in the magnetic arcades
(Antiochos et al. 1994), where condensing material can settle and
form prominences (filaments) (Antiochos et al. 1999, 2000). Hence,
we wish to correlate the characteristics of footpoint motions with
the process of the formation of prominences in the investigated
active regions by using H-alpha observations. This will allow us
to test the model of the prominence formation.

THEMIS observations have been scheduled for this period.


MDI:

We request the MDI support in order to study the magnetic field
structure and evolution of the selected active regions, and to
obtain the information about the subphotospheric flows associated
with the active regions, by using the time-distance
helioseismology. The high-resolution MDI observations of magnetic
field and Doppler velocity are preferred if the target is in this
field. If the target is outside the hi-res field then the MDI will
take full-disk magnetograms and Doppler velocity with 1-min
cadence.

TRACE:

We also request support by TRACE (171 A band) in order to study
the morphology and the relevant evolution of the transition and
corona above the selected active regions. These observations are
also useful for detecting the formation of filaments during the
evolution of the active regions.

EIT:

EIT should support JOP 160 from July 27 to August 1 through its
synoptic program. An extra synoptic sequence should be added at 
10:00 UT during these days.