From georgia@creator.space.noa.gr Mon Apr 19 15:53:36 1999 Date: Sun, 18 Apr 1999 20:31:40 +0300 From: georgia@creator.space.noa.gr To: jops@esa.nascom.nasa.gov Cc: georgia@creator.space.noa.gr Subject: JOP 96 Dear colleagues I'm sending to you our proposal for JOP 96 to be run during the MEDOC campaign. Proposal for a JOP TITLE: Magnetic flux emergence in active regions CONTRIBUTORS: C.E. Alissandrakis, H. Dara, C. Gontikakis, G. Tsiropoula, T. Zachariadis, J.-C. Vial (+CDS, SUMER, MDI, EIT teams) INSTRUMENTS TO BE INVOLVED: CDS, SUMER, MDI,EIT GROUND-BASED OBSERVATIONS: At least Ha observations OBJECTIVE: Our aim is to investigate the emergence and development of active regions and especially of the systems of arch-shaped filaments occuring in the interspot region of young bipolar spotgroups. CONDITIONS TO RUN: Occurrence of a young bipolar spotgroup on the solar disk. SCIENTIFIC JUSTIFICATION: The study of the development of active regions is of major interest to solar physicists. According to the widely accepted view, activity occurs where magnetic flux emerges from subphotospheric layers. The magnetic lines of force expand after they emerge out of the photosphere. The rising magnetic arch traps the chromospheric material which drains down both legs due to gravitation as the arch rises. The first evolutionary stage of new sunspot dipoles has a characteristic pattern known as Emerging Flux Region (EFR), which takes place on a variety of lenghts and time scales. The chromospheric manifestation of an EFR seen in Ha is an arcade of predominantly dark, loop-like structures which constitute an Arch Filament System (AFS). The individual arches have a lifetime of 20 to 30 min, while the whole system persists for 3 to 4 days. Then it is replaced by a system of arches which are formed in places where the magnetic field appears to be almost horizontal and are called Field Transition Arches (FTA). As long as the feet are bright (which is and indication of magnetic energy dissipation) we know empirically that flux continues to emerge. No brightenings are observed at the feet FTA. The dynamic characteristics and physical parameters of AFs have been studied by several authors. The classical picture of flow is that of ascending motions near the apex with velocities at ~ 10 km/sec which are interpreted in terms of an upward expansion and descending motions up to 20 km/sec at the footpoints considered as evidence of material draining out of the arches. Although EFRs are of fundamental importance in understanding solar activity their structure and dymanics have not yet been fully understood. One of the major problems is to clarify how magnetic flux is carried from the convection zone to the photosphere and how it expands upwards. Nearly all active regions begin as an AFS. These structures are related to the combined transport of matter and increasing magnetic field during the growth of spotgroup. Thus the AFS could become excellent tools for charting the critical early stages of the evolution of magnetic fields on the solar surface. Our aim is to extend previous works based, especially in the chromosphere, monitoring activity emergence from the photosphere to the transition region through the chromosphere. CDS: Slit choice: 2"x240" Scanned region: 240" x 240" step length: 2.032 number of steps: 120 number of rasters: 2 Dwell time: 30sec total duration of raster=30(sec)x120 = 1 hour Lines: OV 629A logT=5.3 cnts(active Sun)=151 quiet Sun=49.6 MgX 625A logT=6 " =58.5 " = 7.5 SiIX 342A logT=6 " =4.47 " = 3.11 SiIX 349A logT=6 " =13.04 " = 5.2 MgIX 368A logT=6 " =151.04 " =29.77 HeI 522A logT=4.3 " =38.51 " = 4.42 OIII 599A logT=4.9 " =10.54 " = 5.83 OIII 525A logT=4.95 " =7.92 " = 3.79 FeXII 364A logT=6.2 " =34.58 " = 5.63 FeXVI 335A logT=6.39 " =244.63 " = 5.53 FeXIV 334A logT=6.3 " =63.17 " =15.49 telemetry: we have 10kbits/sec to respect The 2x240 slit cover 120 pixels on the detector, we also assume 12 bit per word. One position of the slit will be equal to 11(lines)x120(pixels)x22(spectral pixels)x12bits = 11x31680bits = 348480/30sec = 11616bits/sec, which means 1.2 for the telemetry There is a data compression parameter called CCC that produces a compression of 1.64. We can use it. (The LARGE_BP raster is proposed by Dr Harrison) SUMER: copointing with CDS lines: CIV 1548A, SiII1533A, OVI 1037A and Lbeta 1025A MDI: Frequent magnetograms will be of great value, evenmore if the target is in the high resolution MDI's FOV. EIT: Images of the active region in each of the four lines covering the target area with a cadence of ~10 min. No OF DAYS AND CADENCE OF OBSERVATIONS: ~5-6 days , 2 hours per day. A young evolving bipolar spotgroup must be followed. According to the GB observations it seems that the days in between 11 - 16 May and 2 hours from 13-17 UT are suitable for our observations