SOT: A statistical analysis of the Magnetic fields of the Network Bright Points (NBP) with the BFI and NFI at the boundaries of supergranules
2008-12-11T01:09:50 to 2008-12-11T02:08:58
Science Goal: A statistical analysis of the Magnetic fields of the Network Bright Points (NBP) with the BFI and NFI at the boundaries of supergranules
Program: Mg IV -140mA, 2.8Kx1.4K, 2x2, Q75, G-band, 4Kx2K, 2x2, Q75, 1 min
Target: Granulation
xcen=-3 ycen=0
Instrument: SOT
HOP/JOP: 95
Description:
Target: Supergranular cell boundary in quiet Sun. Sequence 1: duration 1 hour Temporal resolution: 1 minute FOV: small enough to achieve 1 minute cadence (try 1k x 1k, 2x2 summed to begin...) - BFI: G-band - NFI: Na Id in IV mode, standard blue wing tuning Sequence 2: duration 1 hour Temporal resolution: 1 minute FOV: small enough to achieve 1 minute cadence - BFI: G-band - NFI: Mg Ib in IV mode standard blue wing tuning Sequence 3: duration 1 hour FOV: small enough to achieve 1 minute cadence - BFI: G-band - NFI: Mg Ib in shuttered IQUV mode (or only IQU), filter tuned to line CENTER Other Instruments: Scientific Objectives: The physics of intense magnetic flux tubes, which appear in intergranular lanes and at supergranule boundaries as bright points (NBP) is a very active research topic. Hinode can do a lot on this domain at high spatial resolution. Flux tubes may be studied individually at high precision using the vector magnetograph of the SOT. This has already been tempted with Hinode by some observers. Here, we suggest an alternative approach in order to have a larger amount of NBP in the field of view, containing several mesogranules, and probably parts of supergranules, based on BFI and NFI observations. Of course, the accuracy of magnetic field determinations will not be so good, but the number of NBP in the FOV will be much greater. The BFI will provide images in the G band and above, in the low chromosphere, in the CaH line. On such images, NBPs appear as proxies of intense magnetic flux tubes. The NFI will provide the Stokes V in one of the wings of FeI line. The line of sight magnetic field may be deduced from such observations under some asumptions. A short sequence of 1 hour is sufficient to make a good analysis over NPB available in the FOV, mainly at the boundaries of supergranules. We have already made such observations in August 2007 with our 48 H sequence. The new idea is the following: we would like to suggest (we do not know if it is possible or not) to observe the Stokes Q and U parameters with the NFI in the centre of the FeI line where the signal is maximum. This would be of great interest in order to study transverse magnetic fields, and orientations (modulo 180??????), at the boundaries of supergranules. These quantities can be derived under some approximations on the shape and the central depression of the line.
wavelength: G band 4305 cadence: 1 min fov: 223,111 images: 60 JavaScript Landing Page
