JOP180 Connection of photospheric and chromospheric magnetic fields and flows to coronal and transition region brightness and dynamics Short title: JOP180 Magnetic Fields and Flows to Corona/TR, EIT/TRACE/MDI/SUMER/VTT Version 1: 2005/04/25 Investigators: ============== Sami K. Solanki (PI) Andreas Lagg (VTT) Davina Innes (TRACE,EIT) Thomas Wiegelmann (MDI) Luca Teriaca (SUMER) (all MPS) Participating Instruments: ========================= SOHO: EIT, MDI, SUMER TRACE VTT (Tenerife): TIP-2 Observing Time: =============== May 13 - May 20 2005, daily from 9:00 - 12:00 UT Scientific summary: =================== In previous work (Solanki et al. 2003, Nature, Lagg et al. 2004, A&A, Wiegelmann et al. 2005, A&A) we have shown that using the full Stokes measurements of the He 10830 line it is possible to trace magnetic structures such as loops and to detect current sheets. These observations also reveal the presence of highly supersonic flows at many locations in the upper chromosphere (Lagg et al. in preparation). With the new observations we aim to find the relationship between the magnetic structures in the photosphere (VTT, MDI) and in the upper chromosphere (VTT) with EUV brightness images (TRACE, EIT) and velocities measured in EUV lines (SUMER). In this way we propose to uncover the transition region and coronal signatures associated with the magnetic field at different layers in the atmosphere. Since the magnetic field is already very close to force free at the level where the He 10830 line is formed (in contrast to the photosphere, where most observations are carried out), the magnetic structure deduced from this line should be much more closely related to transition region and coronal structures and dynamics. For example, we hope to uncover the relationship between the loops seen in He 10830 and hotter coronal loops seen in the different EIT filters and in TRACE Fe IX/X 171 Angstroms. The relation between the photospheric and chromospheric magnetic structure and flows measured by SUMER in different transition region lines will also be of great interest (as will the relation between flows seen with SUMER and in the He 10830 line). Within the more general aims described above we are also specifically interested in verifying the proposal of De Pontieu et al. (2004, Nature, 2005 ApJ) that the 5-minute photospheric oscillations are guided through the chromosphere and the transition region by inclined magnetic flux tubes (where the cutoff frequency is lower). The basic unknown is the inclination of the magnetic field lines in the different atmospheric layers at the locations at which 5 minute oscillations pass into the upper atmosphere. Using observations in the He 10830 A line recorded with the new TIP 2 detector mounted at the VTT on Tenerife we will be able to determine the full magnetic field vector (and in particular its inclination). The Si I line at 10827 A will provide the photospheric magnetic field vector. The larger field of view and the extended wavelength window compared to the old TIP instrument will significantly improve the capabilities of the VTT for the proposed type of study. The TIP2 / VTT observations will also provide data on oscillations at the photospheric and chromospheric level. However, it will be important to complement these measurements with oscillations recorded by MDI in its high resolution mode (since the TIP2 instrument needs to scan during the build up of a magnetic map). The longitudinal magnetic field measured by MDI is also of interest, since we propose to compare the potential field extrapolated using MDI data with non-linear force-free fields extrapolated on the basis of the Si I line vector field measurements. The Fe IX/X line at 171 A will allow us to study the coronal oscillations. Operational Considerations: =========================== The proposal requires target selection one day in advance. We propose to observe an active region, preferably close to disk center. This would reduce alignment problems and simplify the analysis of the chromospheric magnetic field vector calculation. The observations would require the time slot from 9:00 to 12:00 UT every day from May 13 to May 20. If no active region should be present we propose to carry out a very similar study for the quiet Sun near disk center in order to study the presence or absence of magnetic canopies, the relation of oscillations and brightness structures in the upper atmosphere to the strength and inclination of the field in the photosphere and upper chromosphere. Detailed Observing Sequences per Instrument: ============================================ MDI: High-Resolution Field Doppler shift and magnetic field maps of an active region, 1 minute cadence. Target selection one day in advance. EIT: CME watch program: full Sun 2x2 binned image in 195 every 12 min from 9:00-11:30 UT. Full sun sequence in each of the four filters from 11:30 to 12:00 UT TRACE: High Cadence 171. Cadence: 30s with as few interruptions as possible. Area: 1024x1024 at 0.5". Target selection one day in advance. SUMER: 9:00 -12:00 UT: Scans of a 100"x50" FOV in different spectral lines. One east-west scan in Si II (20,000 K), C IV (100,000 K), Ne VIII (630,000 K) obtained in 50 min. One west-east scan in Si II, O V (250,000 K), Mg X (1,000,000 K) in 50 min. One east-west scan in Lyman beta (20,000 K), C II (50,000 K) and O VI (300,000 K) in 15 min. One west-east scan in Lyman gamma (20,000 K), C III (80,000 K) in 15 min. One east-west scan in Lyman beta, C II and O VI in 15 min. One west-east scan in Lyman gamma, C III in 15 min. Full detector readouts will be also taken to obtain a precise wavelength calibration. Total duration 3 h 6 m. Compensation for the Solar rotation will be performed between scans. VTT: TIP-2 tuned to He 10830 A and Si 10827 A, scans of size 100"x100" in 5-10 minute cadence, fixed slit position to study oscillations.