HOP 0142

abstract of observational proposal

Alfven waves or more generally transverse magneto-hydrodynamic waves (kink waves) would play a key role in coronal heating and solar wind acceleration (e.g. Suzuki & Inutsuka, 2006). Spectro-polarimetric observation is very important to study the dynamics of MHD waves in the magnetic flux. Clear strong fluctuations in the line-of-sight magnetic flux, the line-of-sight velocity, and the intensity are found both in pores and in inter-granular magnetic structure at 25-49 degrees west away from the disk center with SP (Spectro-Polarimeter), and the phase relation between the fluctuations in the line-of-sight magnetic field and the velocity from the observation is consistent with that of both the standing kink wave and the standing sausage wave (Fujimura and Tsuneta, 2009, ApJ, 702, 1443) For further study, we want to identify the mode of MHD wave (i.e. kink mode or sausage mode) in the magnetic flux. For that reason, we would like to perform center-to-limb observation for wide range of μ-angle, say 0－60 degrees.
We are also interested in the dynamics of MHD waves between the photosphere and the corona. Velocity fluctuations in the coronal loop, which can be considered to be the kink waves, have been detected by Van Doorsselaere et al. (2008), Mariska et al. (2008), Doschek et al. (2007), Hara et al. (2008), and Taroyan et al. (2008) using EIS. EIS will perform a repeated scan with the narrow slit to detect the fluctuations in the Doppler velocity and in the intensity in the transition region and the lower corona. SP will perform a repeated scan with high time cadence, which allows us to observe apparent fluctuations in the line-of-sight magnetic flux, in the velocity, and in the intensity at lower photosphere. The collaboration between SP and EIS allows us to study the properties of MHD waves, such as the type of MHD wave (standing or propagating, kink or sausage, and so on) and physical parameters in a flux tubes (Photospheric seismology is possible from the observables (Fujimura and Tsuneta, 2009, ApJ, 702, 1443))

request to SOT

BFI/ Ca II H: FOV 55”x111”, 2x2 sum, 5 min cadence, Q75 -> 14 Mbits/hour
G-band: FOV 55”x111”, 2x2 sum, 5 min cadence, Q75 -> 20 Mbits/hour
NFI: Na I D 5896 IV (-160mA offset): FOV 55”x111”, 2x2 sum, 5 min cadence, Q75 -> 12 Mbits/hour
SP: Fast map, FOV 5"x82" (32 slit pos, 2x2 sum), 60s cadence, 2 side CCDs, Q75-> 600Mbit/1H

Note: SP repeated scan with time cadence of 1min is necessary for detection of MHD waves. The minimum observation time for the SP scan is 1 hour. If the duration is longer than 1 hour, input the command “CT servo OFF/ON” every 1 hour. The focus position should be -39, which is most suitable for SP. Avoid SAA period for SP observation.

request to EIS

DRW_Alf_01 (EIS study #317) is a narrow continuous scan with six positions of the 2” slit (10 second exposures), giving FOV of 12”x152”, at relatively high cadence (60 s). Pointing will be put on the center of the SOT/SP FOV. The observation time of EIS narrow scan will the same as that of SP scan. PRY_slot_context_v2 (EIS study #249) should be repeated twice just before and after DRW_Alf_01 for alignment with XRT.

remarks

Time window:
We need 5 days for total duration. (Consecutive days are not required.) Since we require center-to-limb observation with mu-angle of 0-60 degrees, the pointing will be about 0, 15, 30, 45, and 60 degrees east or west (either is OK) away from the disk center in the equatorial region for each day. Perform the observations when active regions appear in the specified position. We prefer 2-3 hours per day, but 1 hour per day is OK for our observation.

Target of interest:
Since we would like to be sure to contain magnetic structures in the narrow FOV of SOT and EIS (see request for each telescope for detail), and magnetic structure with life time longer than 1 hour is preferable for MHD wave study, we require plage regions for our observation. That is why the proposal is ToO HOP.