HOP 0237 Spectroscopic study of "magnetic tornadoes" plan term: 2013/09/09-2013/09/29 proposer: name : Su, Veronig, Temmer, Goemoery, Rybak e-mail: gomory[at]ta3.sk contact person in HINODE team: name : Culhane e-mail: j.culhane[at]ucl.ac.uk Abstract of observational proposal Tornado-like prominences were first described by Pettit (1932) but have not been paid much attention thereafter. Recently, several groups (e.g., Su et al. 2012; Wedemeyer-Boehm et al. 2012) observed “magnetic tornadoes” with the AIA instrument onboard SDO, and pointed at possible connections among vortex motion on the surface, filament barbs, and solar tornadoes. They proposed a new idea of filament formation and eruption, in which vortices and the rotation of magnetic structures in the corona (“solar magnetic tornadoes”) play a central role. However, whether these magnetic structures are indeed rotating, is a key question in this respect. In order to observationally determine the rotational motion against alternative interpretations and to relate them to the overall filament dynamics, spectroscopic observations in combination with imaging data are necessary. Alternative interpretations of the imaging observations include oscillating motions and plasma motions on helical magnetic fields. Recent observations by Orozco Suarez et al. (2012) show some evidence of rotating plasma motions in filament barbs, but the evidence is still not solid enough to confirm such general tornado scenario. Therefore, Doppler observations of filament barbs and tornado-like structures on the solar limb are essential for distinguishing rotating motion from oscillations and plasma motions along twisted structures. If the barbs are indeed rotating, the Doppler maps are expected to show: a) blue shifts on one side and red shifts on the other side of the “tornado” axis, and this pattern not periodically reversing (which would hint at oscillations); or b) blue shifts when the structure moves to one side and red shift when the structure moves to the other side (off axis rotation). Request to EIS: The high EIS spectral resolution allows to measure Doppler velocities of plasma with very high precision. We would like to use this advantage of the EIS spectrometer and study the dynamics of solar tornadoes in the following spectral lines: Fe X 184.54 A, Fe VIII 185.21 A, Fe XI 188.23 A, Ca XVII 192.82 A, Fe XII 195.12A, Fe IX 197.86 A, Fe XIII 202.04 A, He II 256.32 A, Si VII 275.35 A. For this purpose we designed the EIS program consisting of scanning and sit-and-stare observing mode. In the scanning mode, we plan to take the 2D raster (FoV = 100”×256”) of the area above the WEST solar limb with the potential solar tornado (or, alternatively, on the solar disk with filament target). Then, using the sit-and-stare mode, we plan to take sequences of exposures with the slit crossing the tornado to obtain information on the temporal evolution of its dynamical properties. The technical parameters of the two observing modes are: Sit-and-stare observing mode: slit: 2"x256" compression: DCPM exposure time/delay time: 50.0s/0ms number of exposures: 70 width of spectral windows: 32 (except for Fe X line: 24) number of lines: 9 number of study repetitions: 6-8 Scanning observing mode: slit: 2"x256" step size: 2" number of steps: 49 (total number of exposures: 50) final FoV: 100"x256" compression: DCPM exposure time/delay time: 50.0s/0ms width of spectral windows 32 (except for Fe X line: 24) number of lines: 9 number of study repetitions: 2 (before and after sit-and stare mode) Other participating instruments In the joint campaign study, the following space-based and ground-based instruments are involved: 1) Hinode/EIS: spectroscopic observations in selected EUV spectral lines 2) SDO/AIA: high-cadence full-disk imaging in the EUV 3) CoMP-S (Lomnicky Peak Observatory, Slovakia): coronographic spectroscopy in the H-alpha spectral line 4) Kanzelhoehe Observatory: high-cadence full-disk imaging in the H-alpha spectral line We have guaranteed observing time at CoMP-S and Kanzelhoehe for the period 2013 September 9 - 29, and ask for EIS support during one week of this campaign. According to the long term meteorological statistics of the atmospheric conditions at the Lomnicky Peak Observatory, September is the best observing period for the coronographic observation by CoMP-S at Lomnicky Stit. Preferred observation time is from 5:00 to 9:00 UT (valid for the period mentioned above; the best observing conditions are shifted to 7:00 UT - 10:00 UT during the winter time). 2) SDO/AIA: The Atmospheric Imaging Assembly (AIA; Lemen et al. 2012 ) on board the Solar Dynamics Observatory (SDO; Pesnell et al., 2012 ) is an array of 4 telescopes that together provide full-disk images of the solar corona in 10 UV and EUV wavelengths with a high temporal cadence (about 12 s) and spatial resolution (about 0.6 arcsec; 4096x4096-pixel images). AIA data available at Level 1.0 (corrected for bad pixels and spikes) are processed to Level 1.5 data ready for further scientific analysis by using SolarSoft routines. The “tornado” funnels are observed best in the AIA Fe IX 171 A (0.63 MK) passband, where they appear as dark, cone-shaped column structures connecting the solar surface and the top of the prominence. 3) The CoMP-S is a 2D multi-channel spectro-polarimeter installed at the Lomnicky Peak Observatory (Slovakia). It is attached to a 200/3000 ZEISS coronagraph. The coronagraph is diffraction limited from 530 nm to 1083 nm by changing focus of the objective lens only within a range of 80 mm. This allows us to take the sequential scans in wavelength through the profiles of several spectral lines, namely: Fe XIV 530.3 nm, Ca XV 569.5 nm, Fe X 637.5 nm, Fe XI 789.2 nm, Fe XIII 1074.7 nm, 1079.8 nm, He I 587.6 nm, H I 656.3 nm, Ca II 854.2 nm and He I 1083.0 nm. The spatial resolutions of the coronagraph at the wavelengths 530 nm, 656 nm and 1083 nm are 0.67“, 0.82“ and 1.36“, respectively. Two 16-bit detectors with 2560 × 2160 of 6.5 micron square pixels are used to record the images. For the observations of the solar tornadoes we plan to perform high cadence 2D spectroscopy in the Hα line (the cadence of the full spectral scans will be at the order of 20 seconds). We plan to scan the line profile in 11 points allowing us to detect Doppler shifts up to ± 35 km/s. 4) Kanzelhoehe Observatory (Austria; www.kso.ac.at) performs high-cadence imaging of the full solar disk with a refractor with d/f = 100/2000 and a Lyot band-pass filter centred at the H-alpha spectral line at 656.3 nm with a full-width-at-half-maximum of 0.07 nm. The images are recorded by a CCD camera with 2048 x 2048 Pixels, 12 bit dynamic range, and include frame selection. The spatial resolution is ~ 1 arcsec. In order to support of the magnetic tornado campaign, H-alpha imaging sequences with a time cadence of 6 seconds will be performed in order to get insight into the overall context and dynamics of the filaments/ prominences under study. Targets: Prominences: preferentially above the solar limb, or Filaments: on disk References: Culhane, J. L., Harra, L. K., James, A. M., et al. 2007, The EUV Imaging Spectrometer for Hinode, Sol. Phys., 243, 19 Lemen, J. R., Title, A. M., Akin, D. J., et al. 2012, The Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO), Sol. Phys., 275, 17-40 Su, Y. Wang, T., Veronig, A., Temmer, M., Gan, W., 2012, Solar Magnetized “Tornadoes”: Relation to filaments, ApJ Lett. 756, L41 Wedemeyer-Boehm, S., Scullion, E., Steiner, O., Rouppe van der Voort, L., de La Cruz Rodriguez, J. Fedun, V., Erdelyi, R. 2012, Magnetic tornadoes as energy channels into the solar corona, Nature 486, 505-508. Orozco Suarez, D., Asensio Ramos, A., Trujillo Bueno, J. 2012, Evidence for rotational motions in the feet of a quiescent solar prominence, ApJ Lett. 761, L25. Pesnell, W.D., Thompson, B. J., Chamberlin, P.C., 2012, The Solar Dynamics Observatory (SDO), Sol. Phys., 275, 3-15