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HINODE Operation Plan (HOP)

accepted on


 HOP No.

 HOP title

HOP 0256

A study on the plasma properties of EIT waves from multi-wavelength observations

plan term




 name : Vanninathan, Gomory, Madjarska, Veronig    e-mail : kamalam.vanninathan[at]uni-graz.at

contact person in HINODE team

 name : Culhane    e-mail : j.culhane[at]ucl.ac.uk

 abstract of observational proposal
EIT waves are large scale disturbances that occur in association with Coronal Mass Ejections (CMEs). Such perturbations are seen propagating throughout the solar corona. These phenomena have most commonly been observed with imagers in filters which are centred around wavelengths 171A, 195A from EIT/SoHO, 171A, 195A, 284A from EUVI/STEREO, 193A, 211A, 171A from AIA/SDO and even in soft X-rays from SXI/GOES and XRT/Hinode. Several authors have reported the peak intensity to be in 195A or 193A images and weak intensity enhancements in 211A and 284A images, while the 171A channel shows co-spatial intensity decrease. Such an appearance across the different filters has been interpreted by several authors as localised heating of the plasma (Long et al. 2008, Liu et al. 2010) or a density enhancement as the wave passes through (Patsourakos et al. 2009, Schrijver et al. 2011). However, commenting on plasma properties based on imager data does not give accurate results mainly due to the wide temperature response of the filters used and the contribution to the emission from many spectral lines with a wide range of formation temperatures which includes some lines that are not yet identified. For this reason there is a requirement for spectroscopic studies of these events. However, obtaining such observations is difficult mostly due to their transient nature. The small number of spectroscopic studies (Harra et al. 2003, Chen et al. 2011, Harra et al. 2011, Veronig et al. 2011) which have been done so far have been limited to a few spectral lines. The study of EIT waves in other EUV wavelengths has not been undertaken before.

In the proposed project we would like to obtain sit-and-stare observations in a large set of  spectral lines that have a wide range of formation temperatures (as listed below) during the passage of a wave. The selected lines will enable us to perform a DEM analysis on the wave plasma and subsequently achieve accurate temperature and density diagnostics of the local plasmas. Such a study will also reveal subtle changes that take place in the corona during the passage of the wave. This will provide us with an understanding on the effect the waves have on the solar atmosphere and in turn help us to determine the contribution by the waves in the  transfer of energy across the solar atmosphere.

 request to SOT

 request to XRT

 request to EIS
Spectroscopic observations in the selected EUV spectral lines

The choice of spectral lines available in EIS makes it ideal for the DEM analysis of EIT waves. We would like to take advantage of this to study the plasma properties of these waves in the following spectral lines: OVI 184.12, FeVIII 185.21, FeXII 186.88, FeXI 188.23, CaXVII 192.82, FeXII 195.12, FeIX 197.86, FeXIII 202.04, FeXIII 203.82, SiX 258.37, SiX 261.04, FeXVI ,262.98, FeXXIII 263.76, FeXIV 264.78, FeXVII 269.42, FeXIV 274.20, SiVII 275.35, FeXV 284.16

We designed an EIS study mainly in a sit-and-stare observing mode to increase the possibility of picking up an EIT wave signal. Context images with the slot are requested before and after the sit-and-stare observations to enable us to align the EIS data with the other instruments.

The technical parameters of the two observing modes are:
Sit-and-stare observing mode: slit: 2"x440"
 exposure time/delay time: 40.0s/0ms
 number of exposures: 26
 width of spectral windows: 32 (except OVI: 56, CaXVII: 48, FeXII: 40, FeXVII: 64)
 number of lines: 18
 number of study repetitions: 6-8
 data rate: 46.628 kbps
 feature tracking is required

Observations for context images: slot: 40"x512"
 step size: 40"
 number of steps: 1
 final FoV: 40"x512"
 exposure time/delay time: 45.0s/0ms
 width of spectral windows: 48
 number of lines: 3
 feature tracking is required
         number of study repetitions: 2 (before and after the sit-and stare mode)

 other participating instruments
We would like to have co-observations with IRIS in order to be able to search for the  chromospheric counterpart of EIT waves, called Moreton waves, which have been reported in Hα images since Moreton discovered them in 1960. We also intend to acquire high-cadence full-disk Hα filtergrams from ground based telescope at the Kanzelhoehe Observatory, which is operated by the University of Graz. Observing time on this telescope is only limited by the local seeing conditions.

IRIS: spectroscopic observations similar to the study titled 'Wave study in DC' with OBSID 3820011653 and linelist v38_01 (We request the EIS planner to contact the IRIS planner well in advance for co-observations if possible)

Kanzelhoehe Observatory: high-cadence full-disk imaging in the Hα spectral line (confirmed participation)

SDO/AIA: high-cadence full-disk imaging in the EUV (available)

・Targets: Regions close but outside active regions. The position of the slit should be similar to the position shown in figure 1 of Veronig et al (2011) (http://iopscience.iop.org/2041-8205/743/1/L10/pdf/apjl_743_1_10.pdf). If the active region is in the northern (southern) hemisphere, slit should be placed so as to cover the quiet Sun to the south (north) of the active region. Please contact the observers for more accurate pointing.

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