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HINODE Operation Plan (HOP)

accepted on

21-jul-2016


 HOP No.

 HOP title

HOP 0324

Fine Structure and Dynamics of Solar Filaments/Prominences

plan term

2016/09/01-2016/09/05

@ @

proposer

 name : Su, Liu, Reeves, et al. @  e-mail : ynsu[at]pmo.ac.cn, kreeves[at]cfa.harvard.edu

contact person in HINODE team

 name : Reeves @  e-mail : kreeves[at]cfa.harvard.edu

 abstract of observational proposal
The solar corona contains sheared or twisted magnetic fields overlying polarity inversion lines on the photosphere. The sheared/twisted fields can be observed as filament channels on the disk and as coronal cavities in limb observations; solar prominences are located within these regions. These structures warrant investigation because of their role in prominence eruptions, coronal mass ejections (CMEs), and solar flares. Understanding the topology and evolution of the prominence/cavity magnetic field structure prior to the eruption is key to understanding the onset of solar eruptions. To understand how filaments are supported, we will study the fine structure and dynamics of the observed filament as well as its relation with the corresponding photospheric magnetic fields, and the corresponding structure of the coronal magnetic fields will be reconstructed using photospheric magnetic field observations.

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 gmagnetic tornadoesh with the AIA instrument onboard SDO, and pointed at possible connections among vortex motion on the surface, filament barbs, and solar tornadoes. However, whether these magnetic structures are indeed rotating, is a key question to be answered. Through cooperative observations between BBSO/NST, Hinode, and IRIS, and SDO we aim to address the following questions: what is the nature of the plasma dynamics in prominence barbs or tornado-like prominence? Do these motions play an important role in the formation and evolution of prominences? What is the relation between prominence barbs and tornado-like prominences? What is the magnetic structure supporting this type of prominence/filament?

Our primary target will be an active region with filaments which is most likely to erupt. If there is no eruptive active region filament, our secondary target will be a quiescent filament/prominence with barbs and/or tornado-like features. In the ideal case, we propose to track the filament from disk to west limb.

In case of active region filaments, we can run observations similar to HOP 260.

 request to SOT
In case of active region filaments, we can run observations similar to HOP 260.
<Case 1 (prominences at the limb)>: None

<Case 2 (filaments on the disk)>:
SP - Fast map (cycle 2), cadence=repeat
FOV=100"x82", sum=2x2
FOV may be adjusted depending on the size of the filament and available telemetry.

In case of quiescent filament/prominence:
<Case 1 (prominences at the limb)>: None

<Case 2 (filaments on the disk)>:
SP - Fast map (cycle 2), cadence=repeat
FOV=100"x82", sum=2x2
FOV may be adjusted depending on the size of the filament and available telemetry.

 request to XRT
In case of active region filaments, we can run observations similar to HOP 260.
filter: thin-Be, FOV: 384h x 384h, Cadence: 10 s

In case of quiescent filament/prominence:
following HOP 264
Thin-Be, Al-poly filters with longest possible fixed exposures. FOV should include the coronal cavity when at the limb. Large FOV (768hx768h) with 2x2 binning.

 request to EIS
In case of active region filaments, we can run observations similar to HOP 260.
fast scan: EIS study ID: 464 - Qub_Hi-Cad_Flare_2s-Exp_104hx104h
slit: 2h
Exposure time: 5 sec
Step size: 2h
FOV: 104h x 104h
Lines:
He II 256.32
O V 192.90
O VI 184.12
Mg VI 268.99
Mg VII 280.75
Fe VIII 185.21
Fe X 184.54
Fe XI 182.16
Fe XII 195.12
Fe XIII 202.04
Fe XIV 274.20/264.79
Fe XV 284.16
Fe XVI 262.98
Fe XVII 254.87
Ca XVII 192.82
Fe XXIII 263.76

In case of quiescent filament/prominence:
following HOP 237
The high EIS spectral resolution allows to measure Doppler velocities of plasma with very high precision. We would like to take 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 = 100h~256h) 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
IRIS:
In case of active region filaments, we can run observations similar to HOP 260.
OBS ID: 3660259133  |  Large coarse 8-step raster 14x120 8s  C II   Si IV   Mg II h/k Deep x   |      74.74    |      93.27    |       0.9     |  9.3+/-0.1 | 74.8+/-0.0 | 37.4+/-0.1 | 37.3+/-0.1 | 37.3+/-0.1 |  0.0+/-0.0
We always need a low data rate option as well in case the telemetry is limited on that day.
We could use this one, which is identical, except that the data is summed spatially by 2 and spectrally by 2:
OBS ID: 3660109133  |  Large coarse 8-step raster 14x120 8s  C II   Si IV   Mg II h/k Deep x   |      73.11    |      30.80    |       0.3     |  9.1+/-0.1 | 73.1+/-0.0 | 36.6+/-0.1 | 36.5+/-0.1 | 36.5+/-0.1 |  0.0+/-0.0

In case of quiescent filament/prominence:
Both Sit-Stare:  OBS ID 3620261403 and 96-step raster: OBS ID 3620261465 are required.


BBSO/NST, SDO

 remarks
| Target of interest:
   Primary: active regions with filament, which is most likely to erupt
   Secondary: quiescent filament with barbs or tornado-like feature
| The daily best-seeing observing time at BBSO is from 17:00 UT to 21:00 UT.

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