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HINODE Operation Plan (HOP)

accepted on

26-nov-2017

 HOP No.

  HOP title

HOP 0345
Spinning Plasma in Long-Lived Coronal Cavities

plan term

ToO

 　 　

proposer

  name : Jibben, Reeves 　  e-mail : pjibben[at]cfa.harvard.edu, kreeves[at]cfa.harvard.edu

contact person in HINODE team

  name : Golub 　  e-mail : golub[at]head.cfa.harvard.edu

 abstract of observational proposal
Main Objective: Observe long-lived polar crown coronal cavities at or near solar minimum to determine if they exhibit spinning motions like those reported by Wang & Stenborg (2010).

Scientific Justification:
Spinning coronal cavities were observed during the last solar minimum when there were small active regions near the equator. Wang & Stenborg theorize that the direction of the spinning motion of the coronal cavity is determined by a steep poleward gradient in magnetic field strength and that the spinning motion represents a detached flux rope. Periodic observations of a long-lived polar crown prominence could help determine if spinning cavities are due to the emergence of a flux rope or creation of a flux rope due to magnetic reconnection of a sheared arcade. We will utilize data from Hinode, IRIS, CoMP, and AIA to provide a complete picture of the evolution of a coronal cavity to a spinning coronal cavity. Observations would include long-lived, E-W aligned polar crown filament channels that have a coronal cavity on the limb. Once a target has been identified, the requested observations consist of 1) portions of the on-disk filament channel and 2) coronal cavity at the limb several days later. These observations are needed periodically over several rotations to observe coronal cavity evolution.

Hinode provides temperature and coronal velocity information of the cavity and overlying arcade as well as magnetic field information of the on disk portion of the filament channel. We would like  to run an observation program similar to HOP 264 for EIS and XRT with the addition of SOT vector magnetograms IQUV taken along the on-disk portion of the filament channel at central meridian several days prior to that portion of the filament channel reaching the limb.

The IRIS observations of the prominence material on the limb will determine how the coronal cavity spins relative to the cool prominence material. Wang & Stenborg theorize the prominence material lies below the pinched off portion of the flux rope. If and how the prominence interacts with a spinning coronal cavity would yield insights on how the magnetic field of a prominence-cavity system (i.e. filament channel) evolves.

 request to SOT
1) On disk filament channel
SP: Large FOV Stokes IQUV at pointing along filament channel that crosses the central meridian, serval days before the cavity reaches the limb. Want central meridian to be in center of FOV.

2) Cavity at limb
No request

 request to XRT
XRT Requests:
1) On disk filament channel CME watch (bin 4x4) with long exposures (AEC2 or fixed exposure at least 8s Al/poly and 16s for thin/Be. 30-60s cadence.

2) Cavity at limb
XOB similar to #1BCE. 768x768 FOV bin=2 with thin-be/al-poly longest possible exposure times.
Either fixed exposure or AEC2 30-60s cadence.

 request to EIS
1) On disk filament channel
No request

2) Cavity at limb
Please run program similar to HOP114 with suitably long exposure times covering the coronal cavity.

 other participating instruments
IRIS:

1) On disk filament channel
Please run program that includes Mg II and Mg II wings:

High data rate:
3600010343  |  Very large coarse 16-step raster 30x175 16s  C II   Mg II h/k   Mg II   |     267.11    |     491.50    |       1.3     | 16.7+/-0.1 |  267+/-0   | 45.5+/-16.9 |  0.0+/-0.0 | 33.4+/-0.1 | 133.6+/-0.0

Low data rate:
3600010341  |  Medium coarse 16-step raster 30x60 16s  C II   Mg II h/k   Mg II w s D  |     265.66    |     139.28    |       0.4     | 16.6+/-0.1 |  266+/-0   | 45.3+/-16.8 |  0.0+/-0.0 | 33.2+/-0.1 | 132.8+/-0.0

2) Cavity at limb
Please run program similar to HOP 264 with the slit parallel to the limb and at least one slit position completely on the disk.

High data rate:
3620261434  |  Very large coarse 8-step raster 14x175 8s  Si IV   Mg II h/k Deep x 15  |     131.18    |     156.95    |       0.8     | 16.4+/-0.1 |  131+/-0   |  0.0+/-0.0 | 32.8+/-0.1 | 32.8+/-0.1 |  0.0+/-0.0

Low data rate:
3620263434  |  Very large coarse 8-step raster 14x175 8s  Si IV   Mg II h/k Deep x 30  |     251.78    |     156.95    |       0.4     | 31.5+/-0.1 |  252+/-0   |  0.0+/-0.0 | 63.0+/-0.1 | 62.9+/-0.1 |  0.0+/-0.0

 remarks
Dates: ToO. Solar conditions needed to observe this type of phenomena may occur at anytime but may be rare. We therefore ask for a several month window of opportunity.

Time window: Ideally, 4-6 hours observations per day after the 18UT synoptic including the SOT magnetograms after a target has been identified. However, if another HOP is scheduled during this time, any 4-6 hour time would work.

Target(s) of interest: Polar crown filament channel that is mostly E-W aligned and exhibits a coronal cavity. The target region will be identified by a cavity on the east limb and then observed on the west limb with XRT, EIS, and IRIS. SOT will take magnetograms when the target rotates to the Central Meridian.

Previous HOP information: 114 & 264

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