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HINODE Operation Plan (HOP)

accepted on


 HOP No.

 HOP title

HOP 0445

Searching for Non-Maxwellian Distributions with EIS and IRIS (without COMP): Coordinated observations of Fe XII off-limb

plan term


@ @


 name : Dudik, Del Zanna, Polito, Dzifcakova, Young, De Pontieu, Mason @  e-mail : jaroslav.dudik[at]asu.cas.cz, gd232[at]damtp.cam.ac.uk, vanessa.polito[at]cfa.harvard.edu, elena[at]asu.cas.cz, pyoung9[at]gmu.edu, hm11[at]damtp.cam.ac.uk, bdp[at]lmsal.com

contact person in HINODE team

 name : Savage @  e-mail : sabrina.savage[at]nasa.gov

 abstract of observational proposal
Main Objective: Coordinated EIS/IRIS observations focused on Fe XII lines in both instruments, as well as neighbouring Fe XI and XIII for diagnostics of the non-Maxwellian kappa-distributions and electron density.

Scientific Justification: This submission is a modified version of IHOP 343. The proposers are attempting to see if the Fe XII 192 / 1349 A ratio confirms the presence of non-Maxwellians in another AR with larger signal-to-noise than we got Del Zanna et al. (2022). This ratio is currently the best available diagnostic.
This IHOP is proposed to acquire joint observations to probe the diagnostics for the non-Maxwellian distributions from Hinode/EIS and IRIS. The target will be a limb active region and this will be a Target-of-Opportunity (ToO) HOP.

We note that the previous IHOP 316 was run for multiple days. The data were analyzed, however we found that no IRIS Fe XII emission was present off-limb at the heights observable with the COMP instrument (i.e., about 40 arc sec above the limb). Therefore, we had no overlap between IRIS and EIS. Signal in IRIS at low heights at limb was present though. To ensure an overlap, the observations should be performed on an active region approaching the solar limb, partially covering the limb and AR core with both EIS and IRIS.

The assumption of a Maxwellian distribution is common in the analysis of solar spectra. However, this assumption may be incorrect if the emitting plasma is heated dynamically e.g. by nanoflares. A possible signature of such dynamic heating in the solar corona would be the presence of non-Maxwellian distributions. The kappa-distributions, characterized by a high-energy tail, have been diagnosed in a transient coronal loop observations made by EIS in Fe XI and Fe XII (Dudik et al. 2015, ApJ, 807, 123) and are also commonly observed in the solar wind (e.g. Maksimovic et al. 1997, Zouganelis 2008). Such distributions should result in an increase in the intensity of the coronal forbidden lines compared to the EUV ones (Dudik et al. 2014, A&A, 570, A124), an effect detectable by coordinated EIS and IRIS observations by using the Fe XII lines.

In order to disentangle the effect of kappa-distributions from the effects of the electron density and differential emission measure (DEM), observations of additional EUV lines by EIS are needed for density and DEM diagnostics. These additional lines can also be used for diagnostics of from EIS lines alone.

The proposers will examine data from SDO and STEREO-A to determine, ahead of an observing plan, whether the observations should go ahead, and at which position angle on the limb. Given this point in the solar cycle, however, active regions are still expected to be present.

 request to SOT
Context scans of target, if telemetry allows and if target extends onto the disk.

 request to XRT
Due to the long-duration nature of the EIS exposures, it would be helpful to have observations from XRT on a cadence matching the EIS exposures, and a duration matching the EIS observations, primarily for alignment purposes. The cadence of XRT should therefore be about 30 seconds, in Thin-Be.

 request to EIS
CompS_NonMax has 4 different variations: 120, 90, 60 and 30 (number indicates the slit exposures in seconds).
Use the CompS_NonMax 60 studies specified by proposer.

All variations use 2" slit to scan an 80"x512" off-limb region in 2" steps. We have opted to use DPCM compression.

Observations should be run in the following sequence:
- CompS_NonMax_60
- CompS_NonMax_60
- PRY_slot_context_v3

Typically, the sequence should be repeated 3 times.
Pointing and study variation to be selected by J. Dudik (dudik@asu.cas.cz)

Typically, observe a limb AR. Raster near the limb so that a part of the EIS FOV includes the solar disk with the moss and loop footpoints, where the Fe XII should be strongest.

Depending on the size of the AR, the proposer may specify that several rasters are to be stitched together to cover a wider range in X, in which case, this will be indicated in the instructions.

Repeat the observations for two consecutive days if possible.

 other participating instruments
IRIS Requests:
3610115167 | Very large sparse 96-step raster 95x175 96s C II Si IV Mg IIh/k | 5902.94 | 742.88 | 0.17 | 61.5+/-0.1 | 5903+/-0 | 184.5+/-0.0 | 184.5+/-0.0 | 184.5+/-0.0 | 0.0+/-0.0

Please make sure that AEC is OFF for these deep-exposure observations.

spacecraft rolled at 90 degrees (if possible)
repeat during the entire EIS observation time

Dates: ToO

Time window: 2 consecutive days, 1 cycle each
            2022/09/19-24  2022/09/27-10/02
Target(s) of interest: Active region, at limb

Previous HOP information:
HOP 226, HOP 265, IHOP 316
Dudik et al. 2015, ApJ, 807, 123

Additional Remarks:
The previous run of IHOP343 in 2017 had the IRIS AEC on by mistake, which limited the visibility of the IRIS Fe XII forbidden line.

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