HOP 0506

other participating instruments

This has been agreed with the IRIS team:
1. OBSID for prominences far from the equator (at large latitudes).

off-limb
3400111762 | Very large coarse 64-step raster 126x175 64s Mg II h/k Deep x 15 Spat | 1048.26 | 495.26 | 0.32 | 16.4+/-0.0 | 1048+/-0 | 0.0+/-0.0 | 0.0+/-0.0 | 16.4+/-0.0 | 0.0+/-0.0

on-disk
3400111662 | Very large coarse 64-step raster 126x175 64s Si IV Deep x 15 Spatial | 1050.69 | 495.26 | 0.32 | 16.4+/-0.0 | 1051+/-0 | 0.0+/-0.0 | 16.4+/-0.0 | 0.0+/-0.0 | 0.0+/-0.0

2. For prominences near the equator and not too high (smaller number of steps).
off-limb
3400609752 | Very large coarse 32-step raster 62x175 32s Mg II h/k Deep x 8 Spatia | 296.83 | 185.99 | 0.43 | 9.3+/-0.0 | 297+/-0 | 0.0+/-0.0 | 0.0+/-0.0 | 9.3+/-0.0 | 0.0+/-0.0

on-disk 3400609652 | Very large coarse 32-step raster 62x175 32s Si IV Deep x 8 Spatial x | 298.05 | 185.99 | 0.42 | 9.3+/-0.0 | 298+/-0 | 0.0+/-0.0 | 9.3+/-0.0 | 0.0+/-0.0 | 0.0+/-0.0

3. Very large sparse 64-step raster (smaller raster step).

off-limb 3400111760 | Very large sparse 64-step raster 63x175 64s Mg II h/k Deep x 15 Spati | 1048.26 | 495.26 | 0.32 | 16.4+/-0.0 | 1048+/-0 | 0.0+/-0.0 | 0.0+/-0.0 | 16.4+/-0.0 | 0.0+/-0.0

on-disk 3400111660 | Very large sparse 64-step raster 63x175 64s Si IV Deep x 15 Spatial x | 1050.69 | 495.26 | 0.32 | 16.4+/-0.0 | 1051+/-0 | 0.0+/-0.0 | 16.4+/-0.0 | 0.0+/-0.0 | 0.0+/-0.0

4.1. Very large sparse 32-step raster (high telemetry).

off-limb 3410609749 | Very large sparse 32-step raster 31x175 32s Mg II h/k Deep x 8 Spatia | 296.83 | 185.99 | 0.73 | 9.3+/-0.0 | 297+/-0 | 0.0+/-0.0 | 0.0+/-0.0 | 9.3+/-0.0 | 0.0+/-0.0

on-disk 3410609649 | Very large sparse 32-step raster 31x175 32s Si IV Deep x 8 Spatial x | 298.05 | 185.99 | 0.72 | 9.3+/-0.0 | 298+/-0 | 0.0+/-0.0 | 9.3+/-0.0 | 0.0+/-0.0 | 0.0+/-0.0

4.2. Small telemetry version of 4.1. OBSID.

off-limb 3400609749 | Very large sparse 32-step raster 31x175 32s Mg II h/k Deep x 8 Spatia | 296.83 | 185.99 | 0.43 | 9.3+/-0.0 | 297+/-0 | 0.0+/-0.0 | 0.0+/-0.0 | 9.3+/-0.0 | 0.0+/-0.0

on-disk 3400609649 | Very large sparse 32-step raster 31x175 32s Si IV Deep x 8 Spatial x | 298.05 | 185.99 | 0.42 | 9.3+/-0.0 | 298+/-0 | 0.0+/-0.0 | 9.3+/-0.0 | 0.0+/-0.0 | 0.0+/-0.0

Additional instrument coordination:
coordination with NVST, Bialkow and Ondrejov

Previous HOPs:
HOP444, HOP373, and probably a few before...

Some of the co-Is have been using THEMIS and supporting observations in the past years to measure magnetic fields in prominences in the manner described in this proposal with significant success. We would like to put forward the last publication of these efforts on the observation of fast magneto-acoustic waves travelling across the horizontal magnetic field of the prominence (Schmieder et al. ApJ 2013). Observation of waves in prominences is not new. The measurement by THEMIS of the magnetic field simultaneously to the appearance of the wave train observed by Hinode put those waves in a different and unexpected context: unlike the usual assumption of waves propagating along the field lines, these waves were travelling across the field. While this is not forbidden by the models, it is not the usual scenario proposed and sheds light on both the propagation of waves originated in the photosphere towards the corona and on the 3-dimensional structure of the plasma distribution in the prominences. This is the perfect illustration of what this proposal wants to accomplish by providing the magnetic support to the plasma dynamics observed by other instruments. We could compare the measurement of magnetic field obtained with THEMIS and the values determined by MHD simulations (Mackay et al 2020). On the other hand the thesis of P.J. Levens in 2018 contains three papers with magnetic data of THEMIS obtained in 2014 concerning atypical prominences and bubbles. We would like to extend to tornado-structures in order to understand their magnetic configuration following the paper of Ruan et al (2019). We published two papers on solar prominences and tornadoes observed on 28 Sept 2019 but without measurement of the magnetic field. It is crucial for us to understand the magnetic configuration of tornadoes (Peat et al 2021, Barczynski et al 2021). We published one new paper on the spectroscopic observations of THEMIS and IRIS on a prominence with two horns observed in 2022 (Barczynski et al 2023). In 2023 we have obtained observations of prominences with IRIS in Mg II and THEMIS in H-alpha and He D3. We are planning to reduce them and see if there are solutions for fitting only the intensities with the radiative code of Labrosse and Levens (2019) and the new method of profile fitting method (xRMS, developed by Aaron W. Peat (Peat et al A&A 2024)). We just published a new paper on jets- Karki, et al (2025).

remarks

Dates: Our THEMIS observations will run May 29 - June 7, 2025. Seven days represent the time required for a single prominence/filament on the Sun to be visible as prominence above the solar limb, either the east or the west limb. Therefore, the requested period ensures that we will have a possibility to observe all prominences present on the Sun during the observational campaign. During that time period we will be observing for as long as possible seeing permitting. We have agreement to receive support from IRIS at least 2-3 hours per day.

Time window: IRIS will also support SST in that time period, and we've agreed to the following: on one day SST would be supported from 8:00 to 10:00 UT, and THEMIS from 10:00 to 13:00 UT. Every other day, IRIS would support THEMIS from 8:00 to 10:00 UT, and SST from 10:00 to 13:00 UT.

Target(s) of interest: The main objective of our THEMIS observations is to perform polarimetry of prominences and filaments. Targets of interest are off-limb prominences, either quiescent or active (including prominence tornadoes). When adequate prominences or solar tornadoes are not present, we can use the allocated time and THEMIS MTR capabilities to observe and study the magnetic field structure of the ubiquitous spicules protruding from the solar disk. We also propose to observe the magnetic field in the footpoints of filaments on the disk, in the barbs, using Fe I lines around 6302 Angstroms.