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HINODE Operation Plan (HOP)

accepted on


 HOP No.

 HOP title

HOP 0411

Hinode (SOT/SP) and IRIS Observations of the Evolution of Sunspot Penumbrae

plan term


@ @


 name : Tiwari, DeRosa, De Pontie @  e-mail : tiwari[at]lmsal.com,derosa[at]lmsal.com,bdp[at]lmsal.com

contact person in HINODE team

 name : DeRosa, De Pontie @  e-mail : derosa[at]lmsal.com, bdp[at]lmsal.com

 abstract of observational proposal
Main Objective: To study how penumbral filaments and spines in sunspot penumbra, and moving magnetic features nearsunspot penumbra evolve, and what is their transition region response.

Scientific Justification: Sunspot penumbra is formed of filaments and spines (more vertical field between the horizontal-field filaments: Lites et al. 1993, ApJ; Tiwari et al. 2015, A&A). Although observations and modeling now largely agree on penumbral filaments being elongated magnetoconvection cells (Rempel 2012, ApJ; Tiwari et al. 2013, A&A), the interaction of filaments and spines and their evolution are not understood. The lifetime of penumbral filaments is not accurately known due to absence of high-resolution high-cadence spectropolarimetric data of sunspot penumbra for a large span of several to many hours. Moreover, chromospheric/transition-region/coronal dynamic events in sunspot penumbrae e.g., penumbral jets and bright dots might result from the evolution and/or interaction of filaments and spines. Bright Dots are moving bright dot-like transition region events in sunspot penumbrae (Tian et al. 2015, ApJL; Alpert et al. 2016, ApJ). Penumbral jets are narrow transient brightenings best seen in the chromosphere but are proposed to contribute to the transition region and coronal heating (Katsukawa et al. 2007, Sci.; Tiwari et al. 2016, ApJ, Vissers et al 2016).

Penumbral jets are proposed to form by magnetic reconnection between two filaments inclined at an acute angle (Katsukawa et al. 2007, Science), or between the spine field and the opposite polarity magnetic field present at the edges of filaments (Tiwari et al. 2016, ApJ) -- some largest jets form at the tails of filaments, dominant at the outer edges of penumbra. Penumbral jets could alternatively be fast propagating heat fronts (Rouppe van der Voort & Drews, 2019, A&A) - thus their formation mechanism remains unsettled. Some of larger jets also show twisting in them (similar to X-ray jets) but whether all penumbral jets twist remains to be explored using suitable IRIS observations (Tiwari et a. 2018, ApJ; Drews & Rouppe van der Voort 2020).

The proposed observations will also allow investigation of transition region response of moving magnetic features, found in and around sunspot penumbra.

 request to SOT
--- updated on October 22, 2021 ---
SOT/SP: Normal scan mode, Repeated -- as many scans possible (7-8 hours or more). The SP scanning area should be centered on the penumbra either east or west of a sunspot. A good example is on 15-16 September 2017 (penumbral study) that was run for about 7 hours.

Either program below can be used. The programs are the same except for the ROI offset.
ID: 0x1cf Slower Full-Res, ROI 3 (TBC: xx, yy), 18x61" repeat
ID: 0x23c HOP 411, Slower Full-Res, 18x61" repeat

--- obsolete description ---

SOT/SP: Normal scan mode, Repeated -- as many scans possible (7-8 hours or more).
Preferably run the same program as on 15-16 September 2017 (penumbral study) that was run for about 7 hours.

ID: 0x1cf Slower Full-Res, ROI 3, 18x61" repeat
It is expected that SP scans cover the same region as requested for IRIS, and/or vice versa.

 request to XRT

 request to EIS

 other participating instruments
IRIS requests:
Repeated scans of this program:
3624258056 | Large dense 64-step raster 20.8x120 64s Deep x 8 FUV spectrally reb | 598.64 | 757.19 | 0.86 | 9.4+/-0.1 | 599+/-0 | 37.4+/-0.0 | 37.4+/-0.0 | 37.4+/-0.0 | 37.4+/-0.0

Low data rate alternative is:
3624258055 | Medium dense 64-step raster 20.8x60 64s Deep x 8 FUV spectrally reb | 595.28 | 312.98 | 0.36 | 9.3+/-0.1 | 595+/-0 | 37.2+/-0.0 | 37.2+/-0.0 | 37.2+/-0.0 | 37.2+/-0.0

Roll angle of the slit: 0

Dates: ToO

Time window: Any time when a sunspot is close to disk center (<45 degrees). Repeated scans for 2 to 8 hours or as long as possible without significant drift.

Target(s) of interest: Sunspot Penumbra, ToO
Fully developed sunspot (with penumbra) near disk center (within 45 degrees, preferably track penumbra from -30 degrees East to 30 degrees West).

Previous HOPs:

Additional remarks:
Simultaneous IRIS and SP scans are necessary to obtain the desired data set/s. This HOP is best run in the spring or fall when neither Hinode nor IRIS are in eclipse season.

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