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HINODE Operation Plan (HOP)

accepted on


 HOP No.

 HOP title

HOP 0088

Physical mechanisms driving solar microflares and network dynamic fibrils; relevance for coronal heating and mass supply

plan term


@ @


 name : Rybak @  e-mail : choc[at]astro.sk

contact person in HINODE team

 name : Berger @  e-mail : berger[at]lmsal.com

 abstract of observational proposal
This proposal merges together attempts to observe two kinds of solar structures - solar microflares and network dynamic fibrils - which are planned to be investigated to address common open questions on their relevance for the heating and dynamics of the solar corona.

Due to their small sizes and fast dynamics microflares need analysis demanding high spatial resolution observations combined with good temporal cadence.

Our objective is to analyse the dynamics and plasma evolution during microflares by studying the chromospheric response to electron beam and/or conductive heating together with the transition region and coronal response combined with X-ray  spectral analysis. The comparison of these observational data with theoretical predictions in the frame of electron-beam-driven and conductively driven chromospheric evaporation for individual microflares can help us to answer several open questions regarding microflares and the coronal heating.

Network dynamic fibrils (DFs) display in the chromosphere repetitive mass loading by acoustic shocks driven by the global oscillations in the underlying photosphere. This scenario assumes that considerable power of photospheric 5-min oscillations is concentrated at the bases of inclined magnetic fluxtubes giving rise to the chromospheric DFs.

Using H alpha filtergrams obtained by the Dutch Open Telescope we have shown that the DFs exhibit also significant variations in orientation, which are faster for shorter DFs. Recently, downflows and upflows occurring at the base and tops of mottles, respectively, were reported.

To explain this dynamic structure the magnetic reconnection as a potential driver of mottles was suggested.

As an extension of the works mentioned above, in this proposal we aim at identification of the center-to-limb variation of kinematic properties of dynamic fibrils and also center-to-limb variation of terminal wavelength shift of visibility of the fibrils and mottles in the H alpha line profile.

Thus, the spectral observations of chromosphere with the best, spatial and spectral resolution, are needed.

More details: campaign page: http://www.astro.sk/~choc/open/08_dot/08_dot.html

 request to SOT
 - FOV: 55" x 111" (512 x 1024 pxs, binning: 2 x 2 pxs)
 - spectral channels: sequentially in time BFI: G-band, Ca II H
 - cadence: 32s per filtergram (64s per sequence of 2 selected channels)
 - total run duration: 4.0 hours (08:00-12:00 UT) - minimum
                   5.5 hours (07:00-13:30 UT) - optimum
 - compression: JPEG Q75
 - telemetry needed: minimum - 4.0 hours: ~520 Mbits
               optimum - 6.5 hours: ~845 Mbits
   estimated according the tables at http://solar-b.nao.ac.jp/sot_e/operation/
   further possible decrease of telemetry load: slower cadence, smaller FOV
 - no compensation of the solar rotation
 - pointing: around the position of the EIS 1D sit-and-stare mode slit

 request to XRT
 - high cadence images using just one selected filter
 - 256x256 px, no binning
 - exposure time: max. 15s with AEC, the highest possible cadence limited
   by the available telemetry
 - filters: microflares: thin Be filter, network fibrils: thin-Al/Mesh
 - low-less compression
 - no compensation of the solar rotation
 - pointing: around the position of the EIS 1D sit-and-stare mode slit

 request to EIS
  A. Study Title (max. 100 characters):
     "Solar microflares and network dynamic fibrils - relevance for
      coronal heating and mass supply"

  B. Study Description/Acronym (max. 20 characters, no spaces):

  C. Ordering of rasters (by acronym) in the study (with no. of repeats) :

     1. Context_calib_jr_08           ( 3 times) - 3 x  8m44s  (  26m12s in total)
     2. Obs_sit_stare_jr_08           ( 5 times) - 5 x 29m55s  (2h29m45s in total)
        slit placed to the X-center of the previous rasters
     3. Context_calib_jr_08           ( 1 times) - 1 x  8m44s  (   8m44s in total)
        raster positioned around the previous slit position
     4. interruption for the Hinode table upload ~10:30 UT
     5. Context_calib_jr_08           ( 1 times) - 1 x  8m44s  (   8m44s in total)
        position at the same location as previous rasters
     6. Obs_sit_stare_jr_08           ( 5 times) - 5 x 29m55s  (2h29m45s in total)
        slit placed to the X-center of the previous rasters
     7. Context_calib_jr_08           ( 3 times) - 3 x  8m44s  (  26m12s in total)

     Total time: 6h09m28s (Data volume: 371548.09 kb, data rate: 16.7607 kbps

     In the optimum case: the study should start at 07:00UT with three 2D rasters
     taken during the EIT synoptic images acquisition. It is expected that
     the study will be stopped ~10:30 UT for the Hinode table uploads. Before
     and after this break a 2D simple raster is taken. The final repetition
     of three 2D rasters should be co-temporal with another EIT synoptic
     images acquisition just after 13:00 UT. The core of project is repetition
     (twice) of the 1D sit/and/stare rasters - one before, one after
     the Hinode table uploads covering in this way the optimum observing/seeing
     period for the g-b instrument DOT/LaPalma.

   Lines:  wavelength  Type    Window Name     Width        T
           192.82* c Ca XVII 32           log T=6.7  
           195.12* c Fe XII 48           log T=6.1  
           256.32* c He II 48           log T=4.9
   186.88      p       Fe XII          40           log T=6.1
          (186.00 Fe VIII log T=5.6 inside Fe XII 186.88 window)
   263.76      p       Fe XXIII        32           log T=7.1

   No rotation compensation
   Slit: 2"x200"

   Study DEF file prepared as : dot+eis:mic_fibrils_1.def

 other participating instruments
RHESSI; SoHO: CDS, EIT, MDI; TRACE; KanzelhNohe Solar Observatory (KSO): H telescope.

* Time period of proposed observations:
 o period: 6-20/10/2008 - this is the period for which we were granted by the
   DOT/LaPalma observing time (OPTICON time)
 o the minimum number of observation days during the period: none          
 o Requirements for continuity of observations: it is not necessary for
   observations to be on consecutive days

* Time window in day:
 o minimum: start and end times: 08:00-12:00 UT
 o optimum: start and end times: 07:00-13:30 UT
   coordination with the DOT/LaPalma ground-based and SOHO+TRACE JOP 189
   space-based observations
 o short interruptions are allowed over the observing period
* Target of interest:
 o target of interest: microflares: active region on-disk near the disk center
      or their remnants network fibrils: quiet Sun on-disk near the disk center
 o target will be specified well in advance depending on the actual solar activity
 o chance to have the target: we expect that our second target can be observed
   each day due to the regular appearance of the network at the disk center
 o target of opportunity (TOO): no

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