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HINODE Operation Plan (HOP)

accepted on


 HOP No.

 HOP title

HOP 0038

Bright Point Microflaring Oscillations

plan term


@ @


 name : Bloomfield, Jess, McAteer, Mathioudakis, Keenan, Andic @  e-mail : bloomfield[at]mps.mpg.de

contact person in HINODE team

 name : T. Sekii @  e-mail : sekii[at]solar.mtk.nao.ac.jp

 abstract of observational proposal
To study the occurrence of quasi-periodic intensity variations associated with microflares in magnetic bright points.
   Ground-based imaging time series from the Dunn Solar Telescope has shown that oscillations are present in H-alpha blue-wing (-1.3 \AA) intensity during the course of two microflaring events (Jess et al. 2007). Two sites of high-frequency (~30-50 mHz) intensity oscillations are observed to rotate around the bright point centre during both microflare events, and has been interpreted as the
observational signature of waves existing inside two entwined flux tubes. The microflares are proposed to be due to reconnection events caused by the high degree of field line twisting between the entwined flux tubes (c.f., de Moortel & Galsgaard 2006a, 2006b) with the waves also initiated by the reconnection process. Although speckle reconstruction was used to retrieve information from the ground-based imaging data at as high a spatial resolution as possible, the interpretation of high-frequency intensity variations as a signature of waves would benefit from space-based observations that do not require the removal of seeing effects from the Earth's atmosphere.
   We aim to search for corroborating evidence of oscillation sites associated with microflaring events, and their subsequent rotation, with high spatial resolution H-alpha wing imaging that is free from the warping effects of the Earth's atmosphere. The combination of separate red-wing and blue-wing imaging will allow determination of intensity variations previously seen 1.3 Angstroms into the H-alpha blue-wing as being due to either Doppler shifts of the line profile or density enhancements associated with waves. In addition, the
high-cadence magnetograms aim to detect decreases in photospheric magnetic flux associated with microflaring reconnection processes.

 request to SOT
1)  SOT-NFI: Interleaved time series of 3600 s duration. To be run
            with a reduced FOV in the EW direction to allow for
            high-cadence imaging:
              I)   High cadence (~1-2 s) H-alpha blue-wing imaging
                   at - 1.3 \AA,
              II)  High cadence (~1-2 s) H-alpha red-wing imaging
                   at + 1.3 \AA,
            Additionally, if overall cadence not too slow:
              III) High cadence (~3-5 s) Fe I 6301.5 or 6302.5 \AA
                   photospheric magnetograms,
              IV)  High cadence (~3-5 s) Fe I 5576.1 \AA
                   Dopplergram imaging at +/-0.136 \AA,

2)  SOT-BFI: Reduced FOV in EW direction (roughly similar to that of
            the NFI) to allow for high-cadence imaging:
              I)   Context G-band, CN-band, blue continuum, and red
                   continuum images at beginning and end of SOT-NFI
            If data rate permits:
              II)  High cadence (~2-4 s?) CaIIH imaging interleaved
                   into SOT-NFI time series,

3)  SOT-SP:  Context SP map of penumbral/active plage region covering
            a similar EW extent as the reduced SOT-NFI/BFI FOVs. To
            be run before and optionally after the SOT-NFI/BFI time
            series sequence:
               -  3 waveplate rotations,
               -  164 arcsec slit length,
               -  0.16 arcsec slit scan step.

 request to XRT

 request to EIS

 other participating instruments

The chosen region should sample a portion of the solar disk that is close to, but not completely encompassing, an active region (i.e., a region either leading or trailing an active region, containing some penumbra but mostly active plage or quiet sun).
   The sequence should be run on at least six separate regions to allow for greater probability of detecting microflares (e.g., either active plage leading and trailing three separate sunspots or active plage leading and trailing one sunspot on three separate days).

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