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HINODE Operation Plan (HOP)

accepted on

18-sep-2014


 HOP No.

 HOP title

HOP 0271

High cadence study of sunspot light bridgesf activity

plan term

ToO

@ @

proposer

 name : Kanoh, Shimizu @  e-mail : kanoh.ryuichi[at]ac.jaxa.jp
shimizu.toshifumi[at]isas.jaxa.jp

contact person in HINODE team

 name : Shimizu @  e-mail : shimizu.toshifumi[at]isas.jaxa.jp

 abstract of observational proposal
This HOP aims to understand the origin of activities of light bridges, such as long-lasting plasma ejection (Shimizu 2007), super-sonic down flow (Louis 2009).

These activities may be associated with magnetic field. Although magnetic reconnection is specially considered as the driver of these activities, it is not conclusive because of few studies focusing to the high temporal evolution of magnetic fields and chromospheric counterparts in light bridges. Especially, velocity measurements in the chromosphere are important for justifying magnetic reconnection.

Although there are many SOT observations of light bridges, there are only a few SP datasets that provide the evolution of magnetic fields in the cadence less than a few minutes. Furthermore, there are a very limited number of IRIS observations for light bridges simultanetously performd with SP. Especially, the light bridge with long-lasting plasma ejections has not yet been observed by IRIS and SP at the same time.

This proposal is to request the Hinode and IRIS teams to acquire more examples of light bridges. Note that this work is a part of the proposer's Master thesis studies.

 request to SOT
<FG>
Ca II H line and G band, 2x2 sum, 512x512
Cadence - Ca II H: 15 sec, G band : 30 sec
FOV - 55hx55h (necessary to cover the sunspot)
Telemetry - 250 Mbits per 1 hour

<SP>
Fast map mode: 0.32h/pixel, 3.2 sec integration
Cadence - shorter than 2 min
FOV - 10hx55h (necessary to cover the light bridge)
Telemetry - 300 Mbits per 1 hour

 request to XRT
None

 request to EIS
None at the moment - Added later

 other participating instruments
IRIS:
Medium sparse 4 or 8 step raster, 4 seconds exposure times per one slit position
FOV - necessary to cover the light bridge
Slit position - on the light bridge
Slit orientation - no rotation
Slit-jaw - Si IV 1400 and Mg II k 2796 with occasional Mg II w 2832

 remarks
ETime period of proposed observations
 It is better to monitor the evolution of light bridges in the durations as long as possible. Activities in light bridges are typically seen in a limited period of the entire evolution. Considering the telemetry limitation, it is good to repeat the proposed program 4-5 times with an interval of 4-6 hours in a day.

ETime window in day
 Each duration of one program run is 1 hour in minimum. Any short interruptions are not allowed over the observing period.

ETarget of interest
 Sunspot light bridges. The North-South oriented light bridges in sunspots are most suitable because the SP and IRIS can capture the entire light bridges in their narrow slit-scan windows.

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