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HINODE Operation Plan (HOP)

accepted on


 HOP No.

 HOP title

HOP 0071

CORE: VTT-Hinode/SOT collaboration (Search of transient horizontal magnetic fields in the chromosphere)

plan term


@ @


 name : Ishikawa @  e-mail : ryoko.ishikawa[at]nao.ac.jp

contact person in HINODE team

 name : Ishikawa @  e-mail : ryoko.ishikawa[at]nao.ac.jp

 abstract of observational proposal
To find a chromospheric counter part of the transient horizontal magnetic fields (THMFs) seen on the photosphere.

Scientific Background:
Our science objective is to find a chromospheric counterpart of the transient horizontal magnetic fields (THMFs) discovered in the photosphere. The horizontal magnetic fields with high time variation were observed all over the Sun in the photsphere with the SOLIS and GONG instruments (Harvey et al. 2007). Unprecedented high spatial resolution observation with Spectro-polarimeter (SP) aboard Hinode has extended the studies considerably; granular-sized THMFs are indeed ubiquitous in the photosphere (Lites et al. 2008, Orozco Suarez et al. 2007, Centeno et al. 2007, and Ishikawa et al. 2008). Ishikawa & Tsuneta (2009) points out that the magnetic energy flux, with which THMFs potentially provide the quiet Sun (2~106 erg cm-2 sec-1) is comparable to total chromospheric energy loss of 4~106 erg cm-2 sec-1(Withbroe & Noyes 1977), and that THMFs could contribute to the chromospheric and coronal heating (see also Trujillo Bueno et al. 2004; Abbett 2007; Isobe et al. 2008). Thus, whether THMFs reaches the chromosphere (or not) should be observationally pursued to understand the possible role of THMFs for the chromospheric and coronal heating. In broader context, any transient magnetic phenomena in the chromosphere is our observing target. Here we would like to request spectro-polarimetric observation of the Fe I 630.1/630.2nm line. Simultaneously, Tenerife Infrared Polarimeter (TIP) with Vacuum Tower Telescope (VTT) will perform spectro-polarimetric observation of the He I 1083 nm line to detect chromospheric magnetic signals with the joint action of Hanle and Zeeman effects, and we plan to find any transient magnetic phenomena including THMFs both in the chromosphere and in the photosphere simultaneously. Hinode observes the photosphere with SP (630.1/630.2 nm) and with NFI magnetograms (525.02 nm). SP has a very skinny field of view to have ultra high cadence of 1 min or so, and Shutter-less NFI magnetograms provide wide-field context Stokes IQUV images at the blue wing with time cadence of about 30 sec. TIP performs the spectro-polarimetric observation for the He I line also with very skinny FOV of ~3h~80h to have high time cadence between 1 and 3 min. This is an ideal arrangement for the detection of THMF counter part, which has mean lifetime of only 4 min. Uniqueness of our investigation is that we perform simultaneous spectro-polarimetric observations with unprecedented high time cadence combined with very deep exposure for both the chromopshere and the photosphere. This research is a part of Ph. D. thesis topics of R. Ishikawa.

Former projects
We already carried out the joint observation campaign between VTT/TIP and Hinode/SOT from April 29, 2008 to May 12, 2008 (HOP 71). In this campaign, the internetwork region with a narrow FOV (∼15h~80h) was observed by SP and TIP simultaneously with moderate time cadence of 7.5 min, and we found that some of chromospheric magnetic fields drastically changes with the time scale less than 7.5 min (Ishikawa et al. in preparation). However, the time cadence of 7.5 min was too low to see the time evolution of THMFs, and the exposure time for each slit position for VTT/TIP was not enough to obtain good signal-to-noise ratio. Thus, we would like to improve our observation program.

 request to SOT
Ca II H:
FOV 51hx81h, 2x2 sum, 1 min cad, Q75
FOV 51hx81h, 2x2 sum, 1 min cad, Q75
Fe 5250 Sh-less IQUV (-100mA offset):
FOV 51hx81h, 2x2 sum, 1 min cad, Q75
FG total -> ~350 Mbit/1H

Fast map, FOV 5"x82" (32 slit pos, 2x2 sum), 60s cad, 2 side CCDs-> 600Mbit/1H
Note: The SP FOV of 5"x82" is ideal. We would start SP observation with relatively wide FOV (~10hx82h), and confirming the stability of offset between Hinode and VTT through the observation, we would decrease the FOV (cadence). In the core time, please run SP simultaneously as long as the telemetry permits.

 request to XRT
Al/poly, covering SOT and EIS FOV, low cadence (for alignment between SOT and EIS).

 request to EIS
Slot and slit mode with emphasis on lower temperature lines, covering SOT FOV.

Study: DRW_QS_THMF, and DRW_Alf_01 are observation programs used for HOP 89. One of purposes for HOP 89 was to find the chrosmospheric counterpart of THMFs, too. They would be available if the exposure time to observe strong magnetic concentrations is fine. FOVs of VTT/TIP and SOT are very narrow, and the alignment between SOT and EIS would be critical. In order to obtain the information of offsets between them, please run the alignment test program between SOT, EIS, and XRT before our campaign.

 other participating instruments

Time period:
Our observation proposal for VTT/TIP was already accepted by IAC. Our observation will be executed April 30th to May 3rd , and May 25th to June 1st. We also may have an observation June 1st to 8th (now we are negotiating with Christian Beck). Moreover, if we will not be able to obtain good data set during the period described above, we would ask Andreas Lagg to perform our observation June 8 to 25. Note that our proposal is not related to the SUNIRIZE, and will not be done during the SUNRISE observing campaign period.

Time window:
8:30-12:00 UT. Minimum duration is 2 hours (9:00UT-11:00UT) every day.

Target of interest:
He I 1083 nm needs coronal illumination (see Centeno et al. 2008; and more references therein). Strong magnetic concentrations around the super-granular boundary can be observed. If there is an active region, we will observe active regions just to have more illumination for He I 1083 nm.

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