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HINODE Operation Plan (HOP)

accepted on


 HOP No.

 HOP title

HOP 0158

EIS Multi-line Observations of Solar Flares and Active Regions

plan term


@ @


 name : Li, Ding, Chen, Fang @  e-mail : yingli.nju[at]gmail.com

contact person in HINODE team

 name : Watanabe @  e-mail : watanabe[at]uvlab.mtk.nao.ac.jp

 abstract of observational proposal

1: To observe multi-spectral Doppler velocities during the flare impulsive phase.

2: To further understand the nature of chromospheric evaporation and heating mechanisms.

Scientific Background: Chromospheric evaporation is largely accepted to be the dynamic responses of solar flare energy release and heating of the chromosphere. Current flare models predict that evaporation occurs when the chromospheric material is heated either by non-thermal electrons or by thermal conduction. The overpressure of evaporated material drives both upward (at coronal levels) and downward (at chromospheric levels) motions simultaneously. These motions can be detected through Doppler velocity measurements in chromospheric and coronal lines. Antonucci & Dennis (1983), Zarro & Lemen (1988), Canfield et al. (1987), Acton et al. (1982), and Doschek & Warren (2005) obtained blueshifts of 300-400 km/s in the Ca XIX line using SMM/BCS (Acton et al. 1980) and Yohkoh (Culhane et al. 1991), respectively. Similar measurements using data from SOHO/CDS (Harrison et al. 1995) revealed upflow velocities of 150-300 km/s in the Fe XIX line (Brosius & Phillips 2004, Teriaca et al. 2003, Milligan et al. 2006a,,b ). On the other hand, in chromospheric and transition region lines, redshifts were observed, which are the observational signature of downward motions (known as chromospheric condensation). With the launch of Hinode (Kosugi et al. 2007) in September 2006, it is now possible to investigate the process of chromospheric evaporation by observing several emission lines simultaneously with the EUV Imaging Spectrometer (EIS; Culhane et al. 2007). EIS performs high spatial, spectral, and temporal resolution to determine the Doppler velocities. Using EIS spectral data, Milligan & Dennis (2009) measured Doppler shifts in 15 emission lines covering the temperature range T= 0.05-16 MK during the flare impulsive phase. Blueshifts indicative of the evaporation were observed in six lines from Fe XIV - XXIV (2-16 MK) at the loop footpoints, and scaled with temperature as V (km/s) ≈ 5 - 17T (MK). Some O VI - Fe XIII lines (0.5-1.5 MK) were found to be redshifted by V (km/s) ≈ 60 - 17T (MK). Though there have been many researches in this respect, many problems still remain to be solved, such as how to derive velocity-dependent emission measure from the asymmetric profiles and why redshifts appear in lines of higher temperatures than previously expected or reported (Milligam & Dennis 2009). We therefore submit a request for EIS multi-spectral observations in combination with ground-telescope observation to study these unsolved problems. The Solar Tower of Nanjing University can observe chromospheric lines. Moreover, we are trying to theoretically calculate the line profiles from flares using the radiative-hydrodynamic simulation. The calculated results can be compared with the observed ones of high cadence and multi-lines, which provide a diagnostic of solar flare energetics and dynamics.

 request to SOT
BFI: Ca II H channel FOV: 218''x109h Cadence: 10 s
NFI: Stokes I/V Fe 630.2 nm FOV: 328"x164" Cadence: 10 s
SP: Stokes I, Q, U, V; FOV: 40"x164"; Cadence: Fast Map Mode

 request to XRT
filter: Al-poly FOV: 384''x384'' Cadence: several seconds

 request to EIS
fast scan:  EIS study ID: 386 - HH_Flare_180x160_1 (HH_Flare_180"x160"_5"steps_8sExp)
Slit 2h
Exposure time: 8sec
Spectral windows: 10
OVI  184.14
FeX 184.54
FeXXIV 192.04
FeXII 195.12
FeXVII 255.05
FeXVI 262.98
FeXXIII 263.69
FeXIV 264.78
FeXIV 274.20
FeXV 284.16

sit-and-stare observation: EIS study ID: 412 YL_FL0158_v2
Slit 2hx160h
Exposure time: 10 sec
Spectral windows: 15
Lines: Fe XXIV 192.03
Fe XXIII 263.76
Ca XVII 192.82
Fe XVII 254.87
Fe XVI 262.98
Fe XV 264.16
Fe XIV 274.20/264.79
Fe XIII 202.02
Fe XII 195.12
Fe XI 182.16
Fe X 184.54
Fe VIII 185.21
Si VII 275.35
Mg VI 268.99
He II 256.32

About the slit scan & sit-and-stare observations, our plan is using 2''slit to scan several times over an active region (or flare region) first, then putting the slit in the middle of the scan region and repeating a few exposures.

 other participating instruments
Solar Tower of Nanjing University (Ha, Ca II 8542, He I 10830) :
We are going to observe a flare area with a slit scan mode covering three lines, namely H alpha, Ca II 8542 and He I 10830, and the cadence can be less than 1 min.

1. Our daily best-seeing observing time is from 1:00 to 8:00 UT (for 7 hours) in June.

2. Highest priority: to observe the flares near the disk center, and the flare impulsive phase

3. Co-aligned SOT and XRT, we want to get the magnetic field and the images, which are of benefit to our flare study.  Proposers are flexible to accept the  suggestions of lowering the telemetry rate of XRT and SOT.

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