Temporal evolution and characteristics of evaporating flare ribbon sources

Hinode 9 - Belfast September 2015

David Graham, Gianna Cauzzi, Luca Zangrilli INAF - Osservatorio Astrofisico di Arcetri

September 10th 2014 Flare IRIS observation

X1.6 (17:45 UT)

IRIS Sit and stare - 9.4 second cadence

Coronal + chromospheric temperature lines

Fe XXI + Mg II

0.33’’ x 0.167’’ pixel size

1400Å Slitjaw Image (Si IV)

Between 17:25 – 17:35 UT the flare ribbon develops at a constant rate across IRIS’ slit

Every slit pixel shows a unique and complete flare evolution

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Flare Ribbon Evolution (1400Å IRIS Slitjaw)

Between 17:25 – 17:35 UT the flare ribbon develops at a constant rate across IRIS’ slit

Every slit pixel shows a unique and complete flare evolution

81 flares for the price of 1!

Flare Ribbon Evolution (1400Å IRIS Slitjaw)

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Mg II Subordinate line 2791.5Å

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NUV Spectrum

Fe XXI 1354.1ÅFUV Spectrum

Constrained Si II (from Fe XII window)

Fe XXI Window - Fitting example

Fe II tied centroids

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Mg II (red contours) 15 & 30 km/s

Fe XXI (yellow) >270 km/s (dark blue) >200 km/s (blue) >100 km/s

17:26 17:28 17:30 17:32 17:34Start Time (10-Sep-14 17:25:11)

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17:26 17:28 17:30 17:32 17:34Start Time (10-Sep-14 17:25:11)

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Impulsive Phase Plasma Dynamics

Co-spatial Mg II intensity and condensation down-flows

Co-spatial Mg II down-flows and Fe XXI up-flows (chromospheric evaporation)

Apparent delay between Fe XXI and chromospheric flows (~65s)

Graham & Cauzzi 2015

time

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Fe XXI Velocity

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Mg II Velocity (30% bisector)

Temporal evolution of condensation and evaporation

Superposed epoch analysis of all 81 pixels

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Fe XXI Velocity

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Mg II Velocity (30% bisector)

Temporal evolution of condensation and evaporation

Superposed epoch analysis of all 81 pixelsCondensation: 30-60 seconds (consistent with older simulations of Fisher 1986/89)

1986lasf.conf...25F

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Mg II Velocity (30% bisector)

Temporal evolution of condensation and evaporation

Evaporation timescale: > 500 seconds

Remarkably similar curves for all flaring pixels: Evidence of elementary flaring kernels?

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Velocity profile - good proxy for energy deposition in the chromosphere (Fisher 1986/89)

Average temporal profile + average spatial profile

Upper limit to the size - 1.5” (includes ribbon inclination and movement)

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Mg II (sub) Mean Velocity ProfileRibbon Characteristics

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Velocity profile - good proxy for energy deposition in the chromosphere (Fisher 1986/89)

Average temporal profile + average spatial profile

Upper limit to the size - 1.5” (includes ribbon inclination and movement)

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Mg II (sub) Mean Velocity ProfileRibbon Characteristics

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SPEX FERMI GBM Count Flux vs Time

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Detectors: NAI_024.6 to 15.2 keV (Data with Bk)15.2 to 24.3 keV (Data with Bk)24.3 to 50.9 keV (Data with Bk)50.9 to 98.8 keV (Data with Bk)98.8 to 296.4 keV (Data with Bk)296.4 to 601.2 keV (Data with Bk)601.2 to 2000.0 keV (Data with Bk)

3-Feb-2015 10:53

Fermi X-Ray Analysis - spatially integrated

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Fermi X-Ray Analysis

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Capable of similar observations

High cadence Sit-and-Stare

Coverage of hot plasma (500,000 - 10 MK)

Diagnostics of Density

Ca XV logT = 6.6 Fe XII logT = 6.2 O V logT = 5.4

The Astrophysical Journal, 762:133 (7pp), 2013 January 10 Brosius

Figure 3. (a) Light curve and (b) relative Doppler velocity plot for the Fe xxiiiline at 263.8 Å observed by EIS during the C1 flare of 2012 March 7. Intensitiesdisplayed as vertical error bars only (with no symbols) are derived fromexposures in which only one component to the emission line is observed;intensities displayed as boxes represent the sum of a main component (at rest)and a secondary blueshifted component; intensities displayed as Xs correspondto exposures in which no Fe xxiii emission is detected (we fit the noise; statisticaluncertainties are larger than the plotted intensities). The solid horizontal linein (a) shows the pre-flare average noise. Velocities displayed as asterisks withvertical error bars correspond to exposures used to derive the reference (rest)wavelength and its 1σ scatter; velocities displayed as vertical error bars only(no symbols) are derived from exposures with significant Fe xxiii emission;those displayed as boxes correspond to the secondary, blueshifted componentobserved in five EIS exposures.

correspond to exposures in which no significant Fe xxiii emis-sion is detected.

We also ran the CDS stare study FLAREDOP on AR11429, with the slit pointing offset about 30′′ west of theinitial pointing of the EIS slit. The objective was to obtainsimultaneous rapid cadence stare spectra of different features ina flaring loop system. Unfortunately, a particle storm impactedSOHO (located at L1) during this observing run. We visuallyinspected the spectra from the slit segment and the time elementsrelevant to the C1 flare, and removed those that were obviouslycontaminated by particle strikes. We fit profiles to lines inthe remaining spectra (about one-third the total number ofexposures) and generated light curves.

3. RESULTS

Figure 3(a) shows the light curve of Fe xxiii emissionobserved by EIS. The flare is seen in its Fe xxiii emissionbefore it is seen in emission from any other lines observed

Figure 4. Light curves derived from the EIS spectra averaged over five 1′′

y-pixels along the slit around the spatial center of the flare during the run ofFLAREDOP_EIS that observed the C1 flare of 2012 March 7. Color-codedhorizontal lines indicate the pre-flare intensity averaged over the first 171exposures in the sequence (indicated with the thicker, shorter black horizontalline) plus the 1σ scatter over the same exposures. The flare starts in Fe xxiiiemission at 18:49:48 UT (indicated with long black vertical tick marks), asdescribed in the text. For Fe xvii and Fe xvi, the flare starts when the lineintensities continuously exceed their pre-flare averages by more than 1σ , whichcorresponds to 18:51:40 for Fe xvii and 18:56:19 for Fe xvi; in the case ofFe xiv, the flare starts at 19:01:09 UT, but the line intensity drops a bit belowthe 1σ limit during two exposures. S x and Si vii do not participate in the flareat the location of the EIS slit.

with EIS (Figure 4), and we determine its start time by twomethods. The first is based on the statistical uncertainties inthe profile fit parameters, and the second is based on thescatter in the pre-flare noise. In the first method we take theFe xxiii line intensity to be significant only for exposures inwhich the profile fit parameters exceed their own statisticaluncertainties. Using this approach, we first detect significantFe xxiii emission in the 183rd exposure of the 300 exposuresequence, with a start time of 18:49:47.6 UT. In the secondmethod we take the Fe xxiii line intensity to be significant forexposures in which the integrated line intensity continuously(that is, for an uninterrupted sequence of exposures) exceedsits pre-flare average noise (derived from the first 171 exposuresof the observing run) by more than three times the 1σ scatterin that noise. (The solid horizontal line in Figure 3(a) showsthe pre-flare average noise.) Using this approach, we first detectsignificant Fe xxiii emission in the 182nd exposure, with a starttime of 18:49:36.4 UT. Because the two methods yield starttimes that differ by only one exposure, and because the intensityof the emission from the earlier of those two exposures maynot be significant in light of the large uncertainties on the fitparameters therein, we adopt 18:49:48 UT as the starting timeof the flare.

Figure 3(b) shows the Fe xxiii Doppler velocity relative tothe “reference” wavelength (described above) for the expo-sures in which significant Fe xxiii emission is detected. Ve-locities displayed as asterisks with vertical error bars corre-spond to exposures used to derive the reference wavelengthand its 1σ scatter; velocities displayed as vertical error barsalone (no symbols) are derived from exposures with significantFe xxiii emission; those displayed as boxes correspond to thesecondary, blueshifted component observed in five EIS expo-sures. Note that the relative Doppler velocity is directed upward−122 ± 33 km s−1 when the Fe xxiii line first appeared at18:49:48 UT, reached a maximum value −208±14 km s−1 two

5

Hinode/EIS Fe XXIII Brosius 2013

Hinode/EIS

Conclusions

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IRIS gives us the most complete view of evaporation/condensation to date

Evaporation and condensation flows - potentially co-spatial (possible delay)

Fe XXI line is always completely blue-shifted (for > 500 seconds)

Condensation time of ~ 60 seconds close to old simulations

Sources show remarkably similar evolution - flare is a progression of single events

Ribbon size <1.5’’ Excitation time ~ 30 seconds

Ribbon spatial and temporal scales are essential inputs for modelling

“The research leading to these results has received funding from the European Community’s Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 606862 (F-CHROMA)”