Lecture 12 Flare Lightcurves March 1, 2017 Questions regarding - PowerPoint PPT Presentation

Lecture 12 Flare Lightcurves March 1, 2017

Questions regarding flare heating q When is flare plasma heated: only at the very start or throughout the flare evolution? Impulsively or more gradually? q Where is flare plasma heated: is the primary energy deposition in the corona or in the lower atmosphere or both? q What is the mechanism of flare heating: by shocks? Non- thermal particles? Conduction? Or else? q How much is the energy used to heat flare plasma? Time dependent imaging and spectroscopic flare observations in multiple wavelengths have the enormous advantage.

� � Questions regarding flare heating energy& # ∂ t ∂ s & ∂ s ∂ s # ∂ s & 2 " % ) , ∂ T + u ∂ T ' = − p 3 µ ∂ u + 1 A κ ∂ T ∂ ∂ 2 Λ ( T ) + h ( ) + 4 ρ c v Au .− n e $ + # ∂ t ∂ s & A ∂ s ∂ s A ∂ s * ∂ s - heating s tr k 3 k L /2 L /2 dE tot 2 puA tr − κ ∂ T ∫ 2 Λ ( T ) Ads 2 u 3 A ∫ n e tr + 5 ∂ s A h Ads ≈ − + 1 + dt tr s tr s tr enthalpy&flux& radiaBve&loss& conducBve&flux& 𝐷 " 𝑢 = & 𝑆 " (𝑈)𝑜 , (𝑈) 𝑒𝑚 𝑒𝑈 𝑒𝑈 , counts/s/pxl Two approaches of doing this, forward or backward.

coronal loops by Skylab The great “seahorse” H a flare by BBSO Telescopes on the ground and in space have captured the signature morphology of solar flares: ribbons and loop The first X-ray arcades. view of flares in the corona

The standard flare configuration separatrice

Flare emission across the electromagnetic spectrum Bremsstrahlung & hard X-ray 100 keV gyro-synchrontron hard X-ray 20 keV emissions by microwaves non-thermal soft X-rays electrons . thermal emission by 10 6-7 K plasmas flare ribbons flare loops (10 4-5 K) in the (10 6 K) in chromosphere the corona optical H a EUV 171A (TRACE) (BBSO)

Flare emission across the electromagnetic spectrum

The view from the chromosphere to the corona TMR + Civ He II 304 TMR (He II 1640) 3500 K – 10 MK, 1” – 2”, full-disk, 12 – 24s, 24/7, by AIA

Heating (?) and cooling sequence TMR + Civ He II 304 TMR (He II 1640) The order of peak emission: chromosphere 0.1 MK – corona 10 – 6 – 3 - 2 – 1 MK, with time lags of 10, 10, 15, 15, 10 min.

The Neupert Effect: when is the heating? Neupert (1968), “Comparison of Soft X-ray Line Emission with Microwave Emission During Solar Flares”, states that the time integral of microwave burst corresponds best to X-ray line emission from rise to maximum.

The Neupert Effect: when is the heat? Citations history for 1968ApJ...153L..59N from the ADS Databases The Citation database in the ADS is NOT complete. Please keep this in mind when using the ADS Citation lists. RHESSI launch

The Neupert Effect: SXR vs. Microwave Integral Neupert (1968)

The Neupert Effect: SXR derivative vs. HXR 1993SoPh..146..177D 1993SoPh..146..177D Dennis & Zarro 1993: 80% (of 66 large events SMM/HXRBS) show good correlation.

The Neupert Effect: the Larger Story Veronig et al. 2002: Neupert effect in >1000 SXR/HXR events by GOES and Burst and Transient Source Experiment on Compton Gamma-Ray Observatory (BATSE/CGRO; 25–50, 50–100, 100–300 Fig. 1. Histogram of the di ff erence of the SXR maximum and HXR and >300 keV , 1~s, 1997-2000, 2738 end time, given in absolute values (top panel) and normalized to the HXR event duration (bottom panel). Positive values indicate that the pace), HXR events.) maximum of the SXR emission occurs after the end of the HXR emis- sion, negative values vice versa. The shading refers to di ff erent sam- ples of events, which are compatible with the timing expectations of ent the Neupert e ff ect (light grey, set 1), strongly incompatible (dark grey,

Heating during the HXR burst Q Fisher & Hawley 1990 (also Mariska/Emslie/Li, 1990s) Antonucci, Gabriel, Dennis 1984, ApJ

��������������������������� � Heating during the HXR burst ���������������������������������������������������������� ��������������������������� � ����� � �������� € ���������� � ��������������������������� � ���������������������������������������������������������� ��������������������������� � ����� � �������� € ���������� � EBTEL; Klimchuk et al. 2008 Parameter Observed EBTEL 3 × 10 9 (3 ± 0 . 2) × 10 9 Loop half-length [cm] � ������������������������ � Non-thermal flux – Amplitude [erg cm − 2 s − 1 ] 7 × 10 9 5 × 10 8 ± 1 ������������������������������ � – Width [s] ∼ 100 100 ± 50 – Total [erg cm − 2 ] ∼ 1.7 × 10 12 2 . 5 × 10 10 ± 1 ������������ � Direct heating rate � ������������������������ � – Amplitude [erg cm − 3 s − 1 ] ������������������ � � – 0 . 7 ± 0 . 3 – Width [s] – 100 ± 50 ������������������������������ � – Background [erg cm − 3 s − 1 ] ≤ 1 × 10 − 6 – – Total [erg cm − 3 ] – ������������� 175 ± 150 ������������ � Direct / non-thermal heating (best fit parameters) ∼ 4 ������������������ � � Raftery et al. 2009 �������������

Fitting the XR spectrum to find energy, and else 𝜁 45 (Qiu+09) 𝜁 0 Typical flare non-thermal flux: Γ~10 E4F, erg/s/cm 2 𝐽 𝜁 = 𝑏𝜁 45 (photons/s/cm 2 /keV), 𝐺 𝐹 = 𝐵𝐹 49 (electrons/s/keV) ∝ ∝ 𝑂 ;<; = ∫ 𝐺 𝐹 𝑒𝐹 (electrons/s), 𝐹 ;<; = ∫ 𝐹 𝐺 𝐹 𝑒𝐹 (ergs/s) ? @ ? @

Different amount of “non-thermal heating” produces different coronal signatures ( Winter et al. 2011, Liu et al. 2013 )

Raftery et al. 2009

The Neupert Effect: what is not working (1) “Cooling” is slower than expected: decay is not all about cooling (models & observations). (2) Reconnection, energy release, and dynamics well into the decay phase; (3) Perhaps not all places are heated the same way. (4) A good fraction of events do not follow the Neupert effect (Feldman et al. 1982, Veronig et al. 2002).

1-8 A 0.5-4 A T EM Fe XVI velocity EIT 195 intensity upflow Czaykowska et al. 1999

n e L 2 21 k b τ cond = 8 × 10 − 6 T 5/2 T 3/2 3 k b τ rad ~ 1.2 × 10 − 19 n e

(Liu+, 2013)

Thick-target HXR is not found along the entire flare ribbon. (Liu et al ,2007)

Loops are formed and heated sequentially

Heating (?) and cooling sequence TMR + Civ He II 304 TMR (He II 1640) The order of peak emission: chromosphere 0.1 MK – corona 10 – 6 – 3 - 2 – 1 MK, with time lags of 10, 10, 15, 15, 10 min, duration of each ~ 50 min.

Heating (?) and cooling sequence AIA EUV 171 at 2:44:00 UT 120 1600 100 115 km/s 80 60 450 450 40 20 Solar Y (arcsec) 0 120 20 40 60 80 100 120 400 131 400 100 +2 min 80 60 350 40 350 20 0 distance A-B (Mm) 120 20 40 60 80 100 120 94 100 300 +6 min 300 80 60 40 -100 -50 0 50 100 150 -100 -50 0 50 100 150 20 0 120 20 40 60 80 100 120 Solar X (arcsec) 335 100 +10 min 80 60 Flare loops heat (and cool) 40 20 at different times. 0 120 20 40 60 80 100 120 171 100 +40 min 80 60 40 20 0 20 40 60 80 100 120 minutes after 11 UT

500 131 94 foot-point 335 450 400 211 (/5) 193 (/10) 171 (/10) 1600 (/4) counts/s/pixel 400 300 200 350 100 300 0 150 -100 -50 0 50 100 150 11.0 11.5 12.0 12.5 13.0 hours in UT Solar X (arcsec) 500 131 The order of peak emission: 94 335 loop-top 400 211 (/5) 193 (/10) chromosphere 0.1 MK – 171 (/10) 1600 (/4) counts/s/pixel 300 corona 10 – 6 – 3 - 2 – 1 MK, with a little shorter 200 time lags and duration. 100 0 11.0 11.5 12.0 12.5 13.0 hours in UT

� � Differential Emission Measure in single pixels SDO/AIA&–&coronal&Swiss&Army&knife& Lemen&et&al.&2012& Fe&IX& Fe&XII& Fe&XIV& Fe&VIII& Fe&XXI& Fe&XIV& Fe&XVI& Fe&XVIII& Fe&X& 𝑒𝑚 𝐷 " 𝑢 = & 𝑆 " log 𝑈 𝑜 , log 𝑈 𝑒 log 𝑈 𝑒 (log 𝑈) ,

Differential Emission Measure in single pixels (Hannah & Kontar 2012 …...)

4-7 MK 0.5-1 MK 7 - 14 MK 1-2 MK 2-4 MK Differential Emission Measure by Mark Cheung (Cheung et al. 2015)