what are we understanding coronal heatings with “hinode ... · ov feviii heii dashed line:...
TRANSCRIPT
What are we understanding Coronal Heatings with “Hinode”?
waves vs. nanoflares
R.Kano (NAOJ)
What kinds of corona?
• Different regions– Active Regions, Quiet Sun, and Coronal Holes.
• Different magnetic topologies– closed fields (i.e. coronal loops) and open fields.
• Various time scales– (quasi-)steady structures and
transient events (i.e. flares, microflares).• Various spatial scales
– coronal loops, diffuse extended corona, XBPs, …
Classification of Coronal Features by Physical Parameters
Narukage et al. (Hinode-3)
Classification of StarsHR diagram
Mass & AgeB, L, … ?
Evolution of Coronal Features on T-EM diagram
Narukage et al. (Hinode-3)
Ener
gy in
put
Ener
gy in
put shift toshift to
steady statesteady state
decay t
o QR
decay t
o QR
still
open
fiel
d &
st
ill op
en fi
eld
&
chan
ge to
CH
chan
ge to
CH
field clo
ses &
field clo
ses &
change to
QR
change to
QR
Closed loopClosed loop
Ope
n fie
ldO
pen
field
H burning
He burning
Ejection of envelope
Evolution of Stars
Contents• What topics are we studying by Hinode?
– Heating Functions H(s).• Loop-top, footpoint, or uniform heatings.
– Nanoflares.• Super-hot components• Intensity fluctuations
– (Velocity).– Relation with photospheric magnetic fields.
• What topics should we study by Hinode?
• What I hope for Solar-C.
Heating Function
• In (quasi-)steady coronal loops, T(s) is coupled with H(s).
• However, there are – Multi-temperature structures
(due to fine structures?)– Velocity fields– etc.
H(s)
T(s)
Heating Radiative Cooling Conductive
Cooling
H(s) = n2Λ(T) – κ∥∂T∂s
∂∂s
Heating Function:above polar regions
Kano et al. (2008, PASJ)
Eclipse on 2007 Feb.17
Temperature1.0 1.4MK
gradient(?)
1〜2x104
erg sec-1 cm-2
1.3
1.1
1.2
0 100 200h (Mm)
T (MK) 0.7
(Revised due to a new calibration data)
• XRT filter ratio temperature increased with hight above polar regions.
• The T-grad. might suggest heating not near footpoints but at high altitude.
Heating Function:above polar regionswith multi-T analysis
Kano (Hinode-3)
• However, based on multi-Tanalysis, the EIS & XRT data above polar regions are well explain with hydrostatic changes of isothermal vertical threads with several temperaturesas Aschwanden & Nitta (2000 ApJ) suggested.
Isothermal structure suggestsfootpoint heating.
T (K)105 106
1020
1022
1019
1021
1018
DEM (cm-5 K-1)
For 10”
For 50”
For 100”
Hydrostatic change with height
Aschwanden & Nitta (2000 ApJ)
Heating Function:in Loops with multi-temperature analysis
Tripathi et al. (2009, ApJ)
• Single temperature along LOS.
• dT/ds > 0.• Filling factor around
foot points– 0.02 @ FeXII, SiX– ~1 @ MgVII
T-grad. suggests loop-top heating.
EM Loci plots
Footpoint
Looptop
Heating Function: in Quasi-Steady UpflowImada et al. (2007, PASJ), Imada et al. (2007, ASJ meeting)
FeXIIFeXIII
> 1 hour Quasi-Steady 150km/s -150km/s
Upw
ard
Vel
ocity
km
/sec
Log Te
FeXVFeXIV
FeXIII
FeXII
FeXIFeX
FeVIIIOVHeII
Dashed line:Sound Speed
• T-dependence of upflow triggered with a flare.
• H(s) was derived– by assuming a cross-
section model of vertical fields,
– and using energy-eq. momentum-eq. and mass conservation.
20M
m40
Mm
60M
m0M
m
Hei
ght
√A logT Velocity
FeXVFeXIVFeXIII
FeXII
FeXI
FeX
FeVIIIOV
HeII
H(s)
Heating at high altitude.
1A(eA) + (vA) = H(s) – n2Λ(T) + Aκ∥
pA
mnvA
∂T∂s
∂∂s
∂∂s
∂∂s
Nanoflare studies: Super-Hot Plasma(1)Reale et al. (2009, ApJ)
• From a multi-filter observation by XRT, Realeet al. (2009) reported super-hot (10MK) plasma in non-flaring active region.
• Although it is necessary to check the possibility of an artifact by scattered lights in XRT, it might suggest nanoflare heatings.
Nanoflare studies: Super-Hot Plasma(2)Ishibashi et al. (Hinode2 & Hinode3) .
• In Hinode-2, Ishibashi reported that 15MK component was found in quiet-Sun with the filter-ratio analysis of XRT.
• In Hinode-3, he made assurance double sure with the photon-counting analysis by XRT, and detected X-ray spectrum from ~10MK plasma in quiet-Sun.
–X-ray spectrum in
Nanoflare studies: Intensity fluctuationsTerzo (TBD)
• He just started this topic.
• From XRT’s high-cadence (~3 sec) observations, auto-correlation of intensity fluctuations may reveal a typical timescale of nanoflare events.
Sakamoto et al. (2008, ApJ)
Upflow & NT-Velocity in AR LoopsHara et al. (2008, ApJ)
• Upflow of hot plasma was observed near the footpoints.
• Large NT-velocity was also observed near the footpoints in on-disk active regions. It is probably a superposition of many upflow components.
The hot plasma upflowssuggest nanoflare heating.
Small NT-velocity (~20km/s) in limb ARs gives a constraint to Alfven-wave heating.
Fe XIV 274AOn-disk AR Limb AR
Hint from simulationsAntolin et al. (2008, ApJ)
x
t x
t
x
t
x
t
x
t
x
t
Alfvén wave heating Nanoflare heating(footpoint)
Nanoflare heating(uniform)
Tem
pera
ture
Vel
ocity
Temporal variation of T(s) or V(s) along loops is important.
Imada pointed out that reconnection sites in major flares (100Mm) do not look hot due to the time lag for ionization.
How about nanoflares? Local enhancement (~1Mm) in T(s) might be hard to be observed.
Relation between Coronal Activities & Photospheric Magnetic Fields
eg. Kano et al. (2010, submitted)
Emerging
Reconnection
Submerging
11:13:51.472
11:15:42-59
11:15:35
SO
T-F
GM
agne
togr
amSO
T-F
GC
a-II
HX
RT
Al/P
oly.
5”5000 km
fluxemergence
• Microflares around a spot were accompanied with magnetic cancellations, some of which were formed with EMF and MMF.
• Although magnetic buoyancy may prevent the submergence of coronal fields under the photosphere, why magnetic cancellations are associated with microflares?
Multiple reconnections may happen not only corona but also in chromosphere or transition region.
Magnetic SubmergencesSubmergence of photospheric B: Chae et al. (2004, ApJ)
Submergence of chromospheric B: Harvey et al. (1999, SP) • The Submergence of
photospheric and chromospheric magnetic fields were observed.
• Non-thermal emission observed with RHESSI above cancellations suggests that reconnection occurred in the corona.
• However, no evidence for the submergence of coronal fields.
Chifor et al. (2008, AA)
Downflow at cancellation site
Chrom.-B disappeared earlier than photo-B.
Chromospheric magnetogram
Photospheric magnetogram
Interaction regions would like to be observed.
• Velocity fields in chromosphere, transition layer, and lower corona.
• Magnetic configuration in chromosphere.
With Hinode/EISand Solar-C/Plan-B.
Emerging
Reconnection
Submerging
?
Studies of Coronal Heating with Hinode(personal view)
• Heating Functions along magnetic fields.– To analyze T(s) in many quasi-steady features for understanding
H(s). But, we have to consider velocity fields. – To find short-lived small increases in T(s) for understanding
localized elemental events in quasi-steady features.• Nanoflare vs. Wave
– To find super-hot plasma in non-flaring features.– Autocorrelation of temporal/spatial variations may reveal some
properties of nanoflares.– To find relations between NT-width and coronal-T for dissipation
of for waves.
• Relations with lower atmospheres– Where do energetic events happen?
• Magnetic configurations.• Wave excitations or reconnections.
What I hope for Solar-C.
1
100
10000
1000” 100” 1” 1”2”10”
1s
1m
1h
10”dx: spatial
resolution
dt: temporalresolution
X: FOV size
R: spectrumresolution
EISraster scan
XRT
Interaction regions would like to be observed.
• Velocity fields in chromosphere, transition layer, and lower corona.
• Magnetic configuration in chromosphere.
With Hinode/EISand Solar-C/Plan-B.
Emerging
Reconnection
Submerging
?