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 andtransient 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

B, L, … ?

Mass & AgeEvolution of Coronal Features
on T-EM diagram
Narukage et al. (Hinode-3)

still open field & O
pen fieldchange to CH
putniyg
Ener

Closedloopo
shift t testaydaest&se QR
sclo told e
if e ang
chtoycaed

RQ

Evolution of Stars

Ejection ofenvelope

H burning

Heburning

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).

∂T∂
2
H(s) = n Λ(T) –κ∥∂s∂s

Heating Radiative
Conductive
Cooling
Cooling• However, there are– Multi-temperature structures(due to fine structures?)– Velocity fields– etc.

T(s)H(s)

Eclipse on 2007 Feb.17

Heating Function:
above polar regions
Kano et al. (2008, PASJ)• XRT filter ratio temperature increased
with hight above polar regions.
• The T-grad. might suggest heating notnear footpoints but at high altitude.
T (MK)

0.7

1.0

1.4MK

gradient(?)

1.3
1.2
1.1
0

1〜2x104
erg sec-1 cm-2
100h (Mm)

200(Revised due to a new calibration data)

Temperature

Heating Function:
above polar regionswith multi-T analysis
Kano (Hinode-3)

1022
1021

For 10”Hydrostatic
1020
changewith height For 50”
1019
1018

• However, based on multi-Tanalysis, the EIS & XRT data
above polar regions are well explainwith hydrostatic changes ofisothermal vertical threads withseveral temperatures
as Aschwanden & Nitta (2000 ApJ)
suggested.
ÎIsothermal structure suggests
footpoint heating.

DEM (cm-5 K-1)

For 100”

105T (K)106

Aschwanden & Nitta (2000 ApJ)Heating Function:
in Loops with multi-temperature analysis
Tripathi et al. (2009, ApJ)
EM Loci plots• Single temperature
along LOS.
• dT/ds > 0.
• Filling factor aroundfoot points

Footpoint– 0.02 @ FeXII, SiX– ～1 @ MgVII

ÎT-grad. suggests
loop-top heating.
LooptopHeating Function: in Quasi-Steady Upflow
Imada et al. (2007, PASJ), Imada et al. (2007, ASJ meeting)
FeXIIIFeXII• T-dependence ofupflow triggeredwith a flare.
> 1 hour Quasi-Steady-150km/s

Upward Velocity km/sec

150km/sDashed line：
Sound Speed• H(s) was derived

FeXV
FeXIV
FeXIIIFeXIIOV FeVIII

HeII
Log TeFeX

FeXI– by assuming a crosssection model ofvertical fields,– and using energy-eq.
momentum-eq. andmass conservation.

Height

FeXV
FeXIV
FeXIII

FeXII
40Mm

Heatingat high altitude.

60Mmp ∂
1 ∂mnv ∂∂T2(eA) +(vA) = H(s) – n Λ(T) +Aκ∥A ∂sA ∂sA ∂s∂s

20Mm

H(s)

FeX

0Mm

FeXI

FeVIIIOVHeII√ＡlogTVelocity

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 possibilityof an artifact by scattered lights in XRT, it mightsuggest nanoflare heatings.

Nanoflare studies: Super-Hot Plasma(2)Ishibashi et al. (Hinode2 & Hinode3)• In Hinode-2, Ishibashi reported that
15MK component was found inquiet-Sun with the filter-ratio
analysis of XRT.
• In Hinode-3, he made assurance
double sure with the photoncounting analysis by XRT, anddetected Ｘ-ray spectrum from
~10MK plasma in quiet-Sun.
X-ray spectrum in–.

Nanoflare studies: Intensity fluctuations
Terzo (TBD)• He just started this topic.
• From XRT’s high-cadence (~3 sec)
observations, auto-correlation of
intensity fluctuations may reveal atypical timescale of nanoflare events.
Sakamoto et al. (2008, ApJ)

Upflow & NT-Velocity in AR Loops
Hara et al. (2008, ApJ)••

Upflow of hot plasma wasobserved near the footpoints.
Large NT-velocity was also
observed near the footpoints
in on-disk active regions. It is
probably a superposition ofmany upflow components.

ÎThe hot plasma upflows
suggest nanoflare heating.
Small NT-velocity (~20km/s) inlimb ARs gives a constraint toAlfven-wave heating.

On-disk AR

Fe XIV 274A

Limb ARHint from simulations
Antolin et al. (2008, ApJ)
Temporal variation of T(s) or V(s) along loops is important.
Nanoflare heating(footpoint)

Temperature

Alfvén wave heatingtt that reconnection sites
tImada pointed outin majorflares (100Mm) do not look hot due to the time lagfor ionization.
How about nanoflares? Local enhancement(~1Mm) in T(s)observed.
x might be hard to bexttx

Velocityt

Nanoflare heating（uniform）

xxx

Relation between Coronal Activities &Photospheric Magnetic Fields
eg. Kano et al. (2010, submitted)

Al/Poly.

XRTEmerging

11:15:42-59

Ca-II H

Reconnection

fluxemergence

SOT-FGÎMultiple reconnections may
happen not only corona
but also in chromosphereor transition region.

11:13:51.472

SOT-FG• Although magnetic buoyancy may prevent thesubmergence of coronal fields under thephotosphere, why magnetic cancellations areassociated with microflares?

5000 km

Magnetogram• Microflares around a spot were accompaniedwith magnetic cancellations, some of whichwere formed with EMF and MMF.

Submerging

11:15:35

5”

Magnetic Submergences
Submergence of photospheric B: Chae et al. (2004, ApJ)

Chifor et al. (2008, AA)

Downflow atcancellation site

Submergence of chromospheric B:
Harvey et al. (1999, SP)
Chrom.-B disappeared
earlier than photo-B.
Photospheric magnetogram

Chromospheric magnetogram• The Submergence ofphotospheric and chromosphericmagnetic fields were observed.
• Non-thermal emission observedwith RHESSI above cancellations
suggests that reconnection
occurred in the corona.
• However, no evidence for thesubmergence of coronal fields.

Interaction regions
would like to be observed.
• Velocity fields inchromosphere,transition layer, andlower corona.
• Magnetic
configuration inchromosphere.
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 someproperties of nanoflares.
– To find relations between NT-width and coronal-T for dissipationof for waves.

• Relations with lower atmospheres– Where do energetic events happen?
• Magnetic configurations.
• Wave excitations or reconnections.

What I hope for Solar-C.

R: spectrum
resolution
10000

EIS

100

raster scan

X

1

: FOV size
1000”

100”

10” 1”

10”

2”

1”

1h

XRT

1m

dt

1s

: temporal
resolutiondx: spatial
resolution

Interaction regions
would like to be observed.
• Velocity fields inchromosphere,transition layer, andlower corona.
• Magnetic
configuration inchromosphere.
With Hinode/EIS
and Solar-C/Plan-B.

Emerging?

Reconnection

Submerging