The Sun is a dynamic star whose activity and variability directly influence conditions on Earth. The Sun's atmosphere, including the photosphere, chromosphere, and corona, undergo continuous changes driven by the Sun's magnetic field and interior dynamics. Small-scale magnetic features and energetic events throughout the solar atmosphere, such as spicules in the chromosphere and nanoflares in the corona, are thought to play an important role in heating the Sun's million-degree outer atmosphere through dissipation of magnetic energy. Observatories such as SOHO, STEREO, and Hinode provide continuous monitoring of the Sun to improve understanding of its complex variability and influence.

1. Royal Observatory of Belgium
Our Dynamic Star
Elena Podladchikova
The Moving Sun

2. The Sun
Main source of heat and light.
Stability of the Sun – stable Earth conditions at geological scales.
Only for human eye Sun seems to be stable. In reality solar weather
is strongly variable.
The Moving Sun

3. Why study the Sun?
The Star presenting all the details of its surface.
Physical laboratory with the conditions impossible to reproduce on the
Earth.
Influence on the terrestrial environment.
Activity of this Star produced the life on its planet - unique case.
The Moving Sun

4. SOHO/EIT
SOHO (Solar and Heliospheric Observatory) — spacecraft to
observe the Sun. Joint ESA-NASa mission.
launch – 2 december 1995
start ) May 1996
Has 12 instruments onboard.
Information about solar atmopshere, solar inetrior, solar
wind and solar corona activity.
One of the main instruments: EIT (Extreme ultraviolet
Imaging Telescope)
The Moving Sun

5. SOHO and STEREO
Continous Extreme Ultraviolet Imaging of the
Sun ORBITS
STEREO has 2 spacecrafts
SOHO is in the L1 Lagrange point
The "Ahead" spacecraft is flying completely
in the Solar-Terrestrial System away from Earth, and becomes a satellite of
the Sun.
and goes around the Sun
while the "Behind" spacecraft is flying in the
simultaneously with the Earth. opposite direction.
The Moving Sun

6. SOHO and STEREO
SOHO and STEREO monitor the solar corona in 4 central
wavelengths
corresponding to the different temperatures
PARAMETERS
SOHO 171 A 195 A STEREO
Temporal Cadence Temporal Cadence
171 A: 1/h - 4/day 171 A: ~2.5 min
195 A: 15 -12 min 195 A: 10 min
284 A: 1/h - 4/day 284 A: 10 min
304 A: 1/h - 4/day 284 A 304 A 304 A: 10 min
Spatial Resolution Spatial Resolution
1024 x 1024 pxls 2048 x 2048 pxls
The Moving Sun

7. Outline
Introduction
Presentation of 3 aspects:
The Sun and “quiet” atmosphere (permanent regime)
Manifestations of the Solar Activity.
Solar influence on the Earth.
The Moving Sun

8. The Sun: basic characteristics
Ordinary yellow dwarf , type G2
Far from the center in the galactic disk of the
Milky Way.
Phase of principal sequence:
Since 4,5 milliards years
For 5,5 milliards years
Stable structure, but luminosity evolution ~ 10 % on
many milliards years (A-B).
Some Stellar Properties:
Absolute magnitude: +4,5
Effective Temperature: 5780 K
Masse: 2 x 1030 kg
Rayon: 7 x 108 m
Gravitational acceleration at
the surface: 273,8 m/s2
Critical Ejection velocity: 617,7 km/s
Rotation: 25.38 d
The Moving Sun

9. The Multiple solar roles
Gravitational attraction of the planets ( orbits, tides )
Environment determined by solar electromagnetic radiation absorption
(from gamma ray to infrared)
Influence by corpuscular emission (electrons, protons, -particles, etc.):
Solar Wind: Mass lost 2 millions tonnes per second
Solar neutrinos :
No influence, but direct information about nuclear reactions in the core.
The Moving Sun

10. The Sun: structure
The Moving Sun

11. I
From the core to transition region
The Moving Sun

12. Quiet Atmosphere: introduction
Quiet Sun:
Structures with weak time dependences (weak magnetic fileds)
Large solar structures are little variable.
Active Sun:
Variable phenomena.
Brutal local deviations and transitory variations with respect to the quiet Sun.
The Moving Sun

13. The different Faces of the quiet Sun.
4 principal layers:
Photosphere
Chromosphere
Transition region
Corona (heliosphere)
Complete changing of physical conditions trough the layers:
The Sun does not
appear the same
in the different
wavelengths.
The Moving Sun

14. Quiet photosphere: the granulation
The solar surface is covered by
a pattern constituted by bright
granules separated by the dark
network.
Imprint of subphotospheric
convective movements.
Size: 500 - 1500km (1")
Contrast: 10% ( T=150 K)
The Moving Sun

15. Quiet photosphere: the granulation
Developed turbulence:
At large scales: regime of
inetrtial convection
(advection of heat
dominates)
At small scales: regime of
inertial conduction (heat
diffusion)
Velocity field
Granulas center: ascending
Interagranulas: descending
Velocities: 1-2 km/s
Lifetime: <4 min>
Verticale structure of convective cells
The Moving Sun

16. Photosphère calme: Points brillants et tubes de flux
Photopspheric Bright Points:
In the intergranulas
B concentration in the descending flows
Flux tubes:
Diameter: <100km
Magnetic Induction: 1000 à
1500 G
Canals transporting
convective energy in the
form of magneto-acoustic
shocks (Choudhuri, 1993)
Exponential growth of the
amplitude (Kalkofen 1997)
The Moving Sun

17. Magnetic network evolution
Magnetic fields are in the continuous evolution. Their
interaction produce coronal heating.
Ephemeral Regions
Small regions, no specific
magnetic orientation.
Life time <4.4h>
The Moving Sun

18. Photosphere: supergranulation
Organisation of the
granulation in the larger
pattern
Mesogranulation:
Scales: 5000-10000 Km
Trace of turbulent dynamo
at small scales (Cattaneo
et al. 2001).
Supergranulation (Leighton
1962):
Scales: 20 000 – 30 000
Km
Lifetime: <12 h>
The Moving Sun

19. Photosphere: faculaes
More hot regions
The Moving Sun

20. The sunspots: proprties
Photospheric dark regions.
Small spots without structure (pores):
Diameter <2500km
For D >2500km, 2 zones:
Umbra :
Diameter =10 - 15000km
Intensity = 5 - 30% IPhotosphere
Penumbra:
D: 50000km
Intensity = 50 à 70 % IPhotosphere
The Moving Sun

21. The sunspots: penumbra
Vertical field in the umbra
Horizontal field in the penumbra
Radial Filaments structure
Continuous flow from the center to the
borders: Evershed flow
Velocity: 1 - 2 km/s
The Moving Sun

22. Sunspot Dynamics (Dutch Open Telescope)
The Moving Sun

23. Sunspots: Magnetic field
Pass point of intensive magnetic
field trough the thin photospheric
layer.
Global dipolar structure:
N-S Polarity oriented E-W
Inclination with respect to equator:
12°
Group traversed by a neutral line
Complex topology
Intensity:
Umbra: 3000 G
Penombra: 1000 G
The Moving Sun

24. The sunspots: properties
Lifetime: hours-months
Umbra Temperature: 4000K
Quiet photosphere (5800K).
Groupes ellongated in the E-W direction
5 ° - 40° of latitude
The Moving Sun

25. Sunspot Dynamics (SOHO/MDI)
Intensity
The Moving Sun

26. Magnetic field and sunspots.
The sunspots are associated to intensive magnetic field (black and
white spots on the magnetogram at right), that change continuously.
The Moving Sun

27. The sunspots: Field hierarchy
Young groupes:
Compact field
Old groupes:
Dispersive flux
Permanent fields:
Neutre diagonal line
Weak global field
(10-4 T) that inversed
with the Hale cycle
(22 ans)
The Moving Sun

28. Sunspots and activity cycle
The number of sunspots varies with teh
cycle of ~ 11 ans:
Cycle amplitude (maxima):
48 in 1817 and 200 in 1958
~90 years modulation
Archive Bruxelles):
30 cycles
3 centuries
Daily index since 1850
The Moving Sun

29. Sunspots and cycle: distribution in latitude (« Batterfly »)
Toward equator during the cycle:
First spots: at 30° latitude
At maximum: at 15°
Last cycle spots: at < 5° from lthe equator (at 0°)
Spots of 2 cycles coexistent during the activity minimum.
The Moving Sun

30. Solar Dynamo: - effect
Ionized solar plasma:
Plasma movements = large scale currents.
Magnetic field lines are frozen in the plasma under the
surface:
Poloidal (dipolar) magnetic field is elongated and coiled by the
differential rotation -> amplification.
Complete process - 8 m.
Toroidal field production in the opposite direction
The Moving Sun

31. Solar Dynamo: -effect
Magnetic lines torsion by the solar
rotation, via the Coriolis force.
Convection helicity generates a
electromotive force proportional to
this helicity and to toroidal magnetic
field.
The energy of the dynamo comes from
kinetic energy of rotation and fluid
movement at small scales in the
convective zone.
The Moving Sun

32. Ascending and torsion of magnetic loops
B puts pressure on the background medium:
~ B2
Evacuation of plasma in the flux tube up to the
equilibrium of the pressure with background
unmagnetized plasma:
The loop, less dense that ambient plasma go up
toward the surface:
Loop formation in
During the rising - rotation by Coriolis:
DIpole inclinnation (opposite sens)
B helicity
During the cycle the emergent loops ar
ereformed by the reconnection and
fragmentation with global dipolar field:
Reconstitution of the initial poloidal field
The Moving Sun

33. The dynamo in movement
The Moving Sun

34. Looking at far side of the Sun
Helio sesimology informs us about the far side of the
Sun. One can see here how the sunspot group (with
intesive magnetic field) can be followed during many
solar rottaion. (Here the Sun is fixed and the observer is
moving.)
SOHO/MDI
The Moving Sun

35. Waves on the Sun: helioseismology
Thousand of acoustic waves parcourent
continuously the solar surface. One can hear
them accelerated 42000 times. Analysing
these waves one can investigate the Solar
Interior and deduce for example the sound
speed.
SOHO/MDI
The Moving Sun

36. Looking IN the Sun
The helioseismology informs us
about Solar interior as well as
about changing structure of
solar rotation. One can find the
rotation bands more fast (red)
and more slow (green and
bleu)
The Moving Sun

37. Exterior Atmosphere
Chromosphere
and
Transition Region
The Moving Sun

38. The chromosphere: general structure
Much more dynamic medium,
that the photosphere
Important spatio/temporal
variations of the emission.
Chromospheric network:
Scales corresponds to
supergranulation: 20 – 30 000km.
Enhanced emission on the granula
borders, concentration of strong
magnetic field (tubes de flux).
Brightenings around AR,
correspondance with faculaes.
CaII K filtergram,
Kitt Peak Obs., USA
TRACE, Ly
The Moving Sun

39. Fine structure fine: the spicules
Surface covered by the vertical spouts (~100 000 on teh
Sun), the spicules: Temperature: 4500K
Height: 5 000 – 20 000 km
At the limb: bright (spicules)
Section: 500 km
Disk center: dark (mottles) Ejection speed: 20 km/s
Inter-spiculaire space hot (106K) and not dense. Lifetime: 5 à 10 min
Mass flux: 100 x the necessary flux to maintain the solat
wind.
Essential role in the balance of mass flux in the solar
wind.
The Moving Sun

40. The chromosphere: heating source
The turbulent photopsheric convection provides energy to heat upper layers.
It produces propagating acoustic waves:
Acoustic waves:
In the unmagnetized interior of supergranulas.
Excitation by the random vertical movement.
Resonance chromopsheric cavity is on the level of cut-off frequency of p-
modesaAt 5 mHz (P=3min).
MHD modes:
Slow and fast Magnetoacoustic, Alfven.
Excitation by the footpoints displacement.
Transformation in shock waves.
Other sources:
Macroscopic flows (Spicules)
Current dissipation (reconnection magnétique locale)
Reviews: Narain & Ulmschneider (1990), Ulmschneider et al. (1991)
The Moving Sun

41. Atmopsheric Model
Coronal heating problem: why is the corona so hot?
Vertical profile of temperature
and density in the Solar atmosphere
The Moving Sun

42. Dissipation of magnetic energy & small scales
2 traditional approchaes AC/DC
1. Heating by MHD waves
Dissipation of Alfvén waves (Alfvén 1947) problems: how
are they excited? how are they dissipated? how are formed the small
dissipative scales?
Resonance absorption (Ionson 1978) problems: waves with
small periods needed (5 – 300 sec) [Davila, 1987]
Phase mixing (Heyvaerts & Priest 1983)
Ion cyclotron waves (McKenzie et al. 1995)
Turbulent cascade to small scales problems: (next slide)
42
The Moving Sun

43. Turbulent cascade to small scales
Natural mechanism to form small scales
The couplings between waves and turbulence are
universal mechanism in fluid forming small scale
fluctuations:
Developed turbulence. Energy cascade from large scales to small ones.
(Kolmogorov 1941, Frisch 1995):
E(k) ~k -
Conducting fluid. + <B>
But nT and B2 also dissipate after cascade toward small
scales (Iroshnikov et R. Kraichnan),
E(k) ~k -3/2
43
The Moving Sun

44. Turbulent cascade to small scales
Problems :
1. Energy flux of waves transformed to particle energy:
- Only small part of
W diss ~ ( i/ driver)
-1 x W total
Total Energy dissipates
2. Slow processes (open regions). Distance
Lmin ~ Rsol - Spectra forms at very large distance from the Sun
3. Time to form turbulent spectrum:
T~ 10 Lmin / Cs - is too long
4. Sources are not only in large scales
44
The Moving Sun

45. Experimental Evidence of small scale sources
Krucker & Benz , 1998 (SOHO), Parnell & Jupp, 2000, (TRACE),
Koutchmy et al. , 1997(X-ray) etc… – experimental confirmation of
important role of nanoevents in coronal heating.
Aschwanden et al. (2000) - quasi-homogeneous spatial distribution of
nano-flares.(SOHO, TRACE)
Shriver et al. 1998, - (quasi-homogeneous spatial distribution of
small scale dipoles) (SOHO)
Abramenko et al. 1999 – inverse helicity cascade (Big Bear)
Berghmans et al 1999, Benz et al, intracell nanoflares.
Krasnoselskikh et al, 2002 - The characteristic scale of magnetic loops
which provide energy deposition into the corona is of the same order
as the dissipation scale.
Observations of magnetic loops of different large scales in EUV
45
The Moving Sun

46. Dissipation of magnetic energy & small scales
DC
2. Heating by dissipation of DC currents dissipation
• Anomalous resistivity (Handbook of Plasma Physics, edited by M.N. Rozenbluth and R.Z.
Sagdeev, Priest et al, Voitneko et al. )
• Reconnection (Giovanelli,1946)
Comment: There is no strong difference between AC and DC mechanisms:
They both describe the coronal response to perturbation created by sub-photospheric convection
(Heyvaerts,1990).
The distinction essentially depends on time scales
tA >> tphotosph AC
tphotosph>> tA DC
Nowadays DC mechanisms are more compatible with coronal observations. 46
The Moving Sun

47. Chromosphere: spicules and p-modes
Swedish 1-m Solar Telescope
with adaptative optics. Spatial
resolution ~100km (0,15")
New result:
The spicules are forme at the same point and in phase with oscillation of
photopsheric p – modes, with the coherent period of 5 min. (De Pontieu et al.
2004, Nature, Zhugzda et al. 1987, JETP)
The Moving Sun

48. Ejection +30 km/s
The Moving Sun

49. The prominences: general properties
Big light draperies suspended above the
surface suspendues: , BBSO
Cold and dense masses of gaz.
Mix Structures: Coronal and chromospheric.
Properties:
Temperature: 10000 K
Density: 1010 à 1011 cm-3 (500 x coronal
density)
Height: 20 – 100 000 km
Width: 10 000 km
Lenght: up to 1 Rs
TRACE, FeX, 17,1 nm
The Moving Sun

50. The chromosphere: general structure
Observations in H :
Eruption phenomena
Filaments et prominences:
Situated in the corona
Prominences: off-limb.
Filaments: on disk
Coronographe, Obs. Pic-Du-Midi
filtergram, USET, ROB, Bruxelles
Localisation:
Above neutral lines of the
photopsric B:
Often E-W orientation.
The basis of coronal jets.
The Moving Sun

51. The promineces: quiescentes an eruptives
Two evolutionary stage:
Quiescentes prominence:
Stable structure during days.
Eruptive promineces:
Fast ejection ~1 h.
SOHO/EIT, HeII, 30,4 nm
The Moving Sun

52. The prominences: eruptions
Eruptions of prominences:
Associated to flares in AR, can
occur far from AR.
Association to CME.
Vielocity: up to 1000 km/s
Magnetic energy liberation during
the eruption.
The Moving Sun

53. The Prominences: formation mechanism
Different configurations are possible with commn points:
Magnetic arcade above the neutral line.
Horozontal flux trapped in the arcade
The Moving Sun

54. The prominences: strings of twisted fluxes
3D MHD Model:
Appearence of twisted strings by
application of convection velocity
field at the photospheric level.
(Amari, T. et al., ApJ518, 1999; Aly, J.J. & Amari, T. AAp207, 1988, )
The Moving Sun

55. Quiet atmosphere: Transition region
Thin layer: thickness < 100km
Extreme T gradient gradient: from 2 x104 up to 1 x106 K
Abrupt transition betwen chromopshre and corona.
T profile and typical emmission
lines in TR.
The Moving Sun

56. Transition region: structures
Emission in EUV ( <
120nm):
Emission lines of strongly
ionized atoms.
For increasing T transition
transition from
chromsopehric structures:
Cgromospheric newtork,
spicules, prominences
To coronal structures:
Coronal holes, loops.
SOHO/EIT, HeII, 30,4 nm
T= 8 x105 K
The Moving Sun

57. Transition region: structures / temperature
SOHO/SUMER, CIV
SOHO/SUMER, SVI
SOHO/EIT, HeII, 30,4 nm, T= 8 x105 K
The Moving Sun

58. Magnetic transition
In the high chromosphere and transition region, a transition in
the relation bewteen magnetic pressure in the flux tubesand teh
kinetic pressure of the gaz.
Coefficient du plasma:
p
B2 2 0
Photosphere and chromosphere: >>1
Filed confined in the thin flux tubes in the intragranulas space.
Filed frozen in plasma: turbulent convection disturb the filed.
Transition region and Corona: <<1
Magnetic filed expands for whole avaliable volume.
Plasma is entrained by its movements.
NB: In the solar atmopshere not a lot of regions has 1
The Moving Sun

59. Transition region: topology
The Moving Sun

60. Transition region: global dynamics
"Blinkers":
Localized intensity peaks in quiet
Sun
Lifetime < 10 min>
Surface: 100 Mm2
High density
Small velocity.
Injection of heated chromopsheric
plasma (« evaporation »).
The Moving Sun

61. Transition region: global dynamics
The Moving Sun

62. Transition region: global dynamics
The Moving Sun

63. II
Solar Corona and Heliosphere
The Moving Sun

64. The Corona: General Structure
New structure appears
in the coronal emissions
(X-UV)
The Moving Sun

65. Solar Atmopshere: the Corona
Most long part of the Solar
atmosphere
Before space era, observed
during eclipces
Continous expansion avec V
~400km/s: solar wind.
Extension on many AU: the
heliosphere with all solar planets
inside.
Very inhomogeneous layer structured
by magnetic field ( <<1)
The Moving Sun

66. Couronne: structures principales
Jets coronaux (équateur, latitudes
intermédiaires)
Condensations coronales (base des jets,
contenant parfois une cavité)
Trous coronaux sombres (pôles)
Plumes polaires (pôles)
Protubérances (chromosphère, H )
Grands écarts de densité: jets 10 x trous
The Moving Sun

67. Corona: limb brightenings
SOHO/SUMER Si VI SOHO/SUMER C IV
SOHO/EIT Fe XI
The Moving Sun

68. The Solar Cycle
The Solar activity strongly varies with
11 years period as sunspot index
indicates already ~200 years. The
changes are more visible in the corona.
The Moving Sun

69. The Solar cycle
The Moving Sun

70. The Solar Cycle: magnetic field and X-Ray.
1992 1999
Yohkoh Soft X-ray
Kitt Peak magnetograms
The Moving Sun

71. Active Regions dynamic
In the corona, above intensive
magnetic field one can see the
Active Regions in the permanent
evolution. From times to times
they produce magnetic field
instabilities that lead to solar
flares or eruptions.
SOHO/EIT
The Moving Sun

72. The corona: bright points
Small compact structures in the quiest
Sun and coronal holes. Environ 300 sur
toute la surface
Ephemeral AR(small loops)
Lifetime: 2h – 2 days.
High density
Modele: magnetic submerging
dipole.
The Moving Sun

73. The Corona: Coronal Holes
Less dense zones ( factor 4 -
10) and less hot (1 x106K) :
No X-Ray emission – hole.
Quit region of quiet
photopshere.
Open B. Plasma escapes.
The Moving Sun

74. Coronal Loops
In the corona,
magnetic field lines
form loops remplished
by plasma, as one can
see on EIT images.
These loops are in
permanent movement.
The Moving Sun

75. The Coronal Loops
Basic elemnts of quit and
active Corona.
Closed B.
Keeping of coronal plasma.
The Moving Sun

76. The Coronal Loops: Dynamics
Strong thermal
conductivity thermique
along B lines.
Weak conductivity in
perpendicular direction.
Isolated loops with
individual evolution.
PLAsma transport is
possible only along B:
Macroscopic flows along the
loops (v ~ 100 km/s) =
intensive currents.
The Moving Sun

77. Coronal loops dynamic
TRACE
The Moving Sun

78. Coronal Loops
The Moving Sun

79. Coronal Loops
The Moving Sun

80. Boucles coronales
The Moving Sun

81. Boucles coronales
The Moving Sun

82. Coronal Loops
The Moving Sun

83. Conclusion: quiet atmosphere
The quiet Sun forms the context where the violent transitory events may
occur.
It affects and modulates the properties of active penomena (Corona and
solar wind).
It is formed by similar phenomena by at the small scales, weak energies.
Multiple of those micro phenomena create « permannet regime » from teh
global point of view.
The Moving Sun

84. Flares and CMEs
The Moving Sun

85. Solar Flares: definition
Sudden and temporary heat of the certain volume of solar
atmosphere, producing plasma > 107 K and associated to fast
reconfiguration of magnetic field.
First observations in 19 century:
White light flares – very rare phenomena.
Emissions in:
From gamma rays to X – extreme temperature
Radio waves: indication of accelerated particles.
Most energetic solar explosif phenomena in solar :
Energy up to 1032- 1033 ergs in ~ 10 – 103 seconds
The Sun is also a power particle accelerator:
Electrons: ~100s of electrons 1 MeV:
Electrons of energies ~10-100 keV - 50% of whole energy
Generation of 1036 electrons/s and currents of 1017 Amps.
Ions: ~ 10s of particles 1 GeV :
The ions of energies >~1 MeV can transport total energy.
The Moving Sun

86. Solar Flares: Chronologic scenario
Many phases
Precursor:
Small energy release
Radio and soft X Ray
Impulsive phase:
Explosive energy injection
Many fast jumps.
-rays
Principal long phase:
Energy release.
Gradual evolution
Maximum and strat of teh coronal and
chromospheric (continuum,H ).
The Moving Sun Dulk et al. 1985

87. Chronology: Pre-eruption phase.
Slow accumulation and energy storage in the twisted magnetic
filed:
Instability trigger after a treshold.
External Generation :
Emergence of Flux
Flux cancelation.
Random walk of footpoinst loops and by
difeferntial rotation.
The Moving Sun

88. Solar Flares: classification
Reference measurment, GOES:
The Moving Sun

89. Solar Flares: morphology and et dynamics
Mechanism: magnetic reconnection
Observed emmisons come from difefernt
layers.
16/8/2002, USET, ORB
The Moving Sun

90. Model: Motivations
Energy release associated to solar flares. Power
laws, flares, microflares. Power index <
2 for Parker hypothesis.
System with large fluctuations (high probability)!
No thermodynamic equilibrium.
Crosby, Aschwanden & Dennis 1993
flares similarity at different scales and energy?
what is the respective role of flares of different scales and their interaction in the heating?
90
The Moving Sun

91. Motivations
Traditional approchaes do not work:
Some limitations of ‘traditional’ simulations
MHD, Kinetics, PIC simulations may reproduce limited spatio-
temporal scales
For example, ideal MHD does not describe correctly such
dissipative effects as magnetic reconnection or current sheet
instabilities.
But coronal heating is a complex problem, with a lot
of different temporal and spatial scales
91
The Moving Sun

92. Lattice model (since 1991)
92
The Moving Sun

93. Part I
Small Scale drivers of different properties
Different mechanisms of current dissipation
Do they influence
1. Large scale observable magnetic field
&
2. Global Dissipated Energy?
93
The Moving Sun

94. Magnetic field
Mechanism of Electric current
Small-scale sources form magnetic structures:
dissipations influence PDF
of energy :
random source sub-diffusive intermittent
source Anomalous Resistivity-Gaussian
chaotic source (poor navier-stocks) super-diffusive source
Reconnection dissipation –
power law deviations
Main conclusions. Small-Scale
dissipation mechanisms influence electric currents total dissipated Enregy.
94
B-Source influences large scale magnetic field structures.
The Moving Sun

95. Power Law for Flares WTD
Waiting Time Distribution (WTD) between
flares is rather robust and easy characteristic
to compare models and experiment
Problems
Experimental WTD are in power laws. Waiting
Time Distribution for large set of flares (e. g.
Crosby 1993,1996; Weathland 2000)
WTD from models are different. Nowadays all
models including all known SOC, Shell and Lattice
models (including all our previous studies ) shows
Poissonian or exponential laws (e.g. Carbone
2000). 95
The Moving Sun

96. Power Law for Flares WTD
Power Laws: Indicator of long-range
correlations Turbulence?
– effect (turbulent dynamo) explains the
origin of solar magnetic field. -effect
generates structures of larger scales from the
small ones.
Thus – effect can naturally provide us the
“intermediate” and the large scales magnetic
structures as magnetic drivers (to avoid
direct cascade problems).
96
The Moving Sun

97. Intermediate Driving Scales of coronal heating
Inverse cascade by – effect
97
The Moving Sun

98. Turbulent dynamo: history (1/3)
Origin of solar magnetic field by turbulent dynamo (Moffat 1978, Zeldovitch 1983)
effect Parker 1966, Steenbeck et al 1966
The -effect belongs to cinematic dynamos, where the velocity V is imposed.
It is therefore a linear problem, whose goal is to show the large scale growth of an initial “seed” of magnetic
field.
98
The Moving Sun

99. Turbulent dynamo: history (2/3)
99
The Moving Sun

100. Turbulent dynamo: history(3/3)
100
The Moving Sun

101. Introduction of -effect in the model
Dynamo: generation of magnetic field by plasma
turbulence. Can be important near the surface. internal
source of magnetic field. Include alpha-effect in the
induction equation:
101
The Moving Sun

102. Large and intermediate scale sources
Spatial structure of the magnetic field, taking into account the -effect.
Size ~0.3 convection cell
t= 100 t =700
Source is random (inital image is white noise).
Currents are dissipated by reconnection, low instability thresholds.
In this run dissipation stabilizes the development of larger structures
102
Stationary state
The Moving Sun

103. Dynamics: chromosphere
The Moving Sun

104. Dynamics: chromosphere
The Moving Sun

105. Dynamics: chromosphere
Frequent appearance and eruption
of bright double ribbon and neutral
line.
The Moving Sun

106. Waves on the Sun
A flare trigger a Sunquake
SOHO/MDI
The Moving Sun

107. Dynamique: chromosphère
Fast magnetsonic shock
propagation (Moreton wave)
Associated to strong flares.
V ~ 1000 km/s
The Moving Sun

108. Dynamics: Corona (Extreme UV)
TRACE: 19,5nm, T=1,5x106K
The Moving Sun

109. Dynamics: Corona (Extreme UV)
Double flare at 15 avril 2001 (sympathetic flares)
TRACE: 17,1nm, T=1x106K
The Moving Sun

110. Dynamics: Corona (Extreme UV)
Flare sequence d'éruptions Octber -November 2003
SOHO/EIT: 19,5nm, T= 1,5x106K
The Moving Sun

111. Dynamics: Corona (X and Rays)
RHESSI: first images in X and rays
Primary source of heat during impulsive phase.
The Moving Sun

112. Dynamics: Corona (X and Rays)
Thermal emisison in soft X-
Ray (<10 keV) present
along all loop.
Non-Thermal emisison (20 - 50 keV)
concentrated in 3 regions :
Footpoints
Top
Measurment of time lag bewteen reconnection
source and X-Ray source.
The Moving Sun

113. Dynamics: post-eruption arcade
Progressive seperation of arcade
footpoints :
V : ~10 km/s
Indication of reconnection propagating
more and more high from the neutral line.
After hs – reformation of filament into
arcade.
The Moving Sun

114. Solar Flares: magnetic reconnection
All models reproducing the topology of flare energy release imply
Very small scale of disispation
Strong increase of local resisitivity
The Moving Sun

115. Solar Flares: magnetic reconnection
Simplest topology (Sweet 1958, Parker 1963): neutral sheet
Typical X- configuration topology :
Elongated: combined effect of Archimede force and solr wind.
2D analytical Model.
Strong but unsufficient dissipation.
Generation of double plasma flux with Alfven velocity.
The Moving Sun

116. Solar Flares: magnetic reconnection
Petschek Model(1964):
Slow shock waves production from
reconenction site.
Particle acecleration.
Energy converted into heat and
acceleration half by half.
Recent Models :
+ Turbulence Inclusion de la
turbulence
+ 3D Topologies(Brown & Priest 2001)
References:
Reconenction and shocks models: Kopp &
Pneumann 1976, Parker 1979, Priest &
Forbes 1986, Priest & Lee 1990.
Magnetic energy conversion in thermaland
kinetic energy: Syrovatskii 1966, Somov
1994
The Moving Sun

117. Solar Flares: unated model.
The Moving Sun

118. EIT waves: definition
Bright front visible in the
EUV. It propagates in the
solar corona with the
velocity of 100 km/s from
ARs after flare:
Discovered in 1997 by
SOHO/EIT
Can travel trough the whole
hemisphere during 1h.
(SOHO/EIT, 12 mai 1997)
The Moving Sun

119. EIT waves: example du 12 mai 1997
Éruption C1.3 flare with
filament eruption and
halo CME.
SOHO/EIT
Fe XII, 19,5 nm
T ~1.5 MK
The Moving Sun

120. Ondes EIT: exemple du 12 mai 1997
Différences entre images
successives
Vitesse de propagation:
250 km/s
SOHO/EIT
Bande Fe XII, 19,5 nm
T ~1.5 MK
The Moving Sun

121. EIT waves: dimmings
Plasma evacuation
Magnetic lines opening Arcade post-éruption
Association to CME.
Double dimmings
(tranient coronal holes)
The Moving Sun

122. Ondes EIT: déflection (TRACE)
19,5 nm (FeXII) 17,1 nm (FeX) H Ly (121,6 nm)
Images
Différences
The Moving Sun

123. EIT and Moreton waves
Moreton waves associated to flares
are observed in the chromopshere
Les ondes de Moreton
Inital velocities: 750 - 1300 km/s
>> vc dans la chromosphère.
No possible chromospheric origine
Decceléeration
Propagation up to 5 x 105km from
eruptive site.
Images par différences successives en Ha
Observatoire solaire de Kanzelhöhe
(Pohjolainen et al. 2001)
The Moving Sun

124. EIT and Moreton waves
Cospatiality is still
uncertain:
Coincidence only near
eruption cite. (Thompson et
al. 2000).
No correspondence (Eto et
al. 2002).
The Moving Sun

125. Trigger by wave front
Coronal shocks (Thompson, 1998)
125
Th M vin S n
e o g u

126. Solar Influence Data analysis Center
Flares Catalog
Manual NOAA
SEC/NOAA Active Region
for each flare
Flare list, SXI
H Flare EIT Flare
Other
positions positions
o Since 01/01/2004 unique spatial information provided by
Soft X-ray Imager of GOES satellite. Firstly 84 % of all
observed flares are listed with their coordinates. 11% comes
from other sources.
126
The Moving Sun

127. SIDC Flare Catalog
o Since 01/01/2004 SIDC provide correlation between each
flare and NOAA Active Region. This allows statistically valuable
study of time-distance correlation between distant flares.
o 01/01/2004 – 01/09/2005: 3447 flares(B-X classes), 95 %
with coordinates
127
The Moving Sun

128. Velocity of Perturbation
o We compute the distance along
t2 t3 the Sun's surface between all pairs
of flares separated in time shorter
D1 t1 than tmax=1h,2h, … 20h,
assuming that flares separated in
t1 D2 time larger than tmax, are
uncorrelated.
o We introduce the velocity of the
propagating perturbation as follows:
• This quantity would be meaningful only for flares which are
physically connected, if any.
128
The Moving Sun

129. The first consideration of global inter-flaring spatial
properties.
PDF of the speed flare-to-flare
intercommunication signal
PDF
Velocity [km/s]
129
The Moving Sun

130. Time-distance coronal seismology ?
JOINT PDF
Inter-flare distance
Inter-flare time
130
4.817 flares measured with their time and position - complete statistical ensemble
The Moving Sun

131. EIT waves: modeles
Formation of 2 wave
structures:
Big wave with flou
contour is EIT
wave(250 km/s)
Shock driven by the
effect of « piston »
has velocity 770 km/s
Moreton wave
vEIT ~ 0.34vfast
The Moving Sun

132. EIT wave front rotation
EC
EC
front
front
dimmings
dimmings
Podladchkova and Berghmans
2005
The Moving Sun

133. Attrill et al 2007
12th May 1997 ACW event
Reverse “S” sigmoid
ACW rotation Negative Helicity
7th April 1997 CW event
Forward “S” Sigmoid
CW rotation Positive Helicity
The Moving Sun

134. CME flux rope eruption
Evolution in two phases:
First a twisted flux rope is created,
slow and almost quasi-static;
second a disruption, which is
confined for a small initial helicity
and global for a large initial helicity.
Following the evolution of flux rope
AND waves in such geometries is
computationally difficult.
Kink in itself tendentially
slow/alfvenic
Extended unfolding wave source,
might conceivably explain rotation of
Amari et al. 2003 wave front
The Moving Sun

135. Schematic View of Coronal Wave
• The highest point of wavefront (point E) is
percived by both spacecrafts.
• EF: wavefront height
A (STEREO-A)
B (STEREO-B)
E
D
F
C
The Moving Sun

136. Cup of Coffee Analogy
High cup borders close from our view the correspondent bottom
parts
The Moving Sun

137. CMEs 3D Studies
Simultanious View
STEREO - A STEREO - B
The Moving Sun

138. Improving Resolution
exist at Micro-Scales
EUV Micro-Erptions Extracted Micro Dimmings
Area & Intensity 103 smaller!
comparing to
previously
known events
Micro-Eruptions explain Solar Wind Formation near the Sun
The Moving Sun

139. WHI STEREO-A DETECTIONS
STEREO-
30 March Event
of dimming intensity
The Moving Sun

140. WHI STEREO-B DETECTIONS (3/4)
STEREO-
Event March 30
Violent events
can be observed
in EUV corona
even during the
«quiet» WHI
period
The Moving Sun

141. WHI STEREO-B DETECTIONS
STEREO-
Event March 25
Event begins
at Eastren limb,
globally
propagates
trough the
eastern
Hemisphere,
and dissipate
(or disappear)
near solar
center
Global events can be observed in EUV corona even during « quiet» WHI period
The Moving Sun

142. Flares
TRACE
Big Bear Solar Observatory
The Moving Sun

143. Flares
TRACE
The Moving Sun

144. Radiation storms
A Flare in “suitable place” can émettre
in the Earth direction charged particles,
that lead in radiation storms. Such
storms are the danger for satellites and
astronauts. On the animation one can
see “the snow” after the flare.
SOHO/EIT
The Moving Sun

145. Coronal Mass ejection
During Flares, big plasma clouds are
often ejected from the Sun,
producing Coronal Mass Ejection.
SOHO/EIT
The Moving Sun

146. Coronal Mass-Ejection (CME)
SOHO/LASCO
The Moving Sun

147. Eruptive Prominences
Mauna Loa
The prominences that are big clouds of
plasma cooler than coronal environment
can also become instable and explode.
SOHO/EIT
The Moving Sun

148. Halo CME after Prominence Eruption
When CME is directed toward the
Earth we can see it as the Halo
CME. First o all we see the
prominence eruption.
SOHO/EIT
The Moving Sun

149. Halo CME
SOHO/LASCO
The Moving Sun

150. Halo CME
SOHO/LASCO
The Moving Sun

151. cH B2 0
Solar Activity: CME
Bright structure of plasma ball that propagates
from low corona toward heliosphere and can
interact with planet magnetopsheres.
Discovered in 1970 by SKYLAB
Most importnat manifestation of solar
activity(together with flares)
Principal source of geomagnetic storms.
2 aspects of magnetic energy release:
Flares: thermal energy production(heat).
CME: production of global macroscopic fluxes
(kinetic energy), observed by white light.
SMM, 14 avril 1980, W. Wagner
Syntheses: Kahler (1987, 1992),
Hundhausen (1999), Forbes (2000),
Klimchuck (2001), Cargill (2001),
Low (2001)
The Moving Sun

152. CMEs: structure in 3 parts
3 composantes imbriquées :
Bright front supposing expanding magnetic loop.
Dark Cavity
Interior core: fragments of dense filemanents.
In situ measurments show oftehn 4th invisible
composante shock wave before the bright front.
The Moving Sun

153. ICMEs: Sursauts radio
Type II burst (hectometric and kilometric band,
20 - 1000 kHz)
Measured only out of terrestrial atmopshere
The Moving Sun

154. CMEs: structure
Some structures(jets) can be destructed by CME
passage but CMEE keeps its form during whoel
propagation.
Strong magnetic conenction to the Sun.
Connexion magnétique au Soleil persistante:
Desattached plasmoid never clearly observed.
The Moving Sun

155. ICMEs: magnetic clouds
Ejected Magnetic cloud
transports magnetci field.
Caracterised by:
Important and progressive
rotation of magnetic field.
Proton temperature is low with
respect to ambient plasma.
Dimension at 1UA: ~0,25 AU
Transit to the Earth: 1 - 2 days.
Produce negative Bz:
Strong tererstrial magnetopsheric
perturbations.
Principales structures that
influence Solar-Tererstrial
relations.
The Moving Sun

156. ICME in CIR: corotation interaction regions
Density, T and B increase
Crusial 180° inversion of the
direction of the azimutal filed
Important deviations of
Bz(oscillations)
Direct and invers shocks
waves.
The Moving Sun

157. Heliosphere: CIR
Quand un courant de vent rapide suit
un secteur de vent lent, le vent rapide
repousse le vent lent et interagit avec
lui.
Compression: renforcement de la
densité.
Apparition d'une couche d'interface
turbulente.
Formation de chocs:
Zone d'accélération de particules: une des
sources des particules solaires
énergétiques (SEP: solar energetic
particles).
Régions d'interaction en corotation,
RIC (CIR: corotating interaction
region).
The Moving Sun

158. Heliosphere: propagation of ICMEs and CIR
Simulation of
subsequent CMEs of
Ocober 2003).
Animation of
interplanitary magnetic
field.
Red: outoming
(positive)
Bleu: incoming
(negative)
Geophysical Institute,
University of Alaska,
2004
TheMoving Sun

159. CMEs: propagation
The Moving Sun

160. CMEs: structure
Different morphologies:
Interaction with solar wind
and B.
Internal complex
structure:
Multiple of loops
Obsrevations in teh
optically thin corona –
ambiguity.
The Moving Sun

161. CMEs: 18 October - 7 november 2003
Periode of very strong activity in 2 active regions (EIT: Fe XII, 19,5 nm)
The Moving Sun

162. CMEs: 18 october - 7 november 2003
The Moving Sun

163. CMEs: sources and precursors
Eruptive filament
evolution on solar disk
EIT (FeXII)
6 h later CME
detected.
The Moving Sun

164. CMEs: dimmings EIT
Dark regions after EIT waves
triggered by flares: :
Eruption mode: opening of magnetic
field lines.
Assymetry in preexicted magnetic
structre.
The Moving Sun

165. CMEs: EIT dimmings
Flows, 30 km/s (SOHO/CDS, Harra & Sterling 2001)
Disispation during expansion.
NEMO
SOHO/EIT:
12/5/1997,
19,5nm
Diffeernce with initial image Progressive difference:
Shows dimmings Show EIT wave
The Moving Sun

166. Waves on the Sun
In these images obtained by
substraction of the previous
one, one can better follow the
gigantesque shock wave after
a flare.
SOHO/EIT
The Moving Sun

167. CMEs: velocitis and acceleration
2 classes of CMEs (Sheeley et al. 1999):
Gradual CME :
Formed by the prominence and their cavities.
Progressive Acceleration below 30 Rs
Impulsive CME:
Triggerred by the Flares.
Associated to EIT waves.
High velocity, constante or with deceleration.
The Moving Sun

168. The Moving Sun

169. The Moving Sun

170. The Moving Sun

171. The Moving Sun

172. The Moving Sun

173. The Moving Sun

174. CMEs: latitude distribution
Minimum (1996) Maximum (1999)
The Moving Sun

175. CMEs HALO
The most importnat class for solar
tererstrial relation.
Shocks source, SEP and geomagnetic
perturbations.
Frequency (sur base des fréquences globales et des
distribution en latitude et en largeur):
~ 15% of all CMEs
The Moving Sun

176. CMEs halo
The Moving Sun

177. CMEs halo
Progressive differences
The Moving Sun

178. CMEs: modeles
Basic elements to reproduce: the observations imply the shearing/torsion
of magnetic field applyed along the neutral line on the photopsheric level,
« carrying wrapping instability » (kink instability).
2 types of models:
Analytical models:
Quantittaive information about physical mechanisms.
Difficult to reproduce observed morphology.
Numerical Modles :
Better reproduction of observations.
Initial conditions must be known with high pression.
Models in 2 parts:
Fine grid for for the Corona (trigger)
The Grid less dense for reproduction of propagation in the heliosphere.
The Moving Sun

179. CMEs: sources and precursors
Ejected filament is often twisted – helicity
Energy storage in teh helicity.
Unrolling of magnetic line during the propagation. (magnetic energy release).
The Moving Sun

180. CMEs: precursors and helicity
LASCO C2, 2/6/1998, 13h31
The Moving Sun

181. CMEs: precursors and helicity
The Moving Sun

182. CMEs: modeles
5 categories of modeles:
1. Thermal deflagration
2. Dynamo
3. Mass loading
4. Rupture of connections ("tether release")
5. To put under the tension of connections ("
tether straining")
Syntheses of modellng: Low (2001), Wu et al.
(2001).
The Moving Sun

183. CMEs: modèles
Lin et al.
2004
The Moving Sun

184. LASCO as the Comet hunter
With the help of LASCO a
thousand of new comets
are discovered nowadays.
SOHO/LASCO
The Moving Sun

185. Solar Wind: the first indiexes
First observations suggested the expanding
medium in the solar system 19th century:
Carrington (1879): correlation between whit elight
flare and magnetic field measuremnt 2 days later..
Comet observation: gaz and dust tails always in out
Sun direction (Biermann 1951).
The Moving Sun

186. Solar wind: Velocity Profile
Asymptotique velocity at long
distance as the function of teh
temperatur ein teh low corona :
200km/s at T= 0,5 x106 K
400 km/s at T= 1 x106 K
650 km/s at T= 2 x106 K
It strats at 3 Rs (LASCO) Sheeley et al. 1998
The Moving Sun

187. Solar wind: acceleration
Heating and acceleration of teh
fast solar wind by MHD waves
by the mechanism of the ion-
cyclotron resonance.
Different for slow wind (plasma confined in the closed field):
Continous emergence continue of magnetic flux and opening by
reconenction on teh top of the large scale loops.
The Moving Sun

188. Solar wind: the source localization
SOHO/SUMER: observation –
doppler shift in NeVIII (77,0 nm,
T= 650 000K) (cf. Hassler et al.
1997, 1999)
Flux up l'extérieur (décalage vers
la bleu shift ) dominating in the
coronal holes.
Maximum flux – on the trace of
the border of the chromospheric
network
Correspondance with the
underlying magnetic field
structure.
The Moving Sun

189. 189
The Moving Sun

190. 190
The Moving Sun

191. SECCHI suite
191
The Moving Sun

192. HI-1 CME
192
The Moving Sun

193. HI-1 CME-Venus
193
The Moving Sun

194. ICME at the Earth
When CME achieve the
Earth, it perturbs the
terrestrial magnetic
field.
The Moving Sun

195. Polar Aurora
The CME impact on the Earth
trigger very often a geomagnetic
storm, that can cause the polar
aurora.
The Moving Sun

196. Aurores
Au passage d'un CME, injection renforcée d'énergie et de particules
dans la magnétoqueue.
The Moving Sun

197. Impacts sur l’environnement terrestre
The Moving Sun

198. END
That was only a flyover of the Sun,
an exciting star in direct contact with our
environment
and
One of the central research objective for the coming
years
The Moving Sun

199. Solar Space projects in near future
The Moving Sun

200. SDO: AIA
Central satellite of NASa program
"Living with a Star"
Launch: 2008-9
5 - 10 ans
Orbite: geosynchronous
(TB/day)
The Moving Sun

201. SDO: AIA
3 instruments
HMI: helioseismology, vector magnetograph
EVE: spectro-photometre UV-EUV
AIA: telescope EUV 7 wavelength
The Moving Sun

202. Solar Orbiter / EUI: Extreme UV Imager
Mission:
Launch: 2013
5 - 7 ans
Orbit:
Distance to Sun: 0,21 AU (32 millions km, 45
Rs)
Partially heliosynchronous
Inclinaison: 30°
Spatial resolution : 200 km
The Moving Sun