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Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
George C. Ho and Glenn M. Mason
The Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723
June 26th, 2008
Energetic Electrons in Energetic Electrons in 33He Enhanced He Enhanced Solar Energetic Particle EventsSolar Energetic Particle Events
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
Key: proton = neutron = electron =
Helium-3 Helium-4Relative Abundance 1 2500
•Introduction–First Discovery
–Classification Paradigm
•Energetic Electron–Timing
–Occurrence
•Fluence Analysis–Observations
–Implication
•Discussion
Outline
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
Introduction
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
Anglin, 1975
Discovery that small solar particle events sometimes showed enormous enrichments of 3He, without any accompanying 3H or 2H enrichments
(Garrard, Stone & Vogt, NASA SP-342, 1973; Anglin et al. 1974; Serlemitsos & Balasubrahmanyan 1975)
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
Kilometric Type III Association
Reames and Stone, 1986
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
Overall Picture as of Mid 1990s
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
Gradual and Impulsive SEP Events
Mason et al., 1989
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
100
101
102
103
104
2 3 4 5Mass (AMU)
(a)
100
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102
103
2 3 4 5Mass (AMU)
(b)
10-1
100
101
102
103
2 3 4 5Mass (AMU)
(c)
100
101
102
103
2 3 4 5Mass (AMU)
(d)
keV/n
MeV/n
ACE He Mass Resolution
Event onsets often show almost pure velocity dispersion -- but multiple events can overlap in time. These are separated in constructing fluence spectra
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
Solar Cycle Dependence
ACE launchedin August ‘97
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
Fraction of time with 3He present. Points are shown for individual Bartels rotations; lines show running averageover 6 rotations. Unfilled circles and dotted line: unambiguous 3He (categories 2–4); filled circles and solid line: probable 3He (categories 1 and 5) also included.
Wiedenbeck et al., Solar Wind 10
3He-rich Population
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
Ultra-Heavy Particles
Mason et al., 2004
• Ultra-heavy ions ~200 times SW value
• Acceleration depends on M/Q ratio
• No satisfactory theory
Mason et al. (2004)
Coordinated Observations
QuickTime™ and aYUV420 codec decompressor
are needed to see this picture.
TRACE & RHESSI imagingTRACE EUV observations reveal thermal emission (~1.5 MK).
Flare loops and EUV jet observed.(21-Aug-2002 3He-rich event)
jet
Courtesy Säm Krucker, UCBerkeley
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
Ionization States
•Mean Q-states of Fe increase with Energy
•At low-E - ionic charge states correspond to equilibrium Temperature
•At high-E, stripping due to acceleration and transport
Klecker et al. (2005)
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
Energetic Electrons in 3He-rich Events
UT Time
Flu
x
SUN
? e - beam
Earth
Injection study of impulsive electrons
107
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105
104
05:00 07:00 09:00 11:00
type III radio burst
Fre
q (
Hz)
Linghua Wang et al. 2006 SPD
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
Casual Relationship
Ho et al., 2001
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
Timing Analysis
Ho et al., 2003
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
Scatter-free Transport
Ho et al., 2003
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
Lack of Correlation
Ho et al., 2001
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
Association with all Impulsive Events
Ho et al., 2001
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
Fluence Analysis
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
“Apparent” Anti-correlation
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
Upper Limit on 3He Fluence
• Measurements above instrument thresholds
• 4He fluences range over a factor of 10,000 while the 3He fluences in the same SEP range over only a factor of 100
• 3He/4He does not order the data
• A strict upper limit on the 3He fluence
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
Fluence Distributions
Ho, Roelof, Mason., 2005
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
20Ne vs. 4He Fluences
Ho, Roelof, Mason., 2005
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
10-3
10-1
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103
105
107
0.01 0.1 1 10 100
ACE - ULEIS/SIS Spectra: 9/09/1998 (252)
MeV/nucleon
4He
3He
16 O
Fe
Class-1 Events:• power law or double power law form
• above ~1 MeV/n all spectra similar
•3He is power law or double power law
Mason et al., 2002
Spectral Form-Class I
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
100
101
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104
2 3 4 5 6
Mass (AMU)
100
101
102
103
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107
0.01 0.1 1 10 100
ACE - ULEIS/SIS Spectra: 9/27/2000 (271)
MeV/nucleon
4He
3He16 O
FeMass (AMU)
Class-1 Events:
• single power law for all species except 3He
• 3He harder than others below ~1 MeV/n
• 3He:4He peaks from 1-few MeV/n
Mason et al., 2002
Spectral Form-Class I
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
Class-2 Events:• 4He is power law
• 3He and Fe flatten notably at low energies (other heavy ion species not clear)
• 3He and Fe curve at different energies
• highest 3He: 4He
10-1
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0.01 0.1 1 10
ACE - ULEIS/SIS Spectra: 3/21/1999 (080)
MeV/nucleon
4He
3He
16 O
Fe
(a)
Mason et al., 2002
Spectral Form-Class II
10-1
101
103
105
0.01 0.1 1 10
3He 4He 16O Fe
MeV/nucleon
10-1
101
103
105
107
0.01 0.1 1 10
3He 4He 16O Fe
MeV/nucleon
10-3
10-1
101
103
105
107
0.01 0.1 1 10 100
3He 4He 16O Fe
MeV/nucleon
Possible synthesis:
initial 3He enrichment mechanism (Cascade MHD?)
further acceleration results in power law spectra
still further acceleration results in similar spectra for all species
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
Fluence Distributions
Ho, Roelof, Mason., 2005
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
Discussions
• New observations from advanced instrumentations give us new insight into this class of SEP events
• As we learned more about this class of events, we find there is more outstanding questions (personal views):– What enhancement/acceleration mechanism operate in this
remarkable class of SEP event? (Ultra-heavy ion?)– Why is the 3He presented continuously in the interplanetary
space?– What are the causal relationship between the energetic
electrons, flare, and 3He enrichment?– Why is there an apparent upper limit on the 3He fluence in the
interplanetary space? What is its implications?– Why the 3He spectral shape different from other ions?
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
Discussions
• Current observations at 1 AU are hampered by transport effects as we are far from the source
• Require high resolution in-suite observation close to the source of the enrichment/acceleration
Solar Orbiter: Solar Probe + :
Introduction Energetic Electrons Fluence Analysis Summary SHINE 2008
Fluence Analysis
• The remarkable enrichment of the isotope 3He in solar energetic particle (SEP) events is usually described in terms of the ratio of the fluences of the two isotopes (3He/4He)
• However, only weak correlations between 3He/4He and flare properties have been found [Reames, Dennis, and Stone, ApJ., 1988]
• Strong correlation is found between the occurrence of 3He-rich SEP with energetic electrons [Reames, von Rosenvinge, and Lin, ApJ., 1985]
• However, Ho et al. [ApJ., 2001] found same association in all impulsive SEP events with energetic electrons
• Ho, Roelof, & Mason [ApJL., 2005] found during the peak of solar activity, there is an upper limited on the 3He flunence of 0.2 to 2.0 MeV/nuc.