SHINE 2008 Introduction Energetic ElectronsFluence AnalysisSummary George C. Ho and Glenn M. Mason The Johns Hopkins University Applied Physics Laboratory,

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


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


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)


Kilometric Type III Association

Reames and Stone, 1986


Overall Picture as of Mid 1990s


Gradual and Impulsive SEP Events

Mason et al., 1989


100

101

102

103

104

2 3 4 5Mass (AMU)

(a)

100

101

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


Solar Cycle Dependence

ACE launchedin August ‘97


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


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


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)


Energetic Electrons in 3He-rich Events

UT Time

Flu

x

SUN

? e - beam

Earth

Injection study of impulsive electrons

107

106

105

104

05:00 07:00 09:00 11:00

type III radio burst

Fre

q (

Hz)

Linghua Wang et al. 2006 SPD


Casual Relationship

Ho et al., 2001


Timing Analysis

Ho et al., 2003


Scatter-free Transport

Ho et al., 2003


Lack of Correlation

Ho et al., 2001


Association with all Impulsive Events

Ho et al., 2001


Fluence Analysis


“Apparent” Anti-correlation


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


Fluence Distributions

Ho, Roelof, Mason., 2005


20Ne vs. 4He Fluences



10-3

10-1

101

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


100

101

102

103

104

2 3 4 5 6

Mass (AMU)

100

101

102

103

104

105

106

107

0.01 0.1 1 10 100


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


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

100

101

102

103

104

105

106

0.01 0.1 1 10


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


Fluence Distributions



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?


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 + :


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.

SHINE 2008 Introduction Energetic ElectronsFluence AnalysisSummary George C. Ho and Glenn M. Mason The Johns Hopkins University Applied Physics Laboratory,

Documents

fluence slide

spd slide

mass resolution slide

events mason

impulsive events ho

mevn mason

double power law mason

rich events