“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl...
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“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, 7 -- 9 August
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
The Role of Atomic Physics in Spectroscopic Studies of the Extended
The Role of Atomic Physics in Spectroscopic Studies of the Extended
Solar Corona John Kohl Harvard-Smithsonian Center for
Astrophysics
Slide 2
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
Summary Ultraviolet Spectroscopy with UVCS/SOHO Atomic Physics Used
in Analyzing UVCS/SOHO Data Ultraviolet Spectroscopy with Next
Generation Instruments Conclusions
Slide 3
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
Science Goals and Objectives To identify and understand the
physical processes responsible for heating and accelerating the
primary and secondary plasma components of the fast and slow solar
wind To determine how Coronal Mass Ejections (CMEs) are heated and
accelerated, and to determine their role in accelerating
super-energetic particles (SEPs).
Slide 4
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
Approach Use ultraviolet spectroscopy to obtain detailed empirical
descriptions of coronal regions where the primary solar wind and
CME heating and acceleration occurs. Use the empirical descriptions
of the solar wind acceleration regions to constrain and guide
theoretical models in order to identify the dominant physical
processes. Use empirical descriptions of the pre-CME corona and CME
evolution to tailor theoretical CME models to specific events, so
predictions of CME and SEP properties outside the corona can be
used to test and guide the development of those models through
comparisons to in situ measurements of CME and SEP properties
between 0.25 and 1 AU.
Slide 5
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
In June 1996, the first measurements of heavy ion (e.g., O +5 )
line emission in the extended corona revealed surprisingly wide
line profiles... On-disk profiles: T = 13 million K Off-limb
profiles: T > 200 million K !
Slide 6
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
UVCS/SOHO has led to new views of the acceleration regions of the
fast solar wind. The fast solar wind becomes supersonic much closer
to the Sun (~2 R s ) than previously believed. In coronal holes,
heavy ions (e.g., O +5 ) both flow faster and are heated hundreds
of times more strongly than protons and electrons, and have
anisotropic temperatures. (e.g., Kohl et al. 1997,1998)
Slide 7
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
UVCS observations have rekindled theoretical efforts to understand
heating and acceleration of the plasma in the acceleration region
of the solar wind. Alfven waves oscillating E and B fields ions
Larmor motion around radial B-field Ion cyclotron resonance:
Measured ion properties strongly suggest that a specific type of
(collisionless) wave in the corona is damped: ion cyclotron waves
with frequencies of 10 to 10,000 Hz. It is still not clear how
these waves can be generated from the much lower-frequency Alfven
waves known to be emitted by the Sun (5-min periods), but MHD
turbulence and kinetic instability models are being pursued by
several groups. Low freq. Alfven waves may provide some fraction of
the primary heating directly. This can be observationally
constrained
Slide 8
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
Eruptive Prominence/CME &Flare
Slide 9
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
CME-Driven Shock Waves and SEPs UV spectroscopic diagnostics can
determine the parameters describing the shock itself and the pre-
and post-shock plasma. These parameters are needed as inputs to SEP
acceleration models for specific events. Required parameters:
Pre-CME density, temperatures, composition Post-shock ion
temperatures, which probe collisionless heating Shock onset radius
Shock speed ( CME speed) Shock compression ratio & Mach number
Magnetic field strength at onset radius
Slide 10
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
CME Shock Diagnostics Pre-CME density, temperatures, composition:
UVCS has measured these prior to 4 observed shocks. Post-shock ion
temperatures: UVCS has measured high temperatures of shock-heated
plasma (TpTion) Shock onset radius: The high temperatures (at
specific radii) from UVCS indicate the shock has formed; Type II
radio bursts give the density at which the shock forms. Shock
speed: UVCS density measurements allow the Type II density vs. time
to be converted to shock speed (V shock > V CME ) Shock
compression ratio & Mach number: UVCS can measure the density
ratio and the adiabatic proton temperature ratio (Lya), from which
the Mach # can be derived. Magnetic field strength at onset radius:
At the onset radius, Mach # = 1, so measurement of V shock gives V
Alfven, and thus B.
Slide 11
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
Density of Suprathermal Seed Particles Preshock fi (v): Resonantly
scattered Ly constrains the seed particle distribution fe(v):
Thomson-scattered Ly
Slide 12
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
Spectral Lines Observed by UVCS SOHO
Slide 13
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
Spectral Lines Observed by UVCS SOHO
Slide 14
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
Spectral Lines Observed by UVCS SOHO
Slide 15
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
Spectral Lines Observed by UVCS SOHO
Slide 16
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
Line Formation by Electron Impact Excitation
Slide 17
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
Line Formation by Resonant Scattering
Slide 18
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
Line Formation by Thomson Scattering
Slide 19
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
The Role of Charge Transfer Collisions H + + H H + H + Olsen et al.
(1994) and Allen et al. (1998, 2000) found that rapid charge
transfer between protons and neutral hydrogen allows neutral
hydrogen to act as a proxy for protons at heights up to 2.5 solar
in coronal holes and higher heights in more dense structures.
Slide 20
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
The Role of Charge Transfer Collisions He ++ + H He + (nl) + H + He
+ (1s) + h In some coronal structures, He + can act as a proxy for
alpha particles, which play an important role in the corona. The
decay of the n=2 states of He + may contribute to the He II 30.4 nm
intensity.
Slide 21
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
Near Earth Sentinel Concept Provides Improvements over UVCS and
LASCO Improved sensitivity (> 400 times UVCS at 1.5 R o for Ly-a
and OVI; >100 times LASCO C2 at 2.5 R o ) HeII Path: 48 74 nm
first order 26 37 nm second order EUV Path:70 150 nm first order 38
75 nm second order Improved spatial resolution (3.5 arcsec for both
UV and visible) Co-registered FOV extends downward to 1.15 Ro for
both UV and visible light Broader wavelength coverage for UV Direct
measurement of Thompson Scattered Ly-a profile Measurement of
Magnetic Fields using Hanle Effect
Slide 22
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August
2006
Slide 23
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
Additional Spectral Lines to be Observed with Next Generation
Instruments Wavelength (nm) Ion 27.19927.727Si X 29.619Si IX
30.312Si XI 30.378He II 31.2Fe XIII 31.43131.620Si VIII 58.433He I
59.2Si XI 77.04178.032Ne VIII 93.338SVI 134.957Fe XII
Slide 24
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
Conclusions A quantitative understanding of electron impact
excitation, resonant scattering, Thomson scattering, processes
controlling ionization and recombination and charge transfer is
needed to analyze ultraviolet spectroscopic observations of the
extended solar corona. The above processes for transitions in H I,
He II, C II, C III, N I, N II, N III, N V, O I, O III, O V, O VI,
Ne VI, Ne VIII, Ne IX, Mg X, Al XI, Si III, Si VIII, Si IX, Si X,
Si XI, Si XII, S V, S VI, S X, S XIII, Ar XII, Ar XIII, Ca X, Ca
XIV, Ca XV, Fe X, Fe XII, Fe XIII, Fe XV, Fe XVII, Fe XVIII, Ni
XIII, Ni XIV, Ni XV are of interest The UVCS/SOHO data set includes
observations from January 1995 to the present. New instrumentation
is being proposed for observations beginning in the 2011 2012 time
frame.
Slide 25
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
Radial Dependence of Temperature in Polar Coronal Holes and the
Fast Solar Wind at Solar Minimum
Slide 26
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
NON SUNGRAZING COMETS
Slide 27
The Role of Atomic Physics in Spectroscopic Studies of the
Extended Solar Corona John Kohl High Accuracy Atomic Physics in
Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006 High Accuracy
Atomic Physics in Astronomy, 7 -- 9 August 2006 7 -- 9 August 2006
SUNGRAZING COMETS