“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August 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

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August August 2006 Summary Ultraviolet Spectroscopy with UVCS/SOHO Atomic Physics Used in Analyzing UVCS/SOHO Data Ultraviolet Spectroscopy with Next Generation Instruments Conclusions

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August 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).

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August 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.

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August 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 = 1–3 million K Off-limb profiles: T > 200 million K !

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August 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)

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August 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 wave’s oscillating E and B fields ion’s 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

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August August 2006 Eruptive Prominence/CME &Flare

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August 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

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August 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 (Tp≠Tion) 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.

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August August 2006 Density of Suprathermal Seed Particles Preshock  fi (v): Resonantly scattered Ly  constrains the seed particle distribution  fe(v): Thomson-scattered Ly 

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August August 2006 Spectral Lines Observed by UVCS SOHO

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August August 2006 Spectral Lines Observed by UVCS SOHO

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August August 2006 Spectral Lines Observed by UVCS SOHO

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August August 2006 Spectral Lines Observed by UVCS SOHO

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August August 2006 Line Formation by Electron Impact Excitation

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August August 2006 Line Formation by Resonant Scattering

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August August 2006 Line Formation by Thomson Scattering

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August 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.

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August August 2006 The Role of Charge Transfer Collisions He ++ + H → He + (nl) + H + → He + (1s) + hν 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.

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August 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

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August August 2006

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August August 2006 Additional Spectral Lines to be Observed with Next Generation Instruments Wavelength (nm) Ion Si X Si IX Si XI He II 31.2Fe XIII Si VIII He I 59.2Si XI Ne VIII SVI Fe XII

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August 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.

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August August 2006 Radial Dependence of Temperature in Polar Coronal Holes and the Fast Solar Wind at Solar Minimum

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August August 2006 NON SUNGRAZING COMETS

“The Role of Atomic Physics in Spectroscopic Studies of the Extended Solar Corona” – John Kohl “High Accuracy Atomic Physics in Astronomy”, August August 2006 “High Accuracy Atomic Physics in Astronomy”, August August 2006 SUNGRAZING COMETS