November 18, 2008Jonathan Cirtain SCIENCE & MISSION SYSTEMS Solar-C Plan ‘A’ Coronal observations Jonathan Cirtain MSFC/NASA November 18, 2008

Jonathan Cirtain 2 SCIENCE & MISSION SYSTEMS Overview Polar Hole Formation Polar Coronal Holes in the EUV –Bright Points –Jets –Plumes –Origins of the Fast Solar Wind

3 November 18, 2008Jonathan Cirtain SCIENCE & MISSION SYSTEMS Polar Coronal Hole Formation Harvey & Recely (2002) demonstrates: –the formation of polar coronal holes Originates from coronal holes formed ~60° shortly after polar reversal (post solar-max) These high latitude holes migrate toward the pole in just a few solar rotations Average lifetimes of 8 years where decay begins when new cycle flux emerges –absolute magnetic flux in poles compared to the total solar magnetic flux –total net surface area of the polar holes may not be equal between poles, but total net flux appears to be conserved between the pair –Coronal hole open flux has same sign as trailing polarity in ARs

November 18, 2008Jonathan Cirtain SCIENCE & MISSION SYSTEMS EUV Bright Points in Coronal Holes Bright points are always observed with coronal holes in both EUV and X-ray (well sometimes in x- ray) The manner in which the local generation of magnetic flux forms these areas is not well-known Some bright points seem to be at the base of overlying plumes Boundaries of coronal holes less well-defined in EUV than in x-ray

November 18, 2008Jonathan Cirtain SCIENCE & MISSION SYSTEMS Notable characteristics of Bright points QS Bright Points (small ephemeral regions) magnetic field orientation is oriented with AR orientation below ~20° (proper) but prefers to be reversed for higher latitudes Proper orientation BPs live longer than reverse orientation BPs (Martin & Harvey (1979) Generally last for hours to days Average spatial extent ~ Mm Most bright points emit in a range with correspondence to a temperature distribution of MK. No correlation between age of bright point, size or proximity to CH boundary exists to determine whether the BP may form a jet or plume

November 18, 2008Jonathan Cirtain SCIENCE & MISSION SYSTEMS Plan-A observations for BPs The fine scale structure of coronal bright points is not well-understood. High resolution EUV imaging and EUV spectroscopy could: –Observe fine scale (~200 km) dynamics in BP structures –Determine temperature, density and doppler motions for these structures –Need to better understand the latitudinal dependance on the preferred vs reverse polarity of BPs and how do the two differ

7 November 18, 2008Jonathan Cirtain SCIENCE & MISSION SYSTEMS Polar Plumes DEFOREST, LAMY, & LLEBARIA (2001) Plumes are observed to expand with altitude (5- 10%) Most are long-lived with lifetimes approaching 1 day on average Polar coronal holes expand with altitude Doschek, Feldman & Laming (2001) using SUMER: –Characteristic temperatures for plumes MK –Electron Temperatures often observed to increase with altitude between 10-60” Del Zanna, Bromage & Mason (2003) used CDS data to –determine plume temperatures (~0.8MK with CDS) and densities for bases of plumes ~ 1.9 x 10 9 cm -3 (twice that of interplume) –Show there is no FIP enhancement for plumes Variation of the plume emission measure is not observed to occur on timescales approaching the radiative cooling time. No observed fast variation of the temperature of plumes has been reported DeForest et al. 2001

November 18, 2008Jonathan Cirtain 8 SCIENCE & MISSION SYSTEMS Plumes and Jets RAOUAFI ET AL. (2008) –studied 28 jet events –90% of plumes associated with jet events –~70% of the observed plumes formed subsequent to a jet observed by XRT –Plumes were always associated with bright points observed in x-ray, EUV or both. –Some ‘extended’ jets which became substatially larger during the eruptive phase of the event, were followed by an EUV plume some time later (typically 10’s of minutes to an hour) –Some jets occured within plumes which then was followed by an EUV increase Movie Courtsey Patsourakos

November 18, 2008Jonathan Cirtain SCIENCE & MISSION SYSTEMS Plan-A Plume Observations Resolution of the base of the plumes is critical to our understanding of the formation process for plumes as well as the heating & acceleration of the plasma within the plume –Plumes have a typical width of 10 Mm and very narrow temperature distribution. –Must determine the fundamental structure of plumes (fully resolve) Discriminate plume from interplume Determine the structure of the plume from chromosphere to > 60” above the limb. –temperature, emission measure, and magnetic field

November 18, 2008Jonathan Cirtain SCIENCE & MISSION SYSTEMS Polar Jet observations

November 18, 2008Jonathan Cirtain SCIENCE & MISSION SYSTEMS Some Polar Jet Theories Shibata Model [Shibata et al. (PASJ 1992)] Yokoyama & Shibata (PASJ 1996) demonstrate jet reconnection in 2-D Shibata et al. developed a model which demonstrates the temperature variability in a jet as well as wave propagation subsequent to the initial reconnection Moreno-Insertis et al. (2008) developed a numerical model that used magnetic field data from SOT and velocity/density information from EIS to constrain & compare their model Pariat et al. (2008) propose a null point/fan separatrix model and demonstrate with a 3-D MHD code that a twisting motion applied to the emerged flux will store energy until an ideal instability breaks the symmetry and reconnection produces a jet

November 18, 2008Jonathan Cirtain SCIENCE & MISSION SYSTEMS Recent Polar Observational Results M. Shimojo has published numerous papers detailing the characteristics of polar jets using SXT, TRACE and Hinode Savcheva et al. (2007) presents statistics for polar jets –Average duration ~800 sec –Average size ~ 0.8 Mm –Traverse velocity for jets shown to exist for majority of jets Cirtain et al. (2007) demonstrates high speed outflows –Two velocity components: ~700 km s -1 and 200 km s -1 Patsourakos et al. (2007) details observations of a jet using STEREO EUVI data. Stereoscopic observations show twisting motion in the jet. Tsuneta et all (in press) have shown the polar magnetic field from SOT/Hinode data

November 18, 2008Jonathan Cirtain SCIENCE & MISSION SYSTEMS Plan-A Jet Observations Distribution of jets within coronal holes relationship of eruptive region to background field evolution of multi-eruptive regions correlation between jet size, BP size, and other relavant statistics Of course, higher resolution and cadence is required

November 18, 2008Jonathan Cirtain SCIENCE & MISSION SYSTEMS Review: Potential Observations for Plan “A” Out-of -Ecliptic vantage point will permit: –Statistics on BPs, jets, plumes Latitudinal distributions for BP and their polarity alignment to the Hale’s Law ‘preferred’ pairing for equatorward ARs? Is there a Joy’s law for BPs? What is the difference between the structure of BPs in QS, Polar Coronal Holes, Equatorial Coronal Holes, and ARs? What discriminates a BP that produces a jet from one that does not? What is the difference between a BP at the base of a plume and one that produces jets? How do these observations contribute the generation of the fast solar wind? –Nearly edge-on view of AR’s with an extended observation duration 30ºN) Much larger solar coverage for flare and CME observations