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Coronal Mass Ejections, Shocks, & Plasmoids

Coronal Mass Ejections, Shocks, & Plasmoids. Radio CMEs CMEs and type II bursts DH type II bursts Type IV bursts. (Nelson & Labrum, 1985). Radio Sky. coronal. Interplanetary (SIRA). Less messy in the IPM. Radio Sun in Meterwaves.

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Coronal Mass Ejections, Shocks, & Plasmoids

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  1. Coronal Mass Ejections, Shocks, & Plasmoids • Radio CMEs • CMEs and type II bursts • DH type II bursts • Type IV bursts

  2. (Nelson & Labrum, 1985) Radio Sky coronal Interplanetary (SIRA) Less messy in the IPM

  3. Radio Sun in Meterwaves •Thermal emission: optical depth could be large at low frequencies. • Direct imaging using free free emission from the corona & CMEs (Sheridan et al., 1978; Gopalswamy and Kundu, 1992; Maia et al., 2000) CLRO quiet Sun at 50 MHz; Optical Sun blocked to mimic eclipse

  4. Clark Lake CME Jan 16, 1986 Gopalswamy & Kundu, 1992 Radio CMEs Mass can be determined from the observed brightness temperature

  5. Thermal Emission from CMEs • Extremely weak • Often masked by bright nonthermal sources such type II and type III bursts • When nonthermal emission is occulted, thermal emission can be seen easily • Maybe good for anti-earthward halo CMEs

  6. Nonthermal Radio Bursts(Due to accelerated electrons) • Type II bursts are thought to be due to MHD shock waves (shock driver: CMEs or flares?) • Type IV bursts: due to nonthermal particles trapped in CME substructures • Stationary type IV (also known as flare continuum; from post-eruption arcades) • At longer wavelengths, complex type III bursts are associated with CMEs (Macdowall & Kaiser)

  7. A Type II Radio Burst Type III (e beams)v = 0.3 c, Type II (shocks) v = 1000 km/s

  8. Images of a type II Burst • Imaged by the Clark Lake Radioheliograph in the 1980s • Brightness temperature contours • SIRA will see a bigger source at a larger helio-centric distance

  9. Type II Radio Bursts • Fast CMEs drive MHD shocks • Shock accelerates electrons (~10 keV) • Nonthermal electrons generate Langmuir waves at local plasma frequency (fp) • Langmuir waves scatter off of ions or combine themselves to produce radio emission at fp (fundamental) and 2fp (harmonic) • Discovered at metric wavelengths by Payne-Scott et al (1947) from ground; later from space at km wavelengths. • km type IIs due to IP shocks driven by CMEs • Type II bursts in the decameter-hectometric wavelengths are also due to CMEs • DH type II bursts are good indicators of geoeffective CMEs

  10. LASCO CME DH Type II 3.66 Ro 1.5 Ro Type II H F 7 MHz @ 3.66 Ro SA Event (Complex Type III Bursts)

  11. An IP Type II & its CME f = 3MHz  n = 2.8x104 cm-3 Type II Type III Type II bursts track the CME through the IP medium

  12. Properties of Type II producing CMEs -CMEs driving shocks in the near-Sun IP medium are faster and wider than regular CMEs -They tend to decelerate, probably due to coronal drag.

  13. 1-14 MHz Type II burst starts after CME reaches ~ 2 Ro ! • The RAD2 spectral range (14-1 MHz) Wind/WAVES correspond to 2-10 Ro  Type II bursts can identify shock-driving CMEs in the near-Sun IP medium. • Delayed due to accelerating CMEs • CME delay: Disk events

  14. All, FW &DH CMEs • > 5000 CMEs during 1996-2000 • ~150 Fast & Wide (FW) CMEs • ~150 DH Type II bursts • ~ 50 FW frontside western CMEs • ~ 50 Major SEP events • 1-3% of all CMEs are important for SEPs • Electron accelerators are also ion accelerators

  15. Relative Bandwidths of IP type IIs Avg: 0.17 Large number of narrowband Events (ISEE 3 might have missed) Avg: 0.34 Avg: 0.3

  16. Solar Cycle Variation of Energetic Events • DH type IIs, fast and wide CMEs and major SEP events: similar solar-cycle variation. • Close correlation implies physical relationship: the same CME-driven shock accelerates electrons that produce DH type II bursts, and SEPs. • The number of DH type II bursts is the largest because eastern events are also included. • Minor differences due to other parameters like Alfven speed.

  17. Speeds of CMEs associated with Metric & DH type IIs Lara et al. 2003, GRL, in press Average CME speeds increase in this order: . General population (G) .Metric type II related (M) . DH type II related (D) Similar tendency for width and acceleration of CMEs M D G Since DH type II bursts are 100% associated with CMEs, these properties suggest that metric type IIs are also due to CMEs, but less energetic

  18. Shock Source? Type II radio bursts due to shocks: Relation to CME is controversial (Gopalswamy et al., 1998; Cliver et al., 1999; Reiner et al., 2001) Flare or CME? Type II far behind CME leading edge: Blast wave? Type II due to 2nd CME? Robinson & Stewart, 1985

  19. Two Shocks?Wagner & MacQueen1983, Gary, 1984, Cane 1984, Gopalswamy et al., 1995 • - Short-lived drivers • (Gopalswamy et al. 1998) • All shocks are CME driven • (Cliver et al., 1999) • May be two shocks • but both from the CME? • Metric from flanks • IP from the nose • (Gopalswamy et al. 2001, • Gopalswamy and Kaiser 2002)

  20. Two Shocks from the same source? Metric domain • “Alfven-speed hump” expected based on B, n profiles in the quiet corona (Hollweg, 1978; Krogulec et al, 1994; Mann et al. 1999) • Include active region: 3 regions of interest (Gopalswamy et al. 2001) • Easy to drive shocks on either side of the “Alfven-speed hump” Gopalswamy et al. JGR (2001). • Easier to shock the corona in the transverse direction? (Gopalswamy, Kaiser & Pick, 2000). • Type IIs occurring to the right of the hump are likely to be strong and indicative of IP shocks. fp

  21. Type II bursts help us understand the characteristics of the corona & IP medium 02:48-52 Hiraiso – metric type II WAVES type II

  22. The CME propagates thru a tenuous medium where Va is expected to be high 03:42 04:18 05:18 05:42

  23. 2000 06 10 Gopalswamy et al. 2001 ApJ Lett. 548, L91, 2001

  24. The two CMEs are indistinguishable at 23:42 UT >100% 830 km/s (S07E40) 1460 km/s (S07E46)

  25. Type II Summary • Important for Space Weather and LWS objectives because spatial information on shocks when they are most potent in producing solar energetic particles • Provide valuable information on the properties of the solar atmosphere not currently probed by any spacecraft • Best tool to track geoeffective disturbances over the entire Sun-Earth distance.

  26. Moving Plasma Structures • Substructures of CMEs • Known for nearly half a century from ground based observations • Tracked to several solar radii • Nonthermal electrons from 10s of keV to MeV inferred

  27. Clark Lake Moving Type IV ApJL, 365, L31, 1990 Tb MK C V~1600 km/s B~1.4 G; N~1.2x105 cm-3; n~4.6x106 cm-3 A – type II burst; B – Flare continuum (Stationary type IV burst)

  28. Arch-like Moving type IV Type IV radio bursts: nonthermal electrons trapped in CME cores or substructures produce plasma or synchrotron (Boischot, 1957; Stewart, 1985; Gopalswamy & Kundu 1990) Moving structure from type IV The radio and white light structures had a speed of ~ 525 km/s. (Gopalswamy & Kundu, 1989)

  29. Synchrotron Emission from CME Structures Nancay metric source radially above eruption site; 0.5-5 MeV electrons in a few G field (Bastian et al. 2001)

  30. Wind/WAVES Type IV:Nonthermal Emission from CME substructuresComplex Type III bursts start ~ 1 hr before the type IVCommon origin for the nonthermal particles?Flare or shock? Which shock? 2002 04 17 F Complex Type III UT

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