Presentation on theme: "Interaction of coronal mass ejections with large-scale structures N. Gopalswamy, S. Yashiro, H. Xie, S. Akiyama, and P. Mäkelä IHY – ISWI Regional meeting."— Presentation transcript:
Interaction of coronal mass ejections with large-scale structures N. Gopalswamy, S. Yashiro, H. Xie, S. Akiyama, and P. Mäkelä IHY – ISWI Regional meeting on Heliospheric Phenomena and Earth’s Environment September 7 – 13, 2009 Šibenik, Croatia
Large-Scale Structures CMEs Coronal Holes Global Field of the Sun Heliospheric Current Sheet
CME Interactions Non-radial motion of CMEs during the minimum phase CME – CME interactions during solar maximum CME – Coronal hole interaction during the declining phase CMEs tend to align with the heliospheric current sheet: CME rotation
Non-radial motion: Toward Equator 20 km/s 42 km/s S30 Filippov et al., 2001Gopalswamy and Thompson, 2000 Gopalswamy et al., 2003 ApJ
Other Observations Plunkett et al., 2001 F ~ A/r Cremades et al White-light prominences (CME cores): offset similar to Gopalswamy et al Cremades et al considered only equatorward and poleward deflections
Consequence of Equatorward Deflection: More Magnetic Clouds during Solar Minimum Phase Lat (N) Lat (S) CMD Rise: Max: Decl: All: Gopalswamy, 2006 Outstanding question: Is the deflection due to coronal-hole open field or the global dipolar field?
Why driverless shocks from disk center? The limb sources are normal (geometrical reason), but the disk-center sources are anomalous The anomaly seems to be due to the presence of coronal holes near the source region MAX DECLINING
The Solar Source of a “Driverless” Shock Compact AR 0588 to the south of a large coronal hole produced a 1368 km/s CME from S18E15. CMEs from such disk-center location result in shock+ICME at Earth. In this event only the shock arrived. Why? AR 0588 CH 8
SHEATH S1S2 CME1 CME2 Disk-center CMEs, but only shocks at 1 AU (S1, S2) and no ejecta (No depressed Tp) 9
Open Field Lines on the Sun: 2004/04/06 Red: Negative Blue: Positive CME Coronal hole immediately to the north of AR The coronal hole (CH) influence parameter (CHIP), viz., B 2 A/r 2 = 26 G 2 along PA = 137 o due to the NW CH [B = average photospheric field inside CH; A = area of CH; r = Distance of CH to the eruption region]. CHIP is a vector pointing from the CH centroid to the eruption region The smaller CH in the south contributed very little: the CHIP was only 0.75 G 2 The central position angle of the CME was 167 o, which is close to the direction of the CH influence 10
CH AR 0588 S18E15 From: courtesy: M. DeRosa & K. Schrijver Purple: Open White: Closed MDI Magnetogram with extrapolated field lines Based on the east-west orientation of the neutral line and the location of the large coronal hole to the north, we expect the northern leg of the flux rope is negative, as is the coronal hole. No reconnection is possible between the CME leg and the CH field lines. The CH influence parameter has a value of 26 G 2 which pushes the CME below the ecliptic, so the flux rope is not observed at Earth. The northern flank of the shock is observed rendering it a “driverless” shock 2004/04/06 10:46 UT SOHO magnetogram 11 Magnetogram: white = +; black = -
Coronal Hole Influence Parameter F = ∑ f i f i = A i /r i 2 F MPA (Open field lines only shown) riri AiAi MPA Gopalswamy et al., 2009 JGR F = 14 G pointed along the PA (FPA) of 234 o.
The CME direction roughly coincides with the direction of F
Shocks with ICMEs CH have minimal effect: CHs smaller and/or far from the eruption CH deflect CMEs toward Sun-Earth line F generally small (2.5 G vs.5.8 G for driverless)
Deflection Observer Sun Open field lines from coronal hole Shock ahead of the deflected CME Shock Why ‘driverless’ shocks from disk- center CMEs? +
EUV Wave Reflection from CH: Higher Alfven Speed in the CH Gopalswamy, Yashiro, Temmer et al., 2009 ApJL
CME1 839 km/s CME km/s Two CMEs from the same region AR CME Cannibalism
Only one shock and a merged ICME CME interaction most common during the maximum phase
HCS affecting an ICME Coronal field maps calculated for CR2006 with CCMC/PFSS (top and middle) and MAS models (bottom). Panels a, b and c show maps for source surface radius of 1.6 R , d and e show maps at 2.5 R , while panel f shows MAS map at 16.5 R ,. The thick black contour is the coronal neutral line. The red oval represents the halo CME on Aug 14, 2003, which was aligned with the coronal neutral line at 1.6 R . Magnetic topology has changed further outward from the solar surface so that the neutral line rotated by approx. 50 deg. Yurchyshyn, 2008
Summary CME propagation can be affected by global solar field (min), CME interaction (max), and coronal hole deflection (declining) The presence of coronal holes near the eruption regions seem to make the CMEs behave like limb CMEs When magnetic topology changes outward from the solar surface, the neutral line seems rotated and so does the CME axis.