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 EnvironmentSeptember 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/sS30
Filippov et al., 2001Gopalswamy and Thompson, 2000
Gopalswamy et al., 2003 ApJ
Other Observations
Plunkett et al., 2001
F ~ A/r Cremades et al. 2006
White-light prominences (CME cores):offset similar to Gopalswamy et al. 2003
Cremades et al. 2006 considered only equatorward and poleward deflections
Consequence of Equatorward Deflection: More Magnetic Clouds during Solar Minimum
Phase Lat (N) Lat (S) CMDRise: 25.6 -24.2 5.3 Max: 12.6 -20.0 9.7 Decl: 8.2 -13.8 1.8 All: 14.5 -19.7 6.1
Gopalswamy, 2006
Outstanding question:Is the deflection due to coronal-hole open field or theglobal 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 holeproduced 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
S1 S2 CME1
CME2
Disk-center CMEs, but onlyshocks 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 10588
The coronal hole (CH) influence parameter (CHIP), viz., B2A/r2 = 26 G2
along PA = 137o due to the NW CH [B = average photosphericfield 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 thesouth contributed verylittle: the CHIP wasonly 0.75 G2
The central position angle ofthe CME was 167o, which isclose to the direction of theCH influence 10
CH
AR 0588S18E15
From: http://www.lmsal.com/forecast/TRACEview/images courtesy: M. DeRosa & K. Schrijver
Purple:OpenWhite: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 G2 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 = ∑ fi fi = Ai<Bi>/ri2
F
MPA
(Open field lines only shown)
ri
Ai
MPA
Gopalswamy et al., 2009 JGRF = 14 G pointed along the PA (FPA) of 234o.
The CME direction roughly coincides with the direction of F
Shocks with ICMEs
CH have minimal effect:CHs smaller and/or farfrom the eruption
CH deflect CMEs towardSun-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 thedeflected 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 21507 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 ICMECoronal 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.
