Interaction of coronal mass ejections with large-scale structures

N. Gopalswamy, S. Yashiro, H. Xie, S. Akiyama, and P. MkelIHY ISWI Regional meeting on Heliospheric Phenomena and Earths EnvironmentSeptember 7 13, 2009 ibenik, Croatia

Large-Scale StructuresCMEsCoronal Holes Global Field of the SunHeliospheric Current Sheet

CME InteractionsNon-radial motion of CMEs during the minimum phaseCME CME interactions during solar maximumCME Coronal hole interaction during the declining phaseCMEs tend to align with the heliospheric current sheet: CME rotation

Non-radial motion: Toward Equator20 km/s42 km/sS30Filippov et al., 2001Gopalswamy and Thompson, 2000Gopalswamy et al., 2003 ApJ

Other ObservationsPlunkett et al., 2001F ~ A/rCremades et al. 2006White-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 MinimumPhase 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 6.1Gopalswamy, 2006Outstanding 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 regionMAXDECLINING

The Solar Source of a Driverless ShockCompact 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 0588CH*

SHEATHS1S2CME1CME2Disk-center CMEs, but onlyshocks at 1 AU (S1, S2) and no ejecta (No depressed Tp)*

Open Field Lines on the Sun: 2004/04/06Red: NegativeBlue:PositiveCMECoronal hole immediately to the north of AR 10588The coronal hole (CH) influence parameter (CHIP), viz., B2A/r2 = 26 G2along 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*

CHAR 0588S18E15From: http://www.lmsal.com/forecast/TRACEview/images courtesy: M. DeRosa & K. SchrijverPurple:OpenWhite:ClosedMDI Magnetogram with extrapolated field linesBased 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*Magnetogram: white = +; black = -

Coronal Hole Influence ParameterF = fifi = Ai/ri2FMPA(Open field lines only shown)riAiMPAGopalswamy 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 ICMEsCH 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)

DeflectionObserverSunOpen field lines from coronal holeShock ahead of thedeflected CMEShockWhy driverless shocks from disk-center CMEs?+

EUV Wave Reflection from CH: Higher Alfven Speed in the CHGopalswamy, Yashiro, Temmer et al., 2009 ApJL

CME1 839 km/sCME 21507 km/sTwo CMEs from the same region AR CME Cannibalism

Only one shock and a merged ICMECME 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

SummaryCME 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 CMEsWhen magnetic topology changes outward from the solar surface, the neutral line seems rotated and so does the CME axis.

****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.*A CME headed toward Earth is deflected away from the Sun-Earth line by the open field lines from the coronal hole. The net result is that an observer along the Sun-Earth line detects only the shock. In the absence of the coronal holes, the observer would have observed the shock as well as the driving ejecta.

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