1. An Introduction to Observing Coronal Mass Ejections
Russ Howard
SOWG #8
ESAC, Madrid / Jan 2016
SWT, Alcala, 13 Apr 2016

2. Coronal Mass Ejections
Sometimes related to (NOT caused by) solar flares
Properties:
Mass: 1013 to 1017 g
Speed: ~50 to 3000 km/s
Total energy ~ 1030 to 1032 erg
Constant angular span (expand radially)
Well described by Magnetic Flux Rope
Are all CMEs MFRs?
Morphology/Density described by GCS (Graduated Cylindrical Shell) or “Croissant” Model

3. Aug 18, 1980: 3-Part CME (Illing & Hundhausen, 1986)

6. CME and Shock
CME shocks are usually quite fainter than the body of the CME
Note that in this case the shock is to the sides.

7. Shock Shapes
Ontiveras & Vourlidas (2009) identified the shocks associated with the 15 fastest CMEs observed
Streamer deflections can occur

10. CMEs can occur in both types of streamers.

11. Example of fast and slow CMEs

12. Halo CME with Reconnection event at end (PA=~45deg)

13. J-Map J-Maps are Height-Time maps at a particular position angle.
SoloHI will send down in the low-latency pipeline the information to construct the J-Maps at several PA – equator and +/- 20 degrees (TBC).
The following map shows the J-maps for the previous fast & slow CMEs.

15. Example of a Streamer Blowout
37 hours duration
Reconnection signatures must be present

16. CMEs are Optically Thin
The result of the optically thin nature is that what is observed is the integration along the line of sight projected onto the 2D plane.
A different perspective could produce a completely different structure.
The STEREO mission has shown many examples of the differences

17. The black line is the outline from an automatic boundary detector based on image texture.

19. Some Questions Are all CMEs flux ropes?
Are there differences in the spectral characteristics in CMEs
What are the conditions for the generation of a horizontal and a vertical shock and can they be detected? Where does the vertical shock form?
Are the SEPs generated from the horizontal or vertical shock?
Can the source of CME acceleration be detected?(Reconnection behind the CME? Poloidal Flux, etc_
Where does the CME mass originate? Can mass increase be detected?
Relate the structure and details of CMEs to ICMEs
Relate the magnetic field flux expelled to the in-situ flux.

20. Objective 2: How do solar transients drive heliospheric variability?
2.1 How do CMEs evolve through the corona and inner heliosphere?:
Identify CME boundaries and characterise their overall morphology.
Determine CME topology and magnetic connectivity.
Characterise the effects of heating/dissipation inside CMEs.
Measure solar wind plasma composition and establish links to coronal source conditions.
2.2 How do CMEs contribute to solar magnetic flux and helicity balance?
Determine the contributions of CMEs to closed magnetic flux in the inner heliosphere.
Identify reconnection signatures and determine CME history.
Compare with flux-rope and other models to characterise ejected CME magnetic flux.
Investigate how CMEs are related to the reversal of the solar magnetic field.
2.3 How and where do shocks form in the corona?
Identify coronal shocks and characterise their spatial distribution and outward propagation velocity.
Study interaction with coronal plasma.
Characterise the longitudinal distribution of coronal shocks during high latitude orbits.

21. 2.1 How do CMEs evolve through the corona and inner heliosphere?
CME initiation:
SO may not be the best mission to study initiation
But daily SPICE, PHI, EUI observations would be good
CME structure
5-10 min cadence from EUI, Metis, SoloHI
Important to measure in-situ the same CME observed remotely
CME evolution
Track the structure differences with propagation
Type II radio bursts 
Relate Type II (RPW) to Remote Observations (METIS, SoloHI)
Determine field line lengths
Measure energetic particle travel time measurements (EPD), and check connectivity with MAG and suprathermal electrons (SWA).

22. 2.2 How do CMEs contribute to solar magnetic flux and helicity balance?
How do CMEs contribute to the global evolution of magnetic flux in the heliosphere?
Remote observations – PHI, EUVI, METIS, SoloHI
In-situ – Mag, SWA, EPD
MHD Model CME
What is the role of ICMEs in the Sun’s magnetic cycle?
Measure the helicity
Does the helicity change due to the effects of local dynamics
Determine connection/disconnection
Identify SEP counterstreaming dropouts
Track field lines

23. 2.3 How and where do shocks form in the corona?
What are the properties and distribution of coronal and heliospheric shocks?
Understand coronal conditions under which the shocks form,
Determine the interplanetary conditions where they evolve.
RS – PHI, EUI, METIS, SoloHI, RPW
IS – SWA, MAG, EPD
Identify shock accelerated particles
EPD
EUI, Metis, RPW, SoloHI