Coronal Mass Ejection Studies
with SOLAR-C
Angelos Vourlidas, NRLWhy do we care about CMEs?
CMEs:• Are the major explosive energy release phenomenon in the solar system• Are the main driver of space weather for Earth (+other planets)• Provide access to many interesting physics: e.g., modulate Galactic
Cosmic Rays, accelerate particles, etc

SOLAR-C Meeting, ISAS, Nov. 18-21, 2008

CMEs – A. Vourlidas

CMEs in the LASCO Era (1)• CME observations over a FULL solar cycle

CME/day: 0.5 – 4.5
Flare/day: 1.5 – 7.5

CME rates peak ~6 months
AFTER Sunspot rates

SOLAR-C Meeting, ISAS, Nov. 18-21, 2008

CMEs – A. Vourlidas

CME in the LASCO Era (2)Verification of the HaloCME typeFront

Most CME have fluxropestructures

CoreCavity
SOLAR-C Meeting, ISAS, Nov. 18-21, 2008

CMEs – A. Vourlidas

CME Initiation Models (quite a few but…)(from I. Roussev’s ESPM 2008 presentation)

Z [Rs]

5T oK
1.8E+07
1.5E+07
1.1E+077.8E+06
4.4E+06
1.0E+06

0The final
product is Sheared-Arcadealways a fluxrope!
Flux-Rope-505Y [Rs]

10Models

15Models

Amari et al. (2000, 2003, 2007); Antiochos et al. (1999); Forbes & Isenberg (1991); Gibson &Low (1998); Kliem et al. (2004); Lin et al. (2001); Linker et al. (2001); Lynch et al. (2005);
Manchester et al. (2003, 2004); Moore et al. (2001); Sturrock et al. (2001); Titov & Démoulin(1999); Tokman & Bellan (2002); and Roussev et al. (2003, 2004, 2007).
SOLAR-C Meeting, ISAS, Nov. 18-21, 2008

CMEs – A. Vourlidas

CMEs in the LASCO Era (3)• With >15,000 Events recorded, the basic CME
properties are well-known

CME-drivenshock<M> = 4·1015 gr<Ek> = 4·1030 ergs

CME core = fluxrope

SourceRegions~360º

W = 47º~20º~3000 km/s

V = 490~100 km/s~5600 m/s2 (20g)

α = 944 (3.4g)

SOLAR-C Meeting, ISAS, Nov. 18-21, 2008

~29 m/s2 (0.1g)

CMEs – A. Vourlidas

Tendency for
Slow CMEs to Accelerate
andFast CMEs to Decelerate

CME Kinematics – Flare Association(from J. Zhang’s SHINE 2007 presentation)

Three phases:
P1: Initiation
P2: Acceleration
P3: Propagation

CME main acceleration
coincides with flare energy
release phase(e.g.,Zhang et al. ApJ 2001)

From Zhang & Dere (2006)

SOLAR-C Meeting, ISAS, Nov. 18-21, 2008

CMEs – A. Vourlidas

Cycle 23: Review of LASCO Era– Knowledge of CME Properties over a full solar cycle and 1000’s of events– Establishment of relation to coronal phenomena (flares, filamenteruptions)– Discovery of CME counterparts in low corona (EUV-waves, dimmings,plasmoids)– CME role in Sun-Earth Connection is established, extensively analyzed.
– Theory converges towards fluxrope as the ejected structure- 3D MHD modeling captures the main CME features (shock, core, speed, width)– Clear understanding of CME images (shock, core, front, streamers)– But we don’t know
- true size, direction, entrained magnetic field, initiation mechanism, energy
partition, relation to extended corona, propagation in heliosphere,
geoeffectiveness, SEP accelerations, etc…..

SOLAR-C Meeting, ISAS, Nov. 18-21, 2008

CMEs – A. Vourlidas

Cycle 24: The SECCHI Era• Complete coverage of the Sun-Earth Heliosphere• Simultaneous observations from 2 viewpoints

Woods et al (2009)
Vourlidas et al (2009)
SOLAR-C Meeting, ISAS, Nov. 18-21, 2008

CMEs – A. Vourlidas

SECCHI Era: Size & Direction of CME
From Thernisien et al 2009

SOLAR-C Meeting, ISAS, Nov. 18-21, 2008

CMEs – A. Vourlidas

CME Current Sheets & Internal Structure• CMEs DO contain fluxropes• FR-CMEs look VERY similar to ideal fluxropes!
• The tip of the post-CME current sheet is visible.
– The current sheet should be visible in the low corona.

SOLAR-C Meeting, ISAS, Nov. 18-21, 2008

CMEs – A. Vourlidas

Cycle 24: SECCHI Era (Anticipated Contributions)– 3D measurements- true size, velocity, propagation direction, relation to AR– Detail analysis of the acceleration phase- energy partition between CME and flare, initiation mechanism(?)– Propagation in the heliosphere- Interaction with other CMEs & fast/slow solar wind, internal structure– CME formation in the low corona- nature of waves/shocks, interaction w/ background fields– Clearer understanding of CMEs geoeffectiveness- SEP acceleration, interaction with geospace– But we may not know
- entrained magnetic field, initiation mechanism, effects on/from global corona,geoeffectiveness, role in SEP acceleration, …

SOLAR-C Meeting, ISAS, Nov. 18-21, 2008

CMEs – A. Vourlidas

Cycle 25: SOLAR-C Era• Mission Considerations– Max Inclination of 45º– 2016 launch (cycle 24 ~min)– High inclinations in 4-5 yrs (cycle 25 ~max)– Optional co-rotation with Earth (TBD)– Elliptical or circular (1 AU) orbits (TBD)• Synergies in 2016 – 2020
– SDO operational- EUV coverage of inner corona (<1.5 Rs)– STEREO operational(?)- Full coverage of inner heliosphere (+/- 45º from solar limbs)– Solar Probe /Orbiter(?)- In-situ coverage of corona/heliosphere Good EUV coverage in the Ecliptic plane But coronagraphic coverage is uncertain

SOLAR-C Meeting, ISAS, Nov. 18-21, 2008

CMEs – A. Vourlidas

Plan-A

CME Science Objectives for Plan-A• Orbit Advantages– Viewpoint away from symmetry plane- Varying line-of-sight through dust (F-corona)– Simultaneous imaging of far-side and earth-facing solar hemispheres

Plan-A• Science Objectives:– How CMEs affect the large scale corona?
– What is the 3D morphology of CMEs/CIRs/Plumes?
- Validate STEREO results offering a truly independent measurement- Obtain direction with a single observation- Stronger constraints on IPS and Faraday rotation analysis– How does the solar wind structures propagate & interact w/ each other?
- Observed the formation of solar wind and the birth of CIRs.

– Space weather on Earth and inner planets (w/ Heliospheric Imager)- Which CMEs are headed towards Earth, Solar Orbiter/Probe, etc?

SOLAR-C Meeting, ISAS, Nov. 18-21, 2008

CMEs – A. Vourlidas

Why we need out-of-ecliptic CME Observations?
• The effects of CMEs on the global corona are unknown– How does the shock propagate around the Sun?
– Are there sympathetic CMEs?
– How do streamers reform?
– What is the interplay between CMEs, shock waves and Coronal Holes?
– Where does the solar wind originate?
X-planeY-plane

SECCHISOLAR-C Meeting, ISAS, Nov. 18-21, 2008

Z-planeMHD Simulation by Lugaz
CMEs – A. Vourlidas

What to Expect from a 45º Viewing Angle
MHD Simulation provided by N. Lugaz• Decouple shock from streamer bending• Better measurement of CME ecliptic extent• Better estimate of CME mass/density distribution
24º (~ 95 Rs)

4º (~15 Rs)

4º (2.5 – 15 Rs)

SOLAR-C

SOLAR-C

STEREOSTEREOSOLAR-C Meeting, ISAS, Nov. 18-21, 2008

CMEs – A. Vourlidas

Instrument Concepts for Plan-A
Option 1: Use SECCHI/COR2 (almost) as is
FOV (Rs)
Spatial Res. (“)
Exposure (sec)Bandpass (nm)Polarization
Detector
Mass (Kg)
Volume (m)Power (W)TRL

COR2
2.5 -1530
2650-750
Yes

Modified
1.5 - 1530
2650-750
Yes

2kx2k
CCD

2kx2k
APS

10120x142
1095.5120x102
85Why?
– High TRL design, meets science objectives– APS implementation lowers mass/power/volume

Changes from COR2
– CCD APS
– Occulter position mechanism (as in LASCO)SOLAR-C Meeting, ISAS, Nov. 18-21, 2008

CMEs – A. Vourlidas

Instrument Concepts for Plan-A
Option 2: Compact Coronagraph (CCOR)
COR2
2.5 -1530
2650-750
Yes

CCOR
1.5 - 1530~5650-750Yes

2kx2k
CCD

2kx2k
APS

Mass (Kg)

10<4Volume (m)Power (W)TRL

120x142~10945x132~34

FOV (Rs)
Spatial Res. (“)
Exposure (sec)Bandpass (nm)Polarization
Detector

CCD
AssemblyA0 Aperture

Radiator

127 mm
254 mm
171 mmTube Diameter = 132 mm
434 mmWhy?
– Very compact design, meets science objectives– APS implementation lowers mass/power/volume

Changes from COR2
– CCD APS (exists)– Occulter position mechanism (ala LASCO)– Lower TRL (design studies for 3 missions)

SOLAR-C Meeting, ISAS, Nov. 18-21, 2008CMEs – A. Vourlidas

Augmentation Options for Plan-A• Heliospheric Imager (details)– Extend FOV to ~90 Rs (24º) along Sun-Earth line
– Solar wind, dust, Space Weather studies– Moderate to small resource requirements (<4kg, <3W)
– Low risk.

• Compact Spectrograph (details)– Coronal spectroscopy capability with modest resources– Solar wind & CME velocities, thermal broadening, heating profiles– Composition of plasma in CMEs, plumes, solar wind.

SOLAR-C Meeting, ISAS, Nov. 18-21, 2008

CMEs – A. Vourlidas

Summary•

Out-of-ecliptic orbit offers unique advantages for CME& heliospheric studies––•

Coronagraph telescope is an important payload complement––––•

The corona has never been imaged before from such a viewpoint
Better viewing of global corona, better 3D reconstructions of events, better imaging ofsolar wind structures, unique dust & IPS measurements.
Several high TRL options
Small mass & power requirements
Modest telemetry requirements
Large FOV, short exposures, simple electronics

Heliospheric Imager is a viable option––It depends on available s/c resources, orbit design
High payoff for space weather and solar wind studies

SOLAR-C Meeting, ISAS, Nov. 18-21, 2008

CMEs – A. Vourlidas

BACKUP SLIDESSOLAR-C Meeting, ISAS, Nov. 18-21, 2008

CMEs – A. Vourlidas

Reduction in F-Corona Signal for Plan-A Orbit• Reduced F-corona signal improves SNRof white light observations dramatically.
• Orbit is ideal for dust studies!

Expected F-corona levels at 45º

Raw C3 ImageSOLAR-C Meeting, ISAS, Nov. 18-21, 2008

CMEs – A. Vourlidas

Heliospheric Imager for SOLAR-C (HISOC)
COR22.5 -1530
2650-750
Yes

HISOC
4 - 8436
Variable
500-700
No2kx2k
CCD

2kx2k
APS

Mass (Kg)

104.5

Volume (cm)Power (W)TRL

120x142~10942x14x18>14

FOV (Rs)
Spatial Res. (“)
Exposure (sec)Bandpass (nm)Polarization
Detector

Why?
– Expands mission objectives with minimum
resource investment.
– Very compact design– No mechanisms– Uses same APS as the coronagraph– Lower TRL but minimum risk

SOLAR-C Meeting, ISAS, Nov. 18-21, 2008

CMEs – A. Vourlidas

Coronal Spectrograph ConceptNOTE: This is a strawman concept. Needs
further study to adapt it to Solar-C mission
requirements.
Based on Alice Spectrograph

Wavelength range

970-1040 ǺLinesLyγ, Fe XVIII, CIII, Ar XII, Fe XII, Lyβ, FeX, OVI doublet, Si XII (2nd order)

Effective Area

1 cm2Mass<4.4 kg

UV line property

Physical properties measured/ derived

Relevant issues about corona, solar wind and solar transientsLine profile FromO VI (O+5, M/Q=3.2),
Si XII (Si+11, M/Q=2.5),
Lyβ (H+0/proton), C III (C+2)

Non-thermal ion velocity in the corona and solarwind
Line broadening by CME shocks or expansion
Electron temperature

Variations of non-thermal ion velocities with time, heliocentric height, fast/
slow wind regions, and M/Q  Solar wind heating, acceleration andturbulence
Ion temperatures associated with heating by CME shocks (mass or M/Qdependency?)
 CME/ICME properties and SEP production
Electron temperature in the corona and CMEs
 coronal and CME temperature structure

OVI λλ1032/1037 intensity
ratio

Solar wind ion outflow speed (100-400 km/s), O+5as a proxy

Solar wind ion speed as a function of heliocentric height and within slow/
fast wind regions Solar wind heating and acceleration, solar wind origin
CME propagation speed CME energetics

Elemental abundance
From O VI, Lyβ, Si XII, Fe
X andC III line ratios

Si/O, Fe/O, O/H, Si/H, Fe/H in the corona/solar
wind and CMEs

FIP effect associated with location of fast /slow solar wind flows andposition relative to close/open field regions and heliospheric plasma sheet solar wind origin
Possible mass differentiation along SW flow dynamics and propagationof solar wind
Abundances in CME/ICME CME initiation

Line intensity
From O VI, Lyβ, Si XII, CIII andFe XVIIIEmission line fluxes in the corona/solar wind andCMEs
Electron density and temperature

Variations with space and time  solar wind ‘blobs’ and turbulence
Variations with heliocentric height and longitude coronal and solar windspatial structure
CME density, temperature and composition structures CME initiation,
evolution and energetics, relation to ICME properties
CME shock parameters, e,g. compression ratio SEP production
Post-CME current sheet properties CME initiation and reconnection,
SEP production

Doppler shift of lines
From O VI, Lyβ, C III

Line-of-sight velocity

3-D CME velocity structures
CME initiation and evolution, CME/ICME structure

SOLAR-C Meeting, ISAS, Nov. 18-21, 2008

CMEs – A. Vourlidas

Solar Wind Outflow in HI-1
ε = 24°ε = 4°

Approximate
location of Sun(not to scale!)HI1-A observations for the month of April, 2007
SOLAR-C Meeting, ISAS, Nov. 18-21, 2008

CMEs – A. Vourlidas

SOLAR-C Meeting, ISAS, Nov. 18-21, 2008

CMEs – A. Vourlidas

Current Ideas on Interplanetary CMEs

Measurements from ACE

SOLAR-C Meeting, ISAS, Nov. 18-21, 2008

CMEs – A. Vourlidas

Corotating Interaction Regions
Pizzo, V. (1978), J. Geophys. Res., 83, 5563

SOLAR-C Meeting, ISAS, Nov. 18-21, 2008

CMEs – A. Vourlidas