Solar Cycle 24 Group F

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McAteer Notes


STERLING Earliest phases of solar eruptions

preflare phase & trigger mechanism for filaments as tracer of B field, slow rise -> flare + fast rise

few (12) example event studied. 2 may 2007, TRACE & HINODE, good example.

filaments undergo slow rise (few km/s), then fast. the slow rise is linear then flare at start of fast eruption. could be some signatures of 'breakout' or tether cutting

Dimmings - local (near neutral line) or remote (associated with breakout?)

rise of filament in AR is mins rise of quiescent filament is several hours.

also association with flux emergence / cancellation.

filament is tracer of the overlying loop?

WHAT WILL WE LEARN: how common is a slow rise? what triggers slow & fast rise phases?

where to go from here? Clearly Hinode and SECCHI 171 high cadence? so synoptic data modes are fine for this project?

ATRILL Coronal waves and dimmings

EIT waves map the CME footpoints? Angelos -mixing lateral mass expansion & wave? Atrill - the expansion of CME stops when wave stops.

Explains the brightnenings at the CME legs

WD - Tunnelling of waves into coronal hole?

Dimmings: could be evacuation or cooling also agree with deep core and secondary dimmings

Mass measurements from plasma outflows?

Angelos: No brightenings in 304, so not reconnection? McAteer: reflection and refraction problem?

Attril: does not mean there is no wave, the CME footpoints could cause a wave?

why/how do CD disappear while magnetic connectivity of the CME ejecta to Sun is maintained? recovery can be due to Interchange reconnection.

reconnection rate at same speed as the wave? 0.1 X 0.2 alfven speed - too low?

expansion of cme flanks should correspond with eit wave speed.

Occams razor? why add in CME flanks and then introduce wave anyway? Overly complex?

Can also be viewed in XRT on 20-May-2007

WHAT WILL WE LEARN? New tests from multi viewpoint? tenuous results which may collapse in face of new data?

MCATEER CME Kinematics

–Kinematics is the study of the motion

–Energetics is the study of the forces which cause the motion.

•What forces govern the propagation?

•What forces govern the expansion?

from height time profiles -> acceleration profiles

• What are we tracking?

- image to image,

- event to event,

- study to study

• Can we reduce the errors?

• Are we capturing the full profile?

- What about lower down?

combine with mass -> work done, force and power.


Known Knowns

•Well characterized and large sample studies from 3-30RSUN

•Well developed techniques to study energetics and kinematics

Known Unknowns

•Behaviour at 1-3RSUN and greater than 30RSUN

•Even at 3-30RSUN,

–where do the forces act and over what distance?

–when do the forces act and over what timescale?

Unknown Unknowns?

-What is the initiation mechanism?

-What is the CME - flare/filament link?

-The ever-illusive current sheet - any other choice?

from stereo - better H-T low down, and multi direction.

more automated tracking.

STEED locating the solar source

ICME ejecta - components of ICME show a left -handed cloud (-ve helicity)

launch window determined - 80hours before, roughly noon 10-april 2006 no obvious cme signatures (flares, dimmings, etc) survey possible launch regions.

search for source region with -Ve helicity. only one possible no erupting filaments, or possible cmes (because of lack of launch, conclude a back-sided event)

find some evidence of cusp shaped loop - > eruption signature? without vector data- cannot rule out helicity problems.


HOWARD source regions A skeptics view of flare-cme relationship

how do we define a flare and a cme? cme- outward propagation of brightness enhancement in WLC flare - brightening in cr, tr or coronal emmisison

associating lists is dangerous all current theories have a flare as necessary consequence of eruption, but not neccesaary cause and effect.

There are CME without flares -called backside, faint flare (not in GOES) there are cmes which have no chromospheric signatures - 'streamer blowout'

with stereo - we can see these are not backsided.

obvious controversy suggest we are a long way from solving this problem -different people see different conclusions from the same data!

WHAT WILL WE LEARN? Need to nail down an agreed definition? With STEREO we can rule out backsided possibility - can we also rule out the 'too low for GOES? If so, then we have a non-flare CME and we need a new approach.

VERMA A new classification of CMEs?

calculate escape velocity Alphonse- What about LOS projection? - not accounted for.

NEVCME 41%, mostly +ve accleration Ev CMEs 59%, half +ve, half -ve overall 68% show +ve acc


LOS question is vital: problems with just looking at the stats, not looking at the data


WEBB - overall discussion and questions to be addressed

Types of CMES -limb (good for H-T) -earth directed OR spacecraft directed (good for connecting CME / ICME and finding source regions -cradle to grave events

What is source region? dimmings, waves, slow rises extents, locations flares, prominences cavities

How essential are current sheets? 9-Apr-2008 has well observed current sheet?

How do we define an ICME now that we can image ICMEs what do we see in HI and how does this compare to in-situ?

How essential are prominences & eruption - joint with WG J

Campaign Focus events WHI 20 march -16 april 2008 9 apr 2008 event

Events Obs Science

2006 dec 13-15 2 X-ray flare near sun center ICME flux rope, SEP at earth, STEREO space weather event.

2007 Jan 24-25 2 CMEs east limb. SECCHI, SOHO, SMEI papers: Harrison et al, Lugaz et al, Webb et al

2007 May 19-22 2 events near sun center, HINODE & STEREO 3D view of filament lift off

2007 May 23 AR on west, wave, prom eruption, CME HINODE & STEREO

2007 Nov 14-18 3 events, 1 at sun center

2007 Dec 31 east limb

2008 March 25 east limb, during WHI

2008 April 9 west limb, XRT, EIS, SECCHI, UVCS interaction with CH

2008 April 26 near sun center, fast cme & euv wave

2008 May 17 sun - STEREO interaction

2008 Jun 6 magnetic cloud at STEREO B

2008 Feb 4-8 2008 June 2-6 wood et al. 2008 robbrecht et al. 2008

WHAT ARE THE ISSUES? connection with flares - few large (>M) flares since STEREO launched.

LI - May 19, 2007 CME & B field of AR 10956

B9 flare, 960Km/s sun center AR pre eruption sigmoid structure in XRT B field topology - Li et al, ApJL 2008 classic breakout model configuration?

total B flux in region decreased 17% 48 hours before flare, so weakening of overlying field?

pre flare brigthening - tether cutting?

STERLING - May 20, 2007

B7 flare, well observed with TRACE, STEREO pre flare surges. reduction in B field

Angelos- constant flux cancellation, so what can we say quantitatively?

EIS box also rastered over this region.

-persistent red shifted flow and non thermal broadenings

-strongest shifts are 20Km/s

-typical densities of fewX 10^9 cm^-3


Angelos - anything new?

Sterling - can we predict eruption?

Cartoon picture explanation. again person A see different conclusion from same data than person B.

June 2


LIEWER - Stereoscopy

standard model - energy in sheared field marked by filament get confined eruption (surges) and ejective eruption

stereoscopy - -tie point depends on seeing the same feature correctly - constrain it to a 1D problem using the epipolar lines

compare to li et al (2008)

reconstruct the filament and show that H-T shows that ejection follows reconnection consistent with standard model velocity around 100km/s (much slower than CMEs) - kilpua et al. SP 2008)

again different people see different things in the same data- can we get a quantitative test?

compare h-alpha to euv images to discover when filament moves up / moves out of bandpass.

august 31, 2008 promininence eruption on SW and nice CME 3-part structure good for 3D tracking

SU - Filament Channels

sheared loops with filament channels not all filament eruptions are associated with post-event arcades.

emission on two sides is asymmetric

fc are dark channels. sheared loops in xray, not in euv normally no overlying loops observed both emission and 3d B configuration is asymmetric

Sterling - sigmoids not in EUV, so the sheared loops are hotter.

Comment: What about april 25, 2007 -good cavity above the prominence. dark cavity - flux rope, low cavity, also density at tops is low because they are so high (several scale heights)

YURCHYSHYN - Halo-CME orientation vs. underlying flux rope orientation

cme elongation and flux rope orientation select 100 events many halo cmes can be approx by ellipse (zhao et al 2002, xie et al 2004 events from tripathi et al. 2004

manual fitting of ellipse and fitting parameters. measure orientation fo arcade from TRACe and MDI

plot orientation of CME against orientation of arcade shows nice correlation.

also shows that cme orientation changes with time - gradual rotation. CMES tend to rotate towards equator. agrees with negative helicity in N, filaments rotate CCW

angelos - dependent on the person fitting the eclipse and calibration level of images. need automated fitting processes.

WHAT WILL WE LEARN - need automated processing on well calibrated images.

what is full connection of orientation of flux rope / NL and Magnetic cloud ?

NEW CYCLE APPROACHES -fully automated approaches -full appreciate the cailbration

individual events good for getting at the physics, but we end up ignoring the 'boring' events


WANG - An Analytical Model Probing the Internal State of CMEs

internal properties of model -polytrpic index -lorentz force how do the forces change as CMEs propagate?

how well do we know the internal state?

analytical model - axisymmetric cyclinder, self similar evolving, axial length proporitonal to distance from Sun

apply model over large radial distance.

results (1) polytropic index decrease 1.35 to 1.0 (decreases quickly at the beginning) (2) Lorentz force to thermal pressure ratio decreases from 1.0 to less than 0.1 at 70R_s (3) loretnx force is inward, thermal pressure is outward.

Future: study axial CMEs and fully developed CMEs Address heating or thermal energy transfer, expansion of flux ropes, in-situ and infer some physical mechanism regarding initiation.

Angelos: thermal component agrees with in-situ


HUNT thermosphere studies

data from 2002-> cooling by NO delays from KP index curve to NO cooling curve normally 2 days to cme

This is the CME hitting the earth.

also CO2 data avaliable.

alphonse: terrestrial consequences? angelos: primary driver is the EUV. russ: we are seeing CIR coming around, and not detected here.


Vourlidas Questions


20070831- filament lift off kinked feature in B, not A

so are all events kinked?

why are there 2 types of flares? eruptive / confined gradual / impulsive? available B energy? measure Free B energy? access to open field lines?

do flare accelerated particles have access to CME? how do they escape? how many are there?

what is CME -flare lightcurve connection? When does fluxrope form? is there a single initiation mechanism?

wish list? cme-flare connection? behind the cme / above the flare? hrx and radio wish? eclipse like (white light) imaging of corona (0.03 - 3Rsun)

reliable estimate of B non-potent improved extrapolation wish? B field obs above canopy into TR

high cadence EUV obs during early phase at low heights

improved energy measurements better flare energy estimates? CME composition in early phase.

questions? does fluxrope preexist? what can we learn from acc profile? what is role of B_bkg in flares / cmes? are there flares without cmes? what is role of non-B forces in eruption? do we understand 3d reconnection? energy release and partition? reliabily of B field, helicity? role of multipolar system in flares/ cmes? how reliable are goes / sxr curves? what is the role of flares/cme in dynamo-driven evolution of the corona?

define a flare and a cme? all one process - either liberate energy in photons, or mass, or both?

june 2nd event (COR2). seemingly no flare / dimming / filament.

Wills-Davey Notes


Session 1: 14:30 - 16:00 - Intro Talks

Alphonse Sterling: Introduction to Group F Agenda

Alphonse Sterling: The earliest phases of solar eruptions

Gemma Attrill: Coronal ’waves’ and dimmings - what can they tell us about their CME counterparts?

Session 2: 16:30 - 18:00 - Intro talks (continued)

James McAteer: Kinematics of Coronal Mass Ejections: Theory and Observations

Kimberley Steed: Solar source of a magnetic cloud; overview of 13 April 2006 event

Russ Howard: A skeptic’s view of CME-Flare relationship


Session 3: 09:00 - 10:30 – Intro talks (continued), Events Talks

Virendra Verma: On the New Classifications of Solar Coronal Mass Ejections Based on LASCO/SOHO Observations (10 min)

Dave Webb: Possible Events

Yan Li: Overview of 19 May 2007 event

Alphonse Sterling: Overview of 20 May 2007 event

Session 4: 11:00 - 12:30 – Joint with E (Flares)

NOTE: Group E didn’t know we were coming. Not much CME discussion.

Eduard Kontar: X-ray Measurements of Magnetic Field and Density Structure in the Chromoshere

S. Masuda: GEMSIS-Sun: Modeling particle acceleration and transport in solar flares

Pascal Saint-Hilare: X-ray emission from a current sheet in the wake of a CME & Long data accumulations with RHESSI

Lindsay Glesener, Sam Krucker: Coronal HXR sources


Session 5: 09:00 - 10:30 – Joint with J (Filaments)

Paulett Liewer (from J group): Stereoscopic Analysis of Filament Eruptions: Events of 19 May 2007 and 31 August 2007

Yingna Su: Observations of filament channels by Hinode/XRT and STEREO/EUVI

Vasyl Yurchyshyn: CME elongation s and orientations of post-eruption arcades

Discussions: Outstanding questions

Session 6: 11:00 - 12:30 – Talks and Discussion

Yuming Wang: An Analytical Model Probing the Internal State of a Flux Rope and its Application to CMEs

Linda Hunt: Discussion of thermospheric observations

Alphonse Sterling: More on Filaments

Gemma Attrill: Discussion of 23 May 2007 Event

Session 7: 2:30 – 4:00 – Event Talk and Discussion

Angelos Vourlidas: Overview of 02 January 2008 event, 31 August 2007event, 2 June 2008 event

Nariaki Nitta: Discussion of 2 June 2008 event


Linda Hunt: More molecular measurements

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