Heliospheric Transientsand the Imprint of Their Solar Sources

Sensing change in magnetic connections Suprathermal electron tool CMEs Disconnected flux Other transient outflows

Imprint of solar magnetic field on ICMEs Review quantitative results Implications for CME models Application to May 1997 event

New constraints on May ’97 event from deduced magnetic connections

Topics

Suprathermal electronsas sensors of magnetic topology

Closed fields in ICMEs

True solar polarity Sector

boundaries Field

inversions

Disconnected fields

Range from completely open to completely closed

On average, clouds are nearly half open

Within each cloud, open fields mingle randomly with closed fields

Clouds at 5 AU are nearly as closed as those at 1 AU

Closed fieldsin magnetic clouds

Shodhan et al., 2000

Crooker et al., 2004

Conceptual Explanation Gosling, Birn, and Hesse [1995]

explain how a coherent flux rope can have open and closed fields through remote reconnection at the Sun

a. Partial disconnection(closed-closed) creates flux rope coil

b. Interchange reconnection(closed-open) opens coil

Implications for Models, Flux Budget

CME models must open fields in ICMEs initially by about 40% completely over the long term,

to balance heliospheric magnetic flux budget

otherwise closed fields would lead to a continual flux build-up, which is not observed [Gosling, 1975]

alternatively, ICMEs could remain half-closed, and flux could disconnect elsewhere

little evidence of disconnection in suprathermal electron data

interchange reconnection

disconnection

Heat-flux dropout (HFD)[McComas et al., 1989] Disconnection eliminates

strahl Problems

Lin and Kahler [1992] and Fitzenreiter and Ogilvie [1992] find higher-energy electrons still streaming from Sun in McComas HFDs

Scattering also can eliminate strahl

Can differentiate between pure scattering and disconnection by testing for drop in integrated flux

0° Pitch angle 180°

Diff

ere

ntia

l Flu

x

Search for Disconnected Flux

Search for Disconnected Flux [Pagel et al., 2004, 2005]

Heat flux is controlled independently by anisotropy A and integrated flux F

Drop in A and F required for disconnection (Case 2)

Drop in A alone signals pitch angle scattering (Case 3)

Application to 4 yrs of data 419 HFDs 240 candidates tested for

higher-energy electron streaming

Only 2 pass test Conclusions

Disconnection is rare (timescales > 30 min) HFDs are highly unreliable signatures of disconnection

1 2 3

HFD Postscript Gosling et al. [2005] identify

rare case of in situ reconnection between open field lines across HCS using standard plasma signatures

Yields 4-min interval of known disconnected fields (no impact on flux budget)

Electron distributions show expected strahl dropout and remaining halo

Confirms HFD is necessary signature of disconnection

Pagel et al. [2005] establish that it is far from sufficient

Other Transient Outflows

CMEs

smallersteadier

quietloops

plasmaparcels

Quiet Loops

Active region expanding loops [Uchida et al., 1992] Sometimes apparent on successive solar rotations

CR 1890CR 1891CR 1892

Yohkoh images provided by Nariaki Nitta

Sector Boundary with no Field Reversal

Field Reversal with no Sector Boundary

Quiet Loop Signature in Solar Wind?

Mismatches in 1995

27-day recurrence plots of magnetic longitude angle

4-sector structure True sector

boundaries marked in red

Mismatches with marked in yellow Not uncommon

(~1 out of 4) Quasi-recurrent

Loop emerges with leg polarity matching sector structure

Open field line from above or below approaches leg with opposite polarity

Interchange reconnection creates field inversion changes loop to open field

line with toward polarity Sector boundary

separates from HCS

Interchange Reconnection withQuiet Loop Gives Mismatch Signature

Relationship to CMEs

Eight inversions Scale sizes

comparable SB location

consistent A few have

ICME signatures

Most appear to be quiet loops

Dec 18, 1994 24 ?

Jan 16, 1995 16 no

Feb 8, 1995 53 yes

Feb 25, 1995 16 no

Apr 5, 1995 16 ??

Apr 21, 1995 15 ??

May 29, 1995 21 no

Jul 11, 1995 22 no

inversion SB date duration (h) ICME?

Small plasma parcel outflows Sheeley, Wang et al. [1997-2000]

document “blobs” “Time-lapse sequences…

indicate that streamers are far more dynamic than was previously thought, with material continually being ejected at their cusps and accelerating outward along their stalks.”

Difference image indicates outward movement

Synoptic maps can be built from sequential radial strips

Synoptic Height-Time Trajectories

Curved paths indicate ~four events per day

Parcel Release by Interchange Reconnection

Wang et al. [1998] propose interchange reconnection as

release mechanism parcels as transient source of

heliospheric plasma sheet Crooker et al. [2004]

document transient nature of plasma sheets

concur with Wang et al. [1998] suggest interchange

reconnection creates field inversions, consistent with local current sheets found in most plasma sheets

adapted from Wang et al. [1998],modified by Crooker et al.[2004]

Heliospheric plasma sheet What’s wrong with

this picture? Sector boundary

precedes well-defined plasma sheet

Local current sheets in high-beta region

(High beta creates HFD mistakenly interpreted as disconnection)

Observations of the full spectrum of transient outflows suggest that Interchange reconnection at the Sun is ubiquitous Magnetic fields rarely disconnect from the Sun

Observations bear upon two competing models of how the heliospheric magnetic field reverses at solar maximum Fisk model fully consistent

Interchange reconnection is means of continuous flux transport No disconnection required to reverse solar magnetic field

Wang-Sheeley model faces challenge Interchange reconnection essential at coronal hole boundaries Comparable disconnection required for field reversal

Both models highly successful in explaining other phenomena Synthesis view will require incorporation of

dynamics into potential field model of Wang-Sheeley realistic solar fields into Fisk model understanding of solar dynamo

Implications for Models of the Heliospheric Magnetic Field Reversal

Solar Magnetic Field Imprint on CMEs

ICME leg polarity and sector structure[Zhao, Crooker, Kahler]

ICME axis and neutral line/filament orientation [Marubashi, Zhao, Mulligan, Blanco]

ICME leading field and solar dipole orientation [Bothmer, Mulligan, Martin, McAllister]

ICME handedness and source hemisphere [Martin, Bothmer, Rust, McAllister]

Leg polarity obtained from

suprathermal electron signature [Kahler et al., 1999]

10 times more likely to match sector polarity than not

Implies flux rope feet lie on opposite sides of neutral line

Reflects strong imprint of solar dipolar field component

ICMEs blend into sector structure

TruePolarity

toward

away

Counterstreaming electronsSource-surface toward sectorsField inversions

27-day plotsISEE 3 data

Solar imprint on magnetic clouds Cloud axis

Aligns with filament axis (low) and HCS (high)

Directed along dipolar field distorted by differential rotation

Leading field Aligns with skewed

arcade (low) and coronal dipolar field (high)

Handedness LH in NH, RH in SH Independent of

solar cycle

Cloud Axis vs. Filament Axis Tilts 14 cases from Zhao

and Hoeksema [1997] Drawn from

Marubashi [1997], Rust [1994], and hemispheric rule of Martin et al. [1994]

Linear correlation of 0.76

Additional dependencies of duration and intensity of Bz on cloud axis tilt yields Bz prediction from filament tilt

Axis alignment with HCS predicts bipolar (SN or NS) near minimum

unipolar (N or S) near maximum

Mulligan et al. [1998] analyze 63 clouds from PVO find suggestion of pattern with

~3-year lag

Cloud Axis vs. Neutral Line Tilts:Indirect Test

On case-by-case basis, Blanco et al. [unpublished] compared axis tilts of 50 clouds modeled by Lepping to neutral line tilts on source-surface maps at corresponding predicted sector boundary crossings

Linear correlation of 0.57

74% (56%) differ by less than 45° (30°)

Blanco, Rodriguez-Pacheco, and Crooker [2005]

Cloud Axis vs. Neutral Line Tilts:Direct Test

Leading Field from Bothmer and

Rust [1997] SN (south leading)

dominates from ~cycle 20 max to 21 max

NS (north leading) dominates from ~cycle 21 max to 22 max

phase changes after rather than at solar max

Sunspot #

phase shift

from Mulligan et al. [1998] Unipolar dominates bipolar

near solar max Shift from SN to NS confirmed Phase shift confirmed

Possible cause of phase shift After solar maximum, leading fields in low

latitude arcades retain pre-maximum polarity Shift from SN to NS (or vice versa) may be

delayed until polar fields dominate

Kitt Peak Magnetogram

Post-max CME source with pre-max polarity(12 Sep 2000)

Results of Imprint Tests on Clouds Cloud axis orientation, Fair

28/50 (56%) align within 30° of neutral line [Blanco et al., 2005] Handedness, Good (away from active regions)

65/73 (89%) quiescent filaments match hemispheric pattern [Martin et al., 1994]

No pattern in 31 active-region filaments [cf. Leamon et al., 2004]

24/27 (89%) clouds match associated filament [Bothmer and Rust, 1997]

Leading field, Good 33/41 (80%) match solar dipolar component with 2-3 year lag

[Bothmer and Rust, 1997] 28/38 (74%) from PVO match [Mulligan et al., 1998]

Leg polarity, Very Good 1/10 (90%) match solar dipolar component [Kahler et al., 1999]

Mo

de

l im

plic

atio

ns

Implications for CME Models

Taken at face value, imprint of dipolar component on leading field and leg polarity favors streamer over breakout model by ~80%.

STREAMER MODEL Dipolar fields reconnect Leading field matches

dipolar component

BREAKOUT MODEL Quadrupolar fields reconnect Leading field opposes dipolar

component

Test Case: May 1997 Compare imprint predic-

tions with parameters from Webb et al. [2000]

Cloud axis tilt ~matches neutral line tilt orthogonal to filament tilt

Left-handed matches NH source

Leading field southward, matches solar dipolar component

Leg polarity (away) opposite to sector polarity

+

-

satellite trajectory

map mismatch intervals

magnetic cloud interval

Sector Structure ContextElectron pitch angle spectrogram comparison with PFSS prediction

toward fields

away fields

TOWARD

AWAY

Quadrupolar field [courtesy Z. Mikic]

Double dimming implies both feet

above global NL consistent with

island in field map leg polarity local eruption from

quadrupolar structure

Axis rotation to NL creates parallel

fields overhead precludes breakout

model?

Implications for Models

Additional Clues

No counterstreaming implies cloud is open Away polarity of open fields implies interchange

reconnection in negative leg

cloud

Webb et al. [2000]

Interchange reconnection in negative island

Need open positive field lines.Where are they?

Interchange reconnection with polar fields high in corona opens negative CME leg

Freeing connection may facilitate axis rotation

Similar to solar cyclemagnetic field evolution in Wang and Sheeley [2003]

Evidence in X ray images leg opens

Interchange reconnection in asymmetric “breakout” model

1997 Yohkoh SXT images from ~ 25-hour interval (12 May 0114 – 13 May 0241)

Conclusions Knowledge of the true polarity of open field lines in ICMEs

can provide important constraints on CME reconnection configurations.

The solar imprint on magnetic clouds is significant and suggests that incorporation into empirical space weather models would improve predictions.

Taken at face value, the solar imprint implies that 80% of ICMEs cannot arise from the breakout model configuration.

On the other hand, the May 1997 ICME carried the imprint of the solar dipole yet seems to have arisen from an asymmetric “breakout” configuration.

Observations of transient structures in the heliosphere supports ubiquitous interchange reconnection and rare disconnection.

Filament-arcade relationship Reflects cross-scale

pattern Connects predictions

from filament properties to predictions from HCS properties

S. Martin

Closed loops at sector boundaries Small, closed(?) flux rope

(3.5 hrs, 2 x 106 km) No depression in T

[cf. Moldwin et al., 1995, 2000]

Rise in O7+/O6+

Model fit to Wind data matches ACE data

ACE data, 00 – 12 UT, 27 Feb 1998modeled by Qiang Hu