Hinode Observations of the Onset Stage of a Solar Filament

Hinode Observations of the Onset Stage of a Solar Filament Eruption

A. C. Sterling, R. L. Moore, and the Hinode Team

We use Hinode X-Ray Telescope (XRT) and Solar Optical Telescope (SOT) filtergraph (FG) Stokes-V

magnetogram observations, to study the early onset of a solar eruption that includes an erupting filament that we

observe in TRACE EUV images. The filament undergoes a slow rise for about 20 min prior to its fast eruption

and strong soft X-ray flaring, and the new Hinode data elucidate the physical processes occurring during the

slow-rise period. Magnetic flux cancelation occurs along the neutral line of the filament, beginning several

hours before eruption. During the slow-rise phase, a soft X-ray (SXR) sigmoid forms from apparent

reconnection low in the sheared core field traced by the filament, and there is a low-level intensity peak in bothEUV and SXRs at the start of the slow rise.

https://ntrs.nasa.gov/search.jsp?R=20070038370 2018-03-06T23:55:17+00:00Z

Hinode Observations of the OnsetStage of a Solar Filament Eruption

'-

Alphonse C. Sterling! and Ronald L. MooreNASAlMSFC

and the Hinode Team

1 Currently at JAXAJISAS, Sagamihara, Japan

Sterling, Dublin 2007

Introduction• Trying to understand solar eruptions.• Using filaments as tracers of the erupting field.• Detailed examination of several individual

events.• Today we present our first Hinode-observed

filament eruption, from 2007 March 2.• First question addressed: What leads to pre

eruption slow rise of filaments?


Filament pre-eruption, pre-flare slow-rise phase

00:00 03:00 05:00 09:00 12:00nme 1999 April 17 - 18 (UT)

Sterling, Moore, Thompson (2001)

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Hinode Event: Data Sets

• On-disk filament eruption of 2 March 2007.GOES class B 2.5.

• Seen with TRACE, STEREO, Hinode.• Use TRACE for filament• Hinode:

- SOT (FG V magnetogram), etc.- SXRs from XRT

• Also use MDI magnetogram


Image Alignment

• TRACE on MDI: both alignments known.

• Match SOT and MDI magnetograms =>SOT on MDI, TRACE.

• XRT onto SOT: Internal Hinode studies (H.Hara, N. Narukage; privatecommunication), plus "by eye." => XRT·'onto MDI, TRACE.


STEREO 171


TRACE 171


TRACEonMDI


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(This is SOT, but use MDI to get flux.)

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Magnetic Flux in box e<1019 Mx)

3.4

3.0

1.0"

19:00 00:00 05:00UT Time on 1-2 Mar 2007

(Cf. flux of whole region: -- 1021 Mx)Sterling, Dublin 2007


DiscussionThis initial observation from Hinode of a filamenteruption supports the idea that flux changes in ornear the eruption site are responsible for preexplosive phase (e.g., slow-rise phase) dynamics.

Flux changes =flux emergence and/or flux cancelation(also: tether weakening, slow tether cutting).

(E.g., van Ballegooijen & Martens 1989, Moore& Roumeliotis 1992, Rust & Kumar 1996, Lin & Forbes '2000, Feynman &Ruzmaikin 2004, Sterling, Rarra & Moore2007.) (Also Mikic et ale 2007, this meeting.)


Conclusions• Hinode, STEREO, TRACE observations of 2007

March 2 filament eruption and flare.• Results still preliminary, but support that pre-eruption

(pre-flare) filament slow-rise phase is due to earlyflux changes (in this case: cancelation; slowly driventether-cutting reconnection).

• During pre-eruption period, ~ep ,..., 1019 Mx

= ,-.; 1% of flux of total erupting system.

• No comment (yet!) on what triggers the fast-risephase.

'-



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Observed Characteristics• Sample size. So far, we have examined about 10 (including 2

AR) events "in detail" (e.g., motions and intensity changes);mapped trajectories of about 25 additional events.

• Trajectory. Filament eruptions often undergo two stages:slow and fast (e.g., Tandberg-Hanssen et al. 1980, Bong et al.2006; cf. Ohyama & Shibata 1997). ~

• Slow-rise linearity. In several events, slow rise is fit betterwith line than with a polynomial or exponential. (Slow-rise isfrequently complex, however; Akiyama & Sterling.)

• Flaring at start of fast eruption. Onset of SXR and HXRflaring coincides "closely" with start of fast eruption.

• Breakout signatures. Occur close to time of start of fasteruption. (Moore & Sterling 2006; Bong et al. 2006)


'-

Observed Characteristics - Cont.• Dimmings. (Discussed by many workers; hard to generalize,

e.g., Howard & Harrison 2004.)

- Local dimmings. Intensity dimmings next to and along neutralline begin weakly during slow-rise phase (stretching of fieldlines), and become strong dimmings at start of fast-rise phase.

- Remote dimmings (and brightenings). In some cases,dimmings and brightenings occur at locations far removed frommain neutral line, consistent with breakout-type reconnection.

• Magnetic cavities. These show that filaments belong to amore extended magnetic environment; interaction' withoverlying fields can lead to remotebrightenings/dimmings. (Cf. Gibson et ale 2006.)


Some Theories for Eruption Onset:

• Tether cutting.

• Breakout model.

• MHD Instability.

(Generally, this applies to "fast eruption" onset,although slow rise might be part of the process.)

These theories are testable (at least to within somelimits) by our observations.


Some Theories for Eruption Onset:• Tether cutting. Moore & Labonte (1980); Sturrock (1989); Moore

et al. (1997; 2001). (Also Chen & Shibata 2000 and Lin et al.2001.)

~ Fundamentally bipolar.

~ Energy release via reconnection deep inside the "core field."

• Breakout model. Antiochos (1998); Antiochos et al. (1999).

~ Fundamentally multi-polar, with bipole core fields and restr~ining

overlying fields.

~ Earliest energy release via slow reconnection at interface.

• MHD Instability. Sturrock et al (2001); Rust & LaBonte (2005)

~ Rapid rise prior to reconnection onset.


(Moore et al. 2001)

Before Onset

Confined Eruption, End.ing

EruptiDn Onsel

Ejeclive Eruption, Midlife

Sterling, Dublin 20 ........._-- ~ ---'

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Moore & Sterling 2006

What Causes the Slow Rise?

All our events have a slow-rise phase(although characteristics differ). What's thecause?

Consider quiet-region filament eruption of 28Feb 2001 (Sterling, Rarra, & Moore 2007)




300 ... 400200100o

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Cf. Feynman & Ruzmaikin (2004)(also, e.g., Rust 1976, Heyvaerts etal. 1977, and many others).


Slow-rise phase: Tether-Weakening Reconnection?

"

Sterling, Rarra, Moore (2007)

Sterling, Dublin 2007'.

Some Theories for Eruption Onset:• Tether cutting. Moore & Labonte (1980); Sturrock (1989);

Moore et ale (1997; 2001). (Also Chen 0& Shibata 2000 and Linet ale 2001.)

~ Fundamentally bipolar.~ Energy release via reconnection deep inside the "core field."

• Breakout model. Antiochos (1998); Antiochos et al. (1999).~ Fundamentally multi-polar, with bipole core fields and restraining

overlying fields.~ Earliest energy release via slow reconnection at interface. "

• MHD Instability. Sturrock et al (2001); Rust & LaBonte (2005)~ Rapid rise prior to reconnection onset.


Some Theories for Eruption Onset:• Tether cutting. Moore &·Labonte (1980); Sturrock (1989); Moore

et al. (1997; 2001). (Also Chen & Shibata 2000 and Lin et al.2001.)

~ Fundamentally bipolar.'.

~ Energy release via reconnection deep inside the "core field."

• Breakout model. Antiochos (1998); Antiochos et al. (1999).~ Fundamentally multi-polar, with bipole core fields and

restraining overlying fields.~ Earliest energy release via slow reconnection at interface.

• MHD Instability. Sturrock et al (2001); Rust & LaBonte (2005)~ Rapid rise prior to reconnection onset. ~


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SOTFG/V2-Mar-2007 05:54

2-Mar-2007 03: 15

I-Mar-200722:56

2-Mar-2007 04:54

'-

'-

Cancelation Energetics• Field strength, B ,...; 40 G in enhanced network in box.

• V==2"x26"x2"

• f =0.1• Magnetic energy =. (B 2 /81Z")Vf ~ 4x1027 ergs

during six hours or less prior to the eruption. <.

It's no surprise that this is not enough energy to power

the eruption, but it could be enough cancelation

for instability to kick in, or for runaway to take over

(e.g., van Ballegooijen & Martens, Moore

& Roumeliotis, Rust & Kumar, Lin & Forbes).


Documents

Hinode Observations of the Onset Stage of a Solar Filament