phillip chamberlin university of colorado laboratory for atmospheric and space physics (lasp)...

Phillip ChamberlinUniversity of

ColoradoLaboratory for Atmospheric and Space Physics

(LASP)[email protected]

(303)492-9318

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mailto:[email protected]

mailto:[email protected]

June 12, 2007

Chamberlin - Solar Flares - REU 2007

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Outline- Solar Atmosphere- Flux Tubes- Two Ribbon Flare

- Cartoons- Movies

- Irradiance Measurements of Flares- VUV- White Light- TSI

June 12, 2007


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XUV, EUV, and FUV Solar Spectrum

Transition Region

From Lean (1997)

June 12, 2007


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Solar Images - Oct. 28, 2003

PhotosphereTransition Region

Chromosphere

H-Alpha Coron

a

QuickTime™ and aYUV420 codec decompressorare needed to see this picture.

(Images courtesy of Big Bear Solar Observatory and SOHO EIT)

June 12, 2007


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Flux Tubes

(Schrijver and Zwaan, 2000)

June 12, 2007


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Flux Tubes


Absence of B-field within convection cells due to B-field line reconnection

B-field lines concentrated in strands between convection cells to form Flux Tubes

Initial rotating convection zone with weak vertical B-field lines

June 12, 2007


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Emerging Flux

Solar Atmosphere

Convection Zone

Active Regions


Balance between hydrostatic pressure and magnetic pressure causes the flux tubes to be less dense due to their stronger magnetic pressure buoyant flux tubes

June 12, 2007


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Emerging Flux (Title, 2004)

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June 12, 2007


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Phases of Solar Flares

Radio (100-500 MHz) Microwave Radio (~3000 MHz)

H-alpha (656.2 nm)

Broadband EUV (1 - 103 nm)

Soft X-rays (< 10 keV)X-rays (10-30 keV)

Hard X-rays (> 30 keV)

Precursor

Impulsive Phase

Main Phase

(Adapted from Schrijver and Zwaan, 2000)

Note: Soft X-rays: 0.1-10 nm,

Hard X-rays: 0.001-0.1 nm

June 12, 2007


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Two-Ribbon Flare

(Priest, 1981)

Triggered by Emerging Flux?

Eruption when some critical limit is reached

Continued thermal heating and formation of post-flare loops

“Stretching” of field lines

June 12, 2007


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Two-Ribbon Reconnection

Reconnection after instability accelerates material down loop. Observed Hard X-ray (and EUV?) enhancements at loop top.No enhanced emissions during the impulsive phase in the corona due to its low density.

[Ashwanden,2004]

Thick-target model produces Bremsstrahlung radiation in the transition region and chromosphere due to their much higher densities - Impulsive Phase!Energy deposited during the impulsive phase heats the plasma up and rises (chromospheric evaporation) to fill flux tube - Gradual Phase!

June 12, 2007


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Two-Ribbon Flare

Post-Flare Loops

Impulsive Phases for Each Loop

(Somov, 1992)

June 12, 2007


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X28 Flare, Nov 4, 2003

June 12, 2007


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Hinode SOT Observes Flare

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are needed to see this picture.

June 12, 2007


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SOHO (UV) and SORCE XPS (XUV) Observations



June 12, 2007


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Phases of Solar Flares

Radio (100-500 MHz) Microwave Radio (~3000 MHz)

H-alpha (656.2 nm)

Broadband EUV (1 - 103 nm)

Soft X-rays (< 10 keV)X-rays (10-30 keV)

Hard X-rays (> 30 keV)

Precursor

Impulsive Phase

Main Phase

(Adapted from Schrijver and Zwaan, 2000)

Note: Soft X-rays: 0.1-10 nm,

Hard X-rays: 0.001-0.1 nm

June 12, 2007


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Flare/Pre-Flare Irradiance Ratio

EUV irradiance increased by a factor of 2 during the gradual phase

Transition region emissions increased by up to a factor of 10 during the impulsive phase

Flare Variations were as large or larger than the solar cycle variations for the Oct 28, 2003 flare

June 12, 2007


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X-Ray Classification

Due to the large, order-of-magnitude increases in the soft X-rays makes for an ideal and sensitive classifications of the magnitude of flares

June 12, 2007


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White Light Flare• “Carrington Flare” September 1, 1859– Carrington (M.N.R.A.S, 20, 13, 1860)

• One of the largest flares believed to have occurred since then

• Two-Ribbon flare

June 12, 2007


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White Light vs UV (170 nm) Flare



White Light

170 nmTRACE

From Hudson et al., AGU/SPD 2005: http://sprg.ssl.berkeley.edu:80/~hhudson/presentations/spd_wl.050527/

June 12, 2007


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X17 flare observed in TSIFirst detection of flare

in TSI record (G. Kopp, 2003)

Figures from G. Kopp, arranged by T. Woods

June 12, 2007


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Conclusions

• Multiple images and spectral measurements are key to understanding energetic of flares

• New measurements (Hinode, EVE, AIA, etc.) will lead to a much greater understanding of these processes

• Biggest mystery still is the ‘trigger’

• Another topic to that is not fully understood is the relationship of CMEs and Flares

June 12, 2007


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Extra Slides

June 12, 2007


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Simple Loop FlareExisting Flux Loop that Brightens

-Most Common Type

-Are these an actual separate type of flare?

-Only Enhanced Internal Motions (Priest,

1981)

PHOTOSPHERE

CHROMOSPHERE

CORONA TRANSITION REGION

June 12, 2007


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Flares drive waves in the photosphere

QuickTime™ and aCinepak decompressor


June 12, 2007


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Hinode SOT Movie #2

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June 12, 2007


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VUV Irradiance Increases Dominate Flare Variations

• VUV irradiance (0.1-200 nm) accounts for only 0.007% of quite Sun Total Solar Irradiance (TSI)

• VUV irradiance accounts for 30-70% of the increase in the TSI during a flare [Woods et al., 2006]

June 12, 2007


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Flares Cause Sudden Atmospheric Changes

Sudden increase in the dayside density at low latitude regions due to the X17 solar flare on October 28, 2003

(E. Sutton, 2005)

• Increased neutral particle density in low latitude regions on the dayside.

• Sudden Ionospheric Disturbances (SIDs) lead to Single Frequency Deviations (SFDs).

• Cause radio communication blackouts

• Cause increased error in GPS accuracy

GRACE daytime density (490 km)

Latitude (Deg)

2003 Day of Year

phillip chamberlin university of colorado laboratory for atmospheric and space physics (lasp)...

Documents

solar images

phases of solar flares

flare slide

nm slide

flux tubes schrijver

soho eit slide

emerging flux title

flux tube gradual phase