Phillip Chamberlin Solar Flares (303)492-9318 University of Colorado Laboratory for Atmospheric and Space Physics (LASP) Phil.Chamberlin@lasp.colorado.edu (303)492-9318

Chamberlin - Solar Flares - REU 2009 Outline Solar Atmosphere Flux Tubes Two Ribbon Flare Cartoons Movies Irradiance Measurements of Flares VUV White Light TSI June 10, 2009 Chamberlin - Solar Flares - REU 2009

XUV, EUV, and FUV Solar Spectrum Transition Region From Lean (1997) 5700 K : Temp of “Solar Surface” T_min: 4200 K - Optically thin to most emissions June 10, 2009 Chamberlin - Solar Flares - REU 2009

Chamberlin - Solar Flares - REU 2009 Solar Images - Oct. 28, 2003 Chromosphere H-Alpha Corona Photosphere Transition Region (Images courtesy of Big Bear Solar Observatory and SOHO EIT) June 10, 2009 Chamberlin - Solar Flares - REU 2009

Chamberlin - Solar Flares - REU 2009 Flux Tubes (Schrijver and Zwaan, 2000) June 10, 2009 Chamberlin - Solar Flares - REU 2009

Chamberlin - Solar Flares - REU 2009 Flux Tubes Initial rotating convection zone with weak vertical B-field lines B-field lines concentrated in strands between convection cells to form Flux Tubes Absence of B-field within convection cells due to B-field line reconnection (Schrijver and Zwaan, 2000) June 10, 2009 Chamberlin - Solar Flares - REU 2009

Chamberlin - Solar Flares - REU 2009 Emerging Flux Solar Atmosphere 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 Convection Zone (Schrijver and Zwaan, 2000) June 10, 2009 Chamberlin - Solar Flares - REU 2009

Chamberlin - Solar Flares - REU 2009 Emerging Flux (Title, 2004) June 10, 2009 Chamberlin - Solar Flares - REU 2009

Chamberlin - Solar Flares - REU 2009 June 10, 2009 Chamberlin - Solar Flares - REU 2009

Chamberlin - Solar Flares - REU 2009 Phases of Solar Flares (Adapted from Schrijver and Zwaan, 2000) Microwave Radio (~3000 MHz) Radio (100-500 MHz) H-alpha (656.2 nm) Broadband EUV (1 - 103 nm) Soft X-rays (< 10 keV) X-rays (10-30 keV) Main Phase Hard X-rays (> 30 keV) Impulsive Phase Note: Soft X-rays: 0.1-10 nm, Hard X-rays: 0.001-0.1 nm Precursor June 10, 2009 Chamberlin - Solar Flares - REU 2009

Two-Ribbon Reconnection Thick-target model produces Bremsstrahlung radiation in the transition region and chromosphere due to their much higher densities - Impulsive Phase! Reconnection after instability accelerates material down loop. Observed Hard X-ray (and EUV?) enhancements at loop top. [Ashwanden, 2004] No enhanced emissions during the impulsive phase in the corona due to its low density. Energy deposited during the impulsive phase heats the plasma up and rises (chromospheric evaporation) to fill flux tube - Gradual Phase! June 10, 2009 Chamberlin - Solar Flares - REU 2009

Jets Evidence of Small-Scale Reconnection? June 10, 2009 Chamberlin - Solar Flares - REU 2009

Chamberlin - Solar Flares - REU 2009 Two-Ribbon Flare Eruption when some critical limit is reached Triggered by Emerging Flux? Continued thermal heating and formation of post-flare loops “Stretching” of field lines (Priest, 1981) June 10, 2009 Chamberlin - Solar Flares - REU 2009

Chamberlin - Solar Flares - REU 2009 Phases of Solar Flares (Adapted from Schrijver and Zwaan, 2000) Microwave Radio (~3000 MHz) Radio (100-500 MHz) H-alpha (656.2 nm) Broadband EUV (1 - 103 nm) Soft X-rays (< 10 keV) X-rays (10-30 keV) Main Phase Hard X-rays (> 30 keV) Impulsive Phase Note: Soft X-rays: 0.1-10 nm, Hard X-rays: 0.001-0.1 nm Precursor June 10, 2009 Chamberlin - Solar Flares - REU 2009

Chamberlin - Solar Flares - REU 2009 Two-Ribbon Flare Impulsive Phases for Each Loop Post-Flare Loops (Somov, 1992) June 10, 2009 Chamberlin - Solar Flares - REU 2009

Flares drive waves in the photosphere June 10, 2009 Chamberlin - Solar Flares - REU 2009

Chamberlin - Solar Flares - REU 2009 X28 Flare, Nov 4, 2003 June 10, 2009 Chamberlin - Solar Flares - REU 2009

Hinode SOT Observes Flare June 10, 2009 Chamberlin - Solar Flares - REU 2009

SOHO (UV) and SORCE XPS (XUV) Observations June 10, 2009 Chamberlin - Solar Flares - REU 2009

Chamberlin - Solar Flares - REU 2009 Phases of Solar Flares (Adapted from Schrijver and Zwaan, 2000) Microwave Radio (~3000 MHz) Radio (100-500 MHz) H-alpha (656.2 nm) Broadband EUV (1 - 103 nm) Soft X-rays (< 10 keV) X-rays (10-30 keV) Main Phase Hard X-rays (> 30 keV) Impulsive Phase Note: Soft X-rays: 0.1-10 nm, Hard X-rays: 0.001-0.1 nm Precursor June 10, 2009 Chamberlin - Solar Flares - REU 2009

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 10, 2009 Chamberlin - Solar Flares - REU 2009

Flare/Pre-Flare Irradiance Ratio Transition region emissions increased by up to a factor of 10 during the impulsive phase EUV irradiance increased by a factor of 2 during the gradual phase Flare Variations were as large or larger than the solar cycle variations for the Oct 28, 2003 flare June 10, 2009 Chamberlin - Solar Flares - REU 2009

Chamberlin - Solar Flares - REU 2009 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 10, 2009 Chamberlin - Solar Flares - REU 2009

Chamberlin - Solar Flares - REU 2009 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 in the past 200 years Two-Ribbon flare June 10, 2009 Chamberlin - Solar Flares - REU 2009

Flares in Photosphere and Chromosphere Hinode SOT Observations June 10, 2009 Chamberlin - Solar Flares - REU 2009

Chamberlin - Solar Flares - REU 2009 X17 flare observed in TSI First detection of flare in TSI record (G. Kopp, 2003) Figures from G. Kopp, arranged by T. Woods June 10, 2009 Chamberlin - Solar Flares - REU 2009

Chamberlin - Solar Flares - REU 2009 Conclusions Multiple images and spectral measurements are key to understanding energetic of flares New measurements (Hinode, Stereo, 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 10, 2009 Chamberlin - Solar Flares - REU 2009

Chamberlin - Solar Flares - REU 2009 Extra Slides June 10, 2009 Chamberlin - Solar Flares - REU 2009

Chamberlin - Solar Flares - REU 2009 Simple Loop Flare Existing Flux Loop that Brightens TRANSITION REGION CORONA CHROMOSPHERE PHOTOSPHERE -Most Common Type -Are these an actual separate type of flare? -Only Enhanced Internal Motions (Priest, 1981) June 10, 2009 Chamberlin - Solar Flares - REU 2009

Chamberlin - Solar Flares - REU 2009 Hinode SOT Movie #2 June 10, 2009 Chamberlin - Solar Flares - REU 2009

Flares Cause Sudden Atmospheric Changes GRACE daytime density (490 km) 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 Latitude (Deg) 2003 Day of Year (E. Sutton, 2005) Sudden increase in the dayside density at low latitude regions due to the X17 solar flare on October 28, 2003 June 10, 2009 Chamberlin - Solar Flares - REU 2009