Phillip Chamberlin University of Colorado Laboratory for Atmospheric and Space Physics (LASP) (303)

June 12, 2007Chamberlin - Solar Flares - REU Outline -Solar Atmosphere -Flux Tubes -Two Ribbon Flare -Cartoons -Movies -Irradiance Measurements of Flares -VUV -White Light -TSI

June 12, 2007Chamberlin - Solar Flares - REU XUV, EUV, and FUV Solar Spectrum Transition Region From Lean (1997)

June 12, 2007Chamberlin - Solar Flares - REU Solar Images - Oct. 28, 2003 Photosphere Transition Region Chromosphere H-Alpha Corona (Images courtesy of Big Bear Solar Observatory and SOHO EIT)

June 12, 2007Chamberlin - Solar Flares - REU Flux Tubes (Schrijver and Zwaan, 2000)

June 12, 2007Chamberlin - Solar Flares - REU Flux Tubes (Schrijver and Zwaan, 2000) 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, 2007Chamberlin - Solar Flares - REU Emerging Flux Solar Atmosphere Convection Zone Active Regions (Schrijver and Zwaan, 2000) 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, 2007Chamberlin - Solar Flares - REU Emerging Flux (Title, 2004)

June 12, 2007Chamberlin - Solar Flares - REU Phases of Solar Flares Radio ( MHz) Microwave Radio (~3000 MHz) H-alpha (656.2 nm) Broadband EUV ( 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: nm, Hard X-rays: nm

June 12, 2007Chamberlin - Solar Flares - REU 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, 2007Chamberlin - Solar Flares - REU 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, 2007Chamberlin - Solar Flares - REU Two-Ribbon Flare Post-Flare Loops Impulsive Phases for Each Loop (Somov, 1992)

June 12, 2007Chamberlin - Solar Flares - REU X28 Flare, Nov 4, 2003

June 12, 2007Chamberlin - Solar Flares - REU Hinode SOT Observes Flare

June 12, 2007Chamberlin - Solar Flares - REU SOHO (UV) and SORCE XPS (XUV) Observations

June 12, 2007Chamberlin - Solar Flares - REU Phases of Solar Flares Radio ( MHz) Microwave Radio (~3000 MHz) H-alpha (656.2 nm) Broadband EUV ( 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: nm, Hard X-rays: nm

June 12, 2007Chamberlin - Solar Flares - REU 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, 2007Chamberlin - Solar Flares - REU 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, 2007Chamberlin - Solar Flares - REU 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, 2007Chamberlin - Solar Flares - REU White Light vs UV (170 nm) Flare White Light170 nmTRACE From Hudson et al., AGU/SPD 2005:

June 12, 2007Chamberlin - Solar Flares - REU X17 flare observed in TSI First detection of flare in TSI record (G. Kopp, 2003) Figures from G. Kopp, arranged by T. Woods

June 12, 2007Chamberlin - Solar Flares - REU 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, 2007Chamberlin - Solar Flares - REU Extra Slides

June 12, 2007Chamberlin - Solar Flares - REU Simple Loop Flare Existing 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, 2007Chamberlin - Solar Flares - REU Flares drive waves in the photosphere

June 12, 2007Chamberlin - Solar Flares - REU Hinode SOT Movie #2

June 12, 2007Chamberlin - Solar Flares - REU VUV Irradiance Increases Dominate Flare Variations VUV irradiance ( nm) accounts for only 0.007% of quite Sun Total Solar Irradiance (TSI) VUV irradiance accounts for % of the increase in the TSI during a flare [Woods et al., 2006]

June 12, 2007Chamberlin - Solar Flares - REU 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