Angelos CME Energetics
CME Energetics: The Halloween 2003 Events: CME Energetics: The Halloween 2003 Events Angelos Vourlidas NRL CME Energetics – At what phase?: CME Energetics – At what phase? Mass Calculations: Mass Calculations Assumptions: Emission is due to Thomson scattering of photospheric light from coronal electrons. All mass is on the sky plane. Plasma composition is 10% He, 90% H. Limitations: Emission is optically thin. The 3D distribution of the background/ CME electrons is unknown. The temperature of the ejected material is unknown (coronal). Mass Calculations: Method: A coronagraph records the total brightness along the line of sight. We can only measure excess brightness (ICME - IPREEVENT). Error Sources: exposure time (at 10-4 level) solar rotation (not important for fast events) cosmic rays (a few pixels usually, should cancel out) stars (cancel out) 3D structure (more on that later) photometry (rel ~0.1%, abs 2-3%) composition ( ~15% ) Mass Calculations How Good Are CME Mass Estimates?: How Good Are CME Mass Estimates? Mass could be ~2 times larger. Mass much larger if CME is wide and central angle deviates from sky-plane No Halos Mass Energy Calculations : Mass Energy Calculations After measuring the CME mass, M, we can calculate the following types of energy: KINETIC Ek = ½ MV2, where V is the front speed (upper limit) or V is the center-of-mass speed. POTENTIAL Oct-Nov 2003 Events: Oct-Nov 2003 Events 65 events were analyzed (based on Yashiro’s list) Many particle events “Corrupted” Time Intervals (for C3) 10/26 18:18 – 10/27 09:18 (15 hrs) 10/28 12:18 – 10/31 07:12 (67 hrs) 11/02 18:18 – 11/03 23:18 (29 hrs) Many Wide CMEs Events > 150º not reliable Focus on CMEs with X-class flares < 150 º , close to sky-plane, no/few cosmic rays Found 6 Good Events 4 assoc. w/ AR 486 2 assoc. w/ AR 488 Selected Events: Selected Events Courtesy of P. Gallagher (http://beauty.nascom.nasa.gov/~ptg/oct-nov-2003-xflares.html) W70 < Lon < W90 E08 < Lon < W70 E90 < Lon < E08 1085 1406 1136 827 1420 2657 CME Images (1): CME Images (1) 031103 4:42 UT 031103 12:42 UT CME Images (2): CME Images (2) 031022 23:42 UT 031023 11:18 UT CME Images (3): CME Images (3) 031024 00:18 UT 031104 20:42 UT Energy Evolution: Energy Evolution How Unusual Are These Events?: How Unusual Are These Events? Comparison to full CME Sample Masses at the 1-5 % of all events Kinetic Energy at < 1% of all events Suggestions for Further Studies: Suggestions for Further Studies All 6 events are suitable from the LASCO viewpoint My own suggestion would be: Nov, 4 (X28 flare): Very large (the largest?) and fast. The 2 narrow CMEs on Nov, 3 (AR488): Different morphology, same region. Some energetics work could be possible for some of the other halo CMEs. Backups: Backups Overview: Overview The following questions will be addressed: How can we derive information about CME mass/energetics? What assumptions enter in the calculations? Which are the data analysis steps to extract quantitative CME information from white light images? How good are the numbers? Can we estimate the errors? How? What can we do with this information? What statistics tell us? What correlations can we find? Mass/Energy Derivation Flow: Mass/Energy Derivation Flow C3_massimg.pro cme_massimg2total.pro Mass Calculation Methods: Mass Calculation Methods Several ways to obtain a “mass” for an event. The choice depends on the desired measurement: Full event Specific features (i.e., core) Flow measurements “Typical” C3 Mass Image