Photospheric Sources of Very Fast (>1100km/s) Coronal Mass Ejections

1. ARs 39 Filaments 6 No Source 70 Total 115 CMEs Photospheric Sources of Very Fast (>1100km/s) Coronal Mass Ejections Vasyl Yurchyshyn Seiji Yashiro Nat Gopalswamy Big Bear Solar Observatory Catholic University of America NASA/GSFC Recent studies show that only very fast CMEs (> 1100 km/s) are capable of producing strong geomagnetic storms (Dst < -150nT). BIG QUESTION: Where these very fast CMEs come from? We analyzed photospheric sources of 45 very fast CMEs and distinguished four different types of specific magnetic configurations associated with them: i) delta-configurations (47%), ii) magnetic complexes (22%), iii) “tadpole” - shaped sunspots (18%) and iv) quiescent filaments located near active regions (13%). Here we briefly discuss the first three types of magnetic configurations. CME projection speed is related to the intensity of Bz in interplanetary ejecta: 1. Complex Delta Spots (11 - X, 8 - M & 2 – C flare) • Typical features: • two opposite polarity sunspots located in the same penumbra • large magnitude of the magnetic field and high horizontal gradients • highly twisted magnetic fields, strong magnetic shear Delta-sunspots are proposed to be formed via emergence of a twisted loop (Fan et al. 1999) and they are believed to be connected above the photosphere. However, Zirin & Liggett (1987), Shi & Wang (1993) and Liu & Zhang (1999) suggested that delta-sunspots can be formed due to i) emergence of a cluster of sunspots; ii) emergence of a satellite sunspot and iii) collision of two bipolar magnetic features and direct magnetic connections (“post flare” loops) within a delta-sunspot occur only as it decays (Zirin & Liggett 1987). Date Speed Coord NOAA Area Length Flare NOAA AR 9415 Yurchyshyn et al. 2004, Space Weather, 2, S02001 In turn, the intensity of the southward Bz largely determines the intensity (Dst Index) of a geomagnetic storm: Thus, a delta sunspot can be associated with two independent magnetic fluxes which can reconnect and produce a CME as described in the Sweet (1958) and Hirose (2001) models. Those models are based on the Quadruple Reconnection Configuration (see also poster SH51C-03) Yurchyshyn et al. 2004, Space Weather, 2, S02001 2. Tadpole-Shaped ARs (2 - X, 5 - M & 1 – C flare) • Typical features: • a large sunspot w/ many small satellites • twisted magnetic field & strong magnetic shear • well pronounced moat structure • In this magnetic topology, a CME, too, can be a result of reconnection between many closed twisted magnetic loops as suggested by the Quadruple Reconnection Configuration. • (Yurchyshyn et al., 2000, ApJ 540, 1143) AR 8375 on Nov 5, 1998 Date Speed Coord NOAA Area Length Flare Yurchyshyn et al. 2004, ApJ, 619, 599 3. Magnetic Complex (1- X, 8 - M & 1 – C flare) The magnetic complexes are extended magnetic regions which consist of two adjacent decaying active regions or a new magnetic region emerging inside a decaying active region. Because of the age of these active regions, a large scale helical magnetic fields (flux tube) could be formed and CMEs could be associated with their eruptions. Another possibility is that a CME is a result of interaction between the two adjacent active regions. Date Speed Coord NOAA Area Length Flare