Abstracts submitted by Victor Grechnev

Absorption phenomena and a probable blast wave caused by a partially failed CME

V.V.Grechnev [1], A.M.Uralov [1], V.A.Slemzin [2], I.M.Chertok [3], I.V.Kuzmenko [4], K.Shibasaki [5]

[1] Institute of Solar-Terrestrial Physics, Russia [2] Lebedev Physical Institute, Russia [3] IZMIRAN, Russia [4] Ussuriysk Astrophysical Observatory, Russia [5] Nobeyama Radio Observatory, Japan

We present a case study of the 13 July 2004 solar event, in which disturbances caused by eruption of a small filament from a compact active region embraced nearly a quarter of the visible solar surface. Remarkable are absorption phenomena, which showed up in SOHO/EIT 304 A channel and even total radio flux records. Quantitative evaluations from different observations provided close estimates of the ejected mass, ~2 10^15 g. Kinematics of fragments was shown to be described by self-similar expansion. Coronal and Moreton waves observed in this event were kinematically close and both decelerated in accordance with an expected motion of a coronal blast wave driven by the eruption. Multi-spectral data allowed reconstructing a picture of a "partially failed" CME, which disintegrated, and one its part returned to the Sun, while another part flew away. The "failed" part was responsible for the observed large-scale absorption phenomena.
Homologous proton events of 15-20 January 2005 and 13-14 December 2006

V.V.Grechnev [1], I.M.Chertok [2], A.M.Uralov [1], L.K.Kashapova [1], Y.Hanaoka [3], K. Shibasaki [4]

[1]Institute of Solar-Terrestrial Physics, Irkutsk, Russia; [2]IZMIRAN, Troitsk, Russia; [3]National Astronomical Observatory of Japan, Tokyo, Japan; [4]Nobeyama Radio Observatory, Nobeyama, Japan

Two homologous sets of major flare/CME/SEP events occurred during 15-20 January 2005 and on 13-14 December 2006. Several aspects of the January 2005 events exhibited homology; high-speed halo CMEs were among them. However, the major reason for the extremely strong and hard proton flux in the 20 January SEP/GLE event was found to be not in CME parameters, but in the flaring in strong magnetic fields just above sunspot’s umbrae. This clearly showed up in a huge microwave/millimeter burst (up to about 100,000 sfu) with its frequency maximum at about 30 GHz. Similar factors also determined intense, hard proton flux, which originated in the 13 December 2006 flare, unlike a homologous proton-soft 14 December 2006 event. This regularity revealed by the two sets of flares is also typical of many other proton events that is an important argument in favor of initial acceleration of SEP/GLE particles just in flares, rather than in CME-driven shocks. A probable reason for homology was continuous development of an active region towards strengthening a flare-productive configuration under persistence of main structural components for both the active region and its large-scale environment.