천문우주과학과

일시:  2021년 5월 13일 목요일 오후 4시 세미나실(기2514호)
       (ZOOM 회의 ID:878 6419 6027)

연사:  권윤영 박사님(한국천문연구원)

제목: A shocking star: The Sun

 초록:  

  We present the observations of spherical, supernova-shaped, coronal shocks associated with flares and coronal mass ejections (CMEs). This lecture shows the morphology seen from multiple vantage point observations; three-dimensional (3D) geometry determined by a forward modeling method; kinematics all along the shock fronts in 3D; and compression ratio (Mach number). The major findings are as follows: (1) Halo CMEs are the manifestation of spherically shaped fast-mode waves/shocks, rather than a matter of the projection of expanding flux ropes. The footprints of halo CMEs on the coronal base are the so-called EIT/EUV waves. (2) These spherical fronts arise from a driven shock (bow- or piston-type) close to the CME nose, and it is gradually becoming a freely propagating (decaying) fast-mode shock wave at the flank. (3) Such large longitudinal extents of these shock waves in the corona agree with those of the solar energetic particles (SEPs) in the heliosphere. (4) The shock density compressions peak around the CME nose and decrease at larger position angles. (5) Last but not least, the supercritical region extends over a large area of the shock and lasts longer than past reports. These results offer a simple unified picture of the different manifestations for CME-associated waves, such as EUV waves and SEP events observed in a variety of regimes and heliocentric distances.