경희대학교 BK21

아래와 같이 세미나를 진행하오니
관심있는 분들의 많은 참여를 바랍니다.
-------------------- 아 래 --------------------
● 날짜 : 2015년 11월 10일 (화요일)
● 시간 : 16시 30분
● 장소 : 천문대 영상실
● 강사 : Dr. A.Shanmugaraju(1Arul Anandar College, Madurai, India)
           / Dr. Bhuwan Joshi(Udaipur Solar Observatory, Physical Research Laboratory, Udaipur, India)

 

 

Title : Coronal Mass Ejection and Shocks (Dr. A.Shanmugaraju)

 
Abstract :

Coronal mass ejection (CME) is a magnetised plasma ejected from the solar corona into the interplanetary medium. When they are fast enough, they can drive shocks and produce type II radio bursts. These type II bursts can be seen in the dynamic spectrum in the frequency range 300 MHz - 20 MHz using ground-based observations and they are called as metric type II bursts. Using satellite observations, the type II bursts are observed in the frequency range 14 MHz – 1 MHz and they are called as deca-hectametric (DH) type II bursts. The CMEs which produce type II bursts are called as Radio-Loud CMEs and the CMEs which do not produce type II bursts are called as Radio-quiet CMEs. The earlier observations and analysis have revealed that not all the fast CMEs are producing type II bursts. However, the radio-loud CMEs are generally associated with Solar Energetic Particle(SEP) events. Hence, we have analysed several data for answering the question why some CMEs are producing type II bursts and some are not, even when they are Halo CMEs and associated with X-class flares? Also, the propagation of CMEs and their interaction with another preceding CME are important topics in the concept of space-weather studies. The CMEs when they are ejected towards the Earth, they produce geo-magnetic storms and the strength of the storms can be forecasted by some model constructed using the near-sun parameters of CMEs (direction parameter, speed and location). Also, it has been reported that the present solar cycle is weak when compared to the earlier cycle. In this regard, we studied the coronal magnetic field and geoeffectiveness of the CMEs in the current solar cycle and compared the results with that of previous cycles. The results from the above studies will be presented in this seminar.

 

Title : Destabilization and eruption of active region prominences (Dr. Bhuwan Joshi )

 

Abstract :

Prominences, or, equivalently, filaments are relatively cool, dense objects of chromospheric material suspended in the hotter corona by magnetic fields. When these structures erupt, both the prominence material and magnetic field are expelled together. Decades of observations reveal that prominence eruptions are often associated and physically related to solar flares and coronal mass ejections (CMEs). The standard flare model recognizes the rising prominence as an initial driver of the flare process.

In this talk, I will discuss about the destabilization and eruption of solar prominences which are formed in the active regions. Such prominence eruptions produce strong radiative signatures in the form of X-ray, EUV, and radio emissions. We further emphasize the early, quasi-stationary phase of prominence evolution which is associated with multiple pre-flare events. The contemporary observations from TRACE, AIA/SDO and RHESSI will be presented that reveal multiple steps of prominences evolution toward their final eruption from the solar source region