PROGRAM: S-2

Title:

ON SOME STATISTICAL CHARACTERISTICS OF LARGE ENERGY CORONAL MASS EJECTIONS DURING SOLAR CYCLE 23 AND 24

Abstract:

We have studied the characteristics of large energy coronal mass ejections (LE-CMEs) (energy ≥ 1E+31 ergs) observed between the time period years 1996–2015. During the study period total 2000 CMEs has been occurred which has their energy ≥ 1E+31 ergs. Out of these 2000 events; only 309 events have proper acceleration and velocity, so other events are left out due to non availability of acceleration and velocity data. Out of 309 LE-CMEs the 124 LE-CMEs are not associated with solar flares events on solar disc thus we are left with only 186 LCMEs events for present study. Hence in present study we have considered 186 high energy CMEs those are available online at the CDAW Data Center (http://cdaw.gsfc.nasa.gov/CME_list.html). The detailed information for CMEs and solar flares observed LASCO (Brueckner et al., 1995) and other instruments are taken from CDAW catalogue. High energy or large energy CMEs (LE-CMEs) are those CMEs which have their energies equal or larger than 10³⁰ ergs. Our study show that the average and median linear speed of LE-CMEs events are 864 km/s and 830 km/s, respectively and average and median initial speed of LE-CMEs events are 856 km/s and 819 km/s, respectively. We have also found that none of LE-CMEs is halo CME and the angular width of most of LE-CMEs are less than ≤120 degree with mean value of angular width as 86 degree. It is also found that 97% LE-CMEs occurs within ±30 degree of solar latitude and their solar longitude distribution, indicates that they are uniformly distributed on solar disc. We also find that mass and energy of CMEs does not depend on the location of CME on solar disc but very few events having the larger mass and larger energy occurs in ±30 longitudinal range. The mean value of mass and energy of LE-CMEs is 8.32E+31 gms and 2.39E+31 ergs, respectively. The mean value of acceleration of large energy CMEs is -0.08 m/s² . It is also found that most of the events are biased towards acceleration that shows that large energy CMEs accelerate in general. It is also found that most of the events are associated with C-class of SXR flares, which indicates it is not necessary that energetic flares should associate with LE-CMEs. We have also discussed the various results obtained in present investigation in view of recent scenario of solar physics.

Acknowledgements:

The author is thankful to N. Gopalswamy and his team for providing CMEs related data to users through CDAW. The CME catalog used is provided by the Center for Solar Physics and Space Weather, the Catholic University of America, in cooperation with Naval Research Laboratory, and NASA.

References:

Brueckner, G.E., et al., (1995), The Large Angle Spectroscopic Coronagraph (LASCO), Solar Physics, 162(1-2), 357-402