| Session Details | |
| Section | ST - Solar & Terrestrial Sciences |
| Session Title | Transient Phenomena and Magnetic Waves in the Sun and Sun-like Stars |
| Main Convener | Dr. Abhishek Kumar Srivastava (Aryabhatta Research Institute of Observational Sciences (ARIES), India) |
| Co-convener(s) | Prof. Valery Nakariakov (University of Warwick, United Kingdom) Prof. M.J. Aschwanden (Solar & Astrophysics Laboratory, Lockheed Martin Advanced Technology Center, USA., United States) |
| Session Description | The complex magnetic field of the Sun is a key feature of the mega-kelvin hot solar atmosphere and transient phenomena, such as flares, eruptive prominences, spicules and jets, CMEs, bright points, etc. Coupling of the magnetic field and the atmospheric plasma generates a variety of magnetohydrodynamic (MHD) waves. Recent high-resolution observations from space (e.g., TRACE, SOHO, Hinode, STEREO) and ground-based observations (e.g., CoMP, DOT, ROSA, Nobeyama Radioheliograph and SST) provide the abundant evidence of the ubiquitous presence of MHD waves in all layers of solar atmosphere. Exploiting MHD oscillations as a diagnostic tool of physical conditions in the solar plasma is known as MHD seismology, the new research method opened up by the modern generation of solar observational facilities. Also, the waves remain one of the key candidates for coronal heating and wind acceleration, the enigmatic problems of modern stellar astrophysics. Another rapidly growing research field is the study of quasi-periodic pulsations in flares, associated with MHD oscillations, in the context of flare triggering, revealing the mechanisms for the energy conversion and particle acceleration, and plasma diagnostics. Confident detection of oscillatory patterns in the white light, microwave and X-ray emission generated in stellar flares provides the ground for revealing the role played by MHD waves in stellar atmospheres, and for the development of stellar MHD seismology. The plasma diagnostic capabilities of the magnetic waves, based upon the wealth of knowledge recently gained in solar physics, provide important clues about the physics of the hot atmospheres of Sun and Sun-like stars, and impose rigid constraints on the relevant theories. Although the wave heating theory is emerging as one of the potential candidate, the magnetic reconnection is being also a major candidate for the coronal heating and plasma dynamics. Closed-field regions in the solar corona which includes flares, active regions, and the quiet Sun, the most of the heating seems to be also provided by magnetic reconnection. One piece of evidence is the powerlaw distribution of flares and nanoflares has a powerlaw slope of ~1.5 for thermal and nonthermal energies, which puts most of the energy into the largest flares driven by magnetic reconnection. Also, coronal loops seem to be heated impulsively on time scales of a few minutes and then cool down, which again points to bursty reconnection modes. The magnetic reconnection models may also be a good proxy to understand the transient phenomena and heating of stellar atmosphere. Our proposed session provides a joint forum for solar and stellar physicists for the discussion of current trends in solar and stellar wave studies and transient phenomena. The session covers recent observational discoveries, novel data analysis techniques and theoretical breakthroughs. The session will also discuss the future prospectives of the observations and modeling of MHD waves and transient phenomena in the solar and stellar atmospheres. |