Ashok Ambastha  Professor Udaipur Solar Observatory Physical Research Laboratory E-mail: ambastha[at]prl.res.in Telephone: +91-294-2453953 xtn 207

My current research interests include:

• Solar energetic transients: energy buildup and trigger mechanism of flares, CMEs
  
• Velocity and magnetic fields in active regions
  
• Local and global helioseismology
  
• Solar eclipses and planetary transits
  
  

In recent years, I have been studying large flares and their photospheric, chromospheric and helioseismic responses. We have obtained statistically significant amplification of p-mode power in association with large flares. We found that power in low-l modes are stochastic in nature, and there is a poor correlation of with disk-integrated flare index and CME-counts for the period of May 1995--October 2005.

Future research will include, apart from the above topics, studies using the proposed MAST facility to become available at USO; zonal and meridional velocities in deeper layers underneath solar active regions; superflaring and flare-quiet active regions; flare associated variations in magnetic, doppler and helioseismic parameters; and the stability of prominences. Solar helioseismological data now available for over one complete solar cycle will be studied to relate the flare and CME indices with p-mode parameters. Coronal polarization maps will be obtained in green and red emission lines using suitable instruments with higher sensitivity and precision for deriving coronal magnetic fields. The experimental plans included spectroscopic and polarimetric observations of the TSE of July 2009 from China, and using IAF aircrafts.

Selected Publications :

Variations in p-Mode Parameters with Changing Onset Time of a Large Flare
R.A. Maurya, and A. Ambastha (2009). Astrophys.J., 706, L235-L239.

Transient Magnetic and Doppler Features Related to the White-Light Flares in NOAA 10486
R.A. Maurya, and A. Ambastha (2009). Solar Phys., 258, 31-52.

Possibility of Excitation of Low-l P-modes by Energetic Solar Transients
A. Ambastha, H. M. Antia (2006). Solar Phys., 238, 219-230.

Solar P-mode Characteristics Associated with Superactive-Regions Observed during Oct-Nov 2003
A. Ambastha, S. Basu, H.M. Antia, and R.S. Bogart (2004). ESA SP-559, 293.