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  • Fermi Observations of Particle acceleration in Solar Flares

     

    Seminar Title  

    Fermi Observations of Particle acceleration in Solar Flares

       
    Speaker:   Prof Vahe Petrosian(Chairman of Astronomy Program)
       

     Affiliation:    

     (Department of Physics, Stanford University)
       
    When Tuesday afternoon, May 8, 16:00 p.m
       

    Where:   

    Room 212, Astronomy Building
     

                             Welcome to Attend   

     
      ( PMO Academic Committee & Academic Circulating committee)
     

       Abstract:  During the current solar cycle of the Sun the Fermi Large Area Telescope (LAT) has detected more than 40 flares up to GeV energies, some lasting many hours contemporaneous with Solar Energetic Particles (SEPs) and three that originate from active regions (AR) located behind the limb (BTL) as viewed from the Earth and detected by STEREO observations. Almost all are associated with fast Coronal Mass Ejections (CMEs). I will give a brief overview of the observations with focus on two of the three BTL flares that show RHESSI hard X-ray and SDO EUV  emission coming from the top of a relatively large flare loop peeking over the limb. Radio emission with similar light curves is also attributed to this looptop source, while the centroids of the  LAT gamma-rays are some distances away. This multiwavelength coverage of the well isolated looptop (presumably near the coronal acceleration site) combined with Fermi observations provides a unique opportunity to investigate possible mechanisms and sites of acceleration of particles (corona and/or CME shock), their transport and radiative signatures (leptonic or hadronic). I will present some quantitative result on accelerated particle spectra, magnetic field values at the looptop and its structure connecting the AR to the CME and back to the LAT source.

     
      Vahe Petrosian, Professor of physics and applied physics, Chairman of Astronomy Program, Department of Physics, Stanford University.
    Awards and recognition: 1972-74 Alfred P. Sloan Fellow; Member, Eta Kappa Nu, Tau Beta Pi; Center for Space Science and Astrophysics & KIPAC, Stanford University; Co-discoverer of strong gravitational lensing of cluster of galaxies, Inventor of Petrosian criteria (magnitude, ratio) with non-parametric methods for determination of distribution of astronomical sources from truncated data
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