3. Optical Observations of Solar Flares

Observations and modelling of Helium lines in solar flares

We explore the response of the He ii 304 Å and He i 584 Å line intensities to electron beam heating in solar flares using radiative hydrodynamic simulations. Comparing different electron beams parameters, we found that the intensities of both He lines are very sensitive to the energy flux deposited in the chromosphere, or more specifically to the heating rate, with He ii 304 Å being more sensit...

Particle acceleration in solar flares: observations versus numerical simulations

Solar flares are generally agreed to be impulsive releases of magnetic energy. Reconnection in dilute plasma is the suggested trigger for the coronal phenomenon. It releases up to 1026 J, accelerates up to 1038 electrons and ions and must involve a volume that greatly exceeds the current sheet dimension. The Ramaty High-Energy Solar Spectroscopic Imager satellite can image a source in the coron...

Millimeter Observations of Flares

The nature of emission from solar ares at millimeter wavelengths is discussed. In the impulsive phase of ares, millimeter emission should be dominated by gyrosynchrotron emission from MeV{energy electrons. Millimeter telescopes are very sensitive to these electrons and can make high{resolution images of their sources for comparison with HESSI images, allowing us to investigate the behaviour of ...

INTERFEROMETRY OF SOLAR FLARES AT 3-mm WAVELENGTH

K e y w o r d s : Sim: flares Sun: particle emission Sun: radio radiation

Global Properties of Solar Flares