Presentation 1 : Invited
Hard X-ray/gamma-ray imaging spectroscopy of solar flares with RHESSI
N.Vilmer (LESIA-Observatoire de Paris), RHESSI team (PNST)
The main goal of the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) mission is to investigate particle acceleration and energy release in solar flares, through imaging and spectroscopy of hard X-ray(HXR)/gamma-ray(GR) continuum and gamma-ray lines(GRL) emitted by energetic electrons and ions interacting with the solar atmosphere. RHESSI provides observations from 3 keV to 17 MeV with first imaging spectroscopy in HXR with ~2 " angular resolution, time resolution to tens of ms, and ~1 keV energy resolution. It should also provide GRL spectroscopy with ~2-5 keV energy resolution. I shall present here the objectives of RHESSI as well as some initial results.
Presentation 2 : Poster
X-ray and radio observations of the 20 February 2002 solar flare (PNST
N. Vilmer (LESIA-Observatoire de Paris),S Krucker, R.P. Lin (University of California, Berkeley), RHESSI Team
The GOES C7.5 flare on 20 February 2002 at ~11:06 UT is one of the first solar flares observed by RHESSI at X-ray wavelengths. It was simultaneously observed at metric/decimetric wavelengths by the Nançay radioheliograph (NRH). We shall present a first comparison of the time evolution of X-ray images in different energy bands observed with RHESSI and of the time evolution of images of the radio emission sites at 5 frequencies in the 150-450 MHz range observed by the NRH. We shall also investigate whether the evolution in space and time of the X-ray sources are related to any spectral evolution.