G-mode :: A new generation of helioseismic instrument

The GOLF team pushes a new concept of instrument devoted to the search of gravity modes and low order low frequency p modes in order to improve our knowledge of the deep solar interior. The instrumental concept is to measure the Doppler shift together with the time evolution of the D1 sodium line using a 15 point resonance spectrometer. A sodium vapor resonance cell placed in a static magnetic field varying along the longitudinal axis is used to sample simultaneously 8 points on each wing of the line. New Active Pixel Sensor detectors will be specifically designed for this instrument. A Low spatial resolution of the Sun is also under study in this concept. First ground-based observations with this instrument are scheduled for 2001/2002 at Tenerife. The space concept of this instrument is under study in France as an R&T (Research and Technology) study sponsored by CNES, the French Space Agency. After some determining validation tests, this kind of instrument might be placed onboard either a micro satellite or a satellite dedicated to the study of the Sun.