<title>Ultra High Resolution Radial Velocity Spectrometer</title>

Abstract

The solar five minute oscillation was discovered by Leighton in 1960. Since the fundamental period of the Sun is expected to be about an hour, it was at first difficult to account for higher frequencies; but the cause and structure of these oscillations is now reasonably well understood. Recent results by Grec et al whomade a continuous six day observation of the Sun from the South Pole, show clearly that the oscillations are high 'Q', high-order modes of the whole Sun's oscillation. From these results and others it has been inferred that the structure of the Sun must be quite different from that expected. i.e. the convection zone must be thirty percent deeper and the interior temperature may be different giving a possible explanation of the observed solar neutrino flux. There have also been suggestions by Claverie et al2 that the interior of the Sun is rotating between two and nine times faster than the exterior. This could throw light on the Sun's magnetic field generating mechanism, and perhaps explain other solar periods e.g. the 22 year sunspot cycle. Ando and Osaki3 and Unno et al4 have shown that many stars should be subject to non-radial oscillations of small amplitude in a well-defined temporal frequency range, similar to the solar five minute oscillations. The periods would obviously depend strongly on the size of the star but, in any case, the same kind of discrete power spectrum as observed in integrated sunlight would be expected.