Few Problems in Experimental Nuclear Astrophysics

Abstract

Our planet earth is warmed by the prodigious energy output of a nearby star, our sun. This typical and most important star has been studied by scientists over the centuries with ever improving techniques. From these conventional optical studies one knows its mass, luminosity, radius, surface temperature, surface composition and age more accurately than for any other star. An answer to the question “what goes on in the interior of the sun” was not possible until 1920, when Eddington suggested that the energy which powers the sun comes from the fusion of the most abundant species hydrogen into helium

$$4 \ H \rightarrow 1 \ ^4He + 2 \ e^{+} + 2 \ v$$

with an energy release of about 27 MeV. The actual mechanism of this fusion was elucidated not before the late thirthys, when Bethe, Critchfield and Weizsäcker showed that two sets of reactions can provide this fusion, namely the p-p chain and the CNO-cycles. The mass of a given star dictates hereby which of the two sets represents the predominant stellar energy source.

Two lectures delivered at The 1980 International Summer School on Nuclear Structure, Dronten, The Netherlands, 12–23 August 1980 are scheduled for publication by Plenum Publishing Company.