Nuclear Astrophysics - Predictions

Predictions

The theory of stellar nucleosynthesis reproduces the chemical abundances observed in the solar system and galaxy, which from hydrogen to uranium, show an extremely varied distribution spanning twelve orders of magnitude (one trillion). While impressive, these data were used to formulate the theory, and a scientific theory must be predictive in order to have any merit. The theory of stellar nucleosynthesis has been well-tested by observation and experiment since the theory was first formulated.

The theory predicted the observation of technetium (the lightest chemical element with no stable isotopes) in stars, observation of galactic gamma-emitters such as 26Al and 44Ti, observation of solar neutrinos, and observation of neutrinos from supernova 1987a. These observations have far-reaching implications. 26Al has a lifetime a bit less than one million years, which is very short on a galactic timescale, proving that nucleosynthesis is an on-going process even in our own time. Work which lead to the discovery of neutrino oscillation, implying a non-zero mass for the neutrino and thus not predicted by the Standard Model of particle physics, was motivated by a solar neutrino flux about three times lower than expected, which was a long-standing concern in the nuclear astrophysics community such that it was colloquially known simply as the Solar neutrino problem. The observable neutrino flux from nuclear reactors is much larger than that of the Sun, and thus Davis and others were primarily motivated to look for solar neutrinos for astronomical reasons.