Efficient WIMPs would rescue the sun.

Efficient WIMPs would rescue the sun

The sun emits only about a third of the neutrinos it ought to emit, according to theorists' "standard model' of the thermonuclear processes that go on in its center. However, adjustments to account for the neutrino observations tend not to predict properly the acoustic vibrations of the sun. Now, calculations by two groups show that putting WIMPs (weakly interacting massive particles) in the center of the sun would satisfy both criteria. It is the only theory that does so, John Faulkner of the Lick Observatory in Santa Cruz, Calif., told SCIENCE NEWS.

WIMPS (SN: 7/13/85, p. 23) would move energy out of the center of the sun, lowering the temperature, affecting both the thermonuclear processes and the acoustical properties, particularly the speed of sound. WIMPs and the speed of sound came to Faulkner's mind as he heard a description of the theory of the sun's p-wave vibrations by Douglas O. Gough of the Institute of Astronomy in Cambridge, England. To calculate theoretically the sequence of these waves and the differences in frequency from one wave to the next is extremely complicated, but Gough presented a simplification for cases where the differences fall a certain way. Cancellations in the mathematics then result in a very simple equation--"a simple integral,' as Faulkner describes it --on which the differences in these waves depend.

One of the things on which this integral depends is the sun's central temperature, so Gough's simplification yields a way of testing the effects of WIMPs on the acoustic pulsations. Faulkner, Gough and an Indian student, M.N. Vahia, did the calculation in a few days, using hand calculators, and found that the WIMP model predicted the observed differences between the vibration frequencies to within two significant figures.

Meanwhile another group had been at work. Ronald L. Gilliland of the High Altitude Observatory (HAO) in Boulder, Colo., W. Dappen of HAO and J. Christensen-Dalsgaard of Aarhus University in Denmark had been calculating descriptions of the p-waves according to the full theory using a high-speed computer --about the only practical way to do it from this full-dress approach. They had reached the same conclusion about the fitness of the WIMP theory. The two groups decided their approaches were complementary and agreed on simultaneous publication in the May 15 NATURE.

The results do not prove the existence of WIMPs, says Faulkner, but if WIMPs don't exist, something else in the sun has to be efficiently transferring energy out of the center.