Helioseismology is the study of solar vibrations or oscillations. It is impossible to land seismometers on the surface of the sun because the temperature would melt any instrument fabricated on earth, and the "surface" is glowing gas, not a firm soil like the surface of the moon or of mars. In 1960, studies of the doppler shift of spectroscopic lines from the sun showed it was possible to determine how the photosphere of the sun was vibrating. Most oscillations had a period of about 5 minutes, but a few were sometimes noticed that had a much longer period of 160 minutes, or 2 hours and 40 minutes. The longer period oscillations are difficult to explain by the standard model of the sun which Astronomers use.
Standard Solar Model.
The Standard Solar Model is the dominant model for the interior of the Sun and other stars. According to this model a star has a nuclear burning core that produces helium by means of deuterium fusion, at 15 million degrees K. This core goes out to about 25% of the sun's radius. It is modeled as physically isolated from the solar structure above it and heat is transferred from the core by radiation, a process that takes about a million years. This has never actually been observed.
Recently solar oscillations have produced a problem for the Standard Solar Model. Their normal period is about 5 minutes. According to the Standard Solar Model, the maximum possible period is about 1 hour, but the maximum period that has been observed is 2 hours and 40 minutes. The maximum period for a totally homogeneous sun is 2 hours and 47 minutes. Thus the observed period of 2 hours and 40 minutes of oscillation shows the sun's interior to be very homogeneous, that is that the core and surface have similar composition. This also means that the model on which stellar evolution theory is based does not apply to the sun. It may not apply to other stars as well.
It has been shown that the long period is not a beat frequency of the shorter five minute oscillations, nor an artifact of the 24 hour rotation of the earth. The exact period was found to be 160.0095 minutes +-.001 minutes.
It also means that the nuclear burning core produces deuterium from hydrogen fusion at 5 million degrees K or less. The heat is transferred from the core by convection currents so it could reach the surface in days, not a million years. It also leads to an age for the sun based on the deuterium/hydrogen ratio of the local interstellar medium of 6,000-12,857 years.
- Helioseismology: Implications for the Standard Solar Model by Jonathan F. Henry. CRSQ Volume 40, Number 1. June, 2003.