Using solar oscillations to probe the effects of element diffusion in the solar interior

Conference · Fri Jan 01 04:00:00 EST 1993 · American Astronomical Society, Bulletin; (United States)

OSTI ID:6306015

Guzik, J A; Cox, A N

There is growing evidence from solar oscillation and evolution studies that the Sun's convection zone helium mass fraction has decreased by about 0.03 due to element diffusion. Evolution calculations show that diffusion also produces a steep Y and Z composition gradient below the convection zone. Comparisons between calculated and observed solar p-mode frequencies of angular degrees 5 thru 60 that are sensitive to solar structure near the convection zone bottom support this steep composition gradient, rather than one smoothed significantly by turbulent mixing. Turbulent mixing induced by convective overshoot or rotation has been the favored explanation for much of the solar surface lithium depletion by a factor of 200 from its presumed primordial value. These limits on the extent of turbulent mixing imply that either most of the solar lithium destruction occurred pre-main sequence, which is not supported by observation of young star, or that some other mechanism, for example a small amount of early main-sequence mass loss, is responsible for the low observed lithium abundance. Solar models including such mass loss as well as diffusion have a slightly steeper central density gradient. Comparisons between observed and calculated low-degree p-mode frequencies that are sensitive to the Sun's central structure can be used to probe this density gradient and constrain the possible amount of mass loss.

• OSTI ID: 6306015
• Report Number(s): CONF-9306217--
• Conference Information: Journal Name: American Astronomical Society, Bulletin; (United States) Journal Volume: 25:2
• Country of Publication: United States
• Language: English

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