New Insight in Sounding the Solar Interior

Abstract

Abstract.The solar limb is potentially a sharp spatial reference with which we can detect the effects of solar oscillations (both pression and gravitation modes), the quadrupole moment -and higher moments if any-, the true shape of the helioid (the oblateness at the first order), and changes in the solar radius. It is shown in this paper, that the accurate determination of the successive differential gravitational moments are useful to probe the solar interior. We emphasize the main reasons, mainly the accurate determination of the planetary orbits and the adjustement of the Eddington-Robertson coefficient of the PPN gravitational theory. Moreover, both the shape and the radius measurements of the Sun help to determine the solar luminosity, as empirical models of total irradiance (solely based on magnetic effects) can not explain all aspects of irradiance changes. A complete theory is still pending. The space mission Picard, currently scheduled by the end of 2004 and currently under a manufacturing process, will lead to validate our differential theory.

Testing general relativity with satellite laser ranging: Recent developments

“…Nevertheless, according to more recent determinations of J 2⊙ using the analysis of the Sun's pressure modes, both from the ground-based network of observatories and the space based SOHO, J 2⊙ = (2.3±0.1)×10 −7 [106]; in ref. [107] a theoretical estimate of J 2⊙ = (2.0±0.4)×10 −7 is reported. Thus, according to these values of J 2⊙ the observed perihelion advance of Mercury is well in agreement with the general relativistic predictions.…”