1112.4168 (Lorenzo Iorio)
Lorenzo Iorio
The angular momentum of a star is an important astrophysical quantity related
to its internal structure, formation and evolution. On average, helioseismology
yields S = 1.92 10^41 kg m^2 s^-1 for the angular momentum of the Sun. We
constrain it in a model-independent, dynamical way by using the gravitomagnetic
Lense-Thirring effect predicted by general relativity for the orbit of a test
particle moving around a central rotating body. The correction to the standard
Einsteinian/Newtonian precession of the longitude of the perihelion $ of
Mercury, recently inferred by a team of astronomers from a fit of dynamical
models of the forces acting on the planets of the solar system to a long data
record, amounts to 0.4 +/- 0.6 mas cty^-1. The modeled forces did not include
the Lense-Thirring effect itself, which is expected to be as large as -2.0 mas
cty^-1 for the perihelion of Mercury from helioseismological values of S?. By
assuming the validity of general relativity, from its theoretical prediction
for the gravitomagnetic perihelion precession of Mercury we infer S <= 0.57
10^41 kg m^2 s^-1. It disagrees with the currently available values from
helioseismology. MESSENGER, in orbit around Mercury since March 2011, will
collect data for about 1 year, while BepiColombo, to be launched in 2014,
should reach Mercury in 2020 for a yearlong science phase: the analysis of
their data will be important for the orbit determination of the innermost
planet of the solar system. In any case, time to include the gravitomagnetic
force of the Sun in the planetary force models has, perhaps, come right now.
View original:
http://arxiv.org/abs/1112.4168
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