14 research outputs found
Estimations of changes of the Sun's mass and the gravitation constant from the modern observations of planets and spacecraft
More than 635 000 positional observations (mostly radiotechnical) of planets
and spacecraft (1961-2010), have been used for estimating possible changes of
the gravitation constant, the solar mass, and semi-major axes of planets, as
well as the value of the astronomical unit, related to them. The analysis of
the observations has been performed on the basis of the EPM2010 ephemerides of
IAA RAS in post-newtonian approximation. The obtained results indicate on
decrease in the heliocentric gravitation constant per year at the level The positive secular
changes of semi-major axes have been obtained simultaneously
for the planets Mercury, Venus, Mars, Jupiter, Saturn, as expected if the
geliocentric gravitation constant is decreasing in century wise. The change of
the mass of the Sun due to the solar radiation and the solar wind and
the matter dropping on the Sun (comets, meteors, asteroids and dust) was
estimated. Taking into account the maximal limits of the possible
change, the value falls within the interval in year with the 95% probability. The
astronomical unit (au) is only connected with the geliocentric gravitation
constant by its definition. In the future, the connection between
and au should be fixed at the certain time moment, as it is inconvenient highly
to have the changing value of the astronomical unit.Comment: 20 pages, 4 tables, accepted for publication in Solar System
Research, 2011 (Astronomicheskii vestnik
Orbital effects of a monochromatic plane gravitational wave with ultra-low frequency incident on a gravitationally bound two-body system
We analytically compute the long-term orbital variations of a test particle
orbiting a central body acted upon by an incident monochromatic plane
gravitational wave. We assume that the characteristic size of the perturbed
two-body system is much smaller than the wavelength of the wave. Moreover, we
also suppose that the wave's frequency is much smaller than the particle's
orbital one. We make neither a priori assumptions about the direction of the
wavevector nor on the orbital geometry of the planet. We find that, while the
semi-major axis is left unaffected, the eccentricity, the inclination, the
longitude of the ascending node, the longitude of pericenter and the mean
anomaly undergo non-vanishing long-term changes. They are not secular trends
because of the slow modulation introduced by the tidal matrix coefficients and
by the orbital elements themselves. They could be useful to indepenedently
constrain the ultra-low frequency waves which may have been indirectly detected
in the BICEP2 experiment. Our calculation holds, in general, for any
gravitationally bound two-body system whose characteristic frequency is much
larger than the frequency of the external wave. It is also valid for a generic
perturbation of tidal type with constant coefficients over timescales of the
order of the orbital period of the perturbed particle.Comment: LaTex2e, 24 pages, no figures, no tables. Changes suggested by the
referees include
Estimates of the change rate of solar mass and gravitational constant based on the dynamics of the Solar System
The estimate of the change rate of the solar gravitational parameter d(GM⊙)∕dt is obtained from processing modern positional observations of planets and spacecraft. Observations were processed and parameters were determined basing on the numerical planetary ephemeris EPM2019. The obtained annual decrease in solar mass M⊙ accounts for the loss through radiation Ṁ⊙rad, through the outgoing solar wind Ṁ⊙wind, and for the material falling on the Sun Ṁ⊙fall. The estimated relative value is within {-}13.4\times 10^{-14}\,{<}\,(\dot M_{\odot} /M_{\odot})_{\mathrm{rad}+\mathrm{wind}+
\mathrm{fall}}\,{<}\,{-}8.7\times 10^{-14} per year. The following range for the change rate of the gravitational constant G was obtained: −2.9 × 10−14 < Ä âˆ•G < + 4.6 × 10−14 per year (3σ). The new result reduces the interval for the change in G and narrows the limits of possible deviations for alternative gravitational theories from general relativity