33 research outputs found
Density, vapor pressure, and viscosity of solutions of hydrazine mononitrate in hydrazine
Density, vapor pressure, and viscosity of solutions of hydrazine mononitrate in hydrazin
Metals plated on fluorocarbon polymers
Electroplating lead on fluorocarbon polymer parts is accomplished by etching the parts to be plated with sodium, followed by successive depositions of silver and lead from ultrasonically agitated plating solutions. Metals other than lead may be electroplated on the silvered parts
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
Dark Energy and Extending the Geodesic Equations of Motion: Its Construction and Experimental Constraints
With the discovery of Dark Energy, , there is now a universal
length scale, , associated with the
universe that allows for an extension of the geodesic equations of motion. In
this paper, we will study a specific class of such extensions, and show that
contrary to expectations, they are not automatically ruled out by either
theoretical considerations or experimental constraints. In particular, we show
that while these extensions affect the motion of massive particles, the motion
of massless particles are not changed; such phenomena as gravitational lensing
remain unchanged. We also show that these extensions do not violate the
equivalence principal, and that because Mpc, a
specific choice of this extension can be made so that effects of this extension
are not be measurable either from terrestrial experiments, or through
observations of the motion of solar system bodies. A lower bound for the only
parameter used in this extension is set.Comment: 19 pages. This is the published version of the first half of
arXiv:0711.3124v2 with corrections include
Origin of volatiles in the Main Belt
We propose a scenario for the formation of the Main Belt in which asteroids
incorporated icy particles formed in the outer Solar Nebula. We calculate the
composition of icy planetesimals formed beyond a heliocentric distance of 5 AU
in the nebula by assuming that the abundances of all elements, in particular
that of oxygen, are solar. As a result, we show that ices formed in the outer
Solar Nebula are composed of a mix of clathrate hydrates, hydrates formed above
50 K and pure condensates produced at lower temperatures. We then consider the
inward migration of solids initially produced in the outer Solar Nebula and
show that a significant fraction may have drifted to the current position of
the Main Belt without encountering temperature and pressure conditions high
enough to vaporize the ices they contain. We propose that, through the
detection and identification of initially buried ices revealed by recent
impacts on the surfaces of asteroids, it could be possible to infer the
thermodynamic conditions that were present within the Solar Nebula during the
accretion of these bodies, and during the inward migration of icy
planetesimals. We also investigate the potential influence that the
incorporation of ices in asteroids may have on their porosities and densities.
In particular, we show how the presence of ices reduces the value of the bulk
density of a given body, and consequently modifies its macro-porosity from that
which would be expected from a given taxonomic type.Comment: Accepted for publication in MNRA
Phenomenology of the Lense-Thirring effect in the Solar System
Recent years have seen increasing efforts to directly measure some aspects of
the general relativistic gravitomagnetic interaction in several astronomical
scenarios in the solar system. After briefly overviewing the concept of
gravitomagnetism from a theoretical point of view, we review the performed or
proposed attempts to detect the Lense-Thirring effect affecting the orbital
motions of natural and artificial bodies in the gravitational fields of the
Sun, Earth, Mars and Jupiter. In particular, we will focus on the evaluation of
the impact of several sources of systematic uncertainties of dynamical origin
to realistically elucidate the present and future perspectives in directly
measuring such an elusive relativistic effect.Comment: LaTex, 51 pages, 14 figures, 22 tables. Invited review, to appear in
Astrophysics and Space Science (ApSS). Some uncited references in the text
now correctly quoted. One reference added. A footnote adde
Current status of the IAU working group for numerical standards of fundamental astronomy
Current status of the IAU Working Group for Numerical Standards of Fundamental Astronomy
International audienc
The IAU 2009 system of astronomical constants: the report of the IAU working group on numerical standards for Fundamental Astronomy
International audienc