scholarly journals General Relativity And The IAU Resolutions Report of the IAU WGAS Sub-Working Group on Relativity in Celestial Mechanics and Astrometry (RCMA SWG)

1998 ◽  
Vol 11 (1) ◽  
pp. 194-199
Author(s):  
V.A. Brumberg ◽  
P. Bretagnon ◽  
N. Capitaine ◽  
T. Damour ◽  
T.M. Eubanks ◽  
...  
Keyword(s):  
General Relativity ◽  
Time Scales ◽  
Celestial Mechanics ◽  
General Problem ◽  
Working Group ◽  
International System ◽  
Fundamental Astronomy ◽  
Astronomy Concepts ◽  
Relativistic Framework ◽  
Astronomical Constants

RCMA SWG was appointed by the IAU WGAS (Working Group on Astronomical Standards) in accordance with IAU Resolution C6 (1994) with the aim ‘to provide definitions of the astronomical units, of the quantities linking these astronomical units to the units of the International System (SI), and of other astronomical quantities, compatible with the theory of General Relativity’. It is evident that the relativistic aspects of units of measurement cannot be isolated from the more general problem of astronomical constants and fundamental astronomy concepts in the relativistic framework. Therefore, along with the problem of units the main topics of discussion of RCMA SWG concerned also the IAU (1991) Resolutions on References Systems (RSs) and Time Scales (TSs) and their interpretation in IERS Standards (1992) and IERS Conventions (1996). In what follows we tried to summarize the results of these discussions.

scholarly journals Astronomical Units and Constants in a Relativistic Framework

1995 ◽  
Vol 10 ◽  
pp. 201-201
Author(s):  
N. Capitaine ◽  
B. Guinot
Keyword(s):  
General Relativity ◽  
Minimum Degree ◽  
Degree Of Approximation ◽  
Theoretical Background ◽  
Point Of View ◽  
Astronomical Unit ◽  
Dynamical Astronomy ◽  
Unit Of Length ◽  
Relativistic Framework ◽  
Astronomical Constants

In 1991, IAU Resolution A4 introduced General Relativity as the theoretical background for defining celestial space-time reference sytems. It is now essential that units and constants used in dynamical astronomy be defined in the same framework, at least in a manner which is compatible with the minimum degree of approximation of the metrics given in Resolution A4.This resolution states that astronomical constants and quantities should be expressed in SI units, but does not consider the use of astronomical units. We should first evaluate the usefulness of maintaining the system of astronomical units. If this system is kept, it must be defined in the spirit of Resolution A4. According to Huang T.-Y., Han C.-H., Yi Z.-H., Xu B.-X. (What is the astronomical unit of length?, to be published in Asttron. Astrophys.), the astronomical units for time and length are units for proper quantities and are therefore proper quantities. We fully concur with this point of view. Astronomical units are used to establish the system of graduation of coordinates which appear in ephemerides: the graduation units are not, properly speaking astronomical units. Astronomical constants, expressed in SI or astronomical units, are also proper quantities.

scholarly journals Ephemeris Astronomy Definitions and Constants in General Relativity

1997 ◽  
Vol 165 ◽  
pp. 439-446
Author(s):  
Victor A. Brumberg
Keyword(s):  
General Relativity ◽  
Time Scales ◽  
Absolute Space ◽  
Newtonian Mechanics ◽  
Reference Systems ◽  
Absolute Time ◽  
Astronomical Constants

AbstractCurrently employed definitions of ephemeris astronomy and the system of astronomical constants are based on Newtonian mechanics with its absolute time and absolute space. To avoid any relativistic ambiguities in applying new IAU (1991) resolutions on reference systems (RS) and time scales one should specify the astronomical constructions and definitions of constants to make them consistent with general relativity (GRT). Such an approach is developed with the aid of the existing relativisting hierarchy of relativistic reference systems and time scales.

scholarly journals The IAU 2009 system of astronomical constants: the report of the IAU working group on numerical standards for Fundamental Astronomy

2011 ◽  
Vol 110 (4) ◽  
pp. 293-304 ◽  
Author(s):  
Brian Luzum ◽  
Nicole Capitaine ◽  
Agnès Fienga ◽  
William Folkner ◽  
Toshio Fukushima ◽  
...  
Keyword(s):  
Working Group ◽  
Fundamental Astronomy ◽  
Astronomical Constants

scholarly journals “For Milliarcsecond or Better Accuracy”

1989 ◽  
Vol 8 ◽  
pp. 465-500
Author(s):  
P. K. Seidelmann
Keyword(s):  
Observational Data ◽  
Time Scales ◽  
Celestial Mechanics ◽  
Earth Orientation ◽  
Systematic Effects ◽  
Order Of Magnitude ◽  
Working Groups ◽  
Astronomical Constants ◽  
Better Than

The accuracies being achieved in astrometry, celestial mechanics, Earth Orientation, ephemerides and time have been improving significantly in recent years.The introduction of the improved astronomical constants, ephemerides, time scales and nutation as adopted from 1976 to 1984 has had the desired effect of permitting the investigation of systematic effects at precisions of an order of magnitude better than previously possible.Therefore, there have been many developments in observational data, in theories, and in astronomical computations that have promised, or claimed, to deliver accuracies of a milliarcsecond or better.Working Groups had been established with interrelationships in their scopes of activities. It did not appear that any of the working groups were prepared to present final recommendations that would be generally accepted.

Hermann Weyl's Analysis of the “Problem of Space” and the Origin of Gauge Structures

2004 ◽  
Vol 17 (1-2) ◽  
pp. 165-197 ◽  
Author(s):  
Erhard Scholz
Keyword(s):  
General Relativity ◽  
Dirac Equation ◽  
A Priori ◽  
Group Extension ◽  
Central Idea ◽  
German Word ◽  
General Relativistic ◽  
Empirical Turn ◽  
Relativistic Framework ◽  
Internal Symmetries

Hermann Weyl (1885–1955) was one of the early contributors to the mathematics of general relativity. This article argues that in 1929, for the formulation of a general relativistic framework of the Dirac equation, he both abolished and preserved in modified form the conceptual perspective that he had developed earlier in his “analysis of the problem of space.” The ideas of infinitesimal congruence from the early 1920s were aufgehoben (in all senses of the German word) in the general relativistic framework for the Dirac equation. He preserved the central idea of gauge as a “purely infinitesimal” aspect of (internal) symmetries in a group extension schema. With respect to methodology, however, Weyl gave up his earlier preferences for relatively a-priori arguments and tried to incorporate as much empiricism as he could. This signified a clearly expressed empirical turn for him. Moreover, in this step he emphasized that the mathematical objects used for the representation of matter structures stood at the center of the construction, rather than interaction fields which, in the early 1920s, he had considered as more or less derivable from geometrico-philosophical considerations.

scholarly journals Proceedings of the Joint Discussion: Parameters of the Earth's Gravitational Field

1966 ◽  
Vol 12 (2) ◽  
pp. 607-609
Author(s):  
A. H. Cook
Keyword(s):  
Gravitational Field ◽  
Executive Committee ◽  
Working Group ◽  
General Assembly ◽  
International Astronomical Union ◽  
Earth’S Gravitational Field ◽  
International Astronomical ◽  
Astronomical Constants

The Chairman, W. Fricke, President of Commission 4, opened the Joint Discussion by drawing attention to the purpose and proposed procedure for the meeting. The Joint Discussion had been arranged by the Executive Committee of the Union in order to avoid the necessity for separate discussions by each Commission that was affected by the Report of the Working Group on the IAU System of Astronomical Constants. The Organizing Committee therefore proposed the following resolution:‘The members of the IAU at this Joint Discussion recommend to the Executive Committee that the following resolution be put before the General Assembly: “The International Astronomical Union endorses the final list of constants prepared by the Working Group on the System of Astronomical Constants and recommends that it be used in the national and international astronomical ephemerides at the earliest practicable date.’”

scholarly journals Proceedings of the Joint Discussion: Arguments in Favor of the Revision of the Conventional System of Astronomical Constants

1966 ◽  
Vol 12 (2) ◽  
pp. 604-606
Author(s):  
W. Fricke
Keyword(s):  
Executive Committee ◽  
Working Group ◽  
General Assembly ◽  
Conventional System ◽  
International Astronomical Union ◽  
International Astronomical ◽  
Astronomical Constants

The Chairman, W. Fricke, President of Commission 4, opened the Joint Discussion by drawing attention to the purpose and proposed procedure for the meeting. The Joint Discussion had been arranged by the Executive Committee of the Union in order to avoid the necessity for separate discussions by each Commission that was affected by the Report of the Working Group on the IAU System of Astronomical Constants. The Organizing Committee therefore proposed the following resolution:‘The members of the IAU at this Joint Discussion recommend to the Executive Committee that the following resolution be put before the General Assembly: “The International Astronomical Union endorses the final list of constants prepared by the Working Group on the System of Astronomical Constants and recommends that it be used in the national and international astronomical ephemerides at the earliest practicable date.’”

scholarly journals Secular evolution of close-in planets: the effects of general relativity

2020 ◽  
Vol 493 (1) ◽  
pp. 427-436
Author(s):  
F Marzari ◽  
M Nagasawa
Keyword(s):  
General Relativity ◽  
Numerical Integration ◽  
Time Scales ◽  
Initial Conditions ◽  
Outer Planet ◽  
Secular Perturbations ◽  
Secular Evolution ◽  
Eccentric Orbits ◽  
Wide Range ◽  
Comparable Time

ABSTRACT Pairs of planets in a system may end up close to their host star on eccentric orbits as a consequence of planet–planet scattering, Kozai, or secular migration. In this scenario, general relativity and secular perturbations have comparable time-scales and may interfere with each other with relevant effects on the eccentricity and pericenter evolution of the two planets. We explore, both analytically and via numerical integration, how the secular evolution is changed by general relativity for a wide range of different initial conditions. We find that when the faster secular frequency approaches the general relativity precession rate, which typically occurs when the outer planet moves away from the inner one, it relaxes to it and a significant damping of the proper eccentricity of the inner planet occurs. The proper eccentricity of the outer planet is reduced as well due to the changes in the secular interaction of the bodies. The lowering of the peak eccentricities of the two planets during their secular evolution has important implications on their stability. A significant number of two-planet systems, otherwise chaotic because of the mutual secular perturbations, are found stable when general relativity is included.

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