| Author(s): | Wielen, R. |
| Title: | Statistical aspects of stellar astrometry and their implications for high-precision measurements |
| Source: | In: Future possibilities for astrometry in space, Proc. RGO-ESA Workshop, Cambridge, UK, 19-21 June 1995; M.A.C. Perryman, F. van Leeuwen (eds.), ESA SP-379, Noordwijk, p. 65 |
| Year: | 1995 |
| Abstract: | Astrometric binaries represent a challenge for high-precision astrometry. Since astrometric binaries are frequent, their non-linear orbital motions (of the photo-center of the binary with respect to the center-of-mass) may be considered as `cosmic errors' in the positions and proper motions of an ensemble of stars, if one assumes (wrongly) linear motions for all the stars. We outline a coherent scheme for `statistical astrometry' which takes the statistical effect of astrometric binaries on astrometric procedures into account. The basic tools are correlation functions between the orbital displacements in position and velocity of a binary. We estimate the `cosmic errors' in position and proper motion, and find that they are much larger than the measuring errors of a mission like GAIA. We discuss some implications of the astrometric-binary nature of many of the stars on the strategy of a mission and on the applications of the results. We emphasize that the data reduction procedure should include the accurate modelling of a possible orbital motion of all the stars. Then, for example, the high measuring accuracy of the parallaxes would not be lowered for most of the stars. |
| Preprint issued: | August 1995 |
| Remarks: |
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