Analysing weak orbital signals in Gaia data
Abstract
Anomalous orbits are found when minimum-χ2 estimation is applied to synthetic Gaia data for orbits with astrometric signatures comparable to the single-scan measurement error (Pourbaix 2002, A&A, 385, 686). These orbits are nearly parabolic, edge-on, and their major axes align with the line-of-sight to the observer. Such orbits violate the Copernican principle (CPr) and as such could be rejected. However, the preferred alternative is to develop a statistical technique that incorporates the CPr as a fundamental postulate. This can be achieved in a Bayesian context by defining a Copernican prior. Pourbaix's anomalous orbits then no longer arise. Instead, the selected orbits have a somewat higher χ2 but do not violate the CPr. The problem of detecting a weak additional orbit in an astrometric binary with a well-determined orbit is also treated.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- November 2014
- DOI:
- 10.1051/0004-6361/201424405
- arXiv:
- arXiv:1406.3977
- Bibcode:
- 2014A&A...571A..86L
- Keywords:
-
- binaries: visual;
- stars: fundamental parameters;
- methods: statistical;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- 9 pages, 12 figures. Matches published version. Accepted by A&