Orbital inclination of astrometric binaries and the dearth of face-on orbits in Gaia DR3 solutions
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arXiv
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| _version_ | 1866915176385609728 |
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| author | Makarov, Valeri V. |
| author_facet | Makarov, Valeri V. |
| contents | The orbital solutions for astrometric (unresolved) binary stars provided in the Gaia mission Data Release 3 reveal an obvious deficit of face-on orbits with line-of-sight inclinations close to 0 or $π$. This is shown to be an intrinsic mathematical feature of the orbit estimation technique involving the intermediate Thiele-Innes parameters, which are transformed to the Campbell geometric parameters. A direct condition equation defining the inclination angle via the Thiele-Innes values independently of the other orbital elements is used to investigate the origin of this near-degeneracy for face-on orbits. The emerging bias and correlation of inclination and semimajor axis are illustrated using Monte Carlo simulations for two specific template configurations representing face-on and edge-on orbits. The results have significant impact on the interpretation and follow-up confirmation of Gaia-detected binary systems, including candidate exoplanets and brown dwarf companions. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2502_20553 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Orbital inclination of astrometric binaries and the dearth of face-on orbits in Gaia DR3 solutions Makarov, Valeri V. Solar and Stellar Astrophysics Earth and Planetary Astrophysics The orbital solutions for astrometric (unresolved) binary stars provided in the Gaia mission Data Release 3 reveal an obvious deficit of face-on orbits with line-of-sight inclinations close to 0 or $π$. This is shown to be an intrinsic mathematical feature of the orbit estimation technique involving the intermediate Thiele-Innes parameters, which are transformed to the Campbell geometric parameters. A direct condition equation defining the inclination angle via the Thiele-Innes values independently of the other orbital elements is used to investigate the origin of this near-degeneracy for face-on orbits. The emerging bias and correlation of inclination and semimajor axis are illustrated using Monte Carlo simulations for two specific template configurations representing face-on and edge-on orbits. The results have significant impact on the interpretation and follow-up confirmation of Gaia-detected binary systems, including candidate exoplanets and brown dwarf companions. |
| title | Orbital inclination of astrometric binaries and the dearth of face-on orbits in Gaia DR3 solutions |
| topic | Solar and Stellar Astrophysics Earth and Planetary Astrophysics |
| url | https://arxiv.org/abs/2502.20553 |