Orbital Inclination of Astrometric Binaries and the Dearth of Face-on Orbits in Gaia DR3 Solutions
The orbital solutions for astrometric (unresolved) binary stars provided in the Gaia mission DR3 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 interme...
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| Main Author: | |
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| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2025-01-01
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| Series: | The Astrophysical Journal Letters |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/2041-8213/adb840 |
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| Summary: | The orbital solutions for astrometric (unresolved) binary stars provided in the Gaia mission DR3 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. |
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| ISSN: | 2041-8205 |