Potential of long-baseline infrared interferometry for narrow-angle astrometry

摘要: Narrow-angle astrometry has many astrophysical applications, from the measurement of parallaxes to search for planets around nearby stars. Ground-based long-focus telescopes with photoelectric detectors have achieved accuracies about 2-3 milliarcsec in 1 h. This accuracy is limited primarily by atmosphere, and consistent models atmospheric turbulence. However, applying these turbulence observations long-baseline interferometers yields astrometric errors that are far smaller than can be telescopes. The predictions ultimate ground-based narrow-angle using IR (2.2 micron) stellar very promising. With excellent seeing at a high altitude site like Mauna Kea, limit h expected order 10 microarcsec integration. two-order-of-magnitude improvement over conventional measurements due two effects. One interferometer find useful reference stars near an arbitrary target star, so atmospherically-induced motions both highly correlated. second baseline length much larger separation beams turbulent resulting reduction error increasing length.