An Etymological Dictionary of Astronomy and Astrophysics
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1) Relating to or exhibiting adaptation.
2) Capable of adapting or of being adapted. → adaptive optics; → adaptive optics system; → extreme adaptive optics.

→ adapt; → -ive.

A type of → algorithm that dynamically achieves high → resolution in localized regions of multidimensional → numerical simulations. AMR provides a higher → accuracy solution at lower costs, through an automatically → optimal distribution of → grid points for the computation region. It relies on locally refined mesh or mesh patches to increase the resolution of an underlying coarse mesh only where needed. It can alleviate some of the complexities of the generation of high quality grid and reduce the number of → iterations of "trial-and-error" between the grid generation and solution required for tailoring the grid to the specification of a problem. Thus, it can offer orders of magnitude saving in computational and storage costs over an equivalent uniformly refined mesh. AMR was originally developed for → inviscid, → compressible flow (Berger et al., 1984, Adaptive Mesh Refinement for Hyperbolic Partial Differential Equations. J. Comp. Phy., 53, 484). It has been extended to solve → Navier-Stokes equations, time dependent problems and more. Several AMR techniques have been developed and applied to compressible flow fields to capture characteristics at the strong gradient or discontinuous regions requiring higher space resolution, such as regions involving → shock waves, vortices (→ vortex), and → wakes (see, e.g., Qingluan Xue, "Development of Adaptive Mesh Refinement Scheme and Conjugate Heat Transfer Model for Engine Simulations" (2009), Iowa State Univ., Graduate Theses and Dissertations, Paper 10678).
See also → Smoothed Particle Hydrodynamics.

→ adaptive; → mesh; → refinement.

A technique for improving the → image quality of a telescope against → atmospheric turbulence in which image distortions are compensated by high-speed changes in the shape of a small, thin mirror. → wavefront; → wavefront distortion; → wavefront correction; → Strehl ratio; → tip-tilt mirror, → Shack-Hartmann wavefront sensor, → active optics.

→ adaptive; → optics.

An → adaptive optics instrument used on the → European Southern Observatory (ESO) 3.6-m telescope at La Silla. It was an upgraded version of COME-ON-PLUS, the → Very Large Telescope (VLT) adaptive optics prototype. It had 52 → actuators and performed corrections of the mirror 200 times per second. The reference → wavefront was sensed in the → visible. The observation was done in the → near-infrared (1-5 μm).

→ adaptive; → optics; → near-infrared; → system.

An → optical system that uses → adaptive optics.

→ adaptive; → optics; → system.

An → adaptive optics system with high-contrast imaging and spectroscopic capabilities. Extreme adaptive optics systems enable the detection of faint objects (e.g., → exoplanets) close to bright sources that would otherwise overwhelm them. This is accomplished both by increasing the peak intensity of point-source images and by removing light scattered by the atmosphere and the telescope optics into the → seeing disk.

→ extreme; → adaptive; → optics.