NASA's James Webb Space Telescope

Seeing Through the Glare with JWST Coronagraphy

News Feature September 17, 2018

Image of MIRI field of view, showing its four coronagraphs.

The coronagraphic capabilities provided by the James Webb Space Telescope (JWST) will reveal faint structures otherwise hidden by the glare of a bright point source. In many fields of astrophysics, this capability can greatly expand the current frontiers. Owing to the optical stability of the instrument, the freedom from atmospheric turbulence, and low infrared backgrounds in space, JWST will provide a much higher sensitivity and wider field of view in the infrared than current high-contrast AO systems.

JWST has a wide range of coronagraphic capabilities in the near to mid-infrared, providing a unique discovery space for subjects such as:

  • The direct detection and characterization of planetary companions orbiting a variety of stars.
  • Measuring structures in protoplanetary and debris disks, and identifying locations of forming planets or the influence of unseen planets on the circumstellar material.
  • Studies of circumnuclear environments in active galaxies and probing the connection between star-formation and outflows powered by the central supermassive black holes.

 Coronagraphic imaging is offered by both JWST’s Mid-InfraRed Instrument (MIRI) and Near-InfraRed Camera (NIRCam). MIRI coronagraphy is offered in wavelength bands from 10 to 23 μm, using one Lyot-type coronagraph and three 4-quadrant phase-mask (4QPM) coronagraphs. NIRCam offers Lyot coronagraphy with three round and two bar-shaped coronagraphic masks at wavelengths between 2–5 µm.

Detailed information on the instrument-specific coronagraphic modes, including allowed mask-filter combinations, is available on JDox. Another type of high-contrast imaging is offered by the aperture masking interferometric mode of NIRISS.