NARIT Tech
Elevate astronomical research
with the Evanescent Wave Coronagraph (EvWaCo),
the world's first and most advanced model made in Thailand
Today, we introduce the novel optical research instrument called Evanescent Wave Coronagraph, abbreviated as EvWaCo, which is an innovative model of coronagraph that reduces the brightness of stars and is primarily used for binary stars and exoplanets exploration. Thai scientists and researchers at the National Astronomical Research Institute of Thailand (NARIT) developed this cutting-edge state-of-the-art instrument, which is the world's first of its kind.
The EvWaCo was designed to observe stars in the near-infrared and visible wavelengths. The instrument can be used both on the ground and in space to find and study exoplanets, as well as to observe binary stars, quasars, and the center of the galaxy.
The EvWaCo is an optical research instrument developed by NARIT's Center for Optics and Photonics to address an astronomical research problem: investigating exoplanets orbiting massive and very bright stars. When using a telescope to observe or collect data, the sheer brightness of a bright star frequently blocks the light of its “companion star” (a less bright star or planet surrounding that star).
Currently, observing a companion star orbiting an extremely bright star requires the use of an occult disk (a light blocker), a device that reduces brightness in order to reduce the amount of light from the star. However, this device will also block the light from the companion star being investigated.
For this reason, the team of astronomers at NARIT has developed an instrument that effectively reduces the light of the star without blocking or reducing the amount of light from the companion star. The concept of developing such a device has been around for a long time. Originally, a prism was attached to a lens and used an air gap that was not at the point where the lens and prism met (in the main axis), causing the light that fell outside the main axis to refract in different directions. The light of the star will be placed on the main axis, while the light of the companion star will be outside the main axis and refract in another direction. This allows astronomers to take the light of the star and the light from the refracted companion star for further study.
The EvWaCo mainly consists of two components, namely:
1) A new type of light blocker to reduce the amount of stellar light without blocking the light of the object to be observed, allowing the study of exoplanets orbiting close to their host star or even studying binary star systems whose members have very different brightnesses.
2) Adaptive optics system to correct for the effects of atmospheric variability by using wavefront sensor and adjusting the wavefront with a high-frequency deformable reflector, resulting in a sharper image.
NARIT plans to set up the EvWaCo at the Thai National Observatory (TNO) on Doi Inthanon in Chiang Mai in the middle of this year to be used with the 2.4-meter diameter National Telescope, as well as develop the next generation coronagraph system for larger telescopes (6-8 meters in diameter) in collaboration with international astronomical research agencies.