A vortex coronagraph is a type of optical instrument for telescopes that blocks out the glare of bright objects (like stars) so that smaller objects near them can be seen. For example, extrasolar planets near their host star as seen from Earth or space telescopes in Earth's solar system. It is a type of

coronagraph A coronagraph is a telescopic attachment designed to block out the direct light from a star so that nearby objects – which otherwise would be hidden in the star's bright glare – can be resolved. Most coronagraphs are intended to view t ...

. In 2005 a paper described a method for astronomy, by which the light of a parent star could be blocked, while keeping the light from nearby but dimmer exoplanets (or whatever the companion is). Up until the year 2010,

telescopes A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to observe ...

could only directly image exoplanets under exceptional circumstances. Specifically, it is easier to obtain images when the planet is especially large (considerably larger than

Jupiter Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth t ...

), widely separated from its parent star, and hot so that it emits intense infrared radiation. However, in 2010 a team from

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the US federal government responsible for the civil List of government space agencies, space program ...

Jet Propulsion Laboratory The Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center in the City of La Cañada Flintridge, California, United States. Founded in the 1930s by Caltech researchers, JPL is owned by NASA an ...

demonstrated that a vortex coronagraph could enable small telescopes to directly image planets. They did this by imaging the previously imaged

HR 8799 HR 8799 is a roughly 30 million-year-old main-sequence star located away from Earth in the constellation of Pegasus. It has roughly 1.5 times the Sun's mass and 4.9 times its luminosity. It is part of a system that also ...

planets using just a 1.5 m portion of the 5 meter

Hale Telescope The Hale Telescope is a , 3.3 reflecting telescope at the Palomar Observatory in San Diego County, California, US, named after astronomer George Ellery Hale. With funding from the Rockefeller Foundation in 1928, he orchestrated the planning, de ...

. Vortex coronographs have been used in conjunction with

adaptive optics Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effect of incoming wavefront distortions by deforming a mirror in order to compensate for the distortion. It is used in astronomical tele ...

for astronomy. A vortex coronograph was used on the

Keck Observatory The W. M. Keck Observatory is an astronomical observatory with two telescopes at an elevation of 4,145 meters (13,600 ft) near the summit of Mauna Kea in the U.S. state of Hawaii. Both telescopes have aperture primary mirrors, and when co ...

by 2017. The VC was installed on infrared camera at Keck, and allowed bodies to be viewed 2–3 times closer to a parent star than before. HIP 79124 B was imaged at a distance of 23

astronomical unit The astronomical unit (symbol: au, or or AU) is a unit of length, roughly the distance from Earth to the Sun and approximately equal to or 8.3 light-minutes. The actual distance from Earth to the Sun varies by about 3% as Earth orbits ...

s from its host star with a vortex coronograph on the Keck telescope, and it was called a brown dwarf. Next generation VCs are able to dim multiple sources of light. It will be thus possible to use them to image planets around multi-star systems.

References

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External links

High Contrast Imaging with the New Vortex Coronagraph on NACO
(PDF)
The optical vortex coronagraphThe Vector Vortex Coronagraph: sensitivity to central obscuration, low-order aberrations, chromaticism, and polarization
Telescope instruments Astronomy articles needing attention Astronomy articles needing expert attention

See also

References

External links