Six telescopes link to image stars

17 Jun 2002

Astronomers have combined light from six optical telescopes to produce high-resolution images of stars.

A collaboration of US astronomers has, for the first time, combined the light from six optical telescopes. The team says that the approach, known as optical interferometry, is an alternative to large, monolithic single-mirror telescopes that are both expensive and difficult to produce.

This technique has been used to produce high-resolution images of multiple-star systems. To obtain this level of detail with a single, monolithic telescope would require mirror in excess of 50 meters in diameter.

Kenneth Johnston, scientific director of the US Naval Observatory (UNSO) who is part of the team, explained: "This development makes it possible to 'synthesize' telescopes with apertures in excess of hundreds of meters. It will lead to direct imaging of the surfaces of stars and can also be applied to space-based systems for remote sensing of the Earth and other objects in the solar system."

Called the Navy Prototype Optical Interferometer (NPOI), the six-telescope combination is said to have more than quadrupled the data-collection capability of NPOI over its competitors.

To merge the six beams, the NPOI researchers designed a hybrid beam combiner. They then developed hardware and control systems to ensure that the all light collected was properly decoded and the images reconstructed accurately.

"Stellar astrophysics will be revolutionized by the capability to directly image stars other than the Sun," said Johnston. "When employed in space with the experience collected from ground-based experiments, optical interferometry may give us the ability to image Jupiter-sized planets orbiting distant stars," he added.

Astronomers from the US Naval Observatory, the Naval Research Laboratory and the Lowell Observatory form the collaboration. Located at Lowell's Arizona site, the interferometer observed the triple star system Eta Virginis, which is about 130 light-years from Earth.

Author
Jacqueline Hewett is news reporter on Optics.org and Opto & Laser Europe magazine.