It seems counterintuitive, but restricting the amount of light that reaches a telescope can sharpen up its output. The technique will be used on NASA’s successor to the Hubble Space Telescope: the James Webb Space Telescope. But it is already proving its worth here on Earth.

Images of the binary star known as Wolf-Rayet 104 (WR104), published in 2008 by Peter Tuthill of the University of Sydney, reveal the power of the new technique, which is known as aperture masking. WR104 should be difficult to see because it is in a deep cloud of dust, but Peter and his colleagues used aperture masking when observing the star with the Keck telescope in Hawai’i. The mask leads to sharper images because it cuts down complexity and makes the data easier to process and rid of error.

WR104, which can be described as two stars circling around each other spraying out particles in a spiral like a massive lawn sprinkler in the sky, is about 8,000 light years away from Earth in the constellation of Sagittarius. “WR104 is a beautiful, beautiful thing,” says Peter. Wolf-Rayet stars, however, are, by definition, at the end of the line. They have reached the stage where almost all the hydrogen that fuels them has been converted into helium. WR104 will undergo a supernova explosion within the next few hundred thousand years.

“WR104 is a desirable system to study because it displays a lot of physics we couldn’t otherwise get at,” Peter explains. “It’s at the hairy, extreme end of star systems where things are quite unknown, and cause all the stellar fireworks.” The images of WR104 show the two circling stars seemingly face-on to the Earth. More recent evidence, however, suggests that the system is angled far enough away from Earth to prevent the remote possibility of a dose of radiation heading our way when the system blows.

PHOTO: A FALSE-COLOUR COMPOSITE IMAGE OF 11 FRAMES SHOWING THE 8-MONTH CIRCULAR ROTATION OF THE BINARY STAR, WOLF-RAYET 104. CREDIT: PETER TUTHILL.

Sydney Institute for Astronomy, University of Sydney
Dr Peter Tuthill, Tel: +61 (2) 9351 3679, p.tuthill@physics.usyd.edu.au, www.physics.usyd.edu.au/~gekko