Astronomy in New Zealand

The Planet Finders

Over 150 planets outside the solar system have been found since the first was detected in 1995. In 1999 Denis and Tiri Sullivan confirmed the existence of an extra-solar planet when they recorded a drop in the luminosity as a planet passed in front of the star HD209458 - detecting planetary transits is extremely rare as the plane of the planet'´s orbit has to be precisely aligned with the observer.

Most extra-solar planets discovered have been "hot Jupiters" (massive planets in small orbits) detected around nearby stars using the radial velocity technique - the gravitational "wobble" the planet induces in the parent star. Microlensing, a technique pioneered by New Zealander Charles Alcock, currently director of the Harvard-Smithsonian Centre for Astrophysics, is more sensitive to finding smaller planets orbiting at larger distances around distant stars.

Microlensing occurs when light from a distant star or galaxy is bent by the gravity of an intervening star passing directly in front. This produces a magnified, distorted image, the "Einstein ring", which registers as a temporary brightening of the star; small "defects" in the brightening indicate planets around the star.

The MOA project using events of high magnification has been involved in the discovery of every extra-solar planet detected by microlensing. Canterbury astronomers Michael Albrow and Karen Pollard are founding members of PLANET, another successful international microlensing collaboration.

In 2005 Grant Christie and Jennie McCormick of Auckland Astronomical Society, members of MicroFUN, became the first amateurs to have contributed to the discovery of a planet since William Herschel discovered Uranus in 1781.

Research Areas

• University of Canterbury and the Mount John Observatory 
• Radio Astronomy 
• The Planet Finders 
• Astrophysics 
• Cosmic Rays