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New Zealand astronomers have found a new solar system - a scaled-down version of our own - among distant stars in the Milky Way.

A total of 69 scientists in 11 countries provided data and contributed to the discovery, including Paul Tristram at Canterbury's Mt John Observatory.

Mr Tristram - part of the Microlensing Observations in Astrophysics (MOA) collaboration between Japan and New Zealand - was the first New Zealander to detect the solar system.

He used a technique known as gravitational microlensing, based on an effect predicted by Albert Einstein in 1915.

An almost perfect alignment between a background source star, a "lens star", and an observatory allows researchers to detect a planet through the effect of its gravitational field on light from a more distant background star.

The technique was developed partly at Auckland University and is particularly effective in identifying faint or dark objects, using any electromagnetic radiation emitted from the further object to view it.

An alignment of two stars in the constellation of Sagittarius, catalogued as OGLE-2006-BLG-109, was identified by Polish astronomers, led by Professor Andrzej Udalski of Warsaw University, using a telescope based in Chile.

Other astronomers globally - including New Zealanders - continued to monitor the alignment, and the results of their observations are published in this week's issue of the international journal Science.

"It has been an exciting project, really highlighting the international cooperation possible when the scientific stakes are high," said a MOA collaborator, Associate Professor Philip Yock of Auckland University.

Other New Zealand astronomers involved include microFUN collaborators Dr Grant Christie at the Stardome Observatory and amateur astronomer Jennie McCormick at her Farm Cove observatory in Pakuranga; PLANET member Dr Michael Albrow of Canterbury University; and more university-based MOA members, Dr Ian Bond (Massey), lead investigator for the project in New Zealand, Dr Winston Sweatman (Massey), Dr Denis Sullivan (Victoria University) and Professor John Hearnshaw (Canterbury).

Dr Scott Gaudi and Professor Andrew Gould of Ohio State University and Associate Professor David Bennett of Notre Dame University collated and analysed the data from all the telescopes involved.

Their analysis revealed the nearer star was a red dwarf, a smaller and cooler version of our Sun, orbited by two giant planets somewhat smaller than Jupiter and Saturn in earth's solar system.

The complete system has been likened to a half-size version of the Sun, Jupiter and Saturn.