The first scientific observations from the Gemini North telescope have provided a dramatic glimpse into the elusive core of the Milky Way. Gemini has revealed clearly, for the first time a fast-moving star that is ploughing through a gas and dust cloud, near the centre of our Galaxy. Passing through the cloud, the star creates a very obvious bow-shock wave, similar to the wave that forms in front of a boat as it goes through water. The object, known by the unglamorous name of IRS8, was only an ill-defined smudge until Gemini came along.

Galactic center. Photo: Photo courtesy of Gemini Observatory, National Science Foundation and the University of Hawaii Adaptive Optics Group

This discovery could alter our understanding of the relationship between the stars and gas clouds and the nucleus of our galaxy, which is believed to harbour a massive black hole. The Gemini image clearly shows that the star is passing through the gas cloud, suggesting that the cloud is falling in towards the Galactic centre. Examination of the shock-excited material will provide new evidence of the cloud's motion and composition, and perhaps of its ultimate fate.

The Gemini telescopes use a new technology called 'adaptive optics' and the effectiveness of this technology is clearly demonstrated by comparing the same region of sky viewed under natural seeing conditions with the new images from Gemini.

The extent and extreme clarity of the Gemini infrared images offer tantalising hints that the centre of our galaxy is home to even more exotic objects than once believed.

Zoomed in view of bow-shock. Photo: Photo courtesy of Gemini Observatory, National Science Foundation and the University of Hawaii Adaptive Optics Group

Dr Patrick Roche, UK Gemini Project scientist said "This surprise discovery from Gemini has given us a new way to explore the cold gas clouds in the central parts of our Galaxy. I hope it's the first of many discoveries both within our own galaxy and at the edge of the Universe".

The image released represents only a fraction of the total data available to scientists from this study. "Never before have we seen such a large area of the Galactic centre this clearly," said Dr. Francois Rigaut of the Gemini Observatory, who led the project.

Professor Ian Halliday, Chief Executive of the Particle Physics and Astronomy Research Council said 'The UK has a 25% stake in the Gemini telescope project and these first pictures from Gemini North demonstrate what a powerful astronomical tool we now have. I look forward to Gemini South reaching completion next year and to many years of fruitful exploration of our Universe."

"This is the first scientific data to be released to the astronomical community by the Gemini Observatory," says project Director Dr. Matt Mountain, "and to be able to release such a spectacular image and data set shows the tremendous potential of these telescopes."

The new observations
Observing the Galactic centre is especially difficult because its light must travel through thousands of light-years of gas and dust before we can see it from Earth. Only a small portion of the light ever makes it to our planet and most of that is in the infrared (or heat) part of the spectrum.

The Gemini Observatory has been designed to make the most of the trickle of infrared radiation from space by using sophisticated new technologies like adaptive optics that corrects for distortions to starlight caused by turbulence in the Earth's atmosphere and infrared optimisation that capitalises on the ideal infrared conditions on the summit of Mauna Kea, a 14000' high volcano in Hawaii.

The data released today were taken at several infrared wavelengths and combined to create a "colour" image.

The data were obtained over several nights in July and August as part of a preliminary science testing period as the Gemini North telescope nears completion on Mauna Kea in Hawaii. The Gemini image measures 36 arcsec x 39 arcsec corresponding to a size of 1.5 parsecs or 5 light years at the distance of the Galactic centre (25000 light years).