New device will investigate the origin of the Milky Way


Where did the stars in our night sky come from?

Scientists have supercharged one of Earth’s most powerful telescopes with new technology that will reveal how our galaxy formed in unprecedented detail.

The William Herschel Telescope (WHT) in La Palma, Spain will be able to survey 1,000 stars per hour until it records a total of five million.

An ultra-fast mapping device attached to the WHT will analyze the composition of each star and the speed at which it is traveling.

It will show how our Galaxy was formed over billions of years.

Professor Gavin Dalton of the University of Oxford has spent over a decade developing the instrument, known as the ‘Weave’.

He told me he was “beyond excited” to be ready to go.

“It’s a fantastic achievement by a lot of people to make this happen and it’s great that it’s working,” he said. “The next step is the new adventure, it’s brilliant!”

Weaving Instrument: Looks like a large metal disc criss-crossed by fiber optic tubes pointing to all compass points.  Robotic arms hover above him.

Weave’s nimble robotic fingers precisely place a thousand optical fibers, each pointed at a star

Weave is installed at WHT, which is located high on a mountaintop on the Spanish Canary Island of La Palma. The name stands for WHT Enhanced Area Velocity Explorer – and that’s exactly what it does.

It has 80,000 separate parts and is an engineering marvel.

For every patch of sky that the WHT traverses, astronomers determine the positions of a thousand stars. Weave’s nimble robotic fingers then carefully place an optical fiber—a tube that transmits light—at exactly each location on a plate, pointing toward the corresponding star.

These fibers are actually tiny telescopes. Each captures light from a single star and channels it into another instrument. This then separates it into a rainbow spectrum, which holds the secrets of the star’s origin and history.

All this is completed in just one hour. While this is happening, the optics for the next thousand stars are placed on the back side of the plate, which flips over to analyze the next set of targets once the previous survey is complete.


Artwork: The Milky Way is surrounded by “dwarf” satellite galaxies

Our galaxy is a dense spiral vortex with up to 400 billion stars. But it started as a relatively small collection of stars.

It developed from successive mergers with other small galaxies over billions of years. In addition to adding stars from the new galaxies merging with our own, each merger shakes things up enough to lead to brand new star formation.

Weave is able to calculate the speed, direction, age and composition of each star it observes, essentially creating a cinematic film of stars moving through our Galaxy. According to Professor Dalton, by extrapolating backwards, it will be possible to reconstruct the entire formation of the Milky Way in unprecedented detail.

“We will be able to trace the galaxies that have been absorbed as the Milky Way has formed over cosmic time – and see how each absorption triggers the formation of new stars,” he said.

Dr Marc Balcells, who is director general of the WHT told BBC News that he believed Weave would lead to a big change in our understanding of how galaxies form.

”We’ve been hearing for decades that we’re in a golden age of astronomy – but what the future holds is far more important.

“Weave will answer questions that astronomers have been trying to answer for decades, such as how many pieces come together to make a large galaxy, and how many galaxies came together to make the Milky Way?”

Control room

Instrument expert Dr Cecilia Farina says Weave may discover a completely unexpected phenomenon

Dr Cecilia Farina, an instrument expert on the project, said she believed Weav would make astronomical history.

“There are so many things we’re going to discover that we didn’t expect to find,” he said. “Because the Universe is full of surprises.”

You can see Weave and other new telescopes in action in a short film, The Cosmic Hunters, on BBC iPlayer.

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