New device will investigate the origin of the Milky Way

Stars

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 map 1,000 stars per hour until it has cataloged a total of five million.

A superfast mapping unit attached to the WHT will analyze the composition of each star and the speed at which it is moving.

It will show how our Milky Way was built up over billions of years.

Prof Gavin Dalton from Oxford University has spent more than a decade developing the instrument, known as the ‘Weave’.

He told me he was “extremely excited” that it’s ready to go.

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

Weaving Instrument: It looks like a large metal disc crossed by fiber optic tubes that point to all points on the compass.  Robot arms hover over it.

Weave’s nimble robotic fingers precisely place a thousand fiber optics, each one pointed at a star

Weave is installed at WHT, 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 each part of the sky WHT points to, astronomers identify the positions of a thousand stars. Weave’s nimble robotic fingers then carefully place a fiber optic — a light-transmitting tube — precisely at each spot on a disk, pointing toward the corresponding star.

These fibers are actually small telescopes. Each captures light from a single star and channels it to a different instrument. This then divides it into a rainbow spectrum, which contains the secrets of the star’s origin and history.

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

The Milky Way

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

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

It grew from successive mergers with other small galaxies over billions of years. In addition to the addition of stars from the new galaxies joining ours, each merger stirs things up enough to lead to entirely new star formation.

Weave is able to calculate the speed, direction, age, and composition of each star it observes, essentially creating a cinematic image of stars moving through the Milky Way. According to Prof Dalton, by extrapolating backwards it will be possible to reconstruct the entire formation of the Milky Way in detail that has never been seen before.

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

Dr Marc Balcells, who is in charge of the WHT, told BBC News that he believed Weave would lead to a major shift in our understanding of how galaxies form.

”We have heard for decades that we are in a golden era of astronomy – but what the future holds is much more important.

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

Control room

Instrument specialist Dr. Cecilia Farina says that Weave can detect a completely unexpected phenomenon

Dr Cecilia Farina, an instrumentation specialist on the project, said she believed Weave would make astronomical history.

“There’s a huge amount of things we’re going to discover that we didn’t expect to find,” she 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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