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NASA/Desiree Stover

The launch of a new era: Leiden and the James Webb telescope (part II)

After 25 years, December will finally see the launch of the long-awaited James Webb space telescope. Leiden astronomers are watching with great excitement: not only were they involved in the construction of important instruments on board, the telescope will also reveal many new secrets of the universe, both foreseen and unforeseen.

In the first article about Webb, you could read what makes this new telescope so special, and how Leiden scientists contributed to the most important measuring instrument on board. In this part: several Leiden astronomers will soon be able to work with the new, unprecedented data James Webb will provide us with.

In a galaxy far, far away...

Ewine’s upcoming research on planet-forming disks keeps her relatively close to home, but with James Webb we will also be able to zoom in on areas much further away than ever before. This will allow us, so to speak, to look back in time (see box). And that’s exactly what Professor of Cosmology Joe Hennawi will be doing. He investigates the origin of black holes and will be one of the first astronomers to get to work with Webb. ‘We are going to look at the most distant quasars in the universe,' he says. ‘These are supermassive black holes surrounded by a gaseous accretion disc.’

Looking back in time?

The further you look into space, the further you look back in time. This is explained by the speed of light. Light travels at 300,000 kilometres per second and only when the light from an object reaches your eyes, do you actually 'see' it. Objects in the universe are so far away that the light takes a while to reach our earth and eyes.

For example, the moon is 400,000 kilometres away: a 1.3-second journey for light. As a result, you always see the moon as it looked like 1.3 seconds ago. For objects even further away, such as the Andromeda Nebula at 2.2 million light years, this effect is even greater. We see it as it was 2.2 million years ago, when the first humans populated the African steppe. 

Source: NemoKennislink

The complete story

‘It is a great challenge to understand how these quasars form and grow, because the process takes tens of millions of years. So we, as humans, can never witness it from beginning to end. We therefore look at different quasars of different ages, in order to be able to tell the complete story.'

Artist impression of the James Webb Space Telescope in space. Credits: ESA

Looking right through interstellar dust

Astronomer Jacqueline Hodge leads a programme to reveal the hidden stars in the most highly star-forming galaxies in the Universe. ‘Though these distant galaxies -- seen as they were only a couple billion years after the Big Bang -- were discovered already several decades ago, they are notoriously difficult to see with “classical” optical telescopes like the Hubble Space Telescope,’ she tells. ‘This is due to their extreme reservoirs of interstellar dust, which block out the starlight almost entirely. The upcoming observations will reveal these populations of stars for the first time, helping to resolve the long-standing debate over their nature.’

2000 hours of star gazing

In total, the Leiden Observatory is involved in 1400 hours of observation time with Webb, if you also add the observation time via the instrument teams, you come to a total of 2000 hours for Leiden.

In total, 8 Leiden prinicipal investigators had successful open time proposals:

  • Mauro Stefanon (Leiden)
  • Michael Maseda (Leiden, Wisconsin)
  • Melissa Mcclure (Leiden) (2 times)
  • Ewine van Dishoeck (Leiden)
  • Mariska Kriek (Leiden, Berkeley)
  • Tomas Stolker (Leiden)
  • Jackie Hodge (Leiden)
  • Michiel Min (Leiden, SRON)

In addition, many researchers are involved in other proposals.

No more star formation?

Professor of Extragalactic Astronomy Mariska Kriek will use her observation time to unravel the genesis of galaxies. For example, with new, much more detailed data about the chemical composition of stars and the speed at which they move. 'I want to try and solve an astronomical mystery: why do some galaxies stop forming stars?

What if it explodes?

During lunch, Kriek and her colleagues anxiously joke about what to do if the telescope explodes in the atmosphere at launch. And Van Dishoeck also knows that there are a lot of critical moments. ‘The rocket must leave the earth safely, make a smooth journey to its destination - 1.5 million kilometres away - unfold and then everything must start working perfectly,' she told the Financieel Dagblad. ‘The smallest mistake can ruin the whole enterprise.’

‘But well,’ Kriek says laughing, ‘people who can build a telescope like this are so smart, I have every confidence in them. The telescope will be revolutionary no matter what. I’m probably most excited for the things we don’t know yet: things we currently don’t even know exist!

Experience the launch in Leiden

Exciting news! On 25 December, James Webb will finally be launched into space. One day before, on Friday 24 December, Leiden astronomers Ewine van Dishoeck and Bernhard Branl will give lectures on Webb between 11.00-12.00 hrs. Ewines talk will be in Dutch, Bernhards English lecture will start at 11.30.
The lectures will be streamed via YouTube. The launch itself can be followed via a joint NASA-ESA webcast.

More information can be found in our agenda.

Webb in miniature
Going for a walk during the lockdown? Rijksmuseum Boerhaave has a 1:10 scale model of Webb on display. It’s placed in the foyer so it’s visible from the street side. And when our Faculty opens again, your more than welcome to check out our -slightly smaller 1:20 JWST model at the ground floor of the Huygens lab/Oort building, just in front of the Sitter lecture hall.

Media attention

Various media spoke with Leiden scientists about the upcoming launch of James Webb. A small selection of the international media attention:

Headerphoto: The deployed primary mirror of NASA's James Webb Space Telescope looks like a spring flower in full bloom. Credits: NASA/Desiree Stover

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