{"id":20011,"date":"2022-12-05T00:00:00","date_gmt":"2022-12-04T23:00:00","guid":{"rendered":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/?post_type=purple_issue&p=20011"},"modified":"2022-12-09T11:27:24","modified_gmt":"2022-12-09T10:27:24","slug":"james-webbs-first-year-in-space","status":"publish","type":"post","link":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/2022\/12\/05\/james-webbs-first-year-in-space\/","title":{"rendered":"James Webb\u2019s first year in space"},"content":{"rendered":"\n

JAMES WEBB\u2019S FIRST YEAR IN SPACE<\/span><\/h2>\n\n

IN JUST A FEW SHORT MONTHS, THE JAMES WEBB SPACE TELESCOPE HAS IMAGED THE UNIVERSE AS NEVER BEFORE. HERE ARE ITS BIGGEST DISCOVERIES SO FAR <\/strong><\/p>\n\n

WORDS: DR STUART CLARK <\/strong><\/span><\/p>\n\n

T<\/span>he first images beamed back from NASA\u2019s James Webb Space Telescope (JWST) have stunned the world this year. Launched on Christmas Day 2021, it took a month to arrive at its destination in space, a gravitational sweet spot 1.5 million kilometres further out into the Solar System. It then underwent an extraordinary sequence of deployment, unfurling a tennis-court-sized sunshield and unfolding a segmented mirror measuring 6.5 metres in diameter before any further work could take place.<\/p>\n\n

Once everything was powered up and online, operators began the painstaking job of commissioning the instruments and making sure everything was working correctly. <\/p>\n\n

The JWST is the largest telescope ever launched into space. It works at infrared wavelengths of light. These are rays that have a longer wavelength than the light we can see with our eyes. We generally perceive infrared radiation to be heat, which is why so-called \u2018thermal cameras\u2019 are infrared in nature.<\/p>\n\n

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The first image released by the JWST, unveiled by US President Joe Biden at the White House, is a deep field image of the galaxy cluster SMACS 0723<\/figcaption><\/figure><\/div>\n\n

Finally, on 11 July 2022, we got to see its first images. And they were breathtaking. Giant celestial landscapes of dust and gas were revealed, as were the deepest reaches of the Universe. There were huge, interacting galaxies, and dying stars in their final throes of life. <\/p>\n\n

But the images themselves, however mind-blowing, are just the tip of the iceberg. Behind them are mountains of data that are set to reshape our understanding of the Universe. From the deepest realms of the cosmos all the way home to the celestial backyard of our Solar System, there is not a single domain of the Universe that the JWST cannot make a meaningful investigation. <\/p>\n\n

In truth it is still early days for the actual results. Astronomers around the world are still getting used to the data that is now streaming down to Earth. But it is very clear that the JWST looks set to fulfil every science promise and then some. <\/p>\n\n

THE EARLY UNIVERSE<\/span><\/h4>\n\n

One of the JWST\u2019s science objectives is to look into the distant reaches of the Universe to see how the first galaxies were born. It can do this because light takes billions of years to cross our cosmos. When the JWST collects this light, it is seeing those objects as they looked billions of years ago. To reflect this fact, astronomers refer to distances in light-years, which is the distance light can travel in a year. And the first image to be released by the team highlighted this point. It was unveiled on 11 July 2022 by US President Joe Biden, speaking from the White House, and it was a \u2018deep field\u2019 image. Deep fields came to prominence in 1995 when the Hubble Space Telescope peered at a single patch of sky for 10 consecutive days, starting on 18 December. The selected patch was little more than a tiny speck, about one 24-millionth of the whole sky. Yet Hubble revealed around 3,000 previously unknown objects, mostly galaxies that are billions of light-years away. Centred around the galaxy cluster SMACS 0723, the JWST\u2019s deep field spans a similarly minuscule patch of sky. <\/p>\n\n

\u201cIt\u2019s the equivalent to having a grain of sand and holding it at arm\u2019s length, while standing on Earth. That grain of sand will blot out a small sliver of the sky, and yet there are thousands of galaxies and features that we\u2019ve never seen before just in that one image,\u201d says Caroline Harper, head of space science at the UK Space Agency. SMACS 0723 itself is 4.6 billion lightyears away. Its mighty gravitational field acts like a magnifying glass to more distant galaxies behind. Where the gravitational field is the strongest, it distorts the background galaxies into great arcs. In one case, the light from a distant galaxy was measured to have been travelling through space for 13.1 billion years before being collected by the telescope. <\/p>\n\n

As the Universe expands, it stretches the light that is being emitted. The JWST\u2019s main target galaxies are so far away that the stretching has transformed the visible light from their stars into infrared. So by collecting those wavelengths, astronomers can compare the JWST\u2019s observations directly with the visible light images of closer galaxies from Hubble and other observatories. This will reveal the way galaxies evolve through cosmic time, growing larger and building up into the shapes we see today. <\/p>\n\n

Perhaps the most amazing thing about the JWST\u2019s first deep field image is not just the number of galaxies, but the speed with which it can take such images \u2013 just hours, rather than days. In fact, it cannot help but detect galaxies almost everywhere it looks.<\/p>\n\n

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This galaxy emitted its light 13.1 billion years ago. It was captured by the JWST\u2019s microshutter array, part of its NIRSpec instrument. This is so sensitive that it can observe the light of individual galaxies that existed in the early Universe<\/figcaption><\/figure>\n\n

\u201cThe one big feature that jumps out with all the data is the fact that there\u2019s just so many galaxies. Everywhere you point \u2013 particularly in the near-infrared \u2013 you don\u2019t even have to integrate for very long, and you\u2019re gonna have like 200 galaxies all over the place,\u201d says Sarah Kendrew, an instrument and calibration scientist for the European Space Agency. <\/p>\n\n

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The Cartwheel Galaxy formed when a small, unseen galaxy passed through it. This sent a shockwave rippling outwards triggering the star formation captured here by the JWST\u2019s MIRI and NIRCam instruments<\/figcaption><\/figure>\n\n

It is not only galaxy clusters that are serving as magnifying glasses. The JWST\u2019s image of a pair of galaxies, catalogued as VV191, was taken so that the scientists could analyse how light from one of the pair changed as it passed through the other. The analysis will betray the characteristics of the dust in the intervening galaxy. <\/p>\n\n

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Composite image from the JWST and Hubble, showing two galaxies catalogued as VV191 <\/figcaption><\/figure><\/div>\n\n

Astronomers noticed that the telescope had also captured the faint arc of an even more distant galaxy, distorted by one of the galaxies they were studying. Because the lensed galaxy\u2019s shape depends on the mass of the lensing galaxy, they now have a way of measuring the mass of the galaxy that they did not have before. <\/p>\n\n

GALAXIES AND BLACK HOLES<\/span><\/h4>\n\n

One of the first images released by the JWST was of a small group of galaxies known as Stephan\u2019s Quintet. This collection of galaxies features four galaxies that are so close to one another that they are gravitationally interacting. The fifth galaxy in the grouping merely appears close. In reality, it is much closer to us and just happens to lie in the same line of sight. <\/p>\n\n

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Stephan\u2019s Quintet is a laboratory for studying gravitational interactions between galaxies. This image from NIRCam and MIRI contains more than 150 million pixels and is constructed from 1,000 separate image files <\/figcaption><\/figure><\/div>\n\n

Together, the quartet of interacting galaxies form a \u2018laboratory\u2019 in which astronomers can study the way galaxies interact and merge with each other. Such mergers are thought to have been exceptionally common in the early Universe, where they were the principal route for galaxies to grow into the gigantic star cities we see around us today. The mergers are also thought to be responsible for the growth of supermassive black holes, an example of which now lies in the centre of every galaxy. The JWST studied Stephan\u2019s Quintet with its NIRCam and MIRI instruments. In particular, the MIRI images came as a surprise because the shapes of the galaxies were not what astronomers were expecting. <\/p>\n\n

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At mid-infrared wavelengths, as seen by MIRI, the traditional shape of the galaxies disappears. This is because MIRI is not sensitive to starlight, which we traditionally use to define a galaxy\u2019s shape <\/figcaption><\/figure><\/div>\n\n

The Phantom Galaxy M74 also provided the MIRI instrument with another stunning success. Located 32 million light-years away, M74 is a spiral galaxy that we see almost exactly face-on. It is a favourite for studying the giant spiral arms that give spiral galaxies their name. But no one has seen it so clearly before. The spiral arms of the galaxy, where star formation is taking place, can be seen for the first time reaching down into the very centre of the galaxy. <\/p>\n\n

As well as the brand-new discoveries that everyone hopes the JWST will make, collaborations will also be a major focus, combining the telescope\u2019s new observations with those from other observatories in order to unlock a greater understanding of the celestial objects being studied. <\/p>\n\n

For example, the observations of M74 are part of a larger effort to target 19 nearby star-forming galaxies. These galaxies have already been imaged by Hubble and various ground-based observatories. The JWST\u2019s observations will allow astronomers to more accurately pinpoint star-forming regions, measure the masses and ages of star clusters, and uncover the physical and chemical nature of the dust grains drifting through the galaxies. <\/p>\n\n

THE LIFE CYCLE OF STARS<\/span><\/h4>\n\n

One area in which infrared astronomy excels is looking deep into the clouds where stars are forming. This is because longer wavelengths are scattered less by atoms, molecules and dust grains. In effect, the very things that block our view of the stellar nurseries at visual wavelengths become almost transparent in the infrared. <\/p>\n\n

\u201cIT\u2019S GAS AND DUST BEING CARVED BY STARLIGHT, BUT IT LOOKS LIKE A LANDSCAPE\u201d<\/span><\/strong><\/em><\/p><\/blockquote>\n\n

Another image to be released from the JWST was NIRCam\u2019s view of the starforming region NGC 3324 in the Carina Nebula, located 7,500 light-years away. <\/p>\n\n

\u201cThe Carina Nebula is stunning. We know it\u2019s gas and dust being carved by starlight, but it looks like a landscape. The fact that you can now see inside it, using the infrared, is amazing. What\u2019s been private before is now visible in all its glory,\u201d says Harper. <\/p>\n\n

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The \u2018cosmic cliffs\u2019 in the Carina Nebula <\/figcaption><\/figure><\/div>\n\n

At the time of release, it was dubbed \u2018the cosmic cliffs\u2019 because of the way the great gaseous cliffs appeared to resemble a mountain range. In reality, it was the edge of a giant cavity being gradually eroded by powerful ultraviolet light from newborn stars. <\/p>\n\n