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Images from the largest-mirror telescope launched since Hubble reveal new data about exoplanets and galaxies. Astrophysicist, popularizer of science Sergey Popov talks about “James Webb” in detail
About the expert: Sergey Popov, astrophysicist, doctor of physical and mathematical sciences, professor of the Russian Academy of Sciences.
At the end of 2021, the James Webb telescope was launched into orbit, and in July 2022, the first scientific results were obtained from it. Already these data have demonstrated that the James Webb is a truly unique installation. Such large instruments of a new class appear really rarely – about once every 20 years. That is, the next really big breakthrough is expected only in the mid-2040s. And this is despite the fact that every year, and sometimes several times, some new interesting astronomical instruments will be launched.
Next Generation Space Telescope
The James Webb telescope is needed for infrared observations. It has a folding mirror with a diameter of 6,5 m. This is the largest mirror that has ever worked in space. The whole instrument is literally crammed with high technology. Thanks to them, the telescope receives high praise from scientists, but at the same time, it was the presence of a large number of devices that led to numerous delays in the launch of this project.
“James Webb” is designed for detailed study of objects. On board, he has three instruments operating in the near infrared range and one in the more distant one. Observation in all these parts of the world is impossible from Earth, so the instrument must be launched into space.
Imagine yourself with a magnifying glass examining some kind of butterfly – at this moment you do not see anything around. James Webb also looks at a very small part of the sky. If we suddenly wanted to photograph the entire Moon with a telescope, then we would need about a hundred shots to cover the entire lunar disk. That is, looking at a deep shot of James Webb, seeing a huge number of galaxies, you should understand that this is not a huge new universe, but a small keyhole through which we are looking. But even there you can see many interesting objects. First of all, distant objects of galaxies.
Installation in a given orbit
James Webb was launched at the end of 2021. It took some time to get to its working orbit: it is far enough from the earth that the journey took time. Already along the way, scientific tests were carried out. But, of course, the most important thing happened when the telescope was successfully delivered to the right area of outer space, and the first real observations began.
All tests were passed and the instrument was cooled down to the correct temperature. Because the telescope operates in the infrared, it is important that it be cold. For cooling, “James Webb” has a screen that covers the telescope from the Sun. This means that at any moment the telescope cannot be pointed at an arbitrary point in the sky – it cannot look in the direction of the luminary. That is, about half of the sky is immediately inaccessible. But since the Earth revolves around the Sun, naturally, over time, everything becomes available for observation.
Telescope expiration date
The quality of the indicators issued by the telescope even exceeded expectations. However, all devices have their own expiration date. A typical NASA warranty period for such large space projects is five years. What is this limit related to? The telescope is located far from the Earth, it is impossible to fly to it and fix something, bring some equipment or fuel. It is fuel that is the main limiter. However, scientists are sure that no catastrophe will happen to the telescope, and the instrument will work without interruption. The satellite lay very well in the given orbit, which means that precious fuel was saved. Now there is every reason to think that the tool will work for more than twenty years.
infrared range
It is important to understand that making decisions about building an instrument like the Webb is a very complex process associated with great scientific competition. It all starts with the fact that the astronomical community begins to discuss the problems that need to be solved. At the same time, one scientific group is interested in launching a gamma-ray telescope, another – an X-ray, and the amount of money is fixed. Therefore, as a result of numerous discussions, it turns out which work in which range and with the help of which instruments will give the greatest scientific yield per one conventionally invested dollar. And in this case, as a result of discussions, the infrared range was chosen for the telescope. The reasons for the choice are reduced to key astrophysical problems. And one of the first is the study of distant galaxies.
The universe is expanding. Accordingly, the radiation of these galaxies is strongly shifted to the red side. If we want to study how the very first galaxies were formed, infrared observations are more suitable for us.
And if we want to study something close to us, for example, how stars are formed in our galaxy or other nearby ones? It seems that this can be done in different ranges. But dust interferes greatly with observation. It absorbs visible radiation. And already in the center of our galaxy in the visible range it is difficult to see something. In the infrared, dust is very often transparent.
In addition, forming stars emit the main radiation just in the infrared range. They have not yet warmed up sufficiently, and therefore a detailed observation in this range, in that part that is inaccessible from the surface of the earth, at the moment can really give the maximum scientific yield.
We will make the next big breakthrough in another spectral range, for example, in X-rays. One of the future big projects is the Lynx X-ray telescope.
Subtleties of observation
Any astronomer will be able to make observations with the James Webb telescope. This is where another level of competition kicks in. The idea is that a very good tool is created that will be used as efficiently as possible. For this, it is necessary that the largest number of scientists think about scientific problems. And then an independent committee for the distribution of observational time on the telescope will select the most interesting applications. The James Webb telescope will operate in this mode.
There is another rule: if you have been approved, you have observed your program and received results, this data will not be in your exclusive possession all the time. Eventually they will be released to the public. Such openness of data, firstly, intensifies work with them. And, secondly, it allows you to use them to the fullest. Let’s say your program took a snapshot of some area of the sky. You were interested in one single object there, but there are a hundred more on the frame, and they are of interest to other scientists. It will be useful if the data falls into their hands, since “James Webb” exists in a single copy. Finally, the fact that the data will eventually become public will test your conclusions. This means that scientific groups will be more responsible in data processing.
Contests for applications for observations
The first call for proposals was for early observations that scientists could make in the first six months of the telescope’s operation. Many groups took part there, as a rule, international ones, including those with the participation of scientists from our country. As a result, five objects were selected for initial study. And it was on these objects that the first articles were published in July 2022, and the very famous frame was published that demonstrated the main capabilities of the James Webb telescope.
After the end of the semi-annual period, the normal period of work begins, applications will be re-collected every year. More than a thousand applications were submitted for the first cycle. Most likely, there could not be weak ones. Everyone understands how high the competition is, how strict the selection process is for applications. But even among these strong applications, less than one-quarter were satisfied.
In total, all applications requested 25 thousand hours of observation time, while one annual cycle includes only six thousand. True, as the telescope works, the bar for applications decreases slightly. For example, the observation programs of the Hubble telescope, which has been operating for more than thirty years, were very difficult to get into at first. But 10–20 years after the tool started working, this process began to be simplified.
Five objects for the first sightings
It was important for scientists to demonstrate the capabilities of all four instruments of the telescope, which means that they needed objects that would require all the power of James Webb to observe. It was also necessary to observe the diversity of objects associated with key tasks – distant galaxies, the study of exoplanets (planets orbiting other stars. – Trends) and star formation. And, finally, no one canceled PR: the first results had to be accompanied, among other things, by beautiful images.
exoplanets
The observation of exoplanets was included in the tasks to demonstrate the ability of “James Webb” to build good spectra of the atmosphere. Today, more than 5 thousand exoplanets have been discovered. Their number in itself is probably not so interesting to us. But we want to study them in detail.
One of the tasks of the telescope is the registration of so-called biomarkers in the atmospheres of exoplanets, but it will probably be solved over a number of years. For now, it was important to simply show with a vivid example that “James Webb” can receive the spectra of atmospheres. And so an interesting, but relatively easy target was chosen (WASP-96b, in the air of which the NASA apparatus detected traces of water vapor in July 2022. – Trends).
planetary nebula
The observation of the planetary nebula was associated both with solving scientific problems and with obtaining a really beautiful picture. These are astronomical objects of stunning beauty, a picture of which can easily be pasted on a wall and virally distributed on the Internet.
Nearby galactic star forming region
Observations of a nearby galactic star-forming region is important both in itself and in terms of obtaining spectacular images. In addition, all objects had previously been observed by the Hubble Space Telescope, as well as in the previous large infrared observatory launched by NASA, the Spitzer Telescope. At a minimum, it makes sense to compare the results obtained in different ways in order to better understand the operation of the new tool.
A group of nearby galaxies
The nearby group of galaxies is the famous Stefan Quintet. Five galaxies located in the sky close to each other. Four of them definitely form tight groups – they interact with each other. The fifth, perhaps, is projected by chance, but decorates the overall picture. Accordingly, here we have the opportunity to test the ability of “James Webb” to work with those galaxies that we can examine in detail: to study pieces of these galaxies, star formation regions, individual arms. Again, the telescope has been shown to do well with this.
Cluster of galaxies
The cluster of galaxies is, by cosmological standards, not very far from us – the light from it came to us for only a little more than 4 billion years. But this cluster allows us to see more distant galaxies. Numerous groups of astrophysicists in different countries have already worked with the data obtained and have indeed obtained new interesting results. The main direction of this work was associated with the selection of very distant galaxies, since scientists are faced with the task of getting in their study to the very first of them. They emerged about three hundred million years after the Big Bang. And instruments such as the Hubble telescope or the large ground-based Welty and Keck telescopes do not show us the first galaxies. Maybe “James Webb” will be the first.
Modification of the growth pattern of galaxies
Galaxies most likely grow from the bottom up. In the sense that small building blocks – clouds of gas and dark matter, in which stars have already begun to form, merge with each other and form small galaxies. And they, in turn, merge into larger ones. So far, we are reproducing this process in computer simulation, which has been developing very effectively in recent years, also due to motivation by the upcoming observations at that time on the James Webb.
Accordingly, galaxies of different types arise in a hierarchical process of growth. It was unexpected that in the images obtained by “James Webb”, already at fairly large redshifts, that is, a fairly young Universe, at times corresponding to approximately the first billion years after the start of expansion, a large number of disk galaxies are already observed. That is, about the same as ours.
This is a little out of the standard scenario for the formation of galaxies. Therefore, without detailed observations of distant galaxies, among the many existing theoretical models, we cannot choose the right ones. But now, if the first results of “James Webb” are correct not for some small region, but for the Universe as a whole, we will be convinced that disk galaxies arise early enough. Earlier than it came out according to standard scenarios.
This knowledge modifies the picture of the growth of galaxies, which means it will improve and detail our ideas about the evolution of the Universe. Now most of the new emerging data concerns observations of galaxies, and, apparently, the James Webb telescope will make its main contribution in this area. Although it is important to understand that the telescope can observe almost anything in the sky, except for very bright objects.
What to expect from “James Webb”
Among the tasks of James Webb is usually not called the task of seeing the very first stars. Maybe some results will be obtained here. But this is not guaranteed.
There is one very interesting star. It is in the galaxy that we see as it was several hundred million years after the Big Bang. Its redshift is 6,2, which is very far away. Now the distance to this galaxy is about 28 billion light years, that is, it is the most distant known star. And it was discovered on the Hubble Space Telescope. With the help of “James Webb” it can be studied in more detail. This inspires optimism and faith in future discoveries to study the population of very distant and possibly the very first stars.
The first six months of operation of the James Webb Space Telescope showed that the instrument works great. Devices that are so difficult to create and launch should give a guaranteed result, because people cannot spend twenty years and $10 billion promising, perhaps, to discover something interesting. In addition to guaranteed results, the tools give new and unexpected ones. The telescope will also observe the objects of our solar system: maybe even in it, where satellites fly, something important and interesting will be discovered.
It’s safe to say that James Webb’s twenty-year run will bring us many surprises. Fortunately, in astrophysics, such surprises are usually good.