As an expert, what’s your experience with publishing first dates for James Webb?
Ludmila Caroni: Most colleagues pursued online publishing at home. In parallel with the press conference, we shared information with other experts from all over the world on the Internet. Everyone saw the data for the first time and of course immediately started doing the initial primary analyzes in real time. JWT exceeded all expectations, the quality of the recordings is incredible. When we saw the first pictures, many people cried with tears of joy. That was really overwhelming. JWT is a pioneer and will keep us busy with discoveries for decades to come.
What distinguishes the images presented at the press conference from the data obtained by the researchers?
Karon: The images presented to the public at the press conference are really brief representations of the data. We get the unfiltered raw data. This is especially important for spectroscopic analyses: the spectrum of light that has passed through the atmosphere of an exoplanet Wasp 96b is initially a rainbow stained on a photocell. The average person can’t do anything with it, there are spectrographers who process this data and present it in a nice diagram, where you can then see the chemical composition of the atmosphere.
Raw data processing
What should be filtered?
Karon: There are many sources of interference, such as the honeycomb optical artifacts of JWT mirrors. This must be taken into account in order to get good looking images. The nice thing is that different groups are working independently on the same raw data at the same time. This gives us a well-functioning quality control system.
What do you do with the data in your research group?
Karon: We take the spectrum of light that has passed through the atmosphere of an exoplanet and combine it with our models that simulate the physics, chemistry and formation of clouds. Then we look at the parameters we need to change so that the model fits the feedback. This could be the amount of heavy elements – in this context all but hydrogen and helium – temperature or cloud cover. Various other groups are also doing this back and forth internationally and interdisciplinary.
How does JWT differ from predecessors such as Hubble?
Unlike Hubble, which works in the visible and ultraviolet parts of the spectrum, JWT sees light primarily in the infrared. This greatly expands our view of the universe. With Hubble, for example, it showed no sign of clouds in Wasp 96b’s atmosphere. However, JWT has now found evidence in the infrared range. Together we now get a lot of information about the universe through the two telescopes.
Gem clouds on the outer planets
How can detect clouds on a planet outside the solar system?
Karon: We’re looking at a tiny point in the distance, that’s just a pixel on the image sensor, because of course exoplanets can’t be resolved from that distance. But starlight that reaches us through the planet’s atmosphere gives us information about the composition of gases. Wasp 96b is a gas giant that orbits close to its sun. However, the planet only closes off about 1% of the star as it passes in front of it from our viewpoint. Of this region, the atmosphere makes up only one percent. However, we can clearly see a “water hump” in the light spectrum.
Were there any surprises in JWT’s first exoplanet spectrum?
Karon: The water signal was not as strong as was generally assumed. So something is weakening the signal. Based on the data, these could only be clouds! Namely, corundum and quartz, because these are the only materials that can still condense under the conditions on Wasp 96b. So there’s practically a draw of gems out there. A research paper published in 2008 in Nature concluded, based on Hubble’s observations, that there are no clouds on Wasp 96b. This now needs to be reviewed.
What can JWT spectrometers do better than their predecessors?
Karon: Water vapor and methane are completely transparent to both ultraviolet and optical wavelengths. On the other hand, infrared waves are swallowed up by water vapor, methane and carbon dioxide, then the gas appears more opaque. So we can also detect more complex molecules using infrared photons. Dust in the atmosphere becomes visible as well. JWT will teach us a lot about the formation of planets and galaxies and will allow us to look deeper into space and the past than ever before and study the formation of very ancient stars and galaxies.
Will there also be spectroscopic analyzes of the atmospheres of Earth-like planets?
Karon: We probably won’t be able to explore the atmosphere of an Earth-like planet, but in principle JWT can tell if a rocky exoplanet has an atmosphere. We now know that there are countless rocky planets. This is a huge step forward because we didn’t confirm the existence of exoplanets at all until 1995. Since then we have also discovered many exotic types of planets not in our solar system, such as young Neptune. Of course, watching one and seeing the atmosphere would also be great.
Where can we look for rocky exoplanets with an atmosphere?
Karon: Trappist 1 orbits a red dwarf that regularly shows strong bursts of radiation. As a result, the atmosphere can also wear out quickly. But if there is a Venus-like planet in Trappist 1, we should be able to see the atmosphere using JWT. This is the maximum that is possible. Trappist 1 data will start streaming over the next year. If we see an atmosphere, we have confirmed for the first time the existence of gaseous, rocky planets outside our solar system.
look at the past
How far can we see in the past with JWT?
Karon: We go back nearly 300 million years after the Big Bang. At that time, the first galaxies were formed, in which the first generation of stars formed. These giants had only hydrogen, helium, and a little lithium as building materials because all other elements originated first in stars. Iron formation, for example, took two stellar generations.
As a layman, I found recording in the deep field very impressive. Is this also interesting to experts?
Karon: DeepField logging is of course something very special, also from a scientific point of view. Just a few days ago, two new galaxies were published on this basis, with a redshift of 12 and more. This is a deep view of the universe, the two galaxies are candidates for the oldest known objects in the universe. We’ve never been able to see that so far in the past, it’s a whole new area.