“We have a lot of great work coming out of the telescope,” Stefanie Milam, the James Webb Space Telescope (JWST) deputy project scientist for planetary science, told the audience Tuesday (March 14) at the South by Southwest (SXSW) conference and festivals in Austin, Texas.
“The scientific community is working really hard to analyze their own data and put it into peer-reviewed scientific publications, and that’s finally becoming a reality,” added Milam, of the Astrochemistry Lab at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. . .
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A sensational, newly released JWST image of WR 124, a huge, exotic star that has already shed about 10 times its mass the sun, is an example. The splendor of the image—taken last summer, just after JWST began its science operations—illustrates how the telescope’s near- and mid-infrared instruments, combined with the superior optics of its 21.3-foot-wide (6.5-meter) mirror, are able to show astronomers details they have never seen before.
In the case of WR 124, the data from the Near-Infrared Camera (NIRCam) and the Mid-Infrared Instrument (MIRI) reveal the clumpy structure of the dust surrounding WR 124, allowing astronomers to better understand how the dust is produced. size and amount of dust particles present, and how dust from other such “Wolf-Rayet” stars contributes to the total dust content of the Milky Way, which is then recycled into the next generation of stars and planets.
“One area where we’re really getting a lot of new information is the birth of stars,” Milam said at the SXSW event. “(We) understand star formation in a way that we’ve never really had access to, with this whole new sensitivity and detail that we’ve never had before. Not only do we see star formation in our own galaxybut also in others galaxies … and we’re getting this detail now that we used to only have for our own galactic understanding, now expanding to these other galaxies across universe. It’s just really an exciting time to be a part of that field and understand how our sun was born and how the solar system was formedand this gives us the first real glimpse of it.”
By peering through the clouds of dusty gas that surround star-forming regions that are opaque to visible wavelengths of light, JWST’s infrared vision is able to tease out these important details. But astronomers don’t just want to learn about how stars and planets form; they also want to learn more about how they develop. That’s where the WR 124 observations come in – the central star, shedding the nebula from its outer layers, has a mass 30 times that of our Sun and will eventually explode as a supernova. JWST also promises to do the same for planets.
The planets in our solar system are a starting point. “We want to observe the solar system with the James Webb Space Telescope, and we have,” Milam said. Fantastic pictures of Mars, Jupiter and Neptune have already been released by the JWST team, as well as observations of DART impact on the asteroid Dimorphos in September 2022.
“We’re going to observe everything in our solar system that JWST can point to from near Earth asteroids, comets, interstellar objectsall the planets and their satellites to the farthest reaches of our solar system, including our favorite minor planet, PlutoMilam said. “So there’s a lot more to come.”
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In addition to our solar system, there are several planets orbiting other stars. More than 5,000 exoplanets have been discovered to date, ranging in size from massive giants larger than Jupiter to small worlds the size of Mars. However, the easiest exoplanets studying has been the hot Jupiters — gas giants orbit very close to their host star, in orbital radii of just a few million miles—because they produce the strongest signal.
JWST’s earliest exoplanet results have also come from hot Jupiters—for example WASP-39b, a giant planet 700 light years away. JWST performs what is called transit spectroscopy, where as the planet passes (moves across) the surface of its star, some of that starlight passes through the planet’s atmosphere. This light is absorbed by molecules in the planet’s atmosphere, and different molecules absorb light at different wavelengths. JWST’s spectrum of WASP-39b’s atmosphere—showing the absorption lines that allow astronomers to identify the molecules involved—is the most detailed look at an exoplanet’s atmosphere yet.
“We’ve already seen that JWST data is just so good, so precise, that we’re able to detect additional molecules in these distant exoplanet atmospheres that we never really expected to see,” said NASA Goddard’s Knicole Colon, who also spoke at the SXSW event, and who is JWST’s Deputy Project Scientist for Exoplanet Science.
One of these molecules, sulfur dioxide, was created in WASP-39b’s atmosphere by photochemical reactions. In other words, by the effect of sunlight on atoms and molecules in the atmosphere.
“We literally didn’t think we would be able to see (the results of these chemical reactions) with JWST,” Colon said. “Even though we knew it would be a great telescope, (the detection of sulfur dioxide was) still so much better than expected.”
This means that as JWST studies and characterizes more and more exoplanets, new and exciting discoveries will almost certainly be on the menu, discoveries that will be able to teach astronomers about the formation and evolution of these planets. The mix of gases in a planetary atmosphere, for example, can give an indication of how far from its star the planet formed.
Before JWST, studies of exoplanetary atmospheres were limited to hot Jupiters, but JWST has now begun to target atmospheres of smaller, Earth-sized planets, also. Observations of the rocky worlds STAIRCASE-1 system, for example, is underway, but because these planets are much smaller than hot Jupiters and orbit a faint red dwarf star, it will take longer for JWST to tease out the details of their atmospheres, if they have atmospheres at all. But over the next few years, some of the findings from the TRAPPIST-1 planets and other similar worlds may change how we see our own planet the earth in a cosmic context.
“We’re still very much in the early days of deciphering all the exoplanet data,” Colon said. “What we want to do is compare these systems and say, ‘Do they have any similarities to Earth?’ I’m excited to see what we learn about the planets that are around the same size as our own, they may not always have the same temperature, they may not have surfaces with liquid oceans and all that, but we still expect to learn about their overall atmosphere. Is there water in the atmosphere? Is there carbon dioxide? Is there anything we know that we can connect with and relate to to help us better understand (whether) there is other life out there?”
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Whatever those answers are, they are coming, and the next few years will be hugely exciting as JWST makes discoveries that could ultimately become historic milestones.
“The first few years of science with JWST will open the door to big new questions and challenges that we have before us about whether there could be life on another planet,” Milam said.
Another mystery that captures the imagination as much as the search for habitable exoplanets is the dark universe, specifically dark matterwhich is the mysterious substance held responsible for the extra gravity observed in galaxies and clusters of galaxies, and dark energythe unknown force driving the acceleration in the universe’s expansion.
“We think that about 75% of the entire universe’s energy-matter content is this mysterious thing that we call dark energy, and additional 20% is this other mysterious thing called dark matter,” Milam said. “When astronomers don’t know what something is, we perceive it as dark. It’s amazing… the hundreds of billions of galaxies and trillions of stars and countless planets, all of this only makes up about 5% of the entire universe. And the rest, the other 95%, we don’t know what it is.”
Dark matter is located in invisible haloes that surround galaxies, leading Milam to describe dark matter as the “scaffolding” on which galaxies sit.
“JWST will help us learn specifically about dark matter,” Milam said. “By studying how galaxies change over time, we are able to learn more about dark matter.”
JWST will not be able to detect what dark matter is; that is up to the particle physicists. But by seeing how dark matter behaves around galaxies, astronomers will be able to constrain some of its properties, which could help physicists pin down its nature. Scientists have been asking this question since Vera Rubin first identified the presence of dark matter in the 1970s, and JWST could help astronomers take some giant leaps forward in our understanding.
Meanwhile, the new discoveries from JWST keep coming.
“I can say that we have a lot of great work coming out of the telescope,” Milam says. “We have a queue of press releases for future publication coming out so it’s a very exciting time. Every week we release something so just stay tuned and I’m sure you’ll be amazed.”
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