The first stunning images from the James Webb Space Telescope were revealed this week, but the journey of cosmic discovery has only just begun. Here’s a look at two early projects that will take advantage of the orbiting observatory’s powerful instruments. The first stars and galaxies One of the telescope’s great promises is its ability to study the earliest phase of cosmic history, shortly after the Big Bang 13.8 billion years ago. The more distant objects are from us, the longer it takes for their light to reach them, so looking back into the distant universe means looking back into the deep past. “We’re going to look back to that early era to see the first galaxies that formed in the history of the universe,” explained Space Telescope Science Institute astronomer Dan Coe, who specializes in the early universe. Help us reach our next YouTube goal by hitting subscribe. 🙏 🙏 🙏 Credit: NASA Goddard Space Flight Center Astronomers have so far gone 97 percent back to the Big Bang, but “we just see these tiny red blobs when we look at these galaxies that are so far away.” “With Webb, we will finally be able to look inside these galaxies and see what they are made of.” While today’s galaxies are shaped like spirals or ellipticals, the early building blocks were “clumped and irregular,” and Webb should reveal earlier redder stars in them, more like our Sun, that were invisible to the Hubble Space Telescope. Coe is preparing two Webb projects—an observation of one of the most distant known galaxies, MACS0647-JD, which he found in 2013, and Earendel, the most distant star ever found, which was found in March of this year. Webb will turn its instruments on distant stars like Earendel, seen here in an image taken by Hubble. While the public has been enticed by Webb’s stunning photos, which were taken in the infrared because light from the distant universe has spread to these wavelengths as the universe expanded, scientists are just as interested in spectroscopy. Analyzing an object’s light spectrum reveals its properties, including temperature, mass and chemical composition—essentially, the forensic science for astronomy. Science does not yet know what the first stars, which probably began to form 100 million years after the Big Bang, will look like. “We might see things that are very different,” Coe said—so-called “Population III” stars thought to be much more massive than our own Sun and “virgin,” meaning they were composed entirely of hydrogen and helium. These eventually exploded in supernovae, contributing to the cosmic chemical enrichment that created the stars and planets we see today. Some are doubtful that these pristine Population III stars will ever be found—but that won’t stop the astronomical community from trying. Anyone out there? Astronomers earned time at Webb based on a competitive selection process, open to all, regardless of how advanced in their careers they are. Graphic on the James Webb Space Telescope. that a new wave of secular images began to circulate. Olivia Lim, a PhD student at the University of Montreal, is only 25 years old. “I wasn’t even born when people started talking about this telescope,” he told AFP. Its goal: to observe the rocky Earth-sized planets orbiting a star called Trappist-1. They are so close to each other that from the surface of one, you could see the others clearly appearing in the sky. “The Trappist-1 system is unique,” explains Lim. “Almost all conditions there are favorable for the search for life outside our solar system.” Additionally, three of Trappist-1’s seven planets are in the Goldilocks “habitable zone,” neither too close nor too far from their star, allowing the right temperatures for liquid water to exist on their surface. The system is “only” 39 light-years away—and we can see the planets passing in front of their star. This makes it possible to observe the drop in brightness produced by the transit of the star and use spectroscopy to infer planetary properties. It’s not yet known if these planets have atmospheres, but that’s what Lim is looking to find out. If so, light passing through these atmospheres will be “filtered” through the molecules it contains, leaving signatures for Webb. The jackpot for her would be to detect the presence of water vapor, carbon dioxide and ozone. Trappist-1 is such a prime target that many other science teams have also been given time to observe them. Finding traces of life there, if any, will still take time, according to Lim. But “everything we’re doing this year is really important steps to get to that end goal.” NASA has released a teaser photo of the James Webb Telescope © 2022 AFP
Reference: Webb begins hunt for first stars and habitable worlds (2022 July 14) Retrieved July 14, 2022 from
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