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Enlarge / Saturn stars in this near-infrared image taken June 25 by the James Webb Space Telescope. (credit: NASA/ESA/CSA/STSci)
The James Webb Space Telescope has observed Saturn for the first time, completing a family portrait of the Solar System’s ringed planets nearly a year after the mission’s first jaw-dropping image release.
Webb’s near-infrared camera took the picture of Saturn on June 25. Scientists added orange color to the monochrome picture to produce the image released Friday.
The picture shows Saturn’s iconic icy rings shining around the disk of the gas giant, which appears much darker in near-infrared due to the absorption of sunlight by methane particles suspended high in the planet’s atmosphere.
Astronomers are using NASA’s James Webb Space Telescope to peer deeper into the universe and farther back in time than ever before.
Already, the team has discovered hundreds of galaxies that existed when the universe was less than 600 million years old—just 4% of its current age.
The Webb Telescope, or JWST, also has observed galaxies sparkling with a multitude of young, hot stars formed during what researchers call “surprisingly episodic bursts of star formation.”
They made the observations as part of the JWST Advanced Deep Extragalactic Survey, or JADES, which is dedicated to uncovering and studying extremely faint, distant galaxies. Thirty-two days of observing time have been devoted to JADES, which is one of the largest observing programs in Webb’s first year of science.
The key to JWST’s ability to sniff out the extremely faint signatures of distant objects is its large, light-gathering mirror and infrared sensitivity.
“With JADES, we want to answer questions such as, ‘How did the earliest galaxies assemble themselves? How fast did they form stars? Why do some galaxies stop forming stars?'” says Marcia Rieke, a professor of astronomy at the University of Arizona Steward Observatory and a co-lead of the JADES program.
During his doctoral research at Steward Observatory, JADES team member Ryan Endsley, who is now a postdoctoral fellow at the University of Texas at Austin, led an investigation into galaxies that existed 500 to 850 million years after the Big Bang, a crucial time known as the “Epoch of Reionization.”
“Star formation in the early universe is much more complicated than we thought.”
For hundreds of millions of years, the young universe was filled with a gaseous fog that made it opaque to energetic light such as ultraviolet light or X-rays. About 1 billion years after the Big Bang, the fog had cleared and the universe became transparent during a process known as reionization.
Scientists have debated whether active, supermassive black holes or galaxies full of hot, young stars were the primary cause of reionization. As part of the JADES program, Endsley and his colleagues studied these galaxies specifically to look for signatures of star formation—and found them in abundance.
“Almost every single galaxy that we are finding shows these unusually strong emission line signatures indicating intense recent star formation,” Endsley says. “These early galaxies were very good at creating hot, massive stars.”
These bright, massive stars pumped out torrents of ultraviolet light, which transformed surrounding gas from opaque to transparent by ionizing atoms, unbinding their electrons from the nuclei. Since these early galaxies had such a large population of hot, massive stars, they may have been the main driver of the reionization process. The later reuniting of the electrons and nuclei produces the distinctively strong emission lines.
Endsley and his colleagues also found evidence that these young galaxies underwent periods of rapid star formation interspersed with quiet periods during which fewer stars formed. These fits and starts may have occurred as galaxies captured clumps of the gaseous raw materials needed to form stars. Alternatively, since massive stars are short-lived before they explode, they may have injected energy into the surrounding environment periodically, preventing gas from condensing to form new stars.
Another element of the JADES program involves the search for the earliest galaxies that existed when the universe was less than 400 million years old. By studying these galaxies, astronomers can explore how star formation in the early years after the Big Bang was different from today. The light from faraway galaxies is stretched to longer wavelengths and redder colors by the expansion of the universe—a phenomenon called redshift. By measuring a galaxy’s redshift, astronomers can learn how far away it is and, therefore, at what time it existed in the early universe.
“Before JWST, there were only a few dozen galaxies observed above a redshift of 8, when the universe was younger than 650 million years old, but JADES is now uncovering nearly a thousand of these extremely distant galaxies,” Rieke says.
The JADES team identified more than 700 candidate galaxies above redshift 8, which will completely overhaul astronomers’ understanding of early galaxy formation. The sheer number of these sources far exceeded predictions based on observations made before the launch of JWST. Webb’s fine resolution and sensitivity allow astronomers to get an unprecedented view of these distant galaxies.
“Previously, the earliest galaxies we could see just looked like little smudges,” says JADES team member Kevin Hainline, an assistant research professor at Steward Observatory. “And yet those smudges represent millions, or even billions, of stars at the beginning of the universe. Now, we can see, incredibly, that some of them are actually groupings of stars being born only a few hundred million years after the beginning of time.”
“What all this tells us,” Rieke says, “is that star formation in the early universe is much more complicated than we thought.”
The team presented their latest observations at the 242nd meeting of the American Astronomical Society in Albuquerque, New Mexico.
Source: University of Arizona
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Danse Exquise is an animation that evokes the feeling of being inside of a kaleidoscope. I love the brilliant colors and painterly quality of the characters and ever-morphing background. For me, watching this was less about plot and more about having a completely immersive visual experience. — Read the rest
The Committee on Publication Ethics (COPE), whose standards inform the policies and practices of many philosophy journals and their publishers, has declared that “AI tools cannot be listed as an author of a paper.”
[Manipulation of Caravaggio’s “Saint Jerome Writing” by J. Weinberg]
AI tools cannot meet the requirements for authorship as they cannot take responsibility for the submitted work. As non-legal entities, they cannot assert the presence or absence of conflicts of interest nor manage copyright and license agreements.
Authors who use AI tools in the writing of a manuscript, production of images or graphical elements of the paper, or in the collection and analysis of data, must be transparent in disclosing in the Materials and Methods (or similar section) of the paper how the AI tool was used and which tool was used. Authors are fully responsible for the content of their manuscript, even those parts produced by an AI tool, and are thus liable for any breach of publication ethics.
COPE’s position matches up with that of Nature and other publications (see this previous post). (via Brian Earp)
In response to Nature’s earlier announcement, philosophers Ryan Jenkins and Patrick Lin of the Ethics + Emerging Sciences Group at California Polytechnic State University, raised some concerns about this kind of “simple policy”. In their report, “AI-Assisted Authorship: How to Assign Credit in Synthetic Scholarship“, they write:
Nature argues that crediting AI writers in the acknowledgements serves the goal of transparency. While this may be true in many cases, it could also help to hide or grossly understate the role and substantial contributions of AI writers to the paper, which is counterproductive to transparency.
Nature also argues AI writers should not be credited as authors on the grounds that they cannot be accountable for what they write. This line of argument needs to be considered more carefully. For instance, authors are sometimes posthumously credited, even though they cannot presently be held accountable for what they said when alive, nor can they approve of a posthumous submission of a manuscript; yet it would clearly be hasty to forbid the submission or publication of posthumous works.
Thus, a more nuanced, middle-ground solution may be needed, as satisfying as a simple policy might be.
Jenkins and Lin suggest framing the matter around two questions.
The first concerns what they call “continuity”:
How substantially are the contribution of AI writers carried through to the final product? To what extent does the final product resemble the contributions of AI? What is the relative contribution from AI versus a human? The calculations are always difficult, even if the coauthors are human. Some journals routinely require statements of relative contribution to add clarity and nuance when multiple humans are sharing credit.
The second concerns what they call “creditworthiness”:
Is this the kind of product a human author would normally receive credit for? Consider whether the AI’s contributions would typically result in academic or professional credit for a human author. This analysis is similar to how we view student assistants: the greater the substance of their contribution to the final product, and the greater the extent to which this kind of product typically redounds to the credit of the author, the more important it is to credit the range of contributors, both human and artificial.
You can read their report here.
Enlarge / Radio observatories like the Green Bank Telescope in Green Bank, West Virginia, are in radio quiet zones that protect them from interference. (credit: The Washington Post via Getty Images)
Visible light is just one part of the electromagnetic spectrum that astronomers use to study the Universe. The James Webb Space Telescope was built to see infrared light, other space telescopes capture X-ray images, and observatories like the Green Bank Telescope, the Very Large Array, the Atacama Large Millimeter Array, and dozens of other observatories around the world work at radio wavelengths.
Radio telescopes are facing a problem. All satellites, whatever their function, use radio waves to transmit information to the surface of the Earth. Just as light pollution can hide a starry night sky, radio transmissions can swamp out the radio waves astronomers use to learn about black holes, newly forming stars, and the evolution of galaxies.
We are three scientists who work in astronomy and wireless technology. With tens of thousands of satellites expected to go into orbit in the coming years and increasing use on the ground, the radio spectrum is getting crowded. Radio quiet zones—regions, usually located in remote areas, where ground-based radio transmissions are limited or prohibited—have protected radio astronomy in the past.
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