Staggering structure in 19 nearby spiral galaxies

It's oh-so-easy to be absolutely mesmerized by these spiral galaxies. Follow their clearly defined arms, which are brimming with stars, to their centers, where there may be old star clusters and -- sometimes -- active supermassive black holes. Only NASA's James Webb Space Telescope can deliver highly detailed scenes of nearby galaxies in a combination of near- and mid-infrared light -- and a set of these images was publicly released today.

These Webb images are part of a large, long-standing project, the Physics at High Angular resolution in Nearby GalaxieS (PHANGS) program, which is supported by more than 150 astronomers worldwide. Before Webb took these images, PHANGS was already brimming with data from NASA's Hubble Space Telescope, the Very Large Telescope's Multi-Unit Spectroscopic Explorer, and the Atacama Large Millimeter/submillimeter Array, including observations in ultraviolet, visible, and radio light. Webb's near- and mid-infrared contributions have provided several new puzzle pieces.

"Webb's new images are extraordinary," said Janice Lee, a project scientist for strategic initiatives at the Space Telescope Science Institute in Baltimore. "They're mind-blowing even for researchers who have studied these same galaxies for decades. Bubbles and filaments are resolved down to the smallest scales ever observed, and tell a story about the star formation cycle."

Excitement rapidly spread throughout the team as the Webb images flooded in. "I feel like our team lives in a constant state of being overwhelmed -- in a positive way -- by the amount of detail in these images," added Thomas Williams, a postdoctoral researcher at the University of Oxford in the United Kingdom.

Follow the Spiral Arms

It's oh-so-easy to be absolutely mesmerized by these spiral galaxies. Follow their clearly defined arms, which are brimming with stars, to their centers, where there may be old star clusters and -- sometimes -- active supermassive black holes. Only NASA's James Webb Space Telescope can deliver highly detailed scenes of nearby galaxies in a combination of near- and mid-infrared light.

Webb's NIRCam (Near-Infrared Camera) captured millions of stars in these images, which sparkle in blue tones. Some stars are spread throughout the spiral arms, but others are clumped tightly together in star clusters.

The telescope's MIRI (Mid-Infrared Instrument) data highlights glowing dust, showing us where it exists around and between stars. It also spotlights stars that haven't yet fully formed -- they are still encased in the gas and dust that feed their growth, like bright red seeds at the tips of dusty peaks. "These are where we can find the newest, most massive stars in the galaxies," said Erik Rosolowsky, a professor of physics at the University of Alberta in Edmonton, Canada.

Something else that amazed astronomers? Webb's images show large, spherical shells in the gas and dust. "These holes may have been created by one or more stars that exploded, carving out giant holes in the interstellar material," explained Adam Leroy, a professor of astronomy at the Ohio State University in Columbus.

Now, trace the spiral arms to find extended regions of gas that appear red and orange. "These structures tend to follow the same pattern in certain parts of the galaxies," Rosolowsky added. "We think of these like waves, and their spacing tells us a lot about how a galaxy distributes its gas and dust." Study of these structures will provide key insights about how galaxies build, maintain, and shut off star formation.

Dive Into the Interior

Evidence shows that galaxies grow from inside out -- star formation begins at galaxies' cores and spreads along their arms, spiraling away from the center. The farther a star is from the galaxy's core, the more likely it is to be younger. In contrast, the areas near the cores that look lit by a blue spotlight are populations of older stars.

What about galaxy cores that are awash in pink-and-red diffraction spikes? "That's a clear sign that there may be an active supermassive black hole," said Eva Schinnerer, a staff scientist at the Max Planck Institute for Astronomy in Heidelberg, Germany. "Or, the star clusters toward the center are so bright that they have saturated that area of the image."

Research Galore

There are many avenues of research that scientists can begin to pursue with the combined PHANGS data, but the unprecedented number of stars Webb resolved are a great place to begin. "Stars can live for billions or trillions of years," Leroy said. "By precisely cataloging all types of stars, we can build a more reliable, holistic view of their life cycles."

In addition to immediately releasing these images, the PHANGS team has also released the largest catalog to date of roughly 100,000 star clusters. "The amount of analysis that can be done with these images is vastly larger than anything our team could possibly handle," Rosolowsky emphasized. "We're excited to support the community so all researchers can contribute."

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Displays controlled by flexible fins and liquid droplets more versatile, efficient than LED screens

Flexible displays that can change color, convey information and even send veiled messages via infrared radiation are now possible, thanks to new research from the University of Illinois Urbana-Champaign. Engineers inspired by the morphing skins of animals like chameleons and octopuses have developed capillary-controlled robotic flapping fins to create switchable optical and infrared light multipixel displays that are 1,000 times more energy efficient than light-emitting devices.

The new study led by mechanical science and engineering professor Sameh Tawfick demonstrates how bendable fins and fluids can simultaneously switch between straight or bent and hot and cold by controlling the volume and temperature of tiny fluid-filled pixels. Varying the volume of fluids within the pixels can change the directions in which the flaps flip -- similar to old-fashioned flip clocks -- and varying the temperature allows the pixels to communicate via infrared energy.

The study findings are published in the journal Science Advances.

Tawfick's interest in the interaction of elastic and capillary forces -- or elasto-capillarity -- started as a graduate student, spanned the basic science of hair wetting and led to his research in soft robotic displays at Illinois.

"An everyday example of elasto-capillarity is what happens to our hair when we get in the shower," Tawfick said. "When our hair gets wet, it sticks together and bends or bundles as capillary forces are applied and released when it dries out."

In the lab, the team created small boxes, or pixels, a few millimeters in size, that contain fins made of a flexible polymer that bend when the pixels are filled with fluid and drained using a system of tiny pumps. The pixels can have single or multiple fins and are arranged into arrays that form a display to convey information, Tawfick said.

"We are not limited to cubic pixel boxes, either," Tawfick said. "The fins can be arranged in various orientations to create different images, even along curved surfaces. The control is precise enough to achieve complex motions, like simulating the opening of a flower bloom."

The study reports that another feature of the new displays is the ability to send two simultaneous signals -- one that can be seen with the human eye and another that can only be seen with an infrared camera.

"Because we can control the temperature of these individual droplets, we can display messages that can only be seen using an infrared device," Tawfick said, "Or we can send two different messages at the same time."

However, there are a few limitations to the new displays, Tawfick said.

While building the new devices, the team found that the tiny pumps needed to control the pixel fluids were not commercially available, and the entire device is sensitive to gravity -- meaning that it only works while in a horizontal position.

"Once we turn the display by 90 degrees, the performance is greatly degraded, which is detrimental to applications like billboards and other signs intended for the public," Tawfick said. "The good news is, we know that when liquid droplets become small enough, they become insensitive to gravity, like when you see a rain droplet sticking on your window and it doesn't fall. We have found that if we use fluid droplets that are five times smaller, gravity will no longer be an issue."

The team said that because the science behind gravity's effect on droplets is well understood, it will provide the focal point for their next application of the emerging technology.

Tawfick said he is very excited to see where this technology is headed because it brings a fresh idea to a big market space of large reflective displays. "We have developed a whole new breed of displays that require minimal energy, are scaleable and even flexible enough to be placed onto curved surfaces."

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