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Astronomie - NASA James Webb Space Telescope -Update-58

31.01.2024

NASA’s Webb Depicts Staggering Structure in 19 Nearby Spiral Galaxies

The James Webb Space Telescope observed 19 nearby face-on spiral galaxies in near- and mid-infrared light as part of its contributions to the Physics at High Angular resolution in Nearby GalaxieS (PHANGS) program. PHANGS also includes images and data from NASA’s Hubble Space Telescope, the Very Large Telescope’s Multi-Unit Spectroscopic Explorer, and the Atacama Large Millimeter/submillimeter Array, which included observations taken in ultraviolet, visible, and radio light.

NASA, ESA, CSA, STScI, Janice Lee (STScI), Thomas Williams (Oxford), PHANGS Team, Elizabeth Wheatley (STScI)

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.

Two observations of a portion of the galaxy NGC 628 are split diagonally, with Webb’s observations at top left and Hubble’s at bottom right. The galaxy’s core is roughly centered and the galaxy’s arms appear to rotate counterclockwise. The spiraling filamentary structure looks somewhat like a cross section of a nautilus shell. In Webb’s image, the spiny spiral arms are composed of many filaments in shades of orange, with prominent dark gray or black “bubbles,” and there is a blue haze near the core. In Hubble’s image, the spiral arms are a mix of bright blue star clusters, pink star forming areas and dark brown dust lanes, and the core is a pale yellow.

Face-on spiral galaxy, NGC 628, is split diagonally in this image: The James Webb Space Telescope’s observations appear at top left, and the Hubble Space Telescope’s on bottom right. Webb and Hubble’s images show a striking contrast, an inverse of darkness and light. Why? Webb’s observations combine near- and mid-infrared light and Hubble’s showcase visible light. Dust absorbs ultraviolet and visible light, and then re-emits it in the infrared. In Webb's images, we see dust glowing in infrared light. In Hubble’s images, dark regions are where starlight is absorbed by dust.

NASA, ESA, CSA, STScI, Janice Lee (STScI), Thomas Williams (Oxford), and the PHANGS team

Hubble’s image of NGC 628 shows a densely populated face-on spiral galaxy anchored by its central region, which has a light yellow haze that takes up about a quarter of the view. The core is brightest at the center, washing out light from other objects. Delicate spiral arms start near the center and extend to the edges, rotating counterclockwise. There is more brown dust beginning at the center, but as the arms extend outward, brown dust lanes alternate with diffuse lines of bright blue stars. Throughout the spiral arms, there are bright pink patches of star-forming clusters.

NASA, STScI

Webb’s image of NGC 628 shows a densely populated face-on spiral galaxy anchored by its central region, which has a light blue haze that takes up about a quarter of the view. In this circular core is the brightest blue area. Within the core are populations of older stars, represented by many pinpoints of blue light. Spiny spiral arms made of stars, gas, and dust also start at the center, largely starting in the wider area of the blue haze. The spiral arms extend to the edges, rotating counterclockwise. The spiraling filamentary structure looks somewhat like a cross section of a nautilus shell. The arms of the galaxy are largely orange, ranging from dark to bright orange. Scattered across the packed scene are some additional bright blue pinpoints of light, which are stars spread throughout the galaxy. In areas where there is less orange, it is darker, and some dark regions look more circular. A prominent dark “bubble” appears to the top left of the blue core. And a wider, elliptical “bubble” to the bottom right.

Spiral galaxy NGC 628 is 32 million light-years away in the constellation Pisces. Webb’s image of NGC 628 shows a densely populated face-on spiral galaxy anchored by its central region, which has a light blue haze that takes up about a quarter of the view. In this circular core is the brightest blue area. Within the core are populations of older stars, represented by many pinpoints of blue light. Spiny spiral arms made of stars, gas, and dust also start at the center, largely starting in the wider area of the blue haze. The spiral arms extend to the edges, rotating counterclockwise. The spiraling filamentary structure looks somewhat like a cross section of a nautilus shell. The arms of the galaxy are largely orange, ranging from dark to bright orange. Scattered across the packed scene are some additional bright blue pinpoints of light, which are stars spread throughout the galaxy. In areas where there is less orange, it is darker, and some dark regions look more circular. A prominent dark “bubble” appears to the top left of the blue core. And a wider, elliptical “bubble” to the bottom right.

NASA, ESA, CSA, STScI, Janice Lee (STScI), Thomas Williams (Oxford), and the PHANGS team

“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.

Webb’s image of NGC 1300 shows a face-on barred spiral galaxy anchored by its central region, which is circular and shows a bright white point at the center with a light yellow circle around it. The central core is tiny compared to the rest of the galaxy. The core extends into the galaxy’s prominent diagonal bar structure, which is filled with a blue haze of stars. Orange dust filaments cross the bar, extending diagonally to the top and bottom, connecting the yellow circle in the central core to the galaxy’s spiral arms. There are two distinct orange spiral arms made of stars, gas, and dust that start at the edges of the bar and rotate counterclockwise. Together, the arm and bars form a backward S shape. The spiral arms are largely orange, ranging from dark to bright orange. Scattered across the packed scene are very few bright blue pinpoints of light. There are vast areas between where the orange spiral arms wrap that appear black. The top left and bottom right edges are dark black and there are some larger red and blue points of light, some that appear like disks seen from the side.

Spiral galaxy NGC 1300 is 69 million light-years away in the constellation Eridanus.

NASA, ESA, CSA, STScI, Janice Lee (STScI), Thomas Williams (Oxford), and the PHANGS team

Webb’s image of NGC 1087 shows a densely populated face-on spiral galaxy anchored by its central region, which takes the shape of a short light yellow line that is about a fifth of the length of the galaxy. Filamentary spiral arms made of stars, gas, and dust start at the center and extend to the top and bottom edges, rotating clockwise. There is so much light in this region that the spiral arms of the galaxy look muddled. They are largely orange, ranging from dark to bright orange. Scattered across the packed scene are some bright blue pinpoints of light, but they appear more clearly in areas where it is dark gray or black. Several smaller “bubbles” where it’s black appears throughout the galaxy. The edges of the scene are dark black and there are some larger bright blue points of light, along with a few pink shapes, likely background galaxies.

Spiral galaxy NGC 1087 is 80 million light-years away in the constellation Cetus.

NASA, ESA, CSA, STScI, Janice Lee (STScI), Thomas Williams (Oxford), and the PHANGS team

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.

Webb’s image of the galaxy NGC 1566 shows a densely populated face-on spiral galaxy anchored by its slightly oval central region, consisting of a core and small bar structure, which has a light blue haze of stars that covers about a quarter of the view. Two prominent spiny spiral arms made of stars, gas, and dust also start at the center, within the blue haze, and extend to the edges, rotating counterclockwise. The spiral arms of the galaxy are largely orange, ranging from dark to bright orange. The brightest areas of the arms are two large arcs that start at the central region and stretch up to the top and bottom. Scattered across the packed scene are innumerable bright blue pinpoints of light, which are stars spread throughout the galaxy. In areas where there is less orange, it is darker, and some dark regions look more circular. There are bright pink patches of light toward the outer regions of the spiral arms.

Spiral galaxy NGC 1566 is 60 million light-years away in the constellation Dorado.

NASA, ESA, CSA, STScI, Janice Lee (STScI), Thomas Williams (Oxford), and the PHANGS team

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.

Webb’s image of NGC 2835 shows a densely populated face-on spiral galaxy anchored by its small central region, which is immediately engulfed in the orange spiral arms. A blue glow of stars begins at the core and spreads outward. Spiny orange spiral arms made of stars, gas, and dust start at the center and extend to the edges, rotating counterclockwise and taking up most of the area. Tiny pinpoints of blue light, which are stars or star clusters, are scattered across the image, but are easiest to spot where there appear to be black bubbles within the orange dust. The spiral arms of the galaxy are largely orange, ranging from dark to bright orange. In a few areas, there are bright orange patches of light within the orange spiral arms, mainly toward the outer edges of the spiral arms. Toward the bottom are some larger pink and blue points of light, some are likely background galaxies that appear like disks seen from the side.

Spiral galaxy NGC 2835 is 35 million light-years away in the constellation Hydra.

NASA, ESA, CSA, STScI, Janice Lee (STScI), Thomas Williams (Oxford), and the PHANGS team

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.”

Webb’s image of NGC 1512 shows a face-on barred spiral galaxy anchored by its central region, which is circular and shows a bright white point at the center with blue and yellow circles around it. Outside the core is a large bar structure filled with a haze of blue stars, forming a rough parallelogram shape and taking up about a quarter of the area. The bar is crossed by orange filaments made of stars, gas, and dust that extend diagonally to the top left and bottom right. Outside this, the thick orange spiral arms form a rough oval, and within them there are smaller oval areas that appear black. The spiral arms are largely orange, ranging from dark to bright orange and extend beyond the edges of the image. There are many larger blue stars and slightly larger pink points of light spread throughout. Two larger foreground stars with at least six diffraction spikes are at top center and bottom center.

Spiral galaxy NGC 1512 is 30 million light-years away in the constellation Horologium.

NASA, ESA, CSA, STScI, Janice Lee (STScI), Thomas Williams (Oxford), and the PHANGS team

Webb’s image of NGC 1385 shows a messy face-on spiral galaxy in shades of white, yellow, orange, and red. There’s a bright yellow arc-shaped region toward the center, but it is very difficult to see a spiral shape. Scattered across the scene are some bright blue pinpoints of light, but they appear more clearly in areas where it is dark gray or black, below and to the right of the yellow central arc in blobs, with some individual blue points of light across the image. There are many bright red or orange regions in the orange arms, speckled irregularly throughout. The edges of the scene are dark black, containing several very faint pink, blue, and red blobs.

Spiral galaxy NGC 1385 is 30 million light-years away in the constellation Fornax.

NASA, ESA, CSA, STScI, Janice Lee (STScI), Thomas Williams (Oxford), and the PHANGS team

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.”

Webb’s image of the galaxy NGC 1672 shows a portion of a face-on barred spiral galaxy anchored by its central region, which is circular and has a bright white point at the center with blue and then yellow circular regions around it, anchored to the right of center. A roughly horizontal bar structure made of a blue haze of stars and filamentary orange dust lanes tilts up slightly and takes up the majority of the image. Two spiny orange spiral arms made of stars, gas, and dust connect to the end of the bar and extend outward, rotating clockwise. The spiral arms are largely orange, ranging from dark to bright orange and extend beyond the edges of the image. They are brightest orange away from the bright central region at left and right, like knots of orange beads strung together. The spiral shape of the galaxy is less apparent in this view, with the arms looking more like irregular waves in an ocean’s tides. There are many more dark or black regions between where the orange gas and dust of the bar and spiral arms appear. Scattered across the scene are some bright blue pinpoints of light.

Spiral galaxy NGC 1672 is 60 million light-years away in the constellation Dorado.

NASA, ESA, CSA, STScI, Janice Lee (STScI), Thomas Williams (Oxford), and the PHANGS team

Webb Telescopes view face-on of spiral galaxy NGC 4254.

NASA, ESA, CSA, STScI, Janice Lee (STScI), Thomas Williams (Oxford), and the PHANGS team

Quelle: NASA

Astronomie - NASA James Webb Space Telescope -Update-58

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