For the first time, researchers using NASA’s James Webb Space Telescope are seeing star formation, gas and dust in nearby galaxies at unprecedented infrared resolution. These data have led to an initial collection of 21 research papers that provide new insights into how some of the smallest processes in our universe—the beginning of star formation—affect the evolution of the largest objects in our cosmos: galaxies.
The largest survey of nearby galaxies in Webb’s first year of scientific activity is being conducted by the Physics at High Angular resolution in Nearby Galaxies (PHANGS) collaboration, involving more than 100 researchers from around the world. Webb’s observations are led by Janice Lee, principal scientist at the Gemini Observatory in the National Science Foundation’s NOIRLab and an affiliated astronomer at the University of Arizona in Tucson.
The team is studying a diverse sample of 19 spiral galaxies, and five of these targets – M74, NGC 7496, IC 5332, NGC 1365 and NGC 1433 – have been observed during the first few months of Webb’s science operations. The results have already impressed astronomers.
“The clarity with which we can see the fine structure certainly took us by surprise,” said team member David Tilker of Johns Hopkins University in Baltimore, Maryland.
“We can directly see how the energy from the formation of young stars affects the gas around them, and it’s just amazing,” said team member Eric Rosolowski of the University of Alberta, Canada.
In this MIRI image, the spiral arms of NGC 7496 are filled with overlapping cavernous bubbles and shells. These filaments and hollow cavities indicate that young stars are releasing energy and, in some cases, blowing out the gas and dust of the interstellar medium that surrounds them. In this image, NGC 7496 is blue, green, and red attributed to Webb MIRI data at 7.7, 10, and 11.3 and 21 microns (F770W, F1000W, and F1130W and F2100W, respectively). Credit: NASA, ESA, CSA, and J. Lee (NOIRLab). Image processing: A. Pagan (STScI)
Images from the Webb Mid-Infrared Instrument (MIRI) show the presence of a network of highly structured features in these galaxies – glowing dust cavities and huge, cavernous bubbles of gas that line the spiral arms. In some regions of the nearest galaxies observed, this network of elements consists of both separate and overlapping shells and bubbles where young stars release energy.
“Areas that are completely dark in the Hubble images are illuminated in extraordinary detail in these new infrared images, allowing us to study how dust in the interstellar medium absorbs light from the forming stars and emits it back in the infrared, illuminating the complex network of gas and dust,” said team member Karin Sandstrom of the University of California, San Diego.
The high-resolution images needed to study these structures had long eluded astronomers until Webb came along.
“The PHANGS team has spent years observing these galaxies in the optical, radio, and ultraviolet with NASA’s Hubble Space Telescope, the Atacama Large Millimeter/Submillimeter Array, and the Very Large Telescope Multi-Area Spectroscopic Surveyor,” added team member Adam LeRoy of Ohio State University . “But the earliest stages of a star’s life cycle are overlooked because the process is shrouded in clouds of gas and dust.”
Webb’s powerful infrared capabilities can cut through the dust to connect missing puzzle pieces.
For example, specific wavelengths observed by MIRI (7.7 and 11.3 microns) and the Webb Near Infrared Camera (3.3 microns) are sensitive to the emission of polycyclic aromatic hydrocarbons, which play a crucial role in the formation of stars and planets. These molecules were discovered by Webb in the first observations of the PHANGS program.
Studying these interactions at the finest scales can help understand the bigger picture of how galaxies have evolved over time.
During the MIRI observations of NGC 1365, clumps of dust and gas in the interstellar medium absorbed light from the forming stars and re-radiated it back in the infrared, illuminating the tangled network of cavernous bubbles and filaments under the influence of young, energy-emitting stars. in the spiral arms of the galaxy. In this image, NGC 1356 is blue, green, and red attributed to Webb MIRI data at 7.7, 10, and 11.3 and 21 microns (F770W, F1000W, and F1130W and F2100W, respectively). Credit: NASA, ESA, CSA, and J. Lee (NOIRLab). Image processing: A. Pagan (STScI)
“Because these observations are taken as part of the so-called treasury program, they are available to the public when they are observed and received on Earth,” said Eva Schinerer of the Max Planck Institute for Astronomy in Heidelberg, Germany, and leader of the PHANGS Collaboration.
The PHANGS team will work to create and release data sets that align the Webb data with each of the additional data sets previously obtained from other observatories to help accelerate the discovery of the broader astronomical community.
“Thanks to the telescope’s resolution, for the first time we can perform a complete census of star formation and inventory the interstellar medium bubble structures in nearby galaxies outside the Local Group,” Lee said. “This census will help us understand how star formation and its feedback are reflected in the interstellar medium and then give rise to the next generation of stars, or how it actually prevents the next generation of stars from forming.”
The PHANGS team’s research is being conducted as part of the General Observer 2107 program. The team’s initial findings, consisting of 21 separate studies, were recently published in a special issue of The Astrophysical Journal Letters.
The James Webb Space Telescope is the world’s premier space science observatory. Webb will unravel the mysteries of our solar system, peer into distant worlds around other stars, and explore the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners ESA (European Space Agency) and CSA (Canadian Space Agency).
