NASA's Webb Discovers Complex Gas and Dust Networks in Nearby Galaxies

Researchers using NASA's James Webb Space Telescope are getting an unprecedented look at star formation, gas, and dust in nearby galaxies at infrared wavelengths. The data has enabled an initial collection of 21 research papers that provide new insight into how some of our universe's smallest-scale processes - the beginnings of star formation - impact the evolution of our cosmos' largest objects: galaxies.

New imagery from NASA's James Webb Space Telescope provides scientists with their first look at the fine structure of nearby galaxies and how it is influenced by the formation of young stars. NGC 1433 is a barred spiral galaxy with a bright core surrounded by rings of double stars. For the first time, scientists can see cavernous bubbles of gas where forming stars have released energy into their surroundings in Webb's infrared images. Blue, green, and red were assigned to Webb's MIRI data at 7.7, 10, 11, and 21 microns in the image of NGC 1433.
Credits: NASA, ESA, CSA, and J. Lee (NOIRLab). Image processing: A. Pagan (STScI)

The Physics at High Angular Resolution in Nearby Galaxies (PHANGS) collaboration, which includes more than 100 researchers from around the world, is conducting the largest survey of nearby galaxies in Webb's first year of science operations. Janice Lee, Gemini Observatory chief scientist at the National Science Foundation's NOIRLab and affiliate astronomer at the University of Arizona in Tucson, is leading the Webb observations.

The team is studying a diverse sample of 19 spiral galaxies, and observations of five of those targets - M74, NGC 7496, IC 5332, NGC 1365, and NGC 1433 - have taken place in Webb's first few months of science operations. Astronomers are already astounded by the results.

"The clarity with which we are seeing the fine structure took us by surprise," team member David Thilker of Johns Hopkins University in Baltimore, Maryland, said.

"We're directly seeing how the energy from young star formation affects the gas around them, and it's just remarkable," said team member Erik Rosolowsky of the University of Alberta in Canada.

In this MIRI image, the spiral arms of NGC 7496 are filled with cavernous bubbles and shells that overlap one another. These filaments and hollow cavities are evidence of young stars releasing energy and, in some cases, blowing out the gas and dust that surrounds them in the interstellar medium. Blue, green, and red were assigned to Webb's MIRI data at 7.7, 10, 11, and 21 microns in this image of NGC 7496.
Credits: NASA, ESA, CSA, and J. Lee (NOIRLab). Image processing: A. Pagan (STScI)

Webb's Mid-Infrared Instrument (MIRI) images show the presence of a network of highly structured features within these galaxies, including glowing cavities of dust and huge cavernous bubbles of gas that line the spiral arms. This web of features appears to be built from both individual and overlapping shells and bubbles where young stars are releasing energy in some regions of the nearby galaxies observed.

“Areas which are completely dark in Hubble imaging light up in exquisite detail in these new infrared images, allowing us to study how the dust in the interstellar medium has absorbed the light from forming stars and emitted it back out in the infrared, illuminating an intricate network of gas and dust,” said team member Karin Sandstrom of the University of California, San Diego. 

“The PHANGS team has spent years observing these galaxies at optical, radio, and ultraviolent wavelengths using NASA’s Hubble Space Telescope, the Atacama Large Millimeter/Submillimeter Array, and the Very Large Telescope’s Multi Unit Spectroscopic Explorer,” added team member Adam Leroy of the Ohio State University. “But, the earliest stages of a star’s lifecycle have remained out of view because the process is enshrouded within gas and dust clouds.”

Webb's powerful infrared abilities can cut through the dust and reconnect the puzzle pieces.

Specific wavelengths observable by MIRI (7.7 and 11.3 microns) and Webb's Near-Infrared Camera (3.3 microns), for example, are sensitive to emission from polycyclic aromatic hydrocarbons, which play an important role in star and planet formation. Webb discovered these molecules during the first PHANGS observations.

Investigating these interactions at the atomic level can help shed light on the larger picture of how galaxies have evolved over time.

“Because these observations are taken as part of what's called a treasury program, they are available to the public as they are observed and received on Earth,” said Eva Schinnerer of the Max Planck Institute for Astronomy in Heidelberg, Germany, and leader of the PHANGS collaboration.

During the MIRI observations of NGC 1365, clumps of dust and gas in the interstellar medium absorbed light from forming stars and emitted it back out in the infrared, illuminating an intricate network of cavernous bubbles and filamentary shells influenced by young stars releasing energy into the galaxy's spiral arms. Blue, green, and red were assigned to Webb's MIRI data at 7.7, 10, 11, and 21 microns in this image of NGC 1356.
Credits: NASA, ESA, CSA, and J. Lee (NOIRLab). Image processing: A. Pagan (STScI)

To help the broader astronomical community accelerate discovery, the PHANGS team will work to create and release data sets that align Webb's data with each of the complementary data sets obtained previously from the other observatories.

“Thanks to the telescope's resolution, for the first time we can conduct a complete census of star formation, and take inventories of the interstellar medium bubble structures in nearby galaxies beyond the Local Group,” Lee said. “That census will help us understand how star formation and its feedback imprint themselves on the interstellar medium, then give rise to the next generation of stars, or how it actually impedes the next generation of stars from being formed.”