Researchers using the NASA/ESA/CSA James Webb Space Telescope will for the first time get a view of star formation, gas and dust in nearby galaxies with unprecedented resolution at infrared wavelengths. The data has enabled an initial collection of 21 research papers that provide new insight into how some of the smallest processes in the Universe – the beginnings of star formation – influence the evolution of the largest objects in our cosmos: galaxies.
The largest survey of nearby galaxies in Webb’s first year of science operations is being conducted by the Physics at High Angular resolution in Near Galaxies (PHANGS) collaboration, involving more than 100 researchers from around the world. The Webb observations are led by Janice Lee, chief scientist of the Gemini Observatory at the US National Science Foundation’s NOIRLab and an associate astronomer at the University of Arizona in Tucson.
The team is studying a diverse sample of 19 spiral galaxies, and in Webb’s first few months of science operations, observations have been made of five of those targets – M74, NGC 7496, IC 5332, NGC 1365 and NGC 1433. The results are already astounding astronomers.
This image of the nearby galaxy NGC 1433, captured by Webb’s Mid-Infrared Instrument (MIRI), shows compass arrows, scale bar, and color key for reference. The north and east compass arrows indicate the orientation of the image in the sky. Note that the relationship between north and east in the sky (viewed from below) is reversed relative to directional arrows on a map of the ground (viewed from above). At the bottom right is a scale bar labeled 3500 light-years, 30 arcseconds. The length of the scale bar is about one-fifth of the total width of the image. Below the image is a color code that indicates which MIRI filters were used to create the image and what color of visible light is assigned to each filter. In this image of NGC 7496, blue, green, and red were mapped to Webb’s MIRI data at 7.7, 10, and 11.3 and 21 microns (filters F770W, F1000W, and F1130W and F2100W, respectively). Scientists get their first look with the powerful resolution of the NASA/ESA/CSA James Webb Space Telescope on how the formation of young stars influences the evolution of nearby galaxies. The spiral arms of NGC 7496, one of a total of 19 galaxies targeted for study by the Physics at High Angular Resolution in Near Galaxies (PHANGS) collaboration, are filled with cavernous bubbles and shells that overlap in this image from Webb’s Mid-Infrared Instrument (MIRI). These filaments and hollow cavities are evidence that young stars release energy and, in some cases, expel the gas and dust from the interstellar medium into which they plow. Until the advent of Webb’s high resolution at infrared wavelengths, stars at the earliest point of their life cycles in nearby galaxies such as NGC 7496 remained obscured by gas and dust. Webb’s specific wavelength coverage (7.7 and 11.3 microns) enables the detection of polycyclic aromatic hydrocarbons, which play a critical role in the formation of stars and planets. In Webb’s MIRI image, these are mostly found in the main dust lanes in the spiral arms. In their analysis of Webb’s new data, scientists were able to identify nearly 60 new, undiscovered embedded cluster candidates in NGC 7496. These newly identified clusters could be among the youngest stars in the entire galaxy. At the center of NGC 7496, a barred spiral galaxy, is an active galactic core (AGN). An AGN is a supermassive black hole that emits jets and winds. The AGN glows brightly in the center of this Webb image. In addition, Webb’s extreme sensitivity also picks up several background galaxies far from NGC 7496, which appear green or red in some cases. NGC 7496 is located more than 24 million light-years away from Earth in the constellation Grus. MIRI was contributed by ESA and NASA, with the instrument designed and built by a consortium of nationally funded European institutes (The MIRI European Consortium) and NASA’s Jet Propulsion Laboratory, in collaboration with the University of Arizona. Credit: NASA, ESA, CSA and J. Lee (NOIRLAb), A. Pagan (STScI)
The images from Webb’s Mid-Infrared Instrument (MIRI) reveal the presence of a network of highly structured features within these galaxies – glowing pockets of dust and huge cavernous gas bubbles along the spiral arms. In some regions of the observed nearby galaxies, this web of features appears to be made up of both individual and overlapping shells and bubbles where young stars release energy.
The high-resolution imaging needed to study these structures long eluded astronomers — that is, until Webb came into the picture. Webb’s powerful infrared capabilities can penetrate through the dust to connect the missing pieces of the puzzle. For example, specific wavelengths observed by MIRI (7.7 and 11.3 microns) are sensitive to emission of polycyclic aromatic hydrocarbons, which play a critical role in the formation of stars and planets. These molecules were detected by Webb in the first observations by the PHANGS program.
This image of the nearby galaxy NGC 1433, captured by Webb’s Mid-Infrared Instrument (MIRI), shows compass arrows, scale bar, and color key for reference. The north and east compass arrows indicate the orientation of the image in the sky. Note that the relationship between north and east in the sky (viewed from below) is reversed relative to directional arrows on a map of the ground (viewed from above). At the bottom right is a scale bar labeled 8,000 light-years, 30 arcseconds. The length of the scale bar is about one-fifth of the total width of the image. Below the image is a color code that indicates which MIRI filters were used to create the image and what color of visible light is assigned to each filter. In this image of NGC 1356, blue, green, and red were mapped to Webb’s MIRI data at 7.7, 10, and 11.3 and 21 microns (filters F770W, F1000W, and F1130W and F2100W, respectively). Scientists get their first look with the powerful resolution of the NASA/ESA/CSA James Webb Space Telescope on how the formation of young stars influences the evolution of nearby galaxies. NGC 1365, seen here by Webb’s Mid-Infrared Instrument (MIRI), is one of a total of 19 galaxies being examined by the Physics at High Angular Resolution in Near Galaxies (PHANGS) collaboration. As shown by the MIRI observations of NGC 1365, clumps of dust and gas in the interstellar medium have absorbed the light from forming stars and re-emitted it into the infrared, creating an intricate network of hollow bubbles and filamentary envelopes influenced by young stars. is lit releasing energy in the spiral arms of the galaxy. Webb’s superb resolution also picks up several extremely bright star clusters not far from the core and newly observed recently formed clusters along the outer edges of the spiral arms. In addition, the Webb images provide insight into how the orbits of stars and gas vary depending on where they form, and how this results in the population of older clusters outside the inner ring of star formation. NGC 1365 is a double-barred spiral galaxy located about 56 million light-years from Earth. It is one of the largest galaxies currently known to astronomers, spanning twice the length of the Milky Way. MIRI was contributed by ESA and NASA, with the instrument designed and built by a consortium of nationally funded European institutes (The MIRI European Consortium) and NASA’s Jet Propulsion Laboratory, in collaboration with the University of Arizona. Credit: NASA, ESA, CSA and J. Lee (NOIRLAb), A. Pagan (STScI)
Studying these interactions at the finest scale can help understand the bigger picture of how galaxies have evolved over time.
The PHANGS team will work to create and release datasets that align Webb’s data with each of the additional datasets previously obtained from the other observatories to help accelerate discoveries by the wider astronomical community.
The research by the PHANGS team is being conducted as part of the General Observer Program 2107. The team’s initial findings, comprising 21 individual studies, were recently published in a special issue of The Astrophysical Journal Letters.
