NASA’s James Webb Space Telescope Captures Images of Galaxy M82’s Glowing Core and Galactic Wind
A UMD-led team of researchers probed this ‘prototypical starburst galaxy’ to understand the conditions that foster star formation.
A team of astronomers led by University of Maryland Astronomy Professor Alberto Bolatto used NASA’s James Webb Space Telescope to survey Messier 82 (M82), a starburst galaxy that has long captivated scientists with its frenzy of star formation activity. Located 12 million light-years away in the constellation Ursa Major, M82 sprouts new stars 10 times faster than the Milky Way galaxy.
The team directed NIRCam, Webb’s near-infrared camera instrument, toward the starburst galaxy’s center to get a closer look at the physical conditions that foster the formation of new stars.
“M82 has garnered a variety of observations over the years because it can be considered as the prototypical starburst galaxy,” said Bolatto, lead author of the study, which was accepted for publication in The Astrophysical Journal. “Both NASA’s Spitzer and Hubble space telescopes have observed this target. With Webb’s size and resolution, we can look at this star-forming galaxy and see all of this beautiful, new detail.”
UMD astronomy Ph.D. student and study co-author Serena Cronin (M.S. ’23, astronomy) said she was blown away by these latest images of M82, which capture the galaxy’s core in glowing detail—down to the many speckles of space dust—and trace the shape of its galactic wind.
“Alberto called me into his office when he first received the images, and I was immediately stunned at the complexity of the wind,” said Cronin, who is writing her thesis on starburst galaxies and their galactic winds. “There are so many bumps and wiggles that we couldn’t see before, even with Hubble, giving us a better view of the intricate structure of the galactic wind. Being one of the first people to lay eyes on these images reminded me of the sense of wonder and discovery that drew me toward this field in the first place.”
A vibrant community of stars
Star formation continues to be shrouded in mystery because the process can be hidden behind curtains of dust and gas. However, Webb’s infrared capabilities made it possible to peer beyond these murky conditions. Using several wavelengths of light that highlight different properties of the galaxy, Cronin played an important role in helping to isolate the dust from other important features seen in M82.
“My job was to use these different wavelengths to estimate the underlying starlight,” she said. “By subtracting the starlight out of the original observations, I was able to isolate the dust features to their fullest extent."
While dark brown tendrils of heavy dust are threaded throughout M82’s glowing white core even in this infrared view, Webb’s NIRCam revealed a level of detail that has historically been obscured. Closer to the center, small specks depicted in green denote concentrated areas of iron, most of which are remnants of supernovas. Small patches that appear red signify regions where molecular hydrogen is illuminated by a nearby young star’s radiation.
“This image shows the power of Webb,” said study co-author and UMD alumna Rebecca Levy (M.S. ’17, Ph.D. ’21, astronomy) of the University of Arizona, Tucson. “Every single white dot in this image is either a star or a star cluster. We can start to distinguish all of these tiny point sources, which enables us to acquire an accurate count of all the star clusters in this galaxy.”
Following the galactic wind
Looking at M82 in slightly longer infrared wavelengths, clumpy tendrils represented in red can be seen extending above and below the galaxy’s plane. These gaseous streamers are a galactic wind rushing out from the core of the starburst.
In part, Bolatto and his co-authors wanted to understand where this galactic wind originates and how hot and cold components interact within the wind. Webb’s NIRCam was able to trace the structure of the galactic wind by following a trail of polycyclic aromatic hydrocarbons (PAHs)—small dust grains that survive in cooler temperatures but are destroyed in hot conditions.
To the team’s surprise, Webb’s view of the PAH emission highlights the galactic wind’s fine structure—an aspect previously unknown. Depicted as red filaments, the emission extends away from the central region where the heart of star formation is located. Another unanticipated find was the similar structure between the PAH emission and that of hot, ionized gas.
“It was unexpected to see the PAH emission resemble ionized gas,” Bolatto said. “PAHs are not supposed to live very long when exposed to such a strong radiation field, so perhaps they are being replenished all the time. It challenges our theories and shows us that further investigation is required.”
Lighting a path forward
Webb’s observations of M82 in near-infrared light spur further questions about star formation, some of which the team hopes to answer with additional Webb data, including that of another starburst galaxy. The team is also working on papers that will characterize the stellar clusters and correlations among wind components of M82.
The team will soon have spectroscopic observations of M82 from Webb ready for their analysis, as well as complementary large-scale images of the galaxy and wind. Spectral data will help astronomers determine accurate ages for the star clusters and provide a sense of timing for how long each phase of star formation lasts in a starburst galaxy environment.
UMD Astronomy Professor Sylvain Veilleux, who also co-authored the study in The Astrophysical Journal, said that he and Bolatto will continue to use Webb data to study the galactic winds of M82 and other objects.
“This is just the beginning since Alberto and I were recently awarded additional time on Webb to observe 10 objects with known, large-scale galactic winds, including M82,” Veilleux said. “We'll be mapping both the dust and the warm molecular gas, as well as the ionized gas entrained in large-scale galactic winds, to learn how closely they lie relative to each other.”
For astronomers, inspecting the activity in galaxies like M82 can yield a deeper understanding of the early universe.
“Webb’s observation of M82, a target closer to us, is a reminder that the telescope excels at studying galaxies at all distances,” Bolatto said. “In addition to looking at young, high-redshift galaxies, we can look at targets closer to home to gather insight into the processes that are happening here—events that also occurred in the early universe.”
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Other UMD-affiliated co-authors of this study included Rodrigo Herrera-Camus (M.S. ’11, Ph.D. ’15, astronomy), Laura Lenkić (M.S. ’20, Ph.D. ’21, astronomy), Elizabeth Tarantino (M.S. ’18, Ph.D. ’23, astronomy) and Vicente Villanueva (M.S. ’20, Ph.D. ’23, astronomy). Alyssa Pagan (B.S. ’16, astronomy) of the Space Telescope Science Institute (STScI) used Webb data to render the multicolor images of M82.
Their paper, “JWST Observations of Starbursts: Polycyclic Aromatic Hydrocarbon Emission at the Base of the M 82 Galactic Wind,” was accepted for publication in The Astrophysical Journal.
This study was supported by NASA (Contract No. NAS 5-03127). This story does not necessarily reflect the views of this organization.
This article was adapted from text provided by STScI.
