2024-04-07 13:05:17
The starburst galaxy M82 was observed by the Hubble Space Telescope in 2006, which showed the galaxy’s spiral disk, ragged clouds, and hot hydrogen gas. The James Webb Space Telescope observed the core of M82, capturing in unprecedented detail the structure of the galactic wind and characterizing individual stars and star clusters. Credit: NASA, ESA, CSA, STScI, Alberto Bolato (UMD)
Inside a site full of new and young stars hides a complex infrastructure.
NASA’s James Webb Space Telescope has set its sights on the starburst galaxy Messier 82 (M82), a small but massive cluster of rapid star formation. By taking a closer look with Webb’s sensitive infrared capabilities, a team of scientists is reaching the heart of The Galaxy: Gaining a better understanding of how it forms stars, and how this extreme activity affects the galaxy as a whole.
The Webb Space Telescope studies an extreme starburst galaxy
A team of astronomers used NASA’s James Webb Space Telescope to survey the starburst galaxy Messier 82 (M82). Located 12 million light-years away in the constellation Ursa Major, this galaxy is relatively compact in size but hosts a frenzy of Star Formation Activity By comparison, M82 sprouts new stars 10 times faster than the Milky Way Galaxy.
Led by Alberto Bolato of the University of Maryland, College Park, the team aimed Webb’s NIRCam (Near Infrared Camera) instrument at the center of the starburst galaxy, getting a close-up look at the physical conditions that foster the formation of new stars.
“M82 has gained a variety of observations over the years because it can be considered the autotypical starburst galaxy,” said Bulato, lead author of the study. “Both NASA’s Spitzer and Hubble space telescopes observed this target. With the size and resolution of the Web, we can look at the star-forming galaxy and see all these beautiful, new details.”
Astronomers used the James Webb Space Telescope to peer toward the center of M82, where a galactic wind is being launched by rapid star formation and subsequent supernovae. Studying the galactic wind can offer insight into how the loss of gas shapes the future growth of the galaxy.
This image from Webb’s NIRCam (Near Infrared Camera) instrument shows M82’s galactic wind through emission from sooty chemical molecules known as polycyclic aromatic hydrocarbons (PAHs). PAHs are very small dust grains that survive in cooler temperatures but are destroyed in hot conditions. The structure of the emission is similar to that of hot, ionized gas, indicating that the PAH can be regenerated by further ionization of molecular gas.
In this image, light at 3.35 µm is colored red, 2.50 µm is green, and 1.64 µm is blue (filters F335M, F250M, and F164N, respectively).
Credit: NASA, ESA, CSA, STScI, Alberto Bolato (UMD)
A vibrant community of stars
Star formation continues to retain a sense of mystery because it is shrouded in curtains of dust and gas, creating an obstacle in observing this process. Fortunately, Webb’s infrared peering ability is an asset in navigating these murky conditions. In addition, these NIRCam images of the center of the starburst were obtained using an instrument mode that prevented the very bright source from overwhelming the detector.
While dark brown tendrils of heavy dust thread along M82’s luminous white core even in this infrared view, Webb’s NIRCam revealed a level of detail that has historically been hidden. Looking closer to the center, small spots outlined in green indicate concentrated regions of iron, most of which are supernova remnants. Small spots that appear red mark regions where molecular hydrogen is illuminated by radiation from a nearby young star.
“This image shows the power of the web,” said Rebecca Levy, the study’s second author at the University of Arizona in Tucson. “Every single white dot in this image is a star or a star cluster. We can begin to distinguish all these tiny point sources, allowing us to acquire a precise count of all the star clusters in this galaxy.”
A team of astronomers used NASA’s James Webb Space Telescope to survey the starburst galaxy Messier 82 (M82), located 12 million light-years away in the constellation Ursa Major. M82 hosts a frenzy of star formation, growing new stars by a factor of 10 Faster than the Milky Way Galaxy Webb’s infrared capabilities have allowed scientists to peer through curtains of dust and gas that have historically obscured the process of star formation.
This image from Webb’s NIRCam (Near Infrared Camera) instrument shows the center of M82 in unprecedented detail. With Webb’s resolution, astronomers can distinguish small, bright compact sources that are single stars or star clusters. Obtaining an accurate count of the stars and clusters that make up the center of M82 can help astronomers understand the different stages of star formation and the timelines for each stage.
In this image, light at 2.12 µm is colored red, 1.64 µm is green, and 1.40 µm is blue (F212N, 164N, and F140M filters, respectively).
Credit: NASA, ESA, CSA, STScI, Alberto Bolato (UMD)
Finding structure in vibrant conditions
Looking at M82 at slightly longer infrared wavelengths, clumpy tendrils represented in red can be seen extending above and below the galactic plane. These gaseous streams are galactic wind coming out of the starburst core.
One area of focus for this research team has been understanding how this galactic wind, caused by the rapid rate of star formation and subsequent supernovae, corrupts and affects the surrounding environment. By unraveling a central part of M82, scientists could examine where the wind originates, and gain insights into how hot and cold components interact within the wind.
Webb’s NIRCam instrument was suitable for tracing the structure of the galactic wind through emission from sooty chemical molecules known as polycyclic aromatic hydrocarbons (PAHs). PAH can be thought of as very small dust grains that survive in cooler temperatures but are destroyed in hot conditions.
Much to the team’s surprise, Webb’s view of the PAH emission highlights the fine structure of the galactic wind—a previously unknown aspect. Depicted as red filaments, the emission moves away from the central region where the heart of star formation is located. Another unexpected finding was the similar structure between the PAH emission and that of hot and ionized gas.
“It was unexpected to see the PAH emission similar to an ionized gas,” Bolato said. “PAHs shouldn’t live long when exposed to such a strong radiation field, so maybe they’re constantly being regenerated. This challenges our theories and shows us that further investigation is required.”
Annotated image of the starburst galaxy Messier 82 captured by Webb’s NIRCam (Near Infrared Camera) instrument, with compass arrows, scale bar, and color key for reference.
The north and east compass arrows show the direction of the image on the sky. Note that the relationship between north and east in the sky (as seen from below) is reversed in relation to the direction arrows on the ground map (as seen from above).
The scale bar is indicated in light years.
This image shows invisible near-infrared wavelengths of light translated into visible light colors. The color key shows which NIRCam filters were used when collecting the light. The color of each filter name is the visible light color used to represent the infrared light passing through that filter.
Credit: NASA, ESA, CSA, STScI, Alberto Bolato (UMD)
to light a path forward
Webb’s observations of M82 in near-infrared light raise additional questions about star formation, some of which the team hopes to answer with additional data collected with Webb, including that of another starburst galaxy. Two more papers from this team characterizing the star clusters and the correlations between M82’s wind components are almost complete.
In the near future, the team will 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 precise ages for star clusters and provide a sense of timing for how long each stage of star formation lasts in the vicinity of a starburst galaxy. On a larger scale, probing the activity in galaxies like M82 could deepen astronomers’ 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,” Bolato said. “In addition to looking at young, high-redshift galaxies, we can look at targets closer to home to gather insight into the processes going on here – events that also happened in the early universe.”
These findings were accepted for publication in The Astrophysical Journal.
The James Webb Space Telescope is the world’s leading space science observatory. Webb solves mysteries in our solar system, looks beyond to distant worlds around other stars, and explores 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 the Canadian Space Agency.
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