Astronomers used the NASA/ESA/CSA James Webb Space Telescope to look toward M82’s centre, where a galactic wind is being launched as a result of 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 via 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 resembles that of hot, ionised gas, suggesting PAHs may be replenished by continued ionisation of molecular gas.
In this image, light at 3.35 microns is coloured red, 2.50 microns is green, and 1.64 microns is blue (filters F335M, F250M, and F164N, respectively).
[Image description: An edge-on spiral starburst galaxy with a bright white, glowing core set against the black background of space. A white band of the edge-on disc extends from lower left to upper right. Dark brown tendrils of dust are scattered thinly along this band. Many white points in various sizes — stars or star clusters — are scattered throughout the image, but are most heavily concentrated toward the centre. Many clumpy, red filaments extend vertically above and below the plane of the galaxy.]
Credit:
NASA, ESA, CSA, STScI, A. Bolatto (UMD)
NASA’s James Webb Space Telescope has trained its infrared capabilities on the compact but starburst galaxy Messier 82 (M82), located 12 million light-years away in the constellation Ursa Major. The telescope’s international team of astronomers used the NIRCam (Near-Infrared Camera) instrument to get a closer look at the physical conditions fostering new star formation.
The team’s lead author, Alberto Bolatto, noted that while the Spitzer and Hubble space telescopes had already observed M82, Webb’s size and resolution allowed them to view the star-forming galaxy in greater detail.
The NIRCam captured unprecedented levels of detail, revealing that the galaxy is sprouting new stars ten times faster than the Milky Way. The images depicted small specks in green, denoting concentrated iron areas, mostly supernova remnants.
Small patches appearing in red signify molecular hydrogen regions being lit up by radiation from a nearby young star. Additionally, the telescope’s view of the galaxy’s PAH (polycyclic aromatic hydrocarbon) emission highlights the wind’s refined structure, which was previously unknown.
A team of astronomers used the NASA/ESA/CSA James Webb Space Telescope to survey the starburst galaxy Messier 82 (M82), which is located 12 million light-years away in the constellation Ursa Major. M82 hosts a frenzy of star formation, sprouting new stars 10 times faster than the Milky Way galaxy. Webb’s infrared capabilities enabled scientists to peer through curtains of dust and gas that have historically obscured the star formation process.
This image from Webb’s NIRCam (Near-Infrared Camera) instrument shows the centre of M82 with an unprecedented level of detail. With Webb’s resolution, astronomers can distinguish small, bright compact sources that are either individual stars or star clusters. Obtaining an accurate count of the stars and clusters that compose M82’s centre can help astronomers understand the different phases of star formation and the timelines for each stage.
In this image, light at 2.12 microns is coloured red, 1.64 microns is green, and 1.40 microns is blue (filters F212N, 164N, and F140M, respectively).
[Image description: A section of M82 as imaged by Webb. An edge-on spiral starburst galaxy with a bright white, glowing core set against the black background of space. Dark brown tendrils of dust are scattered heavily toward the galaxy’s centre. Many white points in various sizes — stars or star clusters — are scattered throughout the image, but are most heavily concentrated toward the centre.]
Credit:
NASA, ESA, CSA, STScI, A. Bolatto (UMD)
The team’s second author, Rebecca Levy, noted the power of Webb, which allowed them to distinguish between tiny point sources, enabling them to acquire an accurate count of all the star clusters in the galaxy. These NIRCam images of the starburst’s core were obtained using a mode that prevented the very bright source from overwhelming the detector.
The starburst galaxy M82 was observed by the NASA/ESA Hubble Space Telescope in 2006, which showed the galaxy’s edge-on spiral disc, shredded clouds, and hot hydrogen gas. The NASA/ESA/CSA James Webb Space Telescope has observed M82’s core, capturing in unprecedented detail the structure of the galactic wind and characterising individual stars and star clusters.
The Webb image is from the telescope’s NIRCam (Near-Infrared Camera) instrument. The red filaments trace the shape of the cool component of the galactic wind via 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 the ionised gas, suggesting PAHs may be replenished from cooler molecular material as it is ionised.
[Image description: Left: Messier 82 as imaged by Hubble. Hour-glass-shaped red plumes of gas are shooting outward from above and below a bright blue, disc-shaped centre of a galaxy. This galaxy is surrounded by many white stars and set against the black background of space. Right: A section of Messier 82 as imaged by Webb. An edge-on spiral starburst galaxy with a bright white, glowing core set against the black background of space. A white band of the edge-on disc extends from lower left to upper right. Dark brown tendrils of dust are scattered thinly along this band. Many clumpy, red filaments extend vertically above and below the plane of the galaxy.]
Credit:
NASA, ESA, CSA, STScI, A. Bolatto (UMD)
The team’s focus was understanding how the galactic wind, caused by the rapid rate of star formation and subsequent supernovae, launches and influences its surrounding environment. Webb’s NIRCam instrument was ideally suited to tracing the structure of the galactic wind via emission from sooty chemical molecules known as PAHs.
The telescope’s observations of M82 spur further questions about star formation, some of which the team hopes to answer with additional data gathered with Webb.
The team will soon have spectroscopic observations of M82 from Webb ready for analysis, providing a sense of how long each phase of star formation lasts in a starburst galaxy environment. On a broader scale, insights gleaned from the research may further our understanding of galactic evolution.
Journal Reference
Bolatto, A. D., Levy, R. C., Tarantino, E., Boyer, M. L., Fisher, D. B., Leroy, A. K., Cronin, S. A., Klessen, R. S., Smith, J. D., Berg, D. A., Boeker, T., Boogaard, L. A., Ostriker, E. C., Thompson, T. A., Ott, J., Lenkic, L., Lopez, L. A., Dale, D. A., Veilleux, S., . . . Martini, P. (2024). JWST Observations of Starbursts: Polycyclic Aromatic Hydrocarbon Emission at the Base of the M 82 Galactic Wind. ArXiv. DOI: 10.48550/arXiv.2401.16648
