About 12 million light-years away, the spiral galaxy M82 is undergoing a period of explosive star formation. With the help of the James Webb Space Telescope, astronomers have uncovered details that were previously unknown to us.
The Messier 82 galaxy, also known as the “Cigar Galaxy,” was discovered in 1774 and is perhaps the most characteristic example of a star-forming galaxy—that is, a galaxy that produces stars at a particularly high rate. The rapid rate of star formation observed within it, about 10 times greater than that of our own Milky Way, is due to its gravitational interaction with the neighboring galaxy M81, an interaction estimated to last a total of several hundred million years. This period of extreme star formation relative to its mass, as well as its relatively close proximity within our local Universe, make M82 a one-of-a-kind environment for study.
Using the James Webb Space Telescope, a team of astronomers has revealed details of M82 that we are seeing for the first time. These include the bulging structure of its galactic disk, as well as millions of individual stars. This data will contribute to scientists’ efforts to uncover its evolutionary history and to gain a deeper understanding of the physical processes taking place inside it.
The image captured by the James Webb Space Telescope in the near-infrared shows 16.5 million stars as bright blue dots, representing only a small fraction of the galaxy’s total stars, which are too faint to be detected.
“M82 is an ideal laboratory for studying galactic evolution, as its properties allow us to investigate important physical processes, such as how stars form in such environments and how this, in turn, triggers outflows of material,” said Adam Smercina, the study’s lead researcher from the Space Telescope Science Institute in Baltimore and an assistant professor at Tufts University in Massachusetts.
In fact, the explosive star formation within M82 triggers the ejection of bipolar jets of material above and below its galactic disk. Closer to the galactic disk, these outflows (shown in yellow) consist mainly of ionized gas, while the orange hues visible farther away represent small dust grains.
Analysis of the relevant data will help scientists reconstruct at least part of the evolutionary history of the M82 galaxy.
Photo: A composite image of the M82 galaxy in the near-infrared and visible light, taken by the James Webb and Hubble space telescopes [Credit: NASA, ESA, CSA, Adam Smercina (STScI, Tufts), Thomas Williams (University of Manchester); Image Processing: Alyssa Pagan (STScI)].