The James Webb Space Telescope (JWST) has zoomed into the heart of the Cigar Galaxy, a region of space engulfed in flames by an explosive period of star birth.
At the core of this starburst galaxy, also known as Messier 82 (M82), is a compact but turbulent environment that could give scientists a clearer picture of how stars are born en masse and how extreme environments shape the galaxies around them.
Located about 12 million light-years away in the constellation Ursa Major, M82 is forming stars 10 times faster than our relatively quiet galaxy, the Milky Way. The team imaged the core of this starburst galaxy with JWST’s Near Infrared Camera (NIRCam) to investigate what conditions trigger the formation of baby stars.
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“M82 can be considered the prototype of a starburst galaxy because it has collected several observations over the years,” team leader and University of Maryland researcher Alberto Bolatto said in a statement. said. “Both the Spitzer and Hubble space telescopes observed this target.
“Thanks to JWST’s size and resolution, we can look at this star-forming galaxy and see all these beautiful new details.”
How does JWST see through starbursts?
Star formation is common in the cosmos, but the gas and dust that form the raw materials for star formation have also managed to maintain an air of mystery, effectively shrouding the process.
Although gas and dust are very effective at absorbing visible light, infrared light can pass through this material. This means that JWST, with its powerful and sensitive infrared image of the cosmos, is the perfect tool to get to the very heart of star birth.
The NIRCam images collected by Bolatto and colleagues also took advantage of a special mode that prevented bright baby stars at the heart of M82 from overwhelming the instrument.
The JWST M82 shortwave infrared light image shows dark, reddish-brown dust lanes moving through M82’s white, cigar-smoke, bright core. The small green spots in the image represent regions of iron left over from supernova explosions of now-dead massive stars. The red-looking spots indicate areas where molecular hydrogen has been heated by radiation from young stars.
“This image demonstrates the power of JWST,” team member and University of Arizona scientist Rebecca Levy said in the statement. “Each white dot in this image is either a star or a star cluster. We can begin to distinguish all of these small point sources, allowing us to get an accurate count of all star clusters in this galaxy.”
Galactic winds of a smoking cigar
When JWST’s NIRCam imaged M82’s core in infrared light, the star-forming region took on a strikingly new appearance. Suddenly, streams of gaseous galactic winds appeared, extending even further from the galaxy’s previously noticed main starburst core; almost like a network of blood vessels extending from a biological heart rather than a galactic heart.
This galactic wind is powered by star formation and the supernova deaths of old stars. Like the lifeblood pumping through blood vessels in the human body, the galactic wind moves elements that facilitate galactic growth through further star formation, thus strongly influencing the body around it.
NIRCam was able to trace the structure of these galactic winds, which emit sooty chemical molecules known as polycyclic aromatic hydrocarbons (PAHs). Since PAHs are tiny dust grains that survive in cool regions but are destroyed by higher temperatures, this revealed how cold and hot components interact in the wind.
The fine structure of galactic winds in M82 was something the team did not expect to uncover; nor did they expect any similarity in terms of PAH emission and the structure of the hot, ionized gas branches.
“It was unexpected to see that the PAH emission resembled ionized gas,” Bolatto explained. “PAHs are not expected to live very long when exposed to such a strong radiation field, so perhaps they are constantly regenerating. This challenges our theories and tells us that further research is needed.”
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The team hopes that more JWST observations of M82 and other starburst galaxies could help answer some persistent questions about star birth. Scientists will also combine these new images with complementary large-scale images of the Cigar Galaxy and its galactic winds.
Light spectra from this galaxy will help astronomers determine accurate ages of star clusters in M82. This could reveal how long each stage of star formation lasts in starburst galactic environments.
“With these spectacular JWST images and our future spectra, we can examine exactly how strong winds and shock fronts from young stars and supernovae can clear the gas and dust from which new stars form,” team member and European Space Agency (ESA) said. ) scientist Torsten Böker said in his statement. “A detailed understanding of this ‘feedback’ loop is important for theories of how the early universe evolved because intense star explosions like the one in M82 were very common at high redshift.”
The team’s research has been accepted for publication in The Astrophysical Journal.