Maryland Today | UMD-led astronomy team reveals breathtaking…


The same galaxy imaged by Hubble and JWST

Star formation remains a mystery because the process can be hidden behind curtains of dust and gas. However, Webb's infrared capabilities made it possible to see through the darkness with multiple wavelengths of light that highlight different features of the galaxy.

While dark brown tendrils of heavy dust streak M82's bright white core even in infrared view, Webb's NIRCam revealed a level of detail hidden in views from other telescopes. Closer to the center, small green spots mark concentrated areas of iron, most of which are remnants of supernovae. Small red spots indicate regions where molecular hydrogen is illuminated by radiation from a nearby young star.

“This image shows the power of Webb,” said study co-author Rebecca Levy MS ’17, Ph.D. '21 from the University of Arizona, Tucson. “Every single white dot in this image is either a star or a star cluster. We can begin to distinguish all of these tiny point sources, allowing us to accurately count all the star clusters in this galaxy.”

Looking at M82 at slightly longer infrared wavelengths, one can see clumpy tendrils shown in red extending above and below the plane of the galaxy. These gaseous streamers are a galactic wind flowing from the core of the starburst.

Bolatto and his co-authors wanted, in part, to understand where this galactic wind comes from and how hot and cold components within the wind interact. Webb's NIRCam was able to track 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 PAH emission highlights the fine structure of the galactic wind – a previously unknown aspect. The emission, shown as red filaments, extends away from the central region where the heart of star formation is located. Webb's observations of M82 in near-infrared light raise 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 work that will characterize the star clusters and correlations between M82's wind components.

The team will soon have spectroscopic observations of M82 from Webb, as well as complementary large-scale images of the galaxy and wind, available for analysis. Spectral data will help astronomers determine the exact ages of star clusters and give a sense of how long each phase of star formation lasts in a starburst galaxy environment.

UMD astronomy professor Sylvain Veilleux, who was also a co-author of the study, said he and Bolatto will continue to use Webb data to study the galactic winds of M82 and other objects.

“This is just the beginning, as Alberto and I were recently given additional time on Webb to observe ten objects with known large-scale galactic winds, including M82,” Veilleux said. “We will map both the dust and the warm molecular gas, as well as the ionized gas carried away in large galactic winds, to find out how close they are relative to each other.”

This article is based in part on a text from the Space Telescope Science Institute