Webb and Hubble team up to trace interstellar dust in a galactic pair

This article highlights data from the Webb Scientific Process that has not yet been peer-reviewed. Here, interdisciplinary Web scientist Roger Windhorst and his team discuss their observations.

“We got more than we expected by combining data from NASA’s James Webb Space Telescope and NASA’s Hubble Space Telescope! Webb’s new data allowed us to trace the light emitted by the bright white elliptical galaxy (left) through the spiral spiral galaxy on the right—and determine the effect of interstellar dust on spiral galaxy. This image of the VV 191 galaxy pair includes near infrared light by Webb, and ultraviolet and visible light from Hubble.”

“Webb’s near-infrared data also show us the galaxy’s longer, extremely dusty spiral arms, giving the appearance that the arms overlap with the central bulge of the bright white elliptical galaxy to the left. Although the two foreground galaxies are relatively astronomically speaking, they are not actively interacting.’

“VV 191 is the latest addition to a small number of galaxies that helps researchers like us directly compare the properties of galactic dust. This target was selected from nearly 2,000 overlapping pairs of galaxies identified by Galaxy Zoo volunteer scientists.”

“Understanding where dust is present in galaxies is important because dust changes the brightness and colors that appear in galaxy images. Dust grains are partly responsible for the formation of new stars and planets, so we are always keen to identify their presence for further research.”

“The image contains a second discovery that is easier to overlook. Consider the white elliptical galaxy on the left. A faint red arc appears in the 10 o’clock inset. This is a very distant galaxy whose light is being bent by the elliptical galaxy’s gravity. The foreground galaxy is duplicated.” . The stretched red arc is deformed where it reappears—as a dot—at 4 o’clock. These images of the lensed galaxy are so faint and so red that they went unrecognized in the Hubble data, but are unmistakably visible in the Webb near-infrared image . Simulating such galaxies with gravitational lensing helps us reconstruct the mass of individual stars as well as the amount of dark matter in the core of that galaxy.”

“Like many of Webb’s images, this image of VV 191 shows additional galaxies deeper and deeper in the background. The two spotted spirals in the upper left corner of the elliptical galaxy are the same size but very different colors. One is probably very dusty. and the other is very far away, but we—or other astronomers—need to get data, known as spectra, to determine what’s what.”

Courtesy of the Webb Space Telescope