Webb, Hubble Team Up to Trace Interstellar Dust Within a Galactic Pair

Editor’s Note: This post highlights data from Webb science in progress, which has not yet been through the peer-review process. Here, Webb interdisciplinary scientist Rogier Windhorst and his team discuss their observations.

“We got more than we bargained for 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 that was emitted by the bright white elliptical galaxy, at left, through the winding spiral galaxy at right – and identify the effects of interstellar dust in the spiral galaxy. This image of galaxy pair VV 191 includes near-infrared light from Webb, and ultraviolet and visible light from Hubble.

The majority of the image shows the black background of space. Two large, very bright galaxies dominate the center of the image. The elliptical galaxy at left is extremely bright at its circular core, with dimmer white light extending to its transparent circular edges. At right is a bright spiral galaxy. It also has a bright white core, but has red and light purple spiral arms that start at the center and turn clockwise going outward. They end in faint red and appear to overlap the elliptical galaxy at left. Throughout the scene are a range of distant galaxies, the majority of which are very tiny and red, appearing as splotches.
Researchers traced light that was emitted by the bright white elliptical galaxy on the left through the spiral galaxy at right. As a result, they were able to identify the effects of interstellar dust in the spiral galaxy. Webb’s near-infrared data also shows us the galaxy’s longer, extremely dusty spiral arms in far more detail, giving them an appearance of overlapping with the central bulge of the bright white elliptical galaxy on the left, though the pair are not interacting. In this image, green, yellow, and red were assigned to Webb’s near-infrared data taken in 0.9, 1.5, and 3.56 microns (F090W, F150W, and F356W respectively). Blue was assigned to two Hubble filters, ultraviolet data taken in 0.34 microns (F336W) and visible light in 0.61 microns (F606W). Read the full description and download the image files by clicking or tapping the image above. Credit: NASA, ESA, CSA, Rogier Windhorst (ASU), William Keel (University of Alabama), Stuart Wyithe (University of Melbourne), JWST PEARLS Team

“Webb’s near-infrared data also show us the galaxy’s longer, extremely dusty spiral arms in far more detail, giving the arms an appearance of overlapping with the central bulge of the bright white elliptical galaxy on the left. Although the two foreground galaxies are relatively close 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 superimposed galaxy pairs identified by Galaxy Zoo citizen science volunteers.

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

The majority of the image shows the black background of space. Two large, very bright galaxies dominate the center of the image. At right is a bright spiral galaxy. It also has a bright white core, but has red and light purple spiral arms that start at the center and turn clockwise going outward. The elliptical galaxy at left is extremely bright at its circular core, with dimmer white light extending to its transparent circular edges. A light white box overlays the elliptical galaxy and reappears at the bottom left, showing the area in a larger view. A stretched red arc appears above the elliptical galaxy at 10 o’clock and a red dot appears at 4 o’clock.
Above the white elliptical galaxy at left, a faint red arc appears in the inset at 10 o’clock. This is a very distant galaxy whose appearance is warped. Its light is bent by the gravity of the elliptical foreground galaxy. Plus, its appearance is duplicated. The stretched red arc is warped where it reappears – as a dot – at 4 o’clock. In this image, green, yellow, and red were assigned to Webb’s near-infrared data taken in 0.9, 1.5, and 3.56 microns (F090W, F150W, and F356W respectively). Blue was assigned to two Hubble filters, ultraviolet data taken in 0.34 microns (F336W) and visible light in 0.61 microns (F606W). Read the full description and download the image files by clicking or tapping the image above. Credit: NASA, ESA, CSA, Rogier Windhorst (ASU), William Keel (University of Alabama), Stuart Wyithe (University of Melbourne), JWST PEARLS Team

“The image holds a second discovery that’s easier to overlook. Examine the white elliptical galaxy at left. A faint red arc appears in the inset at 10 o’clock. This is a very distant galaxy whose light is bent by the gravity of the elliptical foreground galaxy – and its appearance is duplicated. The stretched red arc is warped 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 Hubble data, but are unmistakable in Webb’s near-infrared image. Simulations of gravitationally lensed galaxies like this help us reconstruct how much mass is in individual stars, along with how much dark matter is in the core of this galaxy.

“Like many Webb images, this image of VV 191 shows additional galaxies deeper and deeper in the background. Two patchy spirals to the upper left of the elliptical galaxy have similar apparent sizes, but show up in very different colors. One is likely very dusty and the other very far away, but we – or other astronomers – need to obtain data known as spectra to determine which is which.”

About the authors:

Webb interdisciplinary scientist Rogier Windhorst of Arizona State University and his team obtained the data used in this image from early results of the Prime Extragalactic Areas for Reionization and Lensing Science (PEARLS) JWST Guaranteed Time Observation (GTO) programs, GTO 1176 and 2738. Additional data from Hubble’s STARSMOG snapshot program (SNAP 13695) and GO 15106, were added. Jake Summers, also of Arizona State, performed the pipeline data reduction. The dust analysis was led by William Keel of the University of Alabama, while the Hubble data acquisition was led by Benne Holwerda of the University of Louisville in Kentucky. The detailed gravitational-lensing analysis was conducted by Giovanni Ferrami and Stuart Wyithe, both of the University of Melbourne, Australia and ASTRO 3D, Australia.

Related science papers:

Webb’s PEARLS: dust attenuation and gravitational lensing in the backlit-galaxy system VV 191

Webb’s PEARLS: Prime Extragalactic Areas for Reionization and Lensing Science: Project Overview and First Results