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When astronomers combine the observational powers of the James Webb Space Telescope and the Hubble Space Telescope, they are capturing more detailed portraits of space.
A new image of the galactic pair shared by NASA on Wednesday is the surprising result of using data from both space observatories.
Each of the telescopes observed different wavelengths of light. Webb can detect infrared light that is invisible to the human eye, while Hubble has the ability to observe two galaxies in visible light as well as in ultraviolet light. The duo of an elliptical galaxy and a spiral galaxy is known as VV 191. and is about 700 million light-years away from Earth.
“By combining data from NASA’s James Webb Space Telescope and NASA’s Hubble Space Telescope, we got more than we bargained for!” Webb wrote interdisciplinary scholar and regents professor at Arizona State University For Rogier Windhorst NASA’s web blog.
“Webb’s new data allowed us to trace the light emitted by the bright white elliptical galaxy to the left, through the spiral galaxy to the right, and to identify the effects of interstellar dust in the spiral galaxy. … Webb’s near-infrared data show us the galaxy’s longer, extremely dusty spiral arms in greater detail, and the arms appear to coincide with the central bulge of the bright white elliptical galaxy on the left.”
The image is the initial result of the observation program Key Extragalactic Fields for Reionization and Lensing Science, or PEARLS, by the Webb Telescope, which has yet to go through the peer-review process. The research was submitted to The Astrophysical Journal.
Scientists selected the galaxy pair from among nearly 2,000 candidates identified by Galaxy Zoo citizen science volunteers. These small galaxies that appear so close together are not actually interacting with each other, but they allow researchers to track and compare the galactic dust.
“Understanding where dust is in galaxies is important because dust changes the brightness and colors seen in images of galaxies,” Windhorst wrote. “Dust grains are partly responsible for the formation of new stars and planets, so we are always looking to identify their presence for future studies.”
But a closer look at this galactic pair isn’t the only celestial wonder revealed in this composite image. Other galaxies are also visible behind the pair, and one of these points of light led to a second discovery within the new image. This phenomenon, called gravitational lensing, occurs when foreground galaxies act as a magnifying glass for objects behind them.
Scientists used the same technique Webb’s first photo was released in July. According to NASA, the space telescope has “delivered the deepest and sharpest infrared image of the distant universe ever.”
Above the white elliptical galaxy is a faint red arc on the left, which is actually a very distant galaxy. The gravitational force of the foreground elliptical galaxy has bent the light of the more distant galaxy. The tilt of the distant galaxy also causes it to reappear as a red dot to the lower right of the elliptical galaxy.
The images of the distant galaxy are so faint that they were not recognized in the Hubble data, but are clearly visible in Webb’s near-infrared observation.
“Simulations of gravitationally lensed galaxies like this help us reconstruct how much mass is in individual stars and how much dark matter is in the core of that galaxy,” Windhorst writes.
He added that, in addition to the insights astronomers have gained about VV 191, the background of this Webb image hints at more unsolved mysteries deeper in the universe. “The two patchy spirals in the upper left of the elliptical galaxy have similar apparent sizes but appear very different colors. It’s likely that one is too dusty and the other too far away, but we or other astronomers need to obtain information known as spectra to determine which is which.
