What’s better than a pair of galaxies observed by a pair of iconic space telescopes? The answer to that, according to researchers using the Hubble and James Webb Space Telescopes, is finding even more galaxies and other remarkable details no one expected in the duo’s observations.
“Galaxies in the foreground, background, deep background, and into the depths,” said astronomer William Keel from Galaxy Zoo, on Twitter.
“We got more than we bargained for by combining data from NASA’s James Webb Space Telescope and NASA’s Hubble Space Telescope,” said Rogier Windhorst of Arizona State University in a JWST blog post. Windhorst used JWST to look at the galaxy pair VV 191 in near-infrared, and combined it with Hubble observations in visible and ultraviolet light.
One of the big anticipations about JWST becoming operational was the ability use the new telescope in tandem with Hubble. Astronomer Helmut Jenkner from the Space Telescope Science Institute told me years ago that the two telescopes operating together would be more powerful than either of them operating alone.
This latest image proves his point. The twin observations allowed astronomers to study how the dust from these two galaxies are potentially interacting, but it also allowed them to find other previously unseen background galaxies and even a hidden gravitational lens.
“This all comes from 30 minutes’ worth of data using 1/8 of the field of view of JWST’s NIRCam camera,” Keel mused. “And there are a lot more galaxies [like these] out there.”
Dust is one of the most important components of the Universe, as it plays a major role in the evolution of galaxies and is an essential ingredient for new stars and planets. Analyzing intergalactic and cosmic dust can provide snapshots of the contents, conditions and processes operating in galaxies – and even in other solar systems — at various stages of their evolution.
Since JWST is an infrared telescope, one of the basic uses of the new telescope is to learn more about the properties of dust in other galaxies, as well as our own galaxy; infrared telescopes have the ability to peer inside the dust to determine its properties.
In that vein, VV 191 was targeted as an early observation for JWST, based on how galactic pairs offer rare glimpses and unique ways to study galactic dust. Volunteers from the citizen scientist/community scientist project Galaxy Zoo were enlisted to contribute to a catalog of nearly 2,000 suitable galaxy pairs. VV 191 was first noted by a Zoo volunteer in 2007.
In a Galaxy Zoo blog post, Keel wrote that silhouetted or overlapping galaxy systems can “highlight effects of dust in the foreground galaxy on passing light, and offer ways to study the dust which are complementary to observations in the deep infrared where the dust itself shines, giving off the energy it absorbs from starlight.”
While the visible-light measurements from Hubble of these types of backlit galaxies show us where the dust is — no matter how cold it might be (and where it can hide from infrared detection) — JWST’s new infrared data a allowed the researchers to identify how the interstellar dust is affecting the spiral galaxy.
They were able to trace the light that was emitted by the bright white elliptical galaxy – the one on the left — which is “backlighting” the spiral galaxy, allowing them to trace the effects of interstellar dust through the winding spiral galaxy at right.
“Understanding where dust is present in galaxies is important, because dust changes the brightness and colors that appear in images of the galaxies,” Windhorst said. “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.”
These two galaxies might look like they are intertwining or colliding – and previously, it was thought they were. But the new observations with JWST show there is actually quite a bit of distance between them and they are not actively interacting. You can see how the dusty, reddish arms on the spiral galaxy at right look like they are overlapping the white elliptical at left. Astronomers said that if you could look at an angle, there would be a noticeable distance between them.
But wait, there’s more!
However, other things popped out in the new JWST observations. A previously unseen galaxy appeared—twice! Take a look at the white elliptical again. A faint red arc appears in the inset at 10 o’clock. Light from a very distant galaxy is bent and magnified by the gravity of the foreground elliptical galaxy—and its image 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,” wrote Windhorst, “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.”
Also, as we’ve said before, basically every JWST image is like a Hubble Deep Field image. So, zoom in to see the array of distant galaxies. For example, 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 researchers said they need to obtain data known as spectra to determine which is which.
Whew …. all this from a short observation from JWST, enhanced by Hubble data.
In short, Keel said, “we got what we came for, and the Universe provided interesting bonuses.”