A new image from the James Webb Space Telescope shows the fleeting patterns of dust and gas in a neighboring galaxy.
It’s named NGC 6822, or Barnard’s Galaxy, and it’s the nearest galaxy to the Milky Way that isn’t one of its satellites, at 1.6 million light-years away. It is a small dwarf galaxy, only 7,000 light-years across, with relatively few heavy elements, but the vast majority of its stars were born during the last 5 billion years.
Because of this apparent mismatch in characteristics, Barnard’s Galaxy is a great laboratory for studying the evolution of galaxies in the early Universe, when there were few metals available.
This is because all elements heavier than hydrogen and helium in the Universe were created by stars. These massive hot balls smash atoms together in their cores, producing heavier elements all the way up to iron; and when they burst or collide at the conclusion of their life, the immense violence produces even heavier elements.
Barnard’s galaxy has spent the most of its existence in relative solitude, with no interaction with other objects. This could be one of the reasons for its low metallicity: it was subjected to minimal gravitational perturbations, which could have compressed its dust and gas and triggered star formation. However, scientists believe it came close enough to the Milky Way around 3 to 4 billion years ago for our larger galaxy’s gravity to mix things up.
As it turns out, this is fantastic news for us. We have a nearby low-metallicity object that is generating stars, providing us a glimpse of what galaxies in the early Universe would have looked like.
And the JWST is an ideal observatory for the job. Its mid-infrared instrument, MIRI, can see the complexities of infrared light released by gas, while its near-infrared instrument, NIRCam, renders dust and gas nearly invisible, allowing it to see the stars it obscures.
JWST’s recently released image combines the perspectives of both sensors. The greeny-yellowy gossamer swirls are gas and dust; the bright red and orange blobs are star formation zones; and the thick field of sparkling stars pervades it all.
The investigation of this fascinating galaxy is still ongoing, but the findings should help astronomers understand a little bit more about how everything in the Universe came to be.
Meanwhile, you can download wallpaper-sized versions of the new image from the ESA Webb website.