WLM is a dwarf galaxy in our galactic neighborhood. It’s fairly close to the Milky Way (only about 3 million light-years from Earth), but it’s also relatively isolated. WLM hasn’t interacted with other systems, which makes it really nice for testing our theories of galaxy formation and evolution. Many of the other nearby galaxies are intertwined and entangled with the Milky Way, which makes them harder to study.
A portion of the dwarf galaxy Wolf–Lundmark–Melotte (WLM) was captured by the Spitzer Space Telescope’s Infrared Array Camera (left) and the James Webb Space Telescope’s Near-Infrared Camera (right). The images demonstrate Webb’s remarkable ability to resolve faint stars outside the Milky Way. The Spitzer image shows 3.6-micron light in cyan and 4.5-micron in orange (IRAC1 and IRAC2). The Webb image includes 0.9-micron light shown in blue, 1.5-micron in cyan, 2.5-micron in yellow, and 4.3-micron in red (filters F090W, F150W, F250M, and F430M). Download the full-resolution version from the Space Telescope Science Institute. SCIENCE CREDIT: NASA, ESA, CSA, STScI, and Kristen McQuinn (Rutgers University). IMAGE PROCESSING: Alyssa Pagan (STScI).
Another interesting and important thing about WLM is that its gas is similar to the gas that made up galaxies in the early universe. It’s fairly unenriched, chemically speaking. (That is, it’s poor in elements heavier than hydrogen and helium.) This is because the galaxy has lost many of these elements through something we call galactic winds. Although WLM has been forming stars recently – throughout cosmic time, really – and those stars have been synthesizing new elements, some of the material gets expelled from the galaxy when the massive stars explode. Supernovae can be powerful and energetic enough to push material out of small, low-mass galaxies like WLM.
This post highlights data from Webb's science in progress, which has not yet been through the peer-review process.
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