Early Universe Clues Found Locally

by | February 21, 2024, 12:50 PM | Galaxies & Cosmology, Stars & Nebulae

A portion of the dwarf galaxy Wolf–Lundmark–Melotte (WLM) captured by the James Webb Space Telescope’s Near-Infrared Camera. The image demonstrates Webb’s remarkable ability to resolve faint stars outside the Milky Way. Color translation: 0.9-micron light is 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). Credit: NASA, ESA, CSA, Kristen McQuinn (RU); Image Processing: Zolt G. Levay (STScI)

There are two ways to go digging for ancient relics in our universe. You can use a telescope like the JWST to look at the light from far-off objects, but our best systems can’t tease too many details out of these distant objects. Alternatively, you can go looking for ancient stars that have managed to live undisrupted lives.

In a new paper in The Astrophysical Journal, researchers led by Kristen McQuinn used the JWST to look for the Methusala of stars. 

Here in our local group, toward the edge of our family of galaxies, is a dwarf galaxy that hasn’t undergone many interactions and has stars of all ages… and I mean all ages. In this system are stars thirteen billion years old and stars still forming. 

As described by McQuinn, “In looking so deeply and seeing so clearly, we’ve been able to, effectively, go back in time. You’re basically going on a kind of archaeological dig, to find the very low-mass stars that were formed early in the history of the universe.”

By studying the distribution of stars in this galaxy, they were able to piece together a star formation history that ebbed and flowed over time. For the system’s – and the Universe’s – first three billion years, star formation raged, but then it ebbed away for a while before reigniting. 

According to Quinn, “The universe back then was really hot. We think the temperature of the universe ended up heating the gas in this galaxy, and kind of turned off star formation for a while. The cool down period lasted a few billion years and then star formation proceeded again.”

This way of studying a galaxy’s history by looking at how many stars remain from different generations is the astronomy equivalent of counting tree rings. Here is to hoping that over time we’re able to see results from a whole forest of galaxies and understand what effects plagued the universe and what effects were unique to each region of space.