Within our galactic neighborhood, there is a galaxy with just 1,000 stars and all signs indicating its days of birthing new stars are over.
Published in The Astrophysical Journal Letters, the new study detailed a dwarf galaxy called Triangulum II out on the Milky Way's outer reaches. Aside from only having a fraction of the stars our own galaxy has (about 100 billion), the dwarf galaxy may have the "highest concentration of dark matter ever found within a galaxy," according to The Washington Post.
"The galaxy is challenging to look at," study lead author Evan Kirby, an assistant professor of astronomy at the California Institute of Technology, said in a press release. "Only six of its stars were luminous enough to see with the Keck telescope." By measuring these stars' velocity, Kirby could infer the gravitational force exerted on the stars and thereby determine the mass of the galaxy.
"The total mass I measured was much, much greater than the mass of the total number of stars - implying that there's a ton of densely packed dark matter contributing to the total mass," he said. "The ratio of dark matter to luminous matter is the highest of any galaxy we know. After I had made my measurements, I was just thinking - wow."
Dark matter is invisible to astronomers, who have to rely on how it interacts with other objects in order to know it is there. Despite its mysterious nature, dark matter is widely believed to make up a majority of the known universe.
"My next steps are to make measurements to confirm that other group's findings," Kirby said. "If it turns out that those outer stars aren't actually moving faster than the inner ones, then the galaxy could be in what's called dynamic equilibrium. That would make it the most excellent candidate for detecting dark matter with gamma rays."
