New work from the Museum and the Carnegie Institution for Science has found nearly 31 confirmed and 1,000 potential members of stellar associations, or “swarms”—stars of similar ages and compositions that are drifting together through space—in our own corner of the Milky Way. The study, published this month in The Astrophysical Journal, could help astronomers better understand the evolution of stars and the properties of exoplanets.
The study was led by Jackie Faherty, a senior scientist in the Museum’s Department of Astrophysics, and Jonathan Gagné, a researcher at the Carnegie Institution for Science and the University of Montreal, based on newly released data from the European Space Agency’s Gaia observatory mapping mission of our galaxy.
“Our sample is mostly comprised of stars called red dwarfs, which are smaller than our Sun and relatively cool,” says Gagné. “Because of their size, they can be difficult to observe, although we know that they are extremely common in the galaxy, which is why the Gaia data is such a great windfall.”
Astronomers can use stellar swarms to glean information about the history of star formation by looking at internal similarities between individual group members and external variations among different groups—particularly when it comes to member ages. These stars’ ages vary from a few million to a billion years old, depending on the group—a range that offers astronomers a sweeping view of stellar evolution among our cosmic neighbors.
What astronomers learn about these stars could also inform their understanding of planets or planet-like objects found within stellar swarms in upcoming space-based missions.
“If future missions like NASA’s Transiting Exoplanet Survey Satellite, or TESS, are able to find exoplanets orbiting our stellar neighbors, the information we’ve gathered about their ages based on their membership in one of these associations will be able to teach us a great deal about what planetary system evolution looks like at different points in time,” says Faherty.
In addition to the bonanza of red dwarf members in neighboring stellar swarms, the team discovered 111 brown dwarfs that are also part of these local associations. Brown dwarfs, sometimes called failed stars or super Jupiters, are smaller than stars—too small to sustain the hydrogen fusion process—but more massive than giant planets. As such, they provide a natural link between astronomy and planetary science and are of great interest to scientists.