Astronomers have compiled the most comprehensive list of nearby brown dwarfs, thanks to discoveries made by thousands of volunteers involved in the Backyard Worlds project. The list and 3D map of 525 brown dwarfs, including 38 first reported, include observational data from a variety of astronomical instruments, including several NOIRLab objects. The results confirm that the Sun’s neighborhoods are remarkably diverse compared to other parts of the Milky Way galaxy.
The result is a map of the location of over 500 cool brown dwarfs in the vicinity of the Sun. An international team of astronomers, supported by volunteer scientists from the Backyard Worlds: Planet 9 collaboration, has announced an unprecedented census of 525 cold brown dwarfs within 65 light-years of the Sun, including 38 new discoveries. By determining the distances to all the census objects, astronomers were able to build a three-dimensional map of the distribution of cold brown dwarfs in the vicinity of the Sun.
This breakthrough was based on new datasets published by DESI Legacy Imaging Surveys, which combine a huge amount of astronomical data from various sources. These powerful survey datasets have been combined with new distance measurements from NASA’s Spitzer Space Telescope to create the best 3D map of the Sun’s surroundings to date.
“Brown dwarfs are low-mass byproducts of star formation, but the least massive of them share many characteristics with exoplanets. These are exoplanet labs, but since they usually work on their own and don’t have the problems caused by the blinding host sun, they’re much easier to study.”
J. Davy Kirkpatrick is a Caltech Scientist.
Brown dwarfs are sometimes referred to as “failed stars.” They are believed to form in the same way as stars, but they do not become massive enough to cause nuclear fusion in their cores. Their weakness and relatively small size make them difficult to identify without careful analysis of data from sensitive telescopes, which means that many of them have not yet been detected. However, by finding and studying brown dwarfs, astronomers can learn more about star formation as well as the planets around other stars.
To help identify elusive brown dwarfs in massive datasets, astronomers enlisted the help of the Backyard Worlds collaboration, a worldwide network of more than 100,000 civilian scientists. Last August, Backyards Worlds announced the discovery of about 100 nearby cold brown dwarfs.
“The Backyard Worlds Project demonstrates that the general public can play an important role in cutting edge astronomy. Volunteers ranging from high school students to retired engineers are helping make groundbreaking discoveries hidden in existing telescope data.”
NOIRLab scientist Aaron Meisner, co-founder of Backyard Worlds.
One of the most intriguing results of this study is that it provides more evidence that the direct proximity of the Sun (within about 7 light-years) is rather unusual. Although most stars in the Milky Way are red dwarfs, earlier results showed that the Sun’s closest neighbors are much more diverse, with different types of objects ranging from stars like the Sun to brown dwarfs like Jupiter that appear in roughly equal numbers. The new results exacerbate this discrepancy as extremely cold brown dwarfs, such as our closest neighbor WISE 0855, the coldest brown dwarf known, are no longer found, although the team expected to find at least a few more within 65 light-years of the Sun, given the sensitivity of the new study. … This result hints at the possibility that even more cool brown dwarfs have so far eluded detection.