Until recently, we weren't aware of the existence of our Sun's closest neighbors. In a study reported by NASA, astronomers report discovering 95 celestial bodies known as brown dwarfs, many of which are relatively close to our Sun. While they are principally around a few dozen light-years away from us, they're close enough that astronomers consider them to be in our "cosmic neighborhood."
Some of the recently discovered specimens are among the coldest brown stars discovered. The discoveries were made thanks to citizens that chose to enroll in NASA citizen science project Backyard Worlds: Planet 9. In this project, data from NASA Near-Earth Object Wide-Field Infrared Survey Explorer (NEOWISE) satellite with the data from retired space telescope Spitzer were presented to the public. The National Space Foundation's NOIRLab was also involved in the project.
Aaron Meisner, an NSF assistant scientist, and the study's lead author said “Vast modern datasets can unlock landmark discoveries, and it’s exciting that these could be spotted first by citizen scientists,” and added, “These Backyard Worlds discoveries show that members of the public can play an important role in reshaping our scientific understanding of our solar neighborhood.”
What is the significance of these brown dwarf discoveries?
Brown dwarfs don't have a magnitude big enough to power themselves as a star would, yet they are heavier than planets by a large margin. Even though we call them "brown" dwarfs, they'd actually appear magenta or orange-red to our eyes if we were to look at one up close.
Some brown dwarfs are extremely hot with some reaching thousands of degrees Fahrenheit, the newly discovered ones have some examples colder than 212 degrees Fahrenheit (100 degrees Celsius). What's more, some of them even enjoy a temperature close to the Earth's, theoretically, these could host water clouds.
Colder brown dwarfs also had smaller diameters, that's why they appear faint in the visible spectrum of light. Yet, these ones still radiate heat and infrared light, which the telescope can capture. But, since their infrared emissions are also less vibrant than the hotter ones, they are easier to detect closer they are.
In 2014, the coldest-known brown dwarf, WISE 0855 was discovered. It had a temperature of -10 degrees Fahrenheit (-23 degrees Celsius). This one is by far the coldest brown dwarf ever observed. It was so cold that there were some suggested that it could be an exoplanet gone rogue, meaning, it was a planet orbiting around a start at first but it got swayed off of its orbit.
Both planets and brown dwarfs go through the same physical processes during formation, the new findings will prove useful in investigations into worlds beyond our solar system.
Co-author Jackie Faherty, whose research primarily focuses on exoplanets and brown dwarfs said, “This paper is evidence that the solar neighborhood is still uncharted territory and citizen scientists are excellent astronomical cartographers,” and added, “Mapping the coldest brown dwarfs down to the lowest masses gives us key insights into the low-mass star-formation process while providing a target list for detailed studies of the atmospheres of Jupiter analogs.”