From Space.com:

The volunteers identified the brown dwarf just days after science organizations released a new tool to help engage the public in the hunt for new worlds at the edges of our solar system. Because the tool relies on hunting for dim moving objects, it was able to reveal the brown dwarf beyond the solar system.

In February, several institutions, including the American Museum of Natural History (AMNH), launched the Backyard Worlds: Planet 9 website to help in the search for the object dubbed “Planet 9.” Although this hypothetical world has not been confirmed, the way the solar system objects move suggests that an additional object — possibly the putative Planet 9 — is exerting a gravitational influence in the solar system. [Brown Dwarfs: Strange Failed Stars of the Universe Explained (Infographic)]

“I was so proud of our volunteers as I saw the data on this new cold world coming in,” Jackie Faherty, a senior scientist at the AMNH, said in a statement. “It was a feel-good moment for science.”

Read more and check out Backyard Worlds: Planet 9