# The First Brown Dwarf Discovered by the Backyard Worlds: Planet 9 Citizen Science Project

## TL;DR

This paper reports the discovery of a new brown dwarf using a citizen science project that leverages WISE infrared data, demonstrating the effectiveness of visual inspection by volunteers to find faint, moving substellar objects.

## Contribution

The study introduces a citizen science approach to identify faint brown dwarfs in WISE data, surpassing previous sensitivity limits of automated searches.

## Key findings

- Discovery of a new T5.5 brown dwarf at 34 pc
- Citizen scientists can detect objects 0.9 magnitudes fainter than previous limits
- Demonstrates the potential of visual inspection in astronomical data analysis

## Abstract

The Wide-field Infrared Survey Explorer (WISE) is a powerful tool for finding nearby brown dwarfs and searching for new planets in the outer solar system, especially with the incorporation of NEOWISE and NEOWISE-Reactivation data. So far, searches for brown dwarfs in WISE data have yet to take advantage of the full depth of the WISE images. To efficiently search this unexplored space via visual inspection, we have launched a new citizen science project, called "Backyard Worlds: Planet 9," which asks volunteers to examine short animations composed of difference images constructed from time-resolved WISE coadds. We report the discovery of the first new substellar object found by this project, WISEA J110125.95+540052.8, a T5.5 brown dwarf located approximately 34 pc from the Sun with a total proper motion of $\sim$0.7 as yr$^{-1}$. WISEA J110125.95+540052.8 has a WISE $W2$ magnitude of $W2=15.37 \pm 0.09$, this discovery demonstrates the ability of citizen scientists to identify moving objects via visual inspection that are 0.9 magnitudes fainter than the $W2$ single-exposure sensitivity, a threshold that has limited prior motion-based brown dwarf searches with WISE.