# CWISEP J193518.59$-$154620.3: An Extremely Cold Brown Dwarf in the Solar Neighborhood Discovered with CatWISE

## TL;DR

This paper reports the discovery of an extremely cold brown dwarf in the solar neighborhood, identified through the CatWISE catalog, with follow-up observations indicating it has one of the lowest temperatures among known brown dwarfs.

## Contribution

The study introduces a new nearby, ultra-cold brown dwarf with detailed photometric analysis and proper motion measurements, expanding knowledge of the coldest substellar objects.

## Key findings

- Effective temperature estimated between 270-360 K.
- Distance estimated between 5.6-10.9 parsecs.
- Proper motion indicates low tangential velocity.

## Abstract

We present the discovery of an extremely cold, nearby brown dwarf in the solar neighborhood, found in the CatWISE catalog (Eisenhardt et al., in prep.). Photometric follow-up with Spitzer reveals that the object, CWISEP J193518.59-154620.3, has ch1$-$ch2 = 3.24$\,\pm\,$0.31 mag, making it one of the reddest brown dwarfs known. Using the Spitzer photometry and the polynomial relations from Kirkpatrick et al. (2019) we estimate an effective temperature in the $\sim$270--360 K range, and a distance estimate in the 5.6$-$10.9 pc range. We combined the WISE, NEOWISE, and Spitzer data to measure a proper motion of $\mu_\alpha \cos \delta = 337\pm69$ mas yr$^{-1}$, $\mu_\delta = -50\pm97$ mas yr$^{-1}$, which implies a relatively low tangential velocity in the range 7$-$22 km s$^{-1}$.