Improved infrared photometry and a preliminary parallax measurement for the extremely cold brown dwarf CWISEP J144606.62$-$231717.8

TL;DR

This study refines the infrared photometry and provides a preliminary parallax for the extremely cold brown dwarf CWISEP J144606.62$-$231717.8, enhancing understanding of its properties and distance.

Contribution

It offers improved infrared color measurements and a first parallax estimate, better constraining the physical characteristics of one of the coldest known brown dwarfs.

Findings

Revised color to ch1−ch2=2.986±0.048 mag, making it the 5th reddest brown dwarf.

Preliminary parallax places the object at approximately 10.1 pc.

Estimated temperature between 310-360 K, mass between 2-20 M_Jup.

Abstract

We present follow-up $Spitzer$ observations at 3.6$\mu$m (ch1) and 4.5$\mu$m (ch2) of CWISEP J144606.62$-$231717.8, one of the coldest known brown dwarfs in the solar neighborhood. This object was found by mining the Wide-field Infrared Survey Explorer ($WISE$) and $NEOWISE$ data via the CatWISE Preliminary Catalog by Meisner et al. (2019b), where an initial $Spitzer$ color of ch1$-$ch2 = 3.71$\pm$0.44 mag was reported, implying it could be one of the reddest, and hence coldest, known brown dwarfs. Additional $Spitzer$ data presented here allows us to revise its color to ch1$-$ch2 = 2.986$\pm$0.048 mag, which makes CWISEP J144606.62$-$231717.8 the 5th reddest brown dwarf ever observed. A preliminary trigonometric parallax measurement, based on a combination of $WISE$ and $Spitzer$ astrometry, places this object at a distance of 10.1$^{+1.7}_{-1.3}$ pc. Based on our improved $Spitzer$ color and preliminary parallax, CWISEP J144606.62$-$231717.8 has a $T_{\rm eff}$ in the 310$-$360 K range. Assuming an age of 0.5$-$13 Gyr, this corresponds to a mass between 2 and 20 $M_{\rm Jup}$.