Distances, Luminosities, and Temperatures of the Coldest Known Substellar Objects

TL;DR

This paper provides precise distance measurements for the coldest known brown dwarfs, enabling accurate determination of their luminosities and temperatures, and explores how their spectral energy distributions are influenced by various physical parameters.

Contribution

It introduces a large, homogeneous dataset of mid-infrared astrometry for cold brown dwarfs, improving understanding of their physical properties and bridging the gap to gas-giant planets.

Findings

Brown dwarfs have temperatures of 400-450 K.

They have masses 5-20 times that of Jupiter.

Spectral energy distributions are affected by multiple physical factors.

Abstract

The coolest known brown dwarfs are our best analogs to extrasolar gas-giant planets. The prolific detections of such cold substellar objects in the past two years has spurred intensive followup, but the lack of accurate distances is a key gap in our understanding. We present a large sample of precise distances based on homogeneous mid-infrared astrometry that robustly establish absolute fluxes, luminosities, and temperatures. The coolest brown dwarfs have temperatures of 400-450 K and masses ~5-20 times that of Jupiter, showing they bridge the gap between hotter brown dwarfs and gas-giant planets. At these extremes, spectral energy distributions no longer follow a simple correspondence with temperature, suggesting an increasing role of other physical parameters such as surface gravity, vertical mixing, clouds, and metallicity.