The First Spectrum of the Coldest Brown Dwarf

TL;DR

This paper presents the first spectrum of the coldest known brown dwarf, WISE 0855, revealing atmospheric water vapor and clouds similar to Jupiter, enabling detailed study of its atmospheric processes.

Contribution

It provides the first mid-infrared spectrum of a very cold brown dwarf, enabling atmospheric analysis similar to planetary studies.

Findings

Detection of atmospheric water vapor and clouds

Spectral similarity to Jupiter's thermal emission

Enables study of atmospheric dynamics and chemistry

Abstract

The recently discovered brown dwarf WISE 0855 presents our first opportunity to directly study an object outside the Solar System that is nearly as cold as our own gas giant planets. However the traditional methodology for characterizing brown dwarfs---near infrared spectroscopy---is not currently feasible as WISE 0855 is too cold and faint. To characterize this frozen extrasolar world we obtained a 4.5-5.2 $\mu$m spectrum, the same bandpass long used to study Jupiter's deep thermal emission. Our spectrum reveals the presence of atmospheric water vapor and clouds, with an absorption profile that is strikingly similar to Jupiter. The spectrum is high enough quality to allow the investigation of dynamical and chemical processes that have long been studied in Jupiter's atmosphere, but now on an extrasolar world.