Cloud structure of brown dwarfs from spectroscopic variability observations

TL;DR

This paper investigates the three-dimensional cloud structures of brown dwarfs through spectroscopic variability, revealing insights into cloud patchiness and its effects on observed spectral changes across different types.

Contribution

It introduces a new patchy cloud model to explain spectral variability and compares observational results from space and ground-based programs.

Findings

Variability is linked to cloud thickness variations, not cloud holes.

Spectral variability patterns differ among L, T, and mid T dwarfs.

A new patchy cloud model successfully explains observed spectral changes.

Abstract

Recent discoveries of variable brown dwarfs have provided us with a new window into their three-dimensional cloud structure. The highest variables are found at the L/T transition, where the cloud cover is thought to break up, but variability has been found to occur also for both cloudy L dwarfs and (mostly) cloud-free mid T dwarfs. We summarize results from recent HST programs measuring the spectral variability of brown dwarfs in the near-infrared and compare to results from ground-based programs. We discuss the patchy cloud structure of L/T transition objects, for which it is becoming increasingly certain that the variability does not arise from cloud holes into the deep hot regions but from varying cloud thickness. We present a new patchy cloud model to explain the spectral variability of 2MASSJ21392676+0220226. We also discuss the curious multi-wavelength variability behavior of the recently discovered very nearby early T dwarf WISE J104915.57-531906.1B (Luhman 16B) and the mid T dwarf 2MASS J22282889-431026.