Disentangling the Signatures of Blended-Light Atmospheres in L/T Transition Brown Dwarfs

TL;DR

This paper introduces a spectrophotometric method to identify variable L/T transition brown dwarfs using low-resolution near-infrared spectra, aiding future observational efforts.

Contribution

The study develops the first formal spectral index-based technique to detect variability in brown dwarfs from single-epoch spectra.

Findings

Identified 62 candidate variable brown dwarfs.

12 candidates confirmed with independent photometric data.

Established spectral indices to distinguish variable from non-variable objects.

Abstract

We present a technique to identify spectrophotometrically variable L7-T3 brown dwarfs with single-epoch, low-resolution, near-infrared SpeX spectra. We calculated spectral indices on known variable brown dwarfs and used them to select 11 index-index parameter spaces where known variables can be distinguished from the rest of the general population of brown dwarfs. We find 62 candidate variables, 12 of which show significant variability amplitude in independent photometric monitoring surveys. This technique constitutes the first formal method to identify a time-dependent effect such as variability from peculiarities in their integrated light spectra. This technique will be a useful tool to prioritize targets for future photometric and spectroscopic monitoring in the era of JWST and 30m-class telescopes.