Resolving the L/T transition binary SDSS J2052-1609 AB

TL;DR

This paper reports the first high-resolution imaging of the brown dwarf binary SDSS J2052-1609, resolving it into a close pair, and provides initial estimates of their spectral types, magnitudes, and total mass, aiding understanding of brown dwarf binary properties.

Contribution

First high-resolution AO imaging of SDSS J2052-1609 resolving it into a binary, with spectral type and mass estimates to improve brown dwarf binary statistics.

Findings

Resolved the binary with a separation of 0.101"

Estimated spectral types T1 and T2.5 for the components

Total system mass > 78 Jupiter masses

Abstract

Binaries provide empirical key constraints for star formation theories, like the overall binary fraction, mass ratio distribution and the separation distribution. They play a crucial role to calibrate the output of theoretical models, like absolute magnitudes, colors and effective temperature depending on mass, metallicity and age. We present first results of our on-going high-resolution imaging survey of late type brown dwarfs. The survey aims at resolving tight brown dwarf binary systems to better constrain the T dwarf binary fraction. We intent to follow-up the individual binaries to determine orbital parameters. Using NACO at the VLT we performed AO-assisted near-infrared observations of SDSS J2052-1609. High-spatial resolution images of the T1 dwarf were obtained in H and Ks filters. We resolved SDSS J2052-1609 into a binary system with a separation of 0.101" \pm 0.001". Archival data from HST/NICMOS taken one year previous to our observations proves the components to be co-moving. Using the flux ratio between the components we infer J, H and Ks magnitudes for the resolved system. From the near-IR colors we estimate spectral types of T1 +1 -4 and T2.5 \pm 1 for component A and B, respectively. A first estimate of the total system mass yields Mtot > 78 Mjup, assuming a circular orbit.