More Observations of Binary T Class Brown Dwarfs

Constraints on the binary Properties of mid to late T dwarfs from Hubble Space Telescope WFC3 Observations

Authors:

Abersturi et al

Abstract:

We used HST/WFC3 observations of a sample of 26 nearby (≤20 pc) mid to late T dwarfs to search for cooler companions and measure the multiplicity statistics of brown dwarfs. Tightly-separated companions were searched for using a double-PSF fitting algorithm. We also compared our detection limits based on simulations to other prior T5+ brown dwarf binary programs.

No new wide or tight companions were identified, which is consistent with the number of known T5+ binary systems and the resolution limits of WFC3. We use our results to add new constraints to the binary fraction of T-type brown dwarfs. Modeling selection effects and adopting previously derived separation and mass ratio distributions, we find an upper limit total binary fraction of less than 16% and less than 25% assuming power law and flat mass ratio distributions respectively, which are consistent with previous results. We also characterize a handful of targets around the L/T transition.