Spectro-photometric characterization of high proper motion sources from WISE

TL;DR

This study characterizes high proper motion stars and brown dwarfs from WISE data, deriving spectral types, distances, and binary status, including the discovery of a nearby T2 brown dwarf and analysis of potential binary systems.

Contribution

It provides new spectral classifications, distances, and binary assessments for high proper motion sources, including the first confirmation of a T2 brown dwarf within 15 pc.

Findings

Confirmed a new T2 brown dwarf within 15 pc.

Derived spectral types for 24 sources, mostly M dwarfs within 50 pc.

Identified and analyzed potential wide binary systems and a microlensing event.

Abstract

The census of the solar neighborhood is almost complete for stars and becoming more complete in the brown dwarf regime. Spectroscopic, photometric and kinematic characterization of nearby objects helps us to understand the local mass function, the binary fraction, and provides new targets for sensitive planet searches. We aim to derive spectral types and spectro-photometric distances of a sample of new high proper motion sources found with the WISE satellite, and obtain parallaxes for those objects that fall within the area observed by the Vista Variables in the V\'ia L\'actea survey (VVV). We used low resolution spectroscopy and template fitting to derive spectral types, multiwavelength photometry to characterize the companion candidates and obtain photometric distances. Multi-epoch imaging from the VVV survey was used to measure the parallaxes and proper motions for three sources. We confirm a new T2 brown dwarf within $\sim$15 pc. We derived optical spectral types for twenty four sources, mostly M dwarfs within 50 pc. We addressed the wide binary nature of sixteen objects found by the WISE mission and previously known high proper motion sources. Six of these are probably members of wide binaries, two of those are new, and present evidence against the physical binary nature of two candidate binary stars found in the literature, and eight that we selected as possible binary systems. We discuss a likely microlensing event produced by a nearby low mass star and a galaxy, that is to occur in the following five years.