An Astrometric Search for a Sub-stellar Companion of the M8.5 Dwarf TVLM 513-46546 Using Very Long Baseline Interferometry

TL;DR

This study used VLBI astrometry to search for sub-stellar companions around the M8.5 dwarf TVLM 513-46546, setting new limits on possible companion masses and orbital periods based on precise measurements.

Contribution

It provides the first VLBI-based astrometric constraints on sub-stellar companions of TVLM 513-46546, extending previous imaging search limits.

Findings

No significant reflex motion detected, constraining companion masses and orbits.

Excluded companions with masses from 3.8 Mjup to 0.3 Mjup within specific orbital ranges.

Achieved precise parallax and proper motion measurements for TVLM 513-46546.

Abstract

We conducted multi-epoch VLBI observations to search for astrometric reflex motion caused by a sub-stellar companion of the M8.5 dwarf TVLM 513-46546. The observations yield an absolute parallax corresponding to a distance of 10.762+/-0.027 pc and a proper motion of 78.09+/-0.17 mas/yr. From the absence of significant residual motion, we place an upper limit to any reflex motion caused by a companion, extending the parameter space covered by previous near-infrared direct-imaging searches. By covering different orbital periods, the data exclude a phase-space of companion masses and orbital periods ranging from 3.8 Mjup with an orbital radius of ~0.05 AU (orbital period of 16 days) to 0.3 Mjup with an orbital radius of ~0.7 AU (orbital period of 710 days).