VLBA26A-295

Probing Ultracool Dwarf Magnetospheres with Sub-mas HSA Polarimetry

Abstract

VLBI has revealed a Jupiter-like synchrotron belt around the M8.5 dwarf LSR J1835+3259, and a much noisier VLBA image hints at either a similar belt, or a close binary companion, around the auroral dwarf TVLM 513-46546. We request full-Stokes 8.4 GHz observations with the complete High Sensitivity Array (VLBA, phased VLA, GBT, Effelsberg), whose unrivalled sensitivity and sub-milliarcsecond resolution will provide the decisive test.
For LSR J1835 we aim to confirm the belt through a clear detection of co-spatial linear polarisation and to track its evolution over two stellar rotations.
For TVLM 513 we will resolve the reported structure and determine whether it is a binary core or the limb-brightened edges of a radiation belt.
By comparing these two canonical ultracool dwarfs, the project will show whether radiation belts are a routine product of the powerful, large-scale dynamos that drive auroral radio emission in the sub-stellar regime.

Investigators

Name	Institution
Juan Bautista Climent Oliver *	València, Universitat de
Jose Guirado	València, Universitat de
HARISH VEDANTHAM	Netherlands Institute for Radio Astronomy
Jan Forbrich	Center for Astrophysics | Harvard & Smithsonian; Hertfordshire, University of
Ivan Marti-Vidal	València, Universitat de
Miguel Perez-Torres	Andalucía, Instituto de Astrofísica de
Rob Kavanagh	Netherlands Institute for Radio Astronomy
Diego Martin Carrero	València, Universitat de; Madrid, Universidad Complutense de
Melodie Kao	Lowell Observatory; California Institute of Technology; Arizona State University; California at Santa Cruz, University of
GBT Operator	Green Bank Observatory

* indicates the PI