Radio Emission from a Nearby M dwarf Binary

Abstract

We present the detection of the binary system 2MASS J02132062+3648506 AB using the Karl G. Jansky Very Large Array (VLA) archive data observed at 4-8 GHz. The system is a triple consisting of a tight binary ($\sim 0.2"$) of two M dwarfs of spectral class M4.5 and M6.5 and a wide T3 brown dwarf companion ($\sim$16.4"). The binary displays coronal and chromospheric activity as traced by previously measured X-ray flux and H$\alpha$ emission. We detect the unresolved binary at a peak flux density of $\sim 356\mu {\mathrm{Jybeam}}^{-1}$ at a signal-to-noise ratio (SNR) of $\sim 36$ and determine a radio luminosity of $\log L_R/\log L_{\mathrm{bol}}\approx -7.76$. The radio emission is quiescent, polarised at a mean circular polarisation fraction $f_{\mathrm{c}}=45.20\pm 1.58$ % and exhibits a spectral index $\alpha =-0.44\pm 0.07$ . We probe the binary using the Enhanced Multi-Element Remotely Linked Interferometer Network (e-MERLIN) with an angular resolution of $\sim 40$ mas at 5 GHz and detect a component at a peak flux density of $\sim 90\mu$Jy ${\mathrm{beam}}^{-1}$ at a SNR $\sim 5$ . We propose a gyrosynchrotron origin for the radio emission and estimate a magnetic field strength $B<174.86$ G, an emitting region of size $L<1.54$ times the radius of the M4.5 primary and a plasma number density $n_{\mathrm{e}}<2.91\times 10^5{\mathrm{cm}}^{-3}$. The brown dwarf companion is not detected. Additionally, we have analysed observations of 2MASS J04183483+213127, a chromospherically active L5 brown dwarf which is also not detected. Accordingly, we place $3\sigma$ flux density upper limits at $36.9\mu$Jy ${\mathrm{beam}}^{-1}$ and $42.3\mu$Jy ${\mathrm{beam}}^{-1}$ for Stokes I and V respectively.

10 pages, 5 figures

References in corpus (29)

• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• CASA, the Common Astronomy Software Applications for Radio Astronomy
• The Solar Neighborhood XVII: Parallax Results from the CTIOPI 0.9m Program -- Twenty New Members of the RECONS 10 Parsec Sample
• The H$\alpha$ emission of nearby M dwarfs and its relation to stellar rotation
• unWISE: unblurred coadds of the WISE imaging
• Simulations of dynamo action in fully convective stars
• The CatWISE2020 Catalog
• Confirmation of the Electron Cyclotron Maser Instability as the Dominant Source of Radio Emission from Very Low Mass Stars and Brown Dwarfs
• Magnetic field generation in fully convective rotating spheres
• Radio Observations of a Large Sample of Late-M, L, and T Dwarfs: The Distribution of Magentic Field Strengths
• Coherent Emission Mechanisms in Astrophysical Plasmas
• The Solar Neighborhood XLV. The Stellar Multiplicity Rate of M Dwarfs Within 25 pc
• BOSS Ultracool Dwarfs I: Colors and Magnetic Activity of M and L dwarfs
• Optical, UV, and X-Ray Evidence for a 7-Year Stellar Cycle in Proxima Centauri
• The Hawaii Infrared Parallax Program. IV. A Comprehensive Parallax Survey of L0-T8 dwarfs with UKIRT
• Monitoring the radio emission of Proxima Centauri
• The AstraLux Multiplicity Survey: Extension to Late M-dwarfs
• Rotation Periods, Inclinations, and Obliquities of Cool Stars Hosting Directly Imaged Substellar Companions: Spin-Orbit Misalignments are Common
• A 3D view of the Hyades stellar and sub-stellar population
• A scaling relationship for non-thermal radio emission from ordered magnetospheres: from the top of the Main Sequence to planets
• A possible activity cycle in Proxima Centauri
• Discovery of Radio Emission from the Tight M8 Binary: LP 349-25
• A high resolution spectral atlas of brown dwarfs
• The Second Arecibo Search for 5 GHz Radio Flares from Ultracool Dwarfs
• Astrometric excess noise in Gaia EDR3 and the search for X-ray binaries
• 2MASS 0213+3648 C: A wide T3 benchmark companion to an an active, old M dwarf binary
• A new L5 brown dwarf member of the Hyades cluster with chromospheric activity
• Radio emission in a nearby ultracool dwarf binary: a multi-frequency study
• Discovery of X-ray emission from the eclipsing brown-dwarf binary 2MASS J05352184-0546085