The First Millimeter Detection of a Non-Accreting Ultracool Dwarf

Abstract

The well-studied M9 dwarf TVLM 513-46546 is a rapid rotator (P_rot ~ 2 hr) hosting a stable, dipolar magnetic field of ~3 kG surface strength. Here we report its detection with ALMA at 95 GHz at a mean flux density of $56\pm 12$ uJy, making it the first ultracool dwarf detected in the millimeter band, excluding young, disk-bearing objects. We also report flux density measurements from unpublished archival VLA data and new optical monitoring data from the Liverpool Telescope. The ALMA data are consistent with a power-law radio spectrum that extends continuously between centimeter and millimeter wavelengths. We argue that the emission is due to the synchrotron process, excluding thermal, free-free, and electron cyclotron maser emission as possible sources. During the interval of the ALMA observation that phases with the maximum of the object's optical variability, the flux density is higher at a ~1.8 sigma significance level. These early results show how ALMA opens a new window for studying the magnetic activity of ultracool dwarfs, particularly shedding light on the particle acceleration mechanism operating in their immediate surroundings.

arXiv comment7 pages, 3 figures, 1 table; ApJ in press

References in corpus (54)

• Astropy: A Community Python Package for Astronomy
• Protoplanetary Disks and Their Evolution
• Circumstellar Dust Disks in Taurus-Auriga: The Submillimeter Perspective
• New Neighbors from 2MASS: Activity and Kinematics at the Bottom of the Main Sequence
• Large-scale magnetic topologies of late M dwarfs
• Rotation and Activity in Mid-M to L Dwarfs
• An Accurate Flux Density Scale from 1 to 50 GHz
• A morphological algorithm for improving radio-frequency interference detection
• Detection of Nine M8.0-L0.5 Binaries: The Very Low Mass Binary Population and its Implications for Brown Dwarf and VLM Star Formation
• The Sloan Digital Sky Survey Data Release 7 Spectroscopic M Dwarf Catalog I: Data
• Post-correlation radio frequency interference classification methods
• The First Direct Measurements of Magnetic Fields on Very Low-Mass Stars
• Confirmation of the Electron Cyclotron Maser Instability as the Dominant Source of Radio Emission from Very Low Mass Stars and Brown Dwarfs
• Activity in Very Cool Stars: Magnetic Dissipation in late-M and L Dwarf Atmospheres
• Radio Observations of a Large Sample of Late-M, L, and T Dwarfs: The Distribution of Magentic Field Strengths
• Periodic Bursts of Coherent Radio Emission from an Ultracool Dwarf
• A Volume-limited Sample of 63 M7-M9.5 Dwarfs II. Activity, magnetism, and the fade of the rotation-dominated dynamo
• Flaring Up All Over -- Radio Activity in Rapidly-Rotating Late-Type M and L Dwarfs
• Magnetospherically driven optical and radio aurorae at the end of the stellar main sequence
• High resolution spectroscopy of ultracool M dwarfs
• Rotational Modulation of the Radio Emission from the M9 Dwarf TVLM 513-46546: Broadband Coherent Emission at the Substellar Boundary?
• Simultaneous Multi-Wavelength Observations of Magnetic Activity in Ultracool Dwarfs. III. X-ray, Radio, and H-alpha Activity Trends in M and L Dwarfs
• Infrared Colors at the Stellar/Substellar Boundary
• The Radio Activity-Rotation Relation of Ultracool Dwarfs
• BOSS Ultracool Dwarfs I: Colors and Magnetic Activity of M and L dwarfs
• Magnetic Inhibition of Convection and the Fundamental Properties of Low-Mass Stars. II. Fully Convective Main Sequence Stars
• An Empirical Correction for Activity Effects on the Temperatures, Radii, and Estimated Masses of Low-Mass Stars and Brown Dwarfs
• A Giant Outburst at Millimeter Wavelengths in the Orion Nebula
• Trends in Ultracool Dwarf Magnetism. I. X-Ray Suppression and Radio Enhancement
• Simultaneous Multi-Wavelength Observations of Magnetic Activity in Ultracool Dwarfs. I. The Complex Behavior of the M8.5 Dwarf TVLM513-46546
• Origin of electron cyclotron maser-induced radio emissions at ultra-cool dwarfs: magnetosphere-ionosphere coupling currents
• Magnetospheric Emissions from the Planet Orbiting tau Boo: A Multi-Epoch Search
• Ionisation in atmospheres of Brown Dwarfs and extrasolar planets I The role of electron avalanche
• An ALMA Disk Mass for the Candidate Protoplanetary Companion to FW Tau
• Periodic Radio Emission from the M7 Dwarf 2MASS J13142039+1320011: Implications for the Magnetic Field Topology
• X-ray emission of brown dwarfs: Towards constraining the dependence on age, luminosity, and temperature
• Constraints to the Masses of Brown Dwarf Candidates from the Lithium Test
• The Radio Spectrum of TVLM513-46546: Constraints on the Coronal Properties of a Late M Dwarf
• Periodic Optical Variability of Radio Detected Ultracool Dwarfs
• Wideband Dynamic Radio Spectra of Two Ultra-cool dwarfs
• Sporadic Long-term Variability in Radio Activity from a Brown Dwarf
• The Rotation Period and Magnetic Field of the T Dwarf 2MASSI J1047539+212423 Measured From Periodic Radio Bursts
• GMRT search for 150 MHz radio emission from the transiting extrasolar planets HD189733b and HD209458b
• The First VLBI Detection of an Ultracool Dwarf: Implications for the Detectability of Sub-stellar Companions
• Captured at Millimeter Wavelengths: a Flare from the Classical T Tauri Star DQ Tau
• Rotational Modulation of M/L Dwarfs due to Magnetic Spots
• Quasi-Quiescent Radio Emission from the First Radio-Emitting T Dwarf
• Steady and Transient Radio Emission from Ultracool Dwarfs
• An Astrometric Search for a Sub-stellar Companion of the M8.5 Dwarf TVLM 513-46546 Using Very Long Baseline Interferometry
• Optical variability of the ultracool dwarf TVLM 513-46546: evidence for inhomogeneous dust clouds
• Timing Analysis of the Periodic Radio and Optical Brightness Variations of the Ultracool Dwarf, TVLM 513-46546
• The magnetosphere of the ultracool dwarf DENIS 1048-3956
• Rotational modulation of the linear polarimetric variability of the cool dwarf TVLM 513$-$46546
• 325 MHz VLA Observations of Ultracool Dwarfs TVLM 513-46546 and 2MASS J0036+1821104

Cited by in corpus (23)

• The Strongest Magnetic Fields on the Coolest Brown Dwarfs
• A Panchromatic View of Brown Dwarf Aurorae
• Direct radio discovery of a cold brown dwarf
• Evidence for a radiation belt around a brown dwarf
• Radio Stars: from kHz to THz
• On the Correlation between L Dwarf Optical and Infrared Variability and Radio Aurorae
• Ionisation and discharge in cloud-forming atmospheres of brown dwarfs and extrasolar planets
• Probing the magnetosphere of the M8.5 dwarf TVLM513-46546 by modelling its auroral radio emission. Hint of star exoplanet interaction?
• A LOFAR mini-survey for low-frequency radio emission from the nearest brown dwarfs
• A Deep Radio Limit for the TRAPPIST-1 System
• Modelling the environment around five ultracool dwarfs via the radio domain
• Physical properties and astrometry of radio-emitting brown dwarf TVLM513-46546 revisited
• The Occurrence Rate of Quiescent Radio Emission for Ultracool Dwarfs using a Generalized Semi-Analytical Bayesian Framework
• Radio Emission from Binary Ultracool Dwarf Systems
• Low-frequency GMRT observations of ultra-cool dwarfs
• Radio Emission from Ultra-Cool Dwarfs
• Another look at AM Herculis $-$ radio-astrometric campaign with the e-EVN at 6 cm
• Constraining the Radio Emission of TRAPPIST-1
• Dust cloud evolution in sub-stellar atmospheres via plasma deposition and plasma sputtering
• The Potential of Detecting Radio-flaring Ultracool Dwarfs at L band in the FAST Drift-scan Survey
• Evolution of spheroidal dust in electrically active sub-stellar atmospheres
• Insight into atmospheres of extrasolar planets through plasma processes
• A search for millimeter emission from the coldest and closest brown dwarf with ALMA