Simultaneous Multiwavelength Observations of Magnetic Activity in Ultracool Dwarfs. IV. The Active, Young Binary NLTT 33370 AB (=2MASS J13142039+1320011)

Abstract

We present multi-epoch simultaneous radio, optical, Hα, UV, and X-ray observations of the active, young, low-mass binary NLTT 33370 AB (blended spectral type M7e). This system is remarkable for its extreme levels of magnetic activity: it is the most radio-luminous ultracool dwarf (UCD) known, and here we show that it is also one of the most X-ray luminous UCDs known. We detect the system in all bands and find a complex phenomenology of both flaring and periodic variability. Analysis of the optical light curve reveals the simultaneous presence of two periodicities, 3.7859 $\pm$ 0.0001 and 3.7130 $\pm$ 0.0002 hr. While these differ by only ~2%, studies of differential rotation in the UCD regime suggest that it cannot be responsible for the two signals. The system's radio emission consists of at least three components: rapid 100% polarized flares, bright emission modulating periodically in phase with the optical emission, and an additional periodic component that appears only in the 2013 observational campaign. We interpret the last of these as a gyrosynchrotron feature associated with large-scale magnetic fields and a cool, equatorial plasma torus. However, the persistent rapid flares at all rotational phases imply that small-scale magnetic loops are also present and reconnect nearly continuously. We present an SED of the blended system spanning more than 9 orders of magnitude in wavelength. The significant magnetism present in NLTT 33370 AB will affect its fundamental parameters, with the components' radii and temperatures potentially altered by ~+20% and ~-10%, respectively. Finally, we suggest spatially resolved observations that could clarify many aspects of this system's nature.

emulateapj, 22 pages, 15 figures, ApJ in press; v2: fixes low-impact error in Figure 15; v3: now in-press

References in corpus (30)

• K-corrections and filter transformations in the ultraviolet, optical, and near infrared
• Achieving better than 1 minute accuracy in the Heliocentric and Barycentric Julian Dates
• Large-scale magnetic topologies of late M dwarfs
• A Re-appraisal of the Habitability of Planets Around M Dwarf Stars
• Large-scale magnetic topologies of early M dwarfs
• Simulations of dynamo action in fully convective stars
• Post-correlation radio frequency interference classification methods
• The First Direct Measurements of Magnetic Fields on Very Low-Mass Stars
• Chromospheric Activity, Rotation, and Rotational Braking in M and L Dwarfs
• 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
• Persistent Magnetic Wreaths in a Rapidly Rotating Sun
• Periodic Bursts of Coherent Radio Emission from an Ultracool Dwarf
• Discovery of a ~250 K Brown Dwarf at 2 pc from the Sun
• Rotational Modulation of the Radio Emission from the M9 Dwarf TVLM 513-46546: Broadband Coherent Emission at the Substellar Boundary?
• On the magnetic topology of partially and fully convective stars
• Magnetospheric Structure and Atmospheric Joule Heating of Habitable Planets Orbiting M-dwarf Stars
• Measuring Magnetic Fields in Ultracool Stars and Brown Dwarfs
• The Monitor project: Data processing and lightcurve production
• The Arecibo Detection of the Coolest Radio-flaring Brown Dwarf
• Simultaneous Multi-Wavelength Observations of Magnetic Activity in Ultracool Dwarfs. II. Mixed Trends in VB10 and LSR1835+32 and the Possible Role of Rotation
• Simultaneous Multi-Wavelength Observations of Magnetic Activity in Ultracool Dwarfs. I. The Complex Behavior of the M8.5 Dwarf TVLM513-46546
• Simultaneous optical and X-ray observations of a giant flare on the ultracool dwarf LP412-31
• New Neighbors: Parallaxes of 18 nearby stars selected from the LSPM-north catalog
• New Evidence for a Substellar Luminosity Problem: Dynamical Mass for the Brown Dwarf Binary Gl 417BC
• A Chandra X-ray detection of the L dwarf binary Kelu-1: Simultaneous Chandra and Very Large Array observations
• Quasi-Quiescent Radio Emission from the First Radio-Emitting T Dwarf
• Chi Values for Blue Emission Lines in M Dwarfs
• Follow-up observations of binary ultra-cool dwarfs

Cited by in corpus (16)

• A Panchromatic View of Brown Dwarf Aurorae
• A scaling relationship for non-thermal radio emission from ordered magnetospheres: from the top of the Main Sequence to planets
• The detection of variable radio emission from the fast rotating magnetic hot B-star HR7355 and evidence for its X-ray aurorae
• Variable and polarized radio emission from the T6 brown dwarf WISEP J112254.73+255021.5
• Photometry and Performance of SPECULOOS-South
• The Second Arecibo Search for 5 GHz Radio Flares from Ultracool Dwarfs
• The Discovery of Solar-like Activity Cycles Beyond the End of the Main Sequence?
• ALMA observations of 4U 1728-34 and 4U 1820-30: first detection of neutron star X-ray binaries at 300 GHz
• A Study of Flares in the Ultra-Cool Regime from SPECULOOS-South
• Recovering planet radial velocity signals in the presence of starspot activity in fully convective stars
• Radio-flaring Ultracool Dwarf Population Synthesis
• WISEP J060738.65+242953.4: A Nearby. Pole-On L8 Brown Dwarf with Radio Emission
• Modelling the environment around five ultracool dwarfs via the radio domain
• The milliarcsecond-scale radio structure of AB Dor A
• Differences in radio emission from similar M dwarfs in the binary system Ross 867-8
• ROME IV. The Arecibo Search for Substellar Magnetospheric Radio Emissions in Purported Exoplanet-Hosting Systems at 5 GHz