Is WISEP J060738.65+242953.4 Really A Magnetically Active, Pole-on L Dwarf?

Abstract

The interplay of rotation and manifested magnetic activity on ultracool dwarfs (UCDs) is of key importance for gathering clues as to the operation of the dynamos within these objects. A number of magnetized UCDs host kG-strength magnetic fields. It was recently reported that the L8 dwarf WISEP J060738.65+242953.4 is a radio-emitting UCD that is likely observed pole-on, due to its lack of photometric variability and narrow spectral lines. Follow-up radio observations at Arecibo Observatory, together with careful analysis of previously published details, however, suggest that the scientific and statistical significance of the radio and spectroscopic data have been overstated. If the UCD is observed along its aligned spin/magnetic axis, the absence of observed H$\alpha$ activity may present challenges to the auroral model of UCD magnetism, although short or long-term cyclic magnetic activity may explain this behavior. Monte Carlo simulations presented here suggest that the source probably rotates with v sin i=6-12 km s${}^{-1}$, indicating that its inclination angle and rotational velocity are unexceptional and that its angular momentum has evolved as expected for brown dwarfs observed in ~1 Myr-old clusters. The discovery and verification of the most rapidly and slowest rotating brown dwarfs place valuable constraints on the angular momentum evolution and magnetic activity history of these objects.

arXiv commentPublished in ApJ; 7 pages, 1 figure

References in corpus (32)

• Weather on Other Worlds. II. Survey Results: Spots Are Ubiquitous on L and T Dwarfs
• 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
• Periodic Bursts of Coherent Radio Emission from an Ultracool Dwarf
• Strong Brightness Variations Signal Cloudy-to-Clear Transition of Brown Dwarfs
• Multiple and changing cycles of active stars II. Results
• Flaring Up All Over -- Radio Activity in Rapidly-Rotating Late-Type M and L Dwarfs
• Colors and Kinematics of L Dwarfs From the Sloan Digital Sky Survey
• Magnetospherically driven optical and radio aurorae at the end of the stellar main sequence
• Rotational Modulation of the Radio Emission from the M9 Dwarf TVLM 513-46546: Broadband Coherent Emission at the Substellar Boundary?
• H-alpha Activity of Old M Dwarfs: Stellar Cycles and Mean Activity Levels For 93 Low-Mass Stars in the Solar Neighborhood
• The Radio Activity-Rotation Relation of Ultracool Dwarfs
• Periodic Radio and H-alpha Emission from the L Dwarf Binary 2MASSW J0746425+200032: Exploring the Magnetic Field Topology and Radius of an L Dwarf
• Trends in Ultracool Dwarf Magnetism. I. X-Ray Suppression and Radio Enhancement
• Discovery of a T Dwarf Binary with the Largest Known J-Band Flux Reversal
• The First Ultra-Cool Brown Dwarf Discovered by the Wide-field Infrared Survey Explorer
• The Arecibo Detection of the Coolest Radio-flaring Brown Dwarf
• Magnetospheric Emissions from the Planet Orbiting tau Boo: A Multi-Epoch Search
• On the Size of Structures in the Solar Corona
• Rotational studies in the Orion Nebula Cluster: from solar mass stars to brown dwarfs
• The Radio Spectrum of TVLM513-46546: Constraints on the Coronal Properties of a Late M Dwarf
• A Chandra X-ray detection of the L dwarf binary Kelu-1: Simultaneous Chandra and Very Large Array observations
• Trends in Ultracool Dwarf Magnetism. II. The Inverse Correlation Between X-ray Activity and Rotation as Evidence for a Bimodal Dynamo
• The ultracool dwarf DENIS-P J104814.7-395606. Chromospheres and coronae at the low-mass end of the main-sequence
• Radio Flaring from the T6 Dwarf WISEPC J112254.73+255021.5 with A Possible Ultra-short Periodicity
• Reference study to characterise plasma and magnetic properties of ultra-cool atmospheres
• The Second Arecibo Search for 5 GHz Radio Flares from Ultracool Dwarfs
• Discovery of Four High Proper Motion L Dwarfs, Including a 10 pc L Dwarf at the L/T Transition
• The Discovery of Solar-like Activity Cycles Beyond the End of the Main Sequence?
• A new approach to the maser emission in the solar corona
• Discovery of a Late L Dwarf: WISEP J060738.65+242953.4
• WISEP J060738.65+242953.4: A Nearby. Pole-On L8 Brown Dwarf with Radio Emission

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