Unravelling sub-stellar magnetospheres
arXiv:2410.18073 · doi:10.1051/0004-6361/202452094
Abstract
At the sub-stellar boundary, signatures of magnetic fields begin to manifest at radio wavelengths, analogous to the auroral emission of the magnetised solar system planets. This emission provides a singular avenue for measuring magnetic fields at planetary scales in extrasolar systems. So far, exoplanets have eluded detection at radio wavelengths. However, ultracool dwarfs (UCDs), their higher mass counterparts, have been detected for over two decades in the radio. Given their similar characteristics to massive exoplanets, UCDs are ideal targets to bridge our understanding of magnetic field generation from stars to planets. In this work, we develop a new tomographic technique for inverting both the viewing angle and large-scale magnetic field structure of UCDs from observations of coherent radio bursts. We apply our methodology to the nearby T8 dwarf WISE J062309.94-045624.6 (J0623) which was recently detected at radio wavelengths, and show that it is likely viewed pole-on. We also find that J0623's rotation and magnetic axes are misaligned significantly, reminiscent of Uranus and Neptune, and show that it may be undergoing a magnetic cycle with a period exceeding 6 months in duration. These findings demonstrate that our method is a robust new tool for studying magnetic fields on planetary-mass objects. With the advent of next-generation low-frequency radio facilities, the methods presented here could facilitate the characterisation of exoplanetary magnetospheres for the first time.
arXiv comment15 pages, 7 figures. Under review at A&A, subject to minor comments
References in corpus (54)
- SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
- Array Programming with NumPy
- CASA, the Common Astronomy Software Applications for Radio Astronomy
- The Australia Telescope Compact Array Broadband Backend (CABB)
- The Rapid ASKAP Continuum Survey I: Design and First Results
- Confirmation of the Electron Cyclotron Maser Instability as the Dominant Source of Radio Emission from Very Low Mass Stars and Brown Dwarfs
- A statistical test for Nested Sampling algorithms
- Periodic Bursts of Coherent Radio Emission from an Ultracool Dwarf
- Collaborative Nested Sampling: Big Data vs. complex physical models
- A magnetic field evolution scenario for brown dwarfs and giant planets
- 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?
- Magnetic fields of M dwarfs
- Magnetically controlled mass loss from extrasolar planets in close orbits
- Auroral radio emission from late L and T dwarfs: A new constraint on dynamo theory in the substellar regime
- The search for radio emission from the exoplanetary systems 55 Cancri, Andromedae, and Boötis using LOFAR beam-formed observations
- The Strongest Magnetic Fields on the Coolest Brown Dwarfs
- Trends in Ultracool Dwarf Magnetism. I. X-Ray Suppression and Radio Enhancement
- Broadband Spectral Modeling of the Extreme Gigahertz-Peaked Spectrum Radio Source PKS B0008-421
- Origin of electron cyclotron maser-induced radio emissions at ultra-cool dwarfs: magnetosphere-ionosphere coupling currents
- The magnetic field and multiple planets of the young dwarf AU~Mic
- Slingshot prominences: nature's wind gauges
- Weather on Other Worlds. V. The Three Most Rapidly Rotating Ultra-Cool Dwarfs
- MOBSTER -- VI. The crucial influence of rotation on the radio magnetospheres of hot stars
- A scaling relationship for non-thermal radio emission from ordered magnetospheres: from the top of the Main Sequence to planets
- Wideband Dynamic Radio Spectra of Two Ultra-cool dwarfs
- Surprisingly Weak Magnetism on Young Accreting Brown Dwarfs
- The Effects of Magnetic Fields on Observational Signatures of Atmospheric Escape in Exoplanets: Double Tail Structures
- Resolved imaging of an extrasolar radiation belt around an ultracool dwarf
- First Detection of a Strong Magnetic Field on a Bursty Brown Dwarf: Puzzle Solved
- Uniform Forward-Modeling Analysis of Ultracool Dwarfs. II. Atmospheric Properties of 55 Late-T Dwarfs
- Direct radio discovery of a cold brown dwarf
- Methane Emission From a Cool Brown Dwarf
- A New Model Suite to Determine the Influence of Cosmic Rays on (Exo)planetary Atmospheric Biosignatures -- Validation based on Modern Earth
- The Discovery of Solar-like Activity Cycles Beyond the End of the Main Sequence?
- Evidence for a radiation belt around a brown dwarf
- Periodic Radio Emission from the T8 Dwarf WISE J062309.94-045624.6
- Electron-Cyclotron-Maser Observable Modes
- Hunting for exoplanets via magnetic star-planet interactions: geometrical considerations for radio emission
- Simulating radio emission from Low Mass Stars
- Radio masers on WX UMa: hints of a Neptune-sized planet, or magnetospheric reconnection?
- Polarised radio pulsations from a new T dwarf binary
- Follow-up LOFAR observations of the Boötis exoplanetary system
- Investigating ionospheric calibration for LOFAR 2.0 with simulated observations
- On the Correlation between L Dwarf Optical and Infrared Variability and Radio Aurorae
- First spectropolarimetric measurement of a brown dwarf magnetic field in molecular bands
- Source of radio emissions induced by the Galilean moons Io, Europa and Ganymede: in situ measurements by Juno
- Data-Driven Spectroscopy of Cool Stars at High Spectral Resolution
- The energetic particle environment of a GJ 436 b-like planet
- Radio Emission from Binary Ultracool Dwarf Systems
- Transitions in magnetic behavior at the substellar boundary
- The Potential of Detecting Radio-flaring Ultracool Dwarfs at L band in the FAST Drift-scan Survey
- Internal Structure and Magnetic Moment of Rocky Planets. Application to the first exoplanets discovered by TESS
- Measurement of stellar and substellar winds using white dwarf hosts