Detection of new strongly variable brown dwarfs in the L/T transition

Abstract

*Abbreviated abstract* Context: Brown dwarfs in the spectral range L9-T3.5, within the so called L/T transition, have been shown to be variable at higher amplitudes and with greater frequency than other field dwarfs. [...] Now, more variables such as these need to be discovered and studied to better constrain atmospheric models. This is also critical to better understand giant exoplanets and to shed light on a number of possible correlations between brown dwarf characteristics and variability. Aims: [...] In this work, we aim to discover new strong variables in this spectral range by targeting ten previously unsurveyed brown dwarfs. Methods: We used the NOTCam at the Nordic Optical Telescope to observe 11 targets, with spectral types ranging from L9.5 to T3.5, in the J-band [...] Results: We report first discoveries of strong and significant variability in four out of the ten targets [...] measuring peak-to-peak amplitudes up to 10.7 +- 0.4% in J for the T1 dwarf 2MASS J22153705+2110554, for which we observe significant light curve evolution between the 2017 and 2018 epochs. We also report a marginally significant detection of strong variability, and confirm that the well known 2MASS J01365662+0933473 is still strongly variable three years after the last reported epoch. Finally, we present an extensive multi-epoch catalogue of strong variables reported in the literature and discuss possible correlations that are identifiable from the catalogue. Conclusions: We significantly add to the number of known strong variables, and through Poisson statistics infer an occurrence rate for strong variability among L9-T3.5 brown dwarfs of 40[+32-19]%, which is in agreement with previous estimates. The new variables identified in this work are also excellently suited for extensive multi-wavelength observations dedicated to probing the 3D structure of brown dwarf atmospheres.

arXiv comment30 pages, 17 figures, 3-page multi-epoch table of all known strongly variable brown dwarfs in appendix D, abbreviated abstract

References in corpus (78)

• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• Understanding the Lomb-Scargle Periodogram
• Precipitating Condensation Clouds in Substellar Atmospheres
• A Giant Planet Candidate near a Young Brown Dwarf
• A Unified Near Infrared Spectral Classification Scheme for T Dwarfs
• Meeting the Cool New Neighbors V: A 2MASS-Selected Sample of Ultracool Dwarfs
• The First Hundred Brown Dwarfs Discovered by the Wide-field Infrared Survey Explorer (WISE)
• The Discovery of Y Dwarfs Using Data from the Wide-field Infrared Survey Explorer (WISE)
• A Near-Infrared Spectroscopic Study of Young Field Ultracool Dwarfs
• Discoveries from a Near-infrared Proper Motion Survey using Multi-epoch 2MASS Data
• Young L Dwarfs Identified in the Field: A Preliminary Low-Gravity, Optical Spectral Sequence from L0 to L5
• The Brown Dwarf Kinematics Project (BDKP) I. Proper Motions and Tangential Velocities for a Large Sample of Late-type M, L and T Dwarfs
• The Brown Dwarf Kinematics Project (BDKP). III. Parallaxes for 70 Ultracool Dwarfs
• Weather on Other Worlds. II. Survey Results: Spots Are Ubiquitous on L and T Dwarfs
• Chromospheric Activity, Rotation, and Rotational Braking in M and L Dwarfs
• Evidence for Cloud Disruption in the L/T Dwarf Transition
• Photometric Variability of the T2.5 Brown Dwarf SIMP J013656.5+093347; Evidence for Evolving Weather Patterns
• The Hawaii Infrared Parallax Program. II. Young Ultracool Field Dwarfs
• Discovery of Two T Dwarf Companions with the Spitzer Space Telescope
• HST Spectral Mapping of L/T Transition Brown Dwarfs Reveals Cloud Thickness Variations
• The Extremely Red, Young L Dwarf PSO J318-22: A Free-Floating Planetary-Mass Analog to Directly Imaged Young Gas-Giant Planets
• A Sample of Very Young Field L Dwarfs and Implications for the Brown Dwarf "Lithium Test" at Early Ages
• Large Amplitude Variations of an L/T Transition Brown Dwarf: Multi-Wavelength Observations of Patchy, High-Contrast Cloud Features
• Strong Brightness Variations Signal Cloudy-to-Clear Transition of Brown Dwarfs
• Discovery of a ~250 K Brown Dwarf at 2 pc from the Sun
• Discovery of a Binary Brown Dwarf at 2 Parsecs from the Sun
• Vertical Atmospheric Structure in a Variable Brown Dwarf: Pressure-dependent Phase Shifts in Simultaneous Hubble Space Telescope-Spitzer Light Curves
• BGLS: A Bayesian formalism for the generalised Lomb-Scargle periodogram
• Brown Dwarf Photospheres are Patchy: A Hubble Space Telescope Near-infrared Spectroscopic Survey Finds Frequent Low-level Variability
• SpeX Spectroscopy of Unresolved Very Low Mass Binaries. II. Identification of Fourteen Candidate Binaries with Late-M/Early-L and T Dwarf Components
• Clouds in the Coldest Brown Dwarfs: FIRE Spectroscopy of Ross 458C
• Discovery of a Highly Unequal-Mass Binary T Dwarf with Keck Laser Guide Star Adaptive Optics: A Coevality Test of Substellar Theoretical Models and Effective Temperatures
• Discovery of the brightest T dwarf in the northern hemisphere
• Fast-evolving weather for the coolest of our two new substellar neighbours
• The Viewing Geometry of Brown Dwarfs Influences Their Observed Colours and Variability Properties
• $ExtrasolarStorms$: Pressure-dependent Changes In Light Curve Phase In Brown Dwarfs From Simultaneous $Hubble$ and $Spitzer$ Observations
• Weather on the Nearest Brown Dwarfs: Resolved Simultaneous Multi-Wavelength Variability Monitoring of WISE J104915.57-531906.1AB
• The Onset of Methane in L Dwarfs
• Discovery of Rotational Modulations in the Planetary-Mass Companion 2M1207b: Intermediate Rotation Period and Heterogeneous Clouds in a Low Gravity Atmosphere
• A Search for L/T Transition Dwarfs With Pan-STARRS1 and WISE. II. L/T Transition Atmospheres and Young Discoveries
• Resolved Near-Infrared Spectroscopy of WISE J104915.57-531906.1AB: A Flux-Reversal Binary at the L dwarf/T dwarf Transition
• Atmospheres of Brown Dwarfs
• Near-infrared photometry of Y dwarfs: low ammonia abundance and the onset of water clouds
• Hip 63510C, Hip 73786B, and nine new isolated high proper motion T dwarf candidates from UKIDSS DR6 and SDSS DR7
• Photometric Variability at the L/T Dwarf Boundary
• An independent analysis of the brown dwarf atmosphere monitoring (BAM) data: large-amplitude variability is rare outside the L/T transition
• The Brown dwarf Atmosphere Monitoring (BAM) Project I: The largest near-IR monitoring survey of L- & T-dwarfs
• Variability in a Young, L/T Transition Planetary-Mass Object
• SIMP J013656.5+093347 is Likely a Planetary-Mass Object in the Carina-Near Moving Group
• Simultaneous, Multi-Wavelength Variability Characterization of the Free-Floating Planetary Mass Object PSO J318.5-22
• WISEP J004701.06+680352.1: An intermediate surface gravity, dusty brown dwarf in the AB Dor Moving Group
• Cloud Atlas: Discovery of Patchy Clouds and High-amplitude Rotational Modulations In a Young, Extremely Red L-type Brown Dwarf
• Parallaxes of Southern Extremely Cool objects - I: Targets, Proper motions and first results
• WISEA J114724.10-204021.3: A Free-Floating Planetary Mass Member of the TW Hya Association
• A Proper Motion Survey Using the First Sky Pass of NEOWISE-Reactivation Data
• NPARSEC: NTT Parallaxes of Southern Extremely Cool objects. Goals, targets, procedures and first results
• An accurate distance to 2M1207Ab
• The First Detection of Photometric Variability in a Y Dwarf: WISE J140518.39+553421.3
• Variability of the Lowest Mass Objects in the AB Doradus Moving Group
• A Targeted Search for Peculiarly Red L and T Dwarfs in SDSS, 2MASS, and WISE: Discovery of a Possible L7 Member of the TW Hydrae Association
• A Monitoring Campaign for Luhman 16AB. I. Detection of Resolved Near-Infrared Spectroscopic Variability
• Cloud Structure of the Nearest Brown Dwarfs II: High-amplitude variability for Luhman 16 A and B in and out of the 0.99 micron FeH feature
• Observed Variability at 1um and 4um in the Y0 Brown Dwarf WISEP J173835.52+273258.9
• The Mass-Luminosity Relation in the L/T Transition: Individual Dynamical Masses for the New J-Band Flux Reversal Binary SDSSJ105213.51+442255.7AB
• Four new T dwarfs identified in PanSTARRS 1 commissioning data
• A Brown Dwarf Census from the SIMP Survey
• Y dwarf Trigonometric Parallaxes from the Spitzer Space Telescope
• Cloud Atlas: Hubble Space Telescope Near-Infrared Spectral Library of Brown Dwarfs, Planetary-mass companions, and hot Jupiters
• Photometric Monitoring of the Coldest Known Brown Dwarf with the Spitzer Space Telescope
• Cloud Atlas: Rotational Spectral Modulations and potential Sulfide Clouds in the Planetary-mass, Late T-type Companion Ross 458C
• Cloud Atlas: Discovery of Rotational Spectral Modulations in a Low-mass, L-type Brown Dwarf Companion to a Star
• Cloud Atlas: Rotational Modulations in the L/T Transition Brown Dwarf Companion HN Peg B
• High Resolution Imaging of Very Low Mass Spectral Binaries: Three Resolved Systems and Detection of Orbital Motion in an L/T Transition Binary
• 2MASS J13243553+6358281 is an Early T-Type Planetary-Mass Object in the AB Doradus Moving Group
• Rotational Light Curves of Jupiter from UV to Mid-Infrared and Implications for Brown Dwarfs and Exoplanets
• A Statistical Survey of Peculiar L and T Dwarfs in SDSS, 2MASS, and WISE
• Spitzer Light Curves of the Young, Planetary-Mass TW Hya Members 2MASS J11193254-1137466AB and WISEA J114724.10-204021.3
• Parallaxes of Cool Objects with WISE: Filling in for Gaia

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