Weather on Other Worlds. III. A Survey for T Dwarfs with High Amplitude Optical Variability

Abstract

We have monitored twelve T dwarfs with the Kitt Peak 2.1m telescope using an f814w filter (0.7-0.95 microns) to place in context the remarkable 10-20% variability exhibited by the nearby T dwarf Luhman 16B in this wavelength regime. The motivation was the poorly known red optical behavior of T dwarfs, which have been monitored almost exclusively at infrared wavelengths, where variability amplitudes greater than 10% have been found to be very rare. We detect highly significant variability in two T dwarfs. The T2.5 dwarf 2MASS 13243559+6358284 shows consistent ~17% variability on two consecutive nights. The T2 dwarf 2MASS J16291840+0335371 exhibits ~10% variability that may evolve from night to night, similarly to Luhman 16B. Both objects were previously known to be variable in the infrared, but with considerably lower amplitudes. We also find evidence for variability in the T6 dwarf J162414.37+002915.6, but since it has lower significance, we conservatively refrain from claiming this object as a variable. We explore and rule out various telluric effects, demonstrating that the variations we detect are astrophysically real. We suggest that high-amplitude photometric variability for T dwarfs is likely more common in the red optical than at longer wavelengths. The two new members of the growing class of high-amplitude variable T dwarfs offer excellent prospects for further study of cloud structures and their evolution.

arXiv commentAccepted to ApJ

References in corpus (23)

• The Ninth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-III Baryon Oscillation Spectroscopic Survey
• Sixty-seven Additional L Dwarfs Discovered by the Two Micron All Sky Survey (2MASS)
• A Unified Near Infrared Spectral Classification Scheme for T Dwarfs
• The First Hundred Brown Dwarfs Discovered by the Wide-field Infrared Survey Explorer (WISE)
• Seventy-One New L and T Dwarfs from the Sloan Digital Sky Survey
• Chromospheric Activity, Rotation, and Rotational Braking in M and L Dwarfs
• Photometric Variability of the T2.5 Brown Dwarf SIMP J013656.5+093347; Evidence for Evolving Weather Patterns
• HST Spectral Mapping of L/T Transition Brown Dwarfs Reveals Cloud Thickness Variations
• Large Amplitude Variations of an L/T Transition Brown Dwarf: Multi-Wavelength Observations of Patchy, High-Contrast Cloud Features
• The Discovery of a Field Methane Dwarf from Sloan Digital Sky Survey Commissioning Data
• Strong Brightness Variations Signal Cloudy-to-Clear Transition of Brown Dwarfs
• Discovery of a Binary Brown Dwarf at 2 Parsecs from the Sun
• Discovery of 11 New T Dwarfs in the Two Micron All-Sky Survey, Including a Possible L/T Transition Binary
• Variability in ultra cool dwarfs: evidence for the evolution of surface features
• A Cross-Match of 2MASS and SDSS: Newly-Found L and T Dwarfs and an Estimate of the Space Densitfy of T Dwarfs
• Spectroscopic rotational velocities of brown dwarfs
• Fast-evolving weather for the coolest of our two new substellar neighbours
• Weather on the Nearest Brown Dwarfs: Resolved Simultaneous Multi-Wavelength Variability Monitoring of WISE J104915.57-531906.1AB
• Infrared Eclipses of the Strongly Irradiated Planet WASP-33b, and Oscillations of its Host Star
• Weather on Other Worlds I: Detection of Periodic Variability in the L3 Dwarf DENIS-P J1058.7-1548 with Precise Multi-Wavelength Photometry
• Characterization of the Nearby L/T Binary Brown Dwarf WISE J104915.57-531906.1 at 2 Parsecs from the Sun
• Rotational Velocities of Individual Components in Very Low Mass Binaries
• Four new T dwarfs identified in PanSTARRS 1 commissioning data

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