Variability of the Lowest Mass Objects in the AB Doradus Moving Group

Abstract

We present the detection of [$3.6\mu$m] photometric variability in two young, L/T transition brown dwarfs, WISE J004701.06+680352.1 (W0047) and 2MASS J2244316+204343 (2M2244) using the \textit{Spitzer Space Telescope}. We find a period of $16.4\pm 0.2$hr and a peak-to-peak amplitude of $1.07\pm 0.04\%$ for W0047, and a period of $11\pm 2$hr and amplitude of $0.8\pm 0.2\%$ for 2M2244. This period is significantly longer than that measured previously during a shorter observation. {We additionally detect significant $J$-band variability in 2M2244 using the Wide-Field Camera on UKIRT. } We determine the radial and rotational velocities of both objects using Keck NIRSPEC data. We find a radial velocity of $-16.0_{-0.9}^{+0.8}$km s${}^{-1}$ for 2M2244, and confirm it as a bona fide member of the AB Doradus moving group. We find rotational velocities of $v\sin i=9.8\pm 0.3$km s${}^{-1}$and $14.3_{-1.5}^{+1.4}$km s${}^{-1}$ for W0047 and 2M2244, respectively. With inclination angles of $85_{-9}^{+5\circ }$ and $76_{-20}^{+14\circ }$, W0047 and 2M2244 are viewed roughly equator-on. Their remarkably similar colours, spectra and inclinations are consistent with the possibility that viewing angle may influence atmospheric appearance. We additionally present \textit{Spitzer} $[4.5\mu \mathrm{m}]$ monitoring of the young, T5.5 object SDSS111010+011613 (SDSS1110) where we detect no variability. For periods $<18$hr, we place an upper limit of $1.25\%$ on the peak-to-peak variability amplitude of SDSS1110.

14 pages, Accepted for publication in MNRAS

References in corpus (16)

• Direct Imaging of Multiple Planets Orbiting the Star HR 8799
• The Evolution of L and T Dwarfs in Color-Magnitude Diagrams
• The UKIRT Wide Field Camera ZYJHK Photometric System: Calibration from 2MASS
• The fast spin-rotation of a young extrasolar planet
• The Hawaii Infrared Parallax Program. II. Young Ultracool Field Dwarfs
• Strong Brightness Variations Signal Cloudy-to-Clear Transition of Brown Dwarfs
• A Sensitive Search for Variability in Late L Dwarfs: The Quest for Weather
• BANYAN. V. A Systematic All-Sky Survey for New Very Late-Type Low-Mass Stars and Brown Dwarfs in Nearby Young Moving Groups
• The Viewing Geometry of Brown Dwarfs Influences Their Observed Colours and Variability Properties
• A Search for L/T Transition Dwarfs With Pan-STARRS1 and WISE. II. L/T Transition Atmospheres and Young Discoveries
• The Brown dwarf Atmosphere Monitoring (BAM) Project I: The largest near-IR monitoring survey of L- & T-dwarfs
• Spectral Variability from the Patchy Atmospheres of T and Y Dwarfs
• Cloud structure of the nearest brown dwarfs: Spectroscopic variability of Luhman 16AB from the Hubble Space Telescope
• 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
• A Pulsation Search Among Young Brown Dwarfs and Very Low Mass Stars

Cited by in corpus (29)

• Let the Great World Spin: Revealing the Stormy, Turbulent Nature of Young Giant Exoplanet Analogs with the Spitzer Space Telescope
• Ultracool Dwarfs Observed with the Spitzer Infrared Spectrograph. II. Emergence and Sedimentation of Silicate Clouds in L Dwarfs, and Analysis of the Full M5--T9 Field Dwarf Spectroscopic Sample
• Atmospheric circulation of brown dwarfs and directly imaged exoplanets driven by cloud radiative feedback: global and equatorial dynamics
• Spitzer Variability Properties of Low-Gravity L Dwarfs
• Weather on Other Worlds. V. The Three Most Rapidly Rotating Ultra-Cool Dwarfs
• As the Worlds Turn: Constraining Spin Evolution in the Planetary-Mass Regime
• The Hawaii Infrared Parallax Program. V. New T-Dwarf Members and Candidate Members of Nearby Young Moving Groups
• On the Detection of Exomoons Transiting Isolated Planetary-Mass Objects
• A High-Contrast Search for Variability in HR 8799bc with VLT-SPHERE
• Cloud Atlas: High-Contrast Time-Resolved Observations of Planetary-Mass Companions
• Ultracool Dwarfs Observed with the Spitzer Infrared Spectrograph -- III. Dust Grains in Young L Dwarf Atmospheres Are Heavier
• Detection of new strongly variable brown dwarfs in the L/T transition
• Jet Streams and Tracer Mixing in the Atmospheres of Brown Dwarfs and Isolated Young Giant Planets
• A Wide Planetary Mass Companion Discovered Through the Citizen Science Project Backyard Worlds: Planet 9
• Cloud Atlas: Unraveling the vertical cloud structure with the time-series spectrophotometry of an unusually red brown dwarf
• Rotation and Abundances of the Benchmark Brown Dwarf HD 33632 Ab from Keck/KPIC High-resolution Spectroscopy
• A Near-infrared Variability Survey of Young Planetary-mass Objects
• On the Correlation between L Dwarf Optical and Infrared Variability and Radio Aurorae
• Measuring the variability of directly imaged exoplanets using vector Apodizing Phase Plates combined with ground-based differential spectrophotometry
• Longitudinally Resolved Spectral Retrieval (ReSpect) of WASP-43b
• High-contrast observations of brown dwarf companion HR 2562 B with the vector Apodizing Phase Plate coronagraph
• X-SHYNE: X-Shooter spectra of young exoplanet analogs II. Presentation and analysis of the full library
• Distinct Rotational Evolution of Giant Planets and Brown Dwarf Companions
• Informed systematic method to identify variable mid and late-T dwarfs
• $L$-band Spectra of Young Brown Dwarfs
• Time-resolved Optical Polarization Monitoring of the Most Variable Brown Dwarf
• The Brown Dwarf Kinematics Project (BDKP). V. Radial and Rotational Velocities of T Dwarfs from Keck/NIRSPEC High-Resolution Spectroscopy
• Disentangling auroral, cloud and magnetic spot driven variability in three early L-dwarfs with HST/WFC3
• Disentangling the Signatures of Blended-Light Atmospheres in L/T Transition Brown Dwarfs