Abstract
We present the detection of [3.6 μm] photometric variability in two young, L/T transition brown dwarfs, WISE J004701.06+680352.1 (W0047) and 2MASS J2244316+204343 (2M2244) using the Spitzer Space Telescope. We find a period of 16.4 ±0.2 h and a peak-to-peak amplitude of 1.07 ± 0.04 per cent forW0047, and a period of 11±2 h and amplitude of 0.8 ± 0.2 per cent 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 ± 0.3 and 14.3 -1.5+1.4 km s-1 for W0047 and 2M2244, respectively. With inclination angles of 85-9 +5° and 76 -20+14° 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 Spitzer [4.5 μm] monitoring of the young, T5.5 object SDSS111010+011613 (SDSS1110) where we detect no variability. For periods < 18 h, we place an upper limit of 1.25 per cent on the peak-to-peak variability amplitude of SDSS1110.
Original language | English |
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Pages (from-to) | 1041-1053 |
Number of pages | 13 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 474 |
Issue number | 1 |
DOIs | |
State | Published - Feb 2018 |
Keywords
- Brown dwarfs
- Stars: low-mass
- Stars: variables: general