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

Johanna M. Vos, Katelyn N. Allers, Beth A. Biller, Michael C. Liu, Trent J. Dupuy, Jack F. Gallimore, Dunni Adenuga, William M. J. Best

Research output: Contribution to journalArticlepeer-review

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 \textit{Spitzer Space Telescope}. We find a period of 16.4±0.2 hr and a peak-to-peak amplitude of 1.07±0.04% for W0047, and a period of 11±2 hr and amplitude of 0.8±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+0.8−0.9 km s−1 for 2M2244, and confirm it as a bona fide member of the AB Doradus moving group. We find rotational velocities of vsini=9.8±0.3 km s−1and 14.3+1.4−1.5 km s−1 for W0047 and 2M2244, respectively. With inclination angles of 85+5∘−9 and 76+14∘−20, 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 μm] 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.
Original languageEnglish
Pages (from-to)1041-1053
Number of pages13
JournalMonthly Notices of the Royal Astronomical Society
Volume474
Issue number1
Early online date24 Oct 2017
DOIs
Publication statusPublished - 1 Feb 2018

Keywords

  • astro-ph.EP
  • astro-ph.SR

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