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Title: ROTATION PERIODS OF YOUNG BROWN DWARFS: K2 SURVEY IN UPPER SCORPIUS

We report rotational periods for 16 young brown dwarfs in the nearby Upper Scorpius association, based on 72 days of high-cadence, high-precision photometry from the Keplerspace telescope’s K2 mission. The periods range from a few hours to two days (plus one outlier at five days), with a median just above one day, confirming that brown dwarfs, except at the very youngest ages, are fast rotators. Interestingly, four of the slowest rotators in our sample exhibit mid-infrared excess emission from disks; at least two also show signs of disk eclipses and accretion in the light curves. Comparing these new periods with those for two other young clusters and simple angular momentum evolution tracks, we find little or no rotational braking in brown dwarfs between 1–10 Myr, in contrast to low-mass stars. Our findings show that disk braking, while still at work, is inefficient in the substellar regime, thus providing an important constraint on the mass dependence of the braking mechanism.
Authors:
 [1] ;  [2] ;  [3] ;  [4]
  1. School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS (United Kingdom)
  2. Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4 (Canada)
  3. Faculty of Science, York University, 355 Lumbers Building, 4700 Keele Street, Toronto, ON M3J 1P2 (Canada)
  4. Nucleo de Astronomía, Facultad de Ingeniería, Universidad Diego Portales, Av. Ejercito 441, Santiago (Chile)
Publication Date:
OSTI Identifier:
22518902
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 809; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; ANGULAR MOMENTUM; COMPARATIVE EVALUATIONS; DIAGRAMS; DWARF STARS; ECLIPSE; EMISSION SPECTRA; LIMITING VALUES; MASS; PHOTOMETRY; ROTATION; TELESCOPES; VISIBLE RADIATION