Rotation periods of young brown dwarfs : K2 survey in Upper Scorpius
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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.
Scholz , A , Kostov , V , Jayawardhana , R & Mužić , K 2015 , ' Rotation periods of young brown dwarfs : K2 survey in Upper Scorpius ' Astrophysical Journal Letters , vol 809 , no. 2 , L29 . DOI: 10.1088/2041-8205/809/2/L29
Astrophysical Journal Letters
© 2015. The American Astronomical Society. All rights reserved. This work is made available online in accordance with the publisher’s policies. This is the final published version of the work, which was originally published at https://dx.doi.org/10.1088/2041-8205/809/2/L29
DescriptionThis work was supported in part by NSERC grants to R.J. Date of Acceptance: 17/06/2015
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