The rotation-disk connection in young brown dwarfs : strong evidence for early rotational braking
MetadataShow full item record
We use Kepler/K2 light curves to measure rotation periods of brown dwarfs and very low mass stars in the Upper Scorpius star-forming region. Our sample comprises a total of 104 periods. Depending on the assumed age of Upper Scorpius, about a third of them are for brown dwarfs. The median period is 1.28 day for the full sample and 0.84 day for the probable brown dwarfs. With this period sample, we find compelling evidence for early rotational braking in brown dwarfs, caused by the interaction between the central object and the disk. The median period for objects with disks is at least 50% longer than for those without. Two brown dwarfs show direct signs of "disk-locking" in their light curves, in the form of dips that recur on a timescale similar to the rotation period. Comparing the period samples for brown dwarfs at different ages, there is a clear need to include rotational braking into period evolution tracks between 1 and 10 Myr. A locked period over several Myr followed by spin-up due to contraction fits the observational data. We conclude that young brown dwarfs are affected by the same rotational regulation as stars, though they start off with significantly faster rotation, presumably set by initial conditions.
Moore , K , Scholz , A & Jayawardhana , R 2019 , ' The rotation-disk connection in young brown dwarfs : strong evidence for early rotational braking ' , Astrophysical Journal , vol. 872 , no. 2 , 159 . https://doi.org/10.3847/1538-4357/aaff5c
Copyright © 2019. 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://doi.org/10.3847/1538-4357/aaff5c
DescriptionThis work was supported in part by a McGill University Tomlinson Doctoral fellowship to K.M., NSERC grant to R.J. and by STFC grant ST/R000824/1 to A.S.
Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.