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Constraints on the spin evolution of young planetary-mass companions

Bryan, Marta L. and Benneke, Björn and Knutson, Heather A. and Batygin, Konstantin and Bowler, Brendan P. (2018) Constraints on the spin evolution of young planetary-mass companions. Nature Astronomy, 2 (2). pp. 138-144. ISSN 2397-3366. http://resolver.caltech.edu/CaltechAUTHORS:20171017-111047569

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Abstract

Surveys of young star-forming regions have discovered a growing population of planetary-mass (<13 M_(Jup)) companions around young stars. There is an ongoing debate as to whether these companions formed like planets (that is, from the circumstellar disk), or if they represent the low-mass tail of the star-formation process3. In this study, we utilize high-resolution spectroscopy to measure rotation rates of three young (2–300 Myr) planetary-mass companions and combine these measurements with published rotation rates for two additional companions to provide a picture of the spin distribution of these objects. We compare this distribution to complementary rotation-rate measurements for six brown dwarfs with masses <20 M_(Jup), and show that these distributions are indistinguishable. This suggests that either these two populations formed via the same mechanism, or that processes regulating rotation rates are independent of formation mechanism. We find that rotation rates for both populations are well below their break-up velocities and do not evolve significantly during the first few hundred million years after the end of accretion. This suggests that rotation rates are set during the late stages of accretion, possibly by interactions with a circumplanetary disk. This result has important implications for our understanding of the processes regulating the angular momentum evolution of young planetary-mass objects, and of the physics of gas accretion and disk coupling in the planetary-mass regime.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1038/s41550-017-0325-8DOIArticle
https://www.nature.com/articles/s41550-017-0325-8PublisherArticle
http://rdcu.be/AsqPPublisherFree ReadCube access
https://arxiv.org/abs/1712.00457arXivDiscussion Paper
ORCID:
AuthorORCID
Bryan, Marta L.0000-0002-6076-5967
Benneke, Björn0000-0001-5578-1498
Knutson, Heather A.0000-0002-0822-3095
Bowler, Brendan P.0000-0003-2649-2288
Additional Information:© 2017 Macmillan Publishers Limited, part of Springer Nature. Received: 12 July 2017; Accepted: 26 October 2017; Published online: 04 December 2017. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. We acknowledge the efforts of the Keck Observatory staff. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. H.A.K. acknowledges support from the Sloan Fellowship Program. Support for this work was provided by NASA through Hubble Fellowship grant HST-HF2-51369.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. Author Contributions: M.L.B. led the observational programme, analysed the resulting data and wrote the paper. B.B. helped to design and execute the observations and provided advice on the analysis as well as on atmosphere models for each object. H.A.K. provided advice and guidance throughout the process. K.B. calculated the approximate angular momentum evolution of a newly formed 10 M_(Jup) object surrounded by a circumplanetary disk. B.P.B. helped to identify and characterize suitable targets, including calculating new mass estimates for all of the brown dwarfs included in this study. Data availability: The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request. The authors declare no competing financial interests.
Funders:
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
NASA Hubble FellowshipHST-HF2-51369.001-A
NASANAS5-26555
Record Number:CaltechAUTHORS:20171017-111047569
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20171017-111047569
Official Citation:Constraints on the spin evolution of young planetary-mass companions Marta L. Bryan, Björn Benneke, Heather A. Knutson, Konstantin Batygin & Brendan P. Bowler Nature Astronomy volume 2, pages 138–144 (2018) doi:10.1038/s41550-017-0325-8
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:82416
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:05 Dec 2017 19:00
Last Modified:03 Feb 2018 00:44

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