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Searching for Scatterers: High-Contrast Imaging of Young Stars Hosting Wide-Separation Planetary-Mass Companions

Bryan, Marta L. and Bowler, Brendan P. and Knutson, Heather A. and Kraus, Adam L. and Hinkley, Sasha and Mawet, Dimitri and Nielsen, Eric L. and Blunt, Sarah C. (2016) Searching for Scatterers: High-Contrast Imaging of Young Stars Hosting Wide-Separation Planetary-Mass Companions. Astrophysical Journal, 827 (2). Art. No. 100. ISSN 0004-637X. doi:10.3847/0004-637X/827/2/100.

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We have conducted an angular differential imaging survey with NIRC2 at Keck in search of close-in substellar companions to a sample of seven systems with confirmed planetary-mass companions (PMCs) on wide orbits (>50 au). These wide-separation PMCs pose significant challenges to all three possible formation mechanisms: core accretion plus scattering, disk instability, and turbulent fragmentation. We explore the possibility that these companions formed closer in and were scattered out to their present-day locations by searching for other massive bodies at smaller separations. The typical sensitivity for this survey is ΔK ~ 12.5 at 1". We identify eight candidate companions, whose masses would reach as low as one Jupiter mass if gravitationally bound. From our multi-epoch astrometry we determine that seven of these are conclusively background objects, while the eighth near DH Tau is ambiguous and requires additional monitoring. We rule out the presence of >7 M_(Jup) bodies in these systems down to 15–50 au that could be responsible for scattering. This result combined with the totality of evidence suggests that dynamical scattering is unlikely to have produced this population of PMCs. We detect orbital motion from the companions ROXs 42B b and ROXs 12 b, and from this determine 95% upper limits on the companions' eccentricities of 0.58 and 0.83 respectively. Finally, we find that the 95% upper limit on the occurrence rate of additional planets with masses between 5 and 15 M_(Jup) outside of 40 au in systems with PMCs is 54%.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Bryan, Marta L.0000-0002-6076-5967
Bowler, Brendan P.0000-0003-2649-2288
Knutson, Heather A.0000-0002-0822-3095
Kraus, Adam L.0000-0001-9811-568X
Hinkley, Sasha0000-0001-8074-2562
Mawet, Dimitri0000-0002-8895-4735
Nielsen, Eric L.0000-0001-6975-9056
Blunt, Sarah C.0000-0002-3199-2888
Additional Information:© 2016 The American Astronomical Society. Received 2016 February 13; revised 2016 May 30; accepted 2016 June 16; published 2016 August 11. 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.
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:methods: statistical; planetary systems; techniques: high angular resolution
Issue or Number:2
Record Number:CaltechAUTHORS:20160707-154148781
Persistent URL:
Official Citation:Marta L. Bryan et al 2016 ApJ 827 100
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:68898
Deposited By: Joy Painter
Deposited On:08 Jul 2016 02:05
Last Modified:11 Nov 2021 04:06

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