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M-Dwarf Fast Rotators and the Detection of Relatively Young Multiple M-Star Systems

Rappaport, S. and Swift, J. and Levine, A. and Joss, M. and Sanchis-Ojeda, R. and Barclay, T. and Still, M. and Handler, G. and Oláh, K. and Muirhead, P. S. and Huber, D. and Vida, K. (2014) M-Dwarf Fast Rotators and the Detection of Relatively Young Multiple M-Star Systems. Astrophysical Journal, 788 (2). Art. No. 114. ISSN 0004-637X.

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We have searched the Kepler light curves of ~3900 M-star targets for evidence of periodicities that indicate, by means of the effects of starspots, rapid stellar rotation. Several analysis techniques, including Fourier transforms, inspection of folded light curves, "sonograms," and phase tracking of individual modulation cycles, were applied in order to distinguish the periodicities due to rapid rotation from those due to stellar pulsations, eclipsing binaries, or transiting planets. We find 178 Kepler M-star targets with rotation periods, P_(rot), of <2 days, and 110 with P_(rot) < 1 day. Some 30 of the 178 systems exhibit two or more independent short periods within the same Kepler photometric aperture, while several have 3 or more short periods. Adaptive optics imaging and modeling of the Kepler pixel response function for a subset of our sample support the conclusion that the targets with multiple periods are highly likely to be relatively young physical binary, triple, and even quadruple M star systems. We explore in detail the one object with four incommensurate periods all less than 1.2 days, and show that two of the periods arise from one of a close pair of stars, while the other two arise from the second star, which itself is probably a visual binary. If most of these M-star systems with multiple periods turn out to be bound M stars, this could prove a valuable way discovering young hierarchical M-star systems; the same approach may also be applicable to G and K stars. The ~5% occurrence rate of rapid rotation among the ~3900 M star targets is consistent with spin evolution models that include an initial contraction phase followed by magnetic braking, wherein a typical M star can spend several hundred Myr before spinning down to periods longer than 2 days.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Rappaport, S.0000-0003-3182-5569
Swift, J.0000-0002-9486-818X
Sanchis-Ojeda, R.0000-0002-6193-972X
Barclay, T.0000-0001-7139-2724
Muirhead, P. S.0000-0002-0638-8822
Huber, D.0000-0001-8832-4488
Additional Information:© 2014 American Astronomical Society. Received 2014 February 13; accepted 2014 April 30; published 2014 May 29. We acknowledge several useful discussions about the particular M star(s) KIC 7740983 with Robert Szabo and Katrien Kolenberg. We also thank Cristina Rodriguez-Lopez, Jim Mac- Donald, Jérôme Quintin, Alex Brown, Günter Houdek, and Lucianne Walkowicz for important discussions about the possibility of observing M-star pulsations with Kepler. Arthur Delarue wrote a very helpful code for automatically extracting significant incommensurate frequencies from FTs. We thank Sasha Hinkley and Benjamin Montet for performing a subset of our Keck AO observations. We are grateful to the Kepler team for providing such valuable data to the community. D.H. acknowledges NASA support through the Kepler Participating Scientist Program under grant NNX14AB92G. R.S.O. acknowledges support through the Kepler Participating Scientist Program and the NASA Origins Program under grants NNX12AC76G and NNX11AG85G. P.S.M. acknowledges support from the Hubble Fellowship Program, provided by NASA through Hubble Fellowship grant HST-HF-51326.01-A awarded by the STScI, which is operated by the AURA, Inc., for NASA, under contract NAS 5-26555. G.H. is grateful for support by the Polish NCN grant 2011/01/B/ST9/05448. K.O. and K.V. acknowledge support from the Hungarian OTKA grants K-81421 and K-109276, and from “Lendület-2012” Young Researchers’ Programs of the Hungarian Academy of Sciences. This research has made use of the NASA Exoplanet Archive, and the Mikulski Archive for Space Telescopes (MAST).We made use of J-band images that were obtained with the United Kingdom Infrared Telescope (UKIRT) which is operated by the Joint Astronomy Centre on behalf of the Science and Technology Facilities Council of the U.K. Some of 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 very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community, and we are most fortunate to have the opportunity to conduct observations from this mountain.
Funding AgencyGrant Number
NASA Hubble FellowshipHST-HF-51326.01-A
Space Telescope Science InstituteUNSPECIFIED
NASANAS 5-26555
National Science Centre (Poland)2011/01/B/ST9/05448
Hungarian Scientific Research Fund (OTKA)K-81421
Hungarian Scientific Research Fund (OTKA)K-109276
Hungarian Academy of SciencesLendület-2012
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:binaries: close; binaries: general; stars: activity; stars: late-type; stars: rotation; starspots; techniques: photometric
Issue or Number:2
Record Number:CaltechAUTHORS:20140717-125330578
Persistent URL:
Official Citation:M-dwarf Rapid Rotators and the Detection of Relatively Young Multiple M-Star Systems S. Rappaport et al. 2014 ApJ 788 114
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:47300
Deposited By: Ruth Sustaita
Deposited On:18 Jul 2014 19:43
Last Modified:09 Mar 2020 13:19

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