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Multiple Explanations for the Single Transit of KIC 5951458 Based on Radial Velocity Measurements Extracted with a Novel Matched-template Technique

Dalba, Paul A. and Fulton, Benjamin and Isaacson, Howard and Kane, Stephen R. and Howard, Andrew W. (2020) Multiple Explanations for the Single Transit of KIC 5951458 Based on Radial Velocity Measurements Extracted with a Novel Matched-template Technique. Astronomical Journal, 160 (3). Art. No. 149. ISSN 1538-3881. doi:10.3847/1538-3881/abad27.

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Planetary systems that show single-transit events are a critical pathway to increasing the yield of long-period exoplanets from transit surveys. From the primary Kepler mission, KIC 5951458 b (Kepler-456b) was thought to be a single-transit giant planet with an orbital period of 1310 days. However, radial velocity (RV) observations of KIC 5951458 from the HIRES instrument on the Keck telescope suggest that the system is far more complicated. To extract precise RVs for this V ≈ 13 star, we develop a novel matched-template technique that takes advantage of a broad library of template spectra acquired with HIRES. We validate this technique and measure its noise floor to be 4–8 m s⁻¹ (in addition to internal RV error) for most stars that would be targeted for precision RVs. For KIC 5951458, we detect a long-term RV trend that suggests the existence of a stellar companion with an orbital period greater than a few thousand days. We also detect an additional signal in the RVs that is possibly caused by a planetary or brown dwarf companion with mass in the range of 0.6–82 M_(Jup) and orbital period below a few thousand days. Curiously, from just the data on hand, it is not possible to determine which object caused the single "transit" event. We demonstrate how a modest set of RVs allows us to update the properties of this unusual system and predict the optimal timing for future observations.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Dalba, Paul A.0000-0002-4297-5506
Fulton, Benjamin0000-0003-3504-5316
Isaacson, Howard0000-0002-0531-1073
Kane, Stephen R.0000-0002-7084-0529
Howard, Andrew W.0000-0001-8638-0320
Additional Information:© 2020 The American Astronomical Society. Received 2020 May 3; revised 2020 July 10; accepted 2020 August 5; published 2020 September 2. The authors thank the anonymous referee for thoughtful comments that improved the quality and clarity of this work. The authors acknowledge Erik Petigura for having the idea to use previously acquired templates rather than obtaining new ones for faint stars. The authors also thank Lee Rosenthal for helpful conversations about The Joker. Lastly, the authors acknowledge all of the observers on the California Planet Search team for their many hours of hard work. P.D. is supported by a National Science Foundation (NSF) Astronomy and Astrophysics Postdoctoral Fellowship under award AST-1903811. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. This paper includes data collected by the Kepler mission and obtained from the MAST data archive at the Space Telescope Science Institute (STScI). Funding for the Kepler mission is provided by the NASA Science Mission Directorate. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. This work presents results from the European Space Agency (ESA) space mission Gaia. Gaia data are being processed by the Gaia Data Processing and Analysis Consortium (DPAC). Funding for the DPAC is provided by national institutions, in particular the institutions participating in the Gaia MultiLateral Agreement (MLA). 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 NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Finally, the authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Facilities: Keck:I(HIRES) - KECK I Telescope, Keck:II(NIRC2) - , Kepler - , Gaia. - Software: Lightkurve (Lightkurve Collaboration et al. 2018), SpecMatch (Petigura 2015; Petigura et al. 2017), SpecMatch-Emp (Yee et al. 2017), The Joker (Price-Whelan et al. 2017).
Group:Astronomy Department, Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
NSF Astronomy and Astrophysics FellowshipAST-1903811
NASANAS 5-26555
Gaia Multilateral AgreementUNSPECIFIED
Subject Keywords:Exoplanet astronomy ; Exoplanet detection methods ; Radial velocity ; Exoplanet systems
Issue or Number:3
Classification Code:Unified Astronomy Thesaurus concepts: Exoplanet astronomy (486); Exoplanet detection methods (489); Radial velocity (1332); Exoplanet systems (484)
Record Number:CaltechAUTHORS:20200817-101831368
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Official Citation:Paul A. Dalba et al 2020 AJ 160 149
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104976
Deposited By: Tony Diaz
Deposited On:17 Aug 2020 18:34
Last Modified:16 Nov 2021 18:38

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