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A Substellar Companion to a Hot Star in K2's Campaign 0 Field

Dholakia, S. and Cody, Ann Marie and Howell, Steve B. and Johnson, Marshall C. and Isaacson, Howard and Everett, Mark E. and Ciardi, David R. and Howard, Andrew W. and Shporer, Avi (2019) A Substellar Companion to a Hot Star in K2's Campaign 0 Field. Publications of the Astronomical Society of the Pacific, 131 (1005). Art. No. 114402. ISSN 1538-3873. doi:10.1088/1538-3873/ab324e.

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The K2 mission has enabled searches for transits in crowded stellar environments very different from the original Kepler mission field. We describe here the reduction and analysis of time series data from K2's Campaign 0 superstamp, which contains the 150 Myr open cluster M35. We report on the identification of a substellar transiting object orbiting an A star at the periphery of the superstamp. To investigate this transiting source, we performed ground based follow-up observations, including photometry with the Las Cumbres Observatory telescope network and high resolution spectroscopy with Keck/High Resolution Echelle Spectrometer. We confirm that the host star is a hot, rapidly rotating star, precluding precision radial velocity measurements. We nevertheless present a statistical validation of the planet or brown dwarf candidate using speckle interferometry from the WIYN telescope to rule out false positive stellar eclipsing binary scenarios. Based on parallax and proper motion data from Gaia Data Release 2 (DR2), we conclude that the star is not likely to be a member of M35, but instead is a background star around 100 pc behind the cluster. We present an updated ephemeris to enable future transit observations. We note that this is a rare system as a hot host star with a substellar companion. It has a high potential for future follow-up, including Doppler tomography and mid-infrared secondary transit observations.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Cody, Ann Marie0000-0002-3656-6706
Howell, Steve B.0000-0002-2532-2853
Johnson, Marshall C.0000-0002-5099-8185
Isaacson, Howard0000-0002-0531-1073
Everett, Mark E.0000-0002-0885-7215
Ciardi, David R.0000-0002-5741-3047
Howard, Andrew W.0000-0001-8638-0320
Shporer, Avi0000-0002-1836-3120
Additional Information:© 2019 The Astronomical Society of the Pacific. Received 2018 December 5; accepted 2019 July 11; published 2019 October 10. We thank Nic Scott for assistance with speckle observations. John Stauffer, Lynne Hillenbrand, Trevor David, Geert Barentsen, and Christina Hedges provided helpful discussion. This paper makes use of EXOFAST (Eastman et al. 2013) as provided by 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 work also made use of PyKE (Eastman et al. 2013), a software package for the reduction and analysis of Kepler data. This open source software project is developed and distributed by the NASA Kepler Guest Observer Office. This work has made use of data from the European Space Agency (ESA) mission Gaia (, processed by the Gaia Data Processing and Analysis Consortium (DPAC, Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. This work makes use of observations from the LCOGT network. 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: WIYN - , Keck:I (HIRES) - , LCOGT - . Software: DAOphot (Stetson 1987), IRAF (Tody 1986), (Tody 1993), PyKE (Still & Barclay 2012), EXOFAST (Eastman et al. 2013), AstroImageJ (Collins et al. 2017), emcee (Foreman-Mackey et al. 2013), vespa (Morton 2012), Astropy (Astropy Collaboration et al. 2013), Matplotlib (Hunter 2007).
Group:Infrared Processing and Analysis Center (IPAC), Astronomy Department
Funding AgencyGrant Number
Gaia Multilateral AgreementUNSPECIFIED
Subject Keywords:brown dwarfs – planets and satellites: gaseous planets
Issue or Number:1005
Record Number:CaltechAUTHORS:20190722-131218385
Persistent URL:
Official Citation:S. Dholakia et al 2019 PASP 131 114402
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:97326
Deposited By: Tony Diaz
Deposited On:22 Jul 2019 20:22
Last Modified:16 Nov 2021 17:30

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