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The K2-ESPRINT Project. I. Discovery of the Disintegrating Rocky Planet K2-22b with a Cometary Head and Leading Tail

Sanchis-Ojeda, R. and Howard, A. W. (2015) The K2-ESPRINT Project. I. Discovery of the Disintegrating Rocky Planet K2-22b with a Cometary Head and Leading Tail. Astrophysical Journal, 812 (2). Art. No. 22. ISSN 0004-637X.

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We present the discovery of a transiting exoplanet candidate in the K2 Field-1 with an orbital period of 9.1457 hr: K2-22b. The highly variable transit depths, ranging from ~0% to 1.3%, are suggestive of a planet that is disintegrating via the emission of dusty effluents. We characterize the host star as an M-dwarf with T_(eff) ≃ 3800 K. We have obtained ground-based transit measurements with several 1-m class telescopes and with the GTC. These observations (1) improve the transit ephemeris; (2) confirm the variable nature of the transit depths; (3) indicate variations in the transit shapes; and (4) demonstrate clearly that at least on one occasion the transit depths were significantly wavelength dependent. The latter three effects tend to indicate extinction of starlight by dust rather than by any combination of solid bodies. The K2 observations yield a folded light curve with lower time resolution but with substantially better statistical precision compared with the ground-based observations. We detect a significant "bump" just after the transit egress, and a less significant bump just prior to transit ingress. We interpret these bumps in the context of a planet that is not only likely streaming a dust tail behind it, but also has a more prominent leading dust trail that precedes it. This effect is modeled in terms of dust grains that can escape to beyond the planet's Hill sphere and effectively undergo "Roche lobe overflow," even though the planet's surface is likely underfilling its Roche lobe by a factor of 2.

Item Type:Article
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URLURL TypeDescription Paper
Sanchis-Ojeda, R.0000-0002-6193-972X
Howard, A. W.0000-0001-8638-0320
Additional Information:© 2015 The American Astronomical Society. Received 2015 April 9; accepted 2015 September 1; published 2015 October 14. We thank Joshua Pepper and Smadar Naoz for helpful comments and an anonymous referee for suggestions that greatly improved the presentation of the material. We thank Allyson Bieryla and Dave Latham for helping us with the FLWO observations of the object. We are grateful to Evan Sinukoff, Erik Petigura, and Ian Crossfield for observing this target with Keck/HIRES. We thank Yi Yang for helping with the HSC images, and Takuya Suenaga for volunteering his time to do so. The help from the Subaru Telescope staff is greatly appreciated. We acknowledge Tsuguru Ryu for his support on the Okayama transit observations. T.H. is supported by Japan Society for Promotion of Science (JSPS) Fellowship for Research (No. 25-3183). I.R. acknowledges support from the Spanish Ministry of Economy and Competitiveness (MINECO) and the Fondo Europeo de Desarrollo Regional (FEDER) through grant ESP2013-48391-C4-1-R. We extend special thanks to those of Hawaiian ancestry on whose sacred mountain of Mauna Kea we are privileged to be guests. Without their generous hospitality, the Keck observations presented herein would not have been possible. This work was performed, in part, under contract with the Jet Propulsion Laboratory (JPL) funded by NASA through the Sagan Fellowship Program executed by the NASA Exoplanet Science Institute. This article is partly based on observations made with the Nordic Optical Telescope operated by the Nordic Optical Telescope Scientific Association and the Gran Telescopio Canarias operated on the island of La Palma by the IAC at the Spanish Observatorio del Roque de los Muchachos. This research has been supported by the Spanish MINECO grant number ESP2013-48391-C4-2-R. The Infrared Telescope Facility is operated by the University of Hawaii under contract NNH14CK55B with the National Aeronautics and Space Administration. FM acknowledges the support of the French Agence Nationale de la Recherche (ANR), under the program ANR-12-BS05-0012 Exo-atmos.
Funding AgencyGrant Number
Japan Society for Promotion of Science (JSPS)25-3183
Ministerio de Economía y Competitividad (MINECO)UNSPECIFIED
Fondo Europeo de Desarrollo Regional (FEDER)ESP2013-48391-C4-1-R
Ministerio de Economía y Competitividad (MINECO)ESP2013-48391-C4-2-R
Agence Nationale de la Recherche (ANR)ANR-12-BS05-0012 Exo-atmos
Subject Keywords:planetary systems – planets and satellites: atmospheres – planets and satellites: detection
Issue or Number:2
Record Number:CaltechAUTHORS:20170619-152701041
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Official Citation:R. Sanchis-Ojeda et al 2015 ApJ 812 112
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:78342
Deposited By: Tony Diaz
Deposited On:19 Jun 2017 22:45
Last Modified:09 Mar 2020 13:19

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