The Photoeccentric Effect and Proto-hot Jupiters. II. KOI-1474.01, a Candidate Eccentric Planet Perturbed by an Unseen Companion

Creators: Dawson, Rebekah I.; Johnson, John Asher; Morton, Timothy D.; Crepp, Justin R.; Fabrycky, Daniel C.; Murray-Clay, Ruth A.; Howard, Andrew W.

Abstract

The exoplanets known as hot Jupiters—Jupiter-sized planets with periods of less than 10 days—likely are relics of dynamical processes that shape all planetary system architectures. Socrates et al. argued that high eccentricity migration (HEM) mechanisms proposed for situating these close-in planets should produce an observable population of highly eccentric proto-hot Jupiters that have not yet tidally circularized. HEM should also create failed-hot Jupiters, with periapses just beyond the influence of fast circularization. Using the technique we previously presented for measuring eccentricities from photometry (the "photoeccentric effect"), we are distilling a collection of eccentric proto- and failed-hot Jupiters from the Kepler Objects of Interest (KOI). Here, we present the first, KOI-1474.01, which has a long orbital period (69.7340 days) and a large eccentricity e = 0.81^(+0.10)_(–0.07), skirting the proto-hot Jupiter boundary. Combining Kepler photometry, ground-based spectroscopy, and stellar evolution models, we characterize host KOI-1474 as a rapidly rotating F star. Statistical arguments reveal that the transiting candidate has a low false-positive probability of 3.1%. KOI-1474.01 also exhibits transit-timing variations of the order of an hour. We explore characteristics of the third-body perturber, which is possibly the "smoking-gun" cause of KOI-1474.01's large eccentricity. We use the host star's period, radius, and projected rotational velocity to measure the inclination of the stellar spin. Comparing KOI 1474.01's inclination, we find that its orbit is marginally consistent with being aligned with the stellar spin axis, although a reanalysis is warranted with future additional data. Finally, we discuss how the number and existence of proto-hot Jupiters will not only demonstrate that hot Jupiters migrate via HEM, but also shed light on the typical timescale for the mechanism.

Additional Information

© 2012 American Astronomical Society. Received 2012 July 3; accepted 2012 October 13; published 2012 December 5. We thank the anonymous reviewer for the helpful and timely report. R.I.D. gratefully acknowledges support by the National Science Foundation Graduate Research Fellowship under grant DGE-1144152. J.A.J. acknowledges support from the Alfred P. Sloan Foundation. D.C.F. (not to be confused with the DCF) is supported by NASA Hubble Fellowship HF-51272.01. A.W.H. acknowledges support from NASA Origins of Solar Systems grant NNX12AJ23G. We thank Zachary Berta, Joshua Carter, Courtney Dressing, Emily Fabrycky, Jonathan Irwin, Scott Kenyon, David Kipping, Maxwell Moe, Norman Murray, Smadar Naoz, and Roberto Sanchis Ojeda for helpful comments and discussions. Special thanks to J. Zachary Gazak for helpful modifications to the TAP code. This paper includes data collected by the Kepler mission. Funding for the Kepler mission is provided by the NASA Science Mission directorate. Some of the data presented in this paper were obtained from the Multimission Archive at the Space Telescope Science Institute (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Support for MAST for non- HST data is provided by the NASA Office of Space Science via grant NNX09AF08G and by other grants and contracts. This research has made use of the Exoplanet Orbit Database and the Exoplanet Data Explorer, as well the SIMBAD database, operated at CDS, Strasbourg, France.

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