Tuesday, June 26, 2012

1206.5579 (Rebekah I. Dawson et al.)

The Photoeccentric Effect and Proto Hot Jupiters II. KOI-1474.01, an eccentric planet perturbed by an unseen companion    [PDF]

Rebekah I. Dawson, John Asher Johnson, Timothy D. Morton, Justin R. Crepp, Daniel C. Fabrycky, Ruth A. Murray-Clay, Andrew W. Howard
The exoplanets known as hot Jupiters---Jupiter-sized planets with periods less than 10 days---likely are relics of dynamical processes that shape all planetary system architectures. Socrates et al. (2012) 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 Keplerphotometry, ground-based spectroscopy, and stellar evolution models, we characterize host KOI-1474 as a rapidly-rotating F-star. Statistical arguments allow us to validate the transiting planet. KOI-1474.01 also exhibits transit timing variations of order an hour. We explore characteristics of the third-body perturber, which is possibly the "smoking-gun" cause of KOI-1474.01's large eccentricity. Using the host-star's rotation period, radius, and projected rotational velocity, we find KOI-1474.01's orbit is marginally consistent with 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.
View original: http://arxiv.org/abs/1206.5579

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