Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published July 20, 2010 | Published
Journal Article Open

The HAT-P-13 Exoplanetary System: Evidence for Spin-Orbit Alignment and a Third Companion

Abstract

We present new radial velocity (RV) measurements of HAT-P-13, a star with two previously known companions: a transiting giant planet "b" with an orbital period of 3 days and a more massive object "c" on a 1.2 yr, highly eccentric orbit. For this system, dynamical considerations would lead to constraints on planet b's interior structure, if it could be shown that the orbits are coplanar and apsidally locked. By modeling the Rossiter-McLaughlin effect, we show that planet b's orbital angular momentum vector and the stellar spin vector are well aligned on the sky (λ = 1.9 ± 8.6 deg). The refined orbital solution favors a slightly eccentric orbit for planet b (e = 0.0133 ± 0.0041), although it is not clear whether it is apsidally locked with c's orbit (Δω = 36^(+27)_( –36) deg). We find a long-term trend in the star's RV and interpret it as evidence for an additional body "d," which may be another planet or a low-mass star. Predictions are given for the next few inferior conjunctions of c, when transits may happen.

Additional Information

© 2010 The American Astronomical Society. Received 2010 March 23; accepted 2010 May 28; published 2010 July 1. We thank Dan Fabrycky for helpful conversations, especially about the dynamical implications of our results. We also thank Debra Fischer and John Brewer for investigating the spectroscopic determination of the stellar rotation rate. We are grateful to Scott Gaudi and Greg Laughlin for comments on the manuscript. J.N.W. gratefully acknowledges support from the NASA Origins program through award NNX09AD36G and the MIT Class of 1942. A.W.H. acknowledges a Townes Postdoctoral Fellowship from the Space Sciences Laboratory at UC Berkeley. G.A.B. was supported by NASA grant NNX08AF23G and an NSF Astronomy & Astrophysics Postdoctoral Fellowship (AST-0702843). G.T. acknowledges partial support from NASA grant NNX09AF59G. S.A. acknowledges the support of the Netherlands Organisation for Scientific Research (NWO). N.N. was supported by a Japan Society for Promotion of Science (JSPS) Fellowship for Research (PD: 20-8141). J.N.W. and N.N. were also supported in part by the National Science Foundation under Grant No. NSF PHY05-51164 (KITP program "The Theory and Observation of Exoplanets" at UCSB). 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 the National Aeronautics and Space Administration, and was made possible by the generous financial support of the W. M. Keck Foundation. 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. Facilities: Keck:I (HIRES)

Attached Files

Published - Winn2010p11066Astrophys_J.pdf

Files

Winn2010p11066Astrophys_J.pdf
Files (839.0 kB)
Name Size Download all
md5:4516ca87718c30f957c61e4d7a206d1b
839.0 kB Preview Download

Additional details

Created:
August 22, 2023
Modified:
October 20, 2023