The HAT-P-13 Exoplanetary System: Evidence for Spin-Orbit Alignment and a Third Companion
Author(s)
Winn, Joshua Nathan
Johnson, John Asher
Howard, Andrew W.
Marcy, Geoffrey W.
Bakos, Gaspar A.
Hartman, Joel D.
Torres, Guillermo
Albrecht, Simon H.
Narita, Norio
Date Issued
July 2010
Journal
Astrophysical Journal
Publisher
Institute of Physics
Citation
Winn, Joshua N. et al. "The HAT-P-13 Exoplanetary System: Evidence for Spin-Orbit Alignment and a Third Companion." 2010 ApJ 718.1 575-582
Version
Author's final manuscript
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 ([lambda] = 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 ([DELTA][omega]= 36[superscript +27] [subscript –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.
MIT Department
Massachusetts Institute of Technology. Department of Physics
MIT Kavli Institute for Astrophysics and Space Research
Terms of Use
Creative Commons Attribution-Noncommercial-Share Alike 3.0
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1088/0004-637x/718/1/575
