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 April 2018 | Published + Accepted Version
Journal Article Open

Validation and Initial Characterization of the Long-period Planet Kepler-1654 b

Abstract

Fewer than 20 transiting Kepler planets have periods longer than one year. Our early search of the Kepler light curves revealed one such system, Kepler-1654b (originally KIC 8410697b), which shows exactly two transit events and whose second transit occurred only five days before the failure of the second of two reaction wheels brought the primary Kepler mission to an end. A number of authors have also examined light curves from the Kepler mission searching for long-period planets and identified this candidate. Starting in 2014 September, we began an observational program of imaging, reconnaissance spectroscopy, and precision radial velocity (RV) measurements that confirm with a high degree of confidence that Kepler-1654b is a bona fide transiting planet orbiting a mature G5V star (T_(eff) = 5580 K, [Fe/H] = −0.08) with a semimajor axis of 2.03 au, a period of 1047.84 days, and a radius of 0.82 ± 0.02 R_(Jup). RV measurements using Keck's HIRES spectrometer obtained over 2.5 years set a limit to the planet's mass of <0.5 (3σ) M_(Jup). The bulk density of the planet is similar to that of Saturn or possibly lower. We assess the suitability of temperate gas giants like Kepler-1654b for transit spectroscopy with the James Webb Space Telescope, as their relatively cold equilibrium temperatures (T_(pl) ~ 200 K) make them interesting from the standpoint of exoplanet atmospheric physics. Unfortunately, these low temperatures also make the atmospheric scale heights small and thus transmission spectroscopy challenging. Finally, the long time between transits can make scheduling JWST observations difficult—as is the case with Kepler-1654b.

Additional Information

© 2018. The American Astronomical Society. Received 2017 December 27; revised 2018 January 29; accepted 2018 February 8; published 2018 March 20. Some of the research described in this publication was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. This research has made use of the NASA/IPAC Infrared Science Archive (IRSA), the Keck Observatory Archive (KOA), and the NASA Exoplanet Archive, which are operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. We used the implementation of EXOFAST available at the NASA Exoplanet Science Institute. We are grateful to an anonymous referee for a careful reading of the manuscript, which led to a number of improvements. Some data presented herein were obtained at the W. M. Keck Observatory from telescope time allocated to the National Aeronautics and Space Administration through the agency's scientific partnership with the California Institute of Technology and the University of California. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Finally, H.G. acknowledges support of a summer internship made possible by Caltech and JPL.

Attached Files

Published - Beichman_2018_AJ_155_158.pdf

Accepted Version - 1802.08945

Files

Beichman_2018_AJ_155_158.pdf
Files (2.8 MB)
Name Size Download all
md5:45d95444a0289f87bc9a138e46162e1a
1.5 MB Download
md5:d35e4710f84a94c78093c3c1621639bc
1.3 MB Preview Download

Additional details

Created:
August 21, 2023
Modified:
February 2, 2024