The Kepler Follow-up Observation Program. II. Stellar Parameters from Medium- and High-resolution Spectroscopy

Creators: Furlan, E.; Ciardi, D. R.; Cochran, W. D.; Everett, M. E.; Latham, D. W.; Marcy, G. W.; Buchhave, L. A.; Endl, M.; Isaacson, H.; Petigura, E. A.; Gautier, T. N., III; Huber, D.; Bieryla, A.; Borucki, W. J.; Brugamyer, E.; Caldwell, C.; Cochran, A.; Howard, A. W.; Howell, S. B.; Johnson, M. C.; MacQueen, P. J.; Quinn, S. N.; Robertson, P.; Mathur, S.; Batalha, N. M.

Abstract

We present results from spectroscopic follow-up observations of stars identified in the Kepler field and carried out by teams of the Kepler Follow-up Observation Program. Two samples of stars were observed over 6 yr (2009–2015): 614 standard stars (divided into "platinum" and "gold" categories) selected based on their asteroseismic detections and 2667 host stars of Kepler Objects of Interest (KOIs), most of them planet candidates. Four data analysis pipelines were used to derive stellar parameters for the observed stars. We compare the T eff, log(g), and [Fe/H] values derived for the same stars by different pipelines; from the average of the standard deviations of the differences in these parameter values, we derive error floors of ~100 K, 0.2 dex, and 0.1 dex for T eff, log(g), and [Fe/H], respectively. Noticeable disagreements are seen mostly at the largest and smallest parameter values (e.g., in the giant star regime). Most of the log(g) values derived from spectra for the platinum stars agree on average within 0.025 dex (but with a spread of 0.1–0.2 dex) with the asteroseismic log(g) values. Compared to the Kepler Input Catalog (KIC), the spectroscopically derived stellar parameters agree within the uncertainties of the KIC but are more precise and thus an important contribution toward deriving more reliable planetary radii.

Additional Information

© 2018. The American Astronomical Society. Received 2017 November 17; revised 2018 May 24; accepted 2018 May 28; published 2018 July 16. Support for this work was provided by NASA through awards issued by JPL/Caltech. ME acknowledges support by NASA under grant NNX14AB86G issued through the Kepler Participating Scientist Program. AWH acknowledges NASA grant NNX12AJ23G. DH acknowledges support by the Australian Research Council's Discovery Projects funding scheme (project number DE140101364). DH and SM acknowledge support by NASA under grant NNX14AB92G issued through the Kepler Participating Scientist Program. SM acknowledges support from the Ramon y Cajal fellowship number RYC-2015-17697. We thank Ivan Ramirez for contributing to the observations carried out at the McDonald Observatory. This research has made use of the NASA Exoplanet Archive and the Exoplanet Follow-up Observation Program website, which are operated by the California Institute of Technology, under contract with NASA under the Exoplanet Exploration Program. It has also made use of NASA's Astrophysics Data System Bibliographic Services. Some of the data presented in this work 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. 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. This work is also based in part on observations at Kitt Peak National Observatory, National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. It also includes data taken at the McDonald Observatory of the University of Texas at Austin. Some of the data were obtained from the Mikulski Archive for Space Telescopes (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.

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