Chromospheric Activity of HAT-P-11: An Unusually Active Planet-hosting K Star
Abstract
Kepler photometry of the hot Neptune host star HAT-P-11 suggests that its spot latitude distribution is comparable to the Sun's near solar maximum. We search for evidence of an activity cycle in the Ca ii H & K chromospheric emission S-index with archival Keck/HIRES spectra and observations from the echelle spectrograph on the Astrophysical Research Consortium 3.5 m Telescope at Apache Point Observatory. The chromospheric emission of HAT-P-11 is consistent with an ≳ 10 year activity cycle, which plateaued near maximum during the Kepler mission. In the cycle that we observed, the star seemed to spend more time near active maximum than minimum. We compare the log R_(HK)^′ normalized chromospheric emission index of HAT-P-11 with other stars. HAT-P-11 has unusually strong chromospheric emission compared to planet-hosting stars of similar effective temperature and rotation period, perhaps due to tides raised by its planet.
Additional Information
© 2017 American Astronomical Society. Received 2017 August 4 Accepted 2017 September 12 Published 2017 October 12 We gratefully acknowledge support from NSF grant AST-1312453. We thank Lauren Weiss, John Lurie, and Daniel Foreman-Mackey for helpful discussions. J.R.A.D. is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-1501418. Work by B.T.M. was performed under contract with the California Institute of Technology (Caltech)/Jet Propulsion Laboratory (JPL) funded by NASA through the Sagan Fellowship Program executed by the NASA Exoplanet Science Institute. C.M.S. acknowledges funding from the Kenilworth Fund of the New York Community Trust. Based on observations obtained with the Apache Point Observatory 3.5 m telescope, which is owned and operated by the Astrophysical Research Consortium. IRAF is distributed by the National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation. Some of 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. 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. Facilities: KeckI:HIRES - , APO/ARC - , Kepler. - Software: ipython (Perez & Granger 2007), numpy (Van Der Walt et al. 2011), scipy (Jones et al. 2001), matplotlib (Hunter 2007), astropy (Astropy Collaboration et al. 2013), forecaster (Chen & Kipping 2017).Attached Files
Published - Morris_2017_ApJ_848_58.pdf
Submitted - 1709.03913.pdf
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Additional details
- Eprint ID
- 82343
- Resolver ID
- CaltechAUTHORS:20171013-110255346
- AST-1312453
- NSF
- AST-1501418
- NSF
- NASA/JPL/Caltech
- New York Community Trust Kenilworth Fund
- W.M. Keck Foundation
- Created
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2017-10-16Created from EPrint's datestamp field
- Updated
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2021-11-15Created from EPrint's last_modified field
- Caltech groups
- Astronomy Department