Chromospheric Activity of HAT-P-11: An Unusually Active Planet-hosting K Star

Journal Article · Tue Oct 10 04:00:00 EDT 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/AA8CCA· OSTI ID:22875684

Morris, Brett M.; Hawley, Suzanne L.; Sakari, Charli; Agol, Eric ^[1]; Hebb, Leslie ^[2]; Davenport, James R. A. ^[3]; Isaacson, Howard ^[4]; Howard, Andrew W. ^[5]

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1. Astronomy Department, University of Washington, Seattle, WA 98195 (United States)
2. Physics Department, Hobart and William Smith Colleges, Geneva, NY 14456 (United States)
3. Department of Physics and Astronomy, Western Washington University, 516 High Street, Bellingham, WA 98225 (United States)
4. Department of Astronomy, UC Berkeley, Berkeley, CA 94720 (United States)
5. Department of Astrophysics, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States)

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 and 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 logR{sub HK}{sup ′} 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.

• OSTI ID: 22875684
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 848; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ASTROPHYSICS
COMPARATIVE EVALUATIONS
DISTRIBUTION
EMISSION
INTERACTIONS
PHOTOMETRY
ROTATION
SPECTRA
STARSPOTS
TELESCOPES