Two Planets Straddling the Habitable Zone of the Nearby K Dwarf Gl 414A

Creators: Dedrick, Cayla M.; Fulton, Benjamin J.; Knutson, Heather A.; Howard, Andrew W.; Beatty, Thomas G.; Cargile, Phillip A.; Gaudi, B. Scott; Hirsch, Lea A.; Kuhn, Rudolf B.; Lund, Michael B.; James, David J.; Kosiarek, Molly R.; Pepper, Joshua; Petigura, Erik A.; Rodriguez, Joseph E.; Stassun, Keivan G.; Stevens, Daniel J.

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Abstract

We present the discovery of two planets orbiting the nearby (D = 11.9 pc) K7 dwarf Gl 414A. Gl 414A b is a sub-Neptune mass planet with M_b sin i_b = 7.60^(+2.44)_(-2.19) M_⊕ and a semimajor axis of 0.23 ± 0.01 au. Gl 414A c is a sub-Saturn mass planet with M_c sin i_c = 53.83^(+9.18)_(-8.58) M_⊕ and a semimajor axis of 1.43 ± 0.06 au. We jointly analyzed radial velocity data from Keck/HIRES and the Automated Planet Finder at Lick Observatory, as well as photometric data from KELT, to detect the two planets and two additional signals related to the rotationally modulated activity and the long-term magnetic activity cycle of the star. The outer planet in this system may be a potential candidate for future direct-imaging missions.

Additional Information

© 2021 The American Astronomical Society. Received 2020 September 11; revised 2020 November 25; accepted 2020 November 27; published 2021 January 28. We are grateful to the time assignment committees of the California Institute of Technology, the University of California, the University of Hawaii, and NASA for their generous allocations of observing time. Without their long-term commitment to RV monitoring, these planets would likely remain unknown. We gratefully acknowledge the efforts and dedication of the staffs of the W. M. Keck Observatory and Mt. Hamilton. Research at the Lick Observatory is partially supported by a generous gift from Google. We thank Geoff Marcy and Debra Fischer for their many nights of observing that contributed to the Keck data presented in this work, and R. Paul Butler and S. S. Vogt for many years of contributing to the data presented here. C.M.D. acknowledges the Caltech Summer Undergraduate Research Fellowship program along with partial support from the family of Samuel P. and Frances Krown. A.W.H. acknowledges NSF grant AST-1517655. M.R.K. acknowledges support from the NSF Graduate Research Fellowship, grant No. DGE 1339067. D.J.S. was supported as an Eberly Research Fellow by the Eberly College of Science at the Pennsylvania State University. The authors extend special thanks to those of Hawaiian ancestry on whose sacred mountain of Maunakea we are privileged to be guests. Without their generous hospitality, the Keck observations presented herein would not have been possible. This work made use of the GNU Parallel package for large-scale multiprocessing (Tange 2011). This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. This work made extensive use of the scipy (Virtanen et al. 2020), numpy (van der Walt et al. 2011), matplotlib (Hunter 2007), and pandas (McKinney 2010) Python packages. Simulations in this paper made use of the REBOUND code which is freely available at http://github.com/hannorein/rebound. Facilities: Automated Planet Finder (Levy) - , Keck:I (HIRES) - , KELT - , Exoplanet Archive. - Software: SpecMatch-Emp (Yee et al. 2017), isoclassify (Berger et al. 2020; Huber et al. 2017), MIST (Dotter 2016; Choi et al. 2016), MINESweeper (Cargile et al. 2020), ATLAS12 (Kurucz 1970), SYNTHE (Kurucz 1993), dynesty (Speagle 2019), RadVel (v1.2.13; Fulton et al. 2018), emcee (Foreman-Mackey et al. 2013), Forecaster (Chen & Kipping 2017), REBOUND (Rein & Liu 2012; Rein & Tamayo 2015), Astropy (Astropy Collaboration et al. 2013, 2018), scipy (Virtanen et al. 2020), numpy (van der Walt et al. 2011), matplotlib (Hunter 2007), pandas (McKinney 2010).

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