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Confirmation of the Long-period Planet Orbiting Gliese 411 and the Detection of a New Planet Candidate

Hurt, Spencer A. and Fulton, Benjamin and Isaacson, Howard and Rosenthal, Lee J. and Howard, Andrew W. and Weiss, Lauren M. and Petigura, Erik A. (2022) Confirmation of the Long-period Planet Orbiting Gliese 411 and the Detection of a New Planet Candidate. Astronomical Journal, 163 (5). Art. No. 218. ISSN 1538-3881. doi:10.3847/1538-3881/ac5c47.

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We perform a detailed characterization of the planetary system orbiting the bright, nearby M dwarf Gliese 411 using radial velocities gathered by APF, HIRES, SOPHIE, and CARMENES. We confirm the presence of a signal with a period near 2900 days that has been disputed as either a planet or a long-period stellar magnetic cycle. An analysis of activity metrics including the Hα and log′R_(HK) indices supports the interpretation that the signal corresponds to a Neptune-like planet, GJ 411 c. An additional signal near 215 days was previously dismissed as an instrumental systematic, but we find that a planetary origin cannot be ruled out. With a semimajor axis of 0.5142 ± 0.0042 au, this candidate's orbit falls between those of its companions and is located beyond the outer edge of the system's habitable zone (determined using the moist greenhouse and maximum greenhouse limits in Kopparapu et al. 2013). It has a minimum mass of 3.89 ± 0.84 M⊕, giving a radial-velocity amplitude of 0.81 ± 0.18 m s⁻¹. If confirmed, this would be one of the lowest-amplitude planet detections from any of these four instruments. Our analysis of the joint radial-velocity data set also provides tighter constraints on the orbital parameters for the previously known planets. Photometric data from TESS do not show any signs of a transit event. However, the outermost planet and candidate are prime targets for future direct imaging missions, and GJ 411 c may be detectable via astrometry.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Hurt, Spencer A.0000-0002-6903-9080
Fulton, Benjamin0000-0003-3504-5316
Isaacson, Howard0000-0002-0531-1073
Rosenthal, Lee J.0000-0001-8391-5182
Howard, Andrew W.0000-0001-8638-0320
Weiss, Lauren M.0000-0002-3725-3058
Petigura, Erik A.0000-0003-0967-2893
Additional Information:© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2021 July 16; revised 2022 February 18; accepted 2022 March 4; published 2022 April 19. We thank Michael Meyer for feedback and insight into determining a planet's detectability in the infrared. 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 use of the SIMBAD database (operated at CDS, Strasbourg, France), NASA's Astrophysics Data System Bibliographic Services. This research has made use of the VizieR catalog access tool, CDS, Strasbourg, France (doi: 10.26093/cds/vizier). The original description of the VizieR service was published in A&AS 143, 23. This work has made use of data from the European Space Agency (ESA) mission Gaia (, processed by the Gaia Data Processing and Analysis Consortium (DPAC, Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. L.M.W. is supported by the Beatrice Watson Parrent Fellowship and NASA ADAP Grant 80NSSC19K0597. We are very grateful for the donations of the Levy family that helped facilitate the construction of the Levy spectrograph on the APF. Without their support, the APF would not be contributing to the discovery of planets like these. Research at the Lick Observatory is partially supported by a generous gift from Google. We are grateful to the time assignment committees of the University of Hawaii, the University of California, and NASA for their generous allocations of observing time. Without their long-term commitment to RV monitoring, these planets would likely remain unknown. We acknowledge R. Paul Butler and S. S. Vogt for many years of contributing to the data presented here. Finally, the authors wish to 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. Software: astropy (Astropy Collaboration et al. 2018), emcee (Foreman-Mackey et al. 2013), exoplanet (Foreman-Mackey et al. 2021), matplotlib (Hunter 2007), numpy (Harris et al. 2020), RadVel (Fulton et al. 2018), RVSearch (Rosenthal et al. 2021).
Group:Astronomy Department
Funding AgencyGrant Number
Gaia Multilateral AgreementUNSPECIFIED
Subject Keywords:Exoplanets; Exoplanet detection methods; Radial velocity; Stellar activity
Issue or Number:5
Classification Code:Unified Astronomy Thesaurus concepts: Exoplanets (498); Exoplanet detection methods (489); Radial velocity (1332); Stellar activity (1580)
Record Number:CaltechAUTHORS:20211006-174848355
Persistent URL:
Official Citation:Spencer A. Hurt et al 2022 AJ 163 218
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:111247
Deposited By: Tony Diaz
Deposited On:06 Oct 2021 17:56
Last Modified:25 Apr 2022 18:00

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