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A Wide Planetary Mass Companion Discovered through the Citizen Science Project Backyard Worlds: Planet 9

Faherty, Jacqueline K. and Gagné, Jonathan and Popinchalk, Mark and Vos, Johanna M. and Burgasser, Adam J. and Schümann, Jörg and Schneider, Adam C. and Kirkpatrick, J. Davy and Meisner, Aaron M. and Kuchner, Marc J. and Bardalez Gagliuffi, Daniella C. and Marocco, Federico and Caselden, Dan and Gonzales, Eileen C. and Rothermich, Austin and Casewell, Sarah L. and Debes, John H. and Aganze, Christian and Ayala, Andrew and Hsu, Chih-Chun and Cooper, William J. and Smart, R. L. and Gerasimov, Roman and Theissen, Christopher A. (2021) A Wide Planetary Mass Companion Discovered through the Citizen Science Project Backyard Worlds: Planet 9. Astrophysical Journal, 923 (1). Art. No. 48. ISSN 0004-637X. doi:10.3847/1538-4357/ac2499.

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Through the Backyard Worlds: Planet 9 citizen science project we discovered a late-type L dwarf co-moving with the young K0 star BD+60 1417 at a projected separation of 37″ or 1662 au. The secondary—CWISER J124332.12+600126.2 (W1243)—is detected in both the CatWISE2020 and 2MASS reject tables. The photometric distance and CatWISE proper motion both match that of the primary within ∼1σ and our estimates for a chance alignment yield a zero probability. Follow-up near-infrared spectroscopy reveals W1243 to be a very red 2MASS (J–K_s = 2.72), low surface gravity source that we classify as L6–L8γ. Its spectral morphology strongly resembles that of confirmed late-type L dwarfs in 10–150 Myr moving groups as well as that of planetary mass companions. The position on near- and mid-infrared color–magnitude diagrams indicates the source is redder and fainter than the field sequence, a telltale sign of an object with thick clouds and a complex atmosphere. For the primary we obtained new optical spectroscopy and analyzed all available literature information for youth indicators. We conclude that the Li i abundance, its loci on color–magnitude and color–color diagrams, and the rotation rate revealed in multiple TESS sectors are all consistent with an age of 50–150 Myr. Using our re-evaluated age of the primary and the Gaia parallax, along with the photometry and spectrum for W1243, we find T_(eff) = 1303 ± 31 K, log g = 4.3 ± 0.17 cm s⁻², and a mass of 15 ± 5 M_(Jup). We find a physical separation of ∼1662 au and a mass ratio of ∼0.01 for this system. Placing it in the context of the diverse collection of binary stars, brown dwarfs, and planetary companions, the BD+60 1417 system falls in a sparsely sampled area where the formation pathway is difficult to assess.

Item Type:Article
Related URLs:
URLURL TypeDescription
Faherty, Jacqueline K.0000-0001-6251-0573
Gagné, Jonathan0000-0002-2592-9612
Popinchalk, Mark0000-0001-9482-7794
Vos, Johanna M.0000-0003-0489-1528
Burgasser, Adam J.0000-0002-6523-9536
Schümann, Jörg0000-0002-7587-7195
Schneider, Adam C.0000-0002-6294-5937
Kirkpatrick, J. Davy0000-0003-4269-260X
Meisner, Aaron M.0000-0002-1125-7384
Kuchner, Marc J.0000-0002-2387-5489
Bardalez Gagliuffi, Daniella C.0000-0001-8170-7072
Marocco, Federico0000-0001-7519-1700
Caselden, Dan0000-0001-7896-5791
Gonzales, Eileen C.0000-0003-4636-6676
Rothermich, Austin0000-0003-4083-9962
Casewell, Sarah L.0000-0003-2478-0120
Debes, John H.0000-0002-1783-8817
Aganze, Christian0000-0003-2094-9128
Hsu, Chih-Chun0000-0002-5370-7494
Cooper, William J.0000-0003-3501-8967
Smart, R. L.0000-0002-4424-4766
Gerasimov, Roman0000-0003-0398-639X
Theissen, Christopher A.0000-0002-9807-5435
Additional Information:© 2021. The American Astronomical Society. Received 2021 June 15; revised 2021 August 3; accepted 2021 August 12; published 2021 December 9. The Backyard Worlds: Planet 9 team would like to thank the many Zooniverse volunteers who have participated in this project, from providing feedback during the beta review stage, to classifying flipbooks, to contributing to the discussions on TALK. We would also like to thank the Zooniverse web development team for their work creating and maintaining the Zooniverse platform and the Project Builder tools. This research was supported by NASA Astrophysics Data Analysis Program grant NNH17AE75I as well as NASA grant 2017-ADAP17-0067, and National Science Foundation grant Nos. 2007068, 2009136, and 2009177. F.M. also acknowledges support from grant 80NSSC20K0452 under the NASA Astrophysics Data Analysis Program. E.G. and J.F. acknowledge support from the Heising-Simons Foundation. This research has made use of: the Washington Double Star Catalog maintained at the U.S. Naval Observatory; the SIMBAD database and VizieR catalog access tool, operated at the Centre de Donnees astronomiques de Strasbourg, France (Ochsenbein et al. 2000); data products from the Two Micron All Sky Survey (2MASS; Skrutskie et al. 2006), which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center (IPAC)/California Institute of Technology (Caltech), funded by the National Aeronautics and Space Administration (NASA) and the National Science Foundation; data products from the Wide-field Infrared Survey Explorer (WISE; and Wright et al. 2010), which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory (JPL)/Caltech, funded by NASA. This work has made use of data from the European Space Agency(ESA) mission Gaia, processed by the Gaia Data Processing and Analysis Consortium. Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. 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. Facilities: Gaia - , NASA IRTF - , LICK Shane - , WISE - , 2MASS. - Software: Aladin, BANYAN Σ (Gagné et al. 2018b), Lightkurve, SEDkit, WISEview.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Heising-Simons Foundation51 Pegasi b Fellowship
Gaia Multilateral AgreementUNSPECIFIED
Subject Keywords:Brown dwarfs; L dwarfs; Direct imaging; Young star clusters; Astrometry; Companion stars; Substellar companion stars
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Brown dwarfs (185); L dwarfs (894); Direct imaging (387); Young star clusters (1833); Astrometry (80); Companion stars (291); Substellar companion stars (1648)
Record Number:CaltechAUTHORS:20211209-456457000
Persistent URL:
Official Citation:Jacqueline K. Faherty et al 2021 ApJ 923 48
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:112329
Deposited By: George Porter
Deposited On:10 Dec 2021 19:58
Last Modified:10 Dec 2021 19:58

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