2026-10-17T09:29:05Zivo://CDS.VizieR/J/ApJ/923/482025-05-19T09:50:00ZJ.ApJIVOADiscovery of an L dwarf co-moving BD+60 1417Through 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 1662au. 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 ~1{sigma} 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-Ks=2.72), low surface gravity source that we classify as L6-L8{gamma}. Its spectral morphology strongly resembles that of confirmed late-type L dwarfs in 10-150Myr 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 LiI 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 50-150Myr. Using our re-evaluated age of the primary and the Gaia parallax, along with the photometry and spectrum for W1243, we find Teff=1303+/-31K, log g=4.3+/-0.17cm/s^2^, and a mass of 15+/-5MJup. We find a physical separation of ~1662au 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.brown-dwarfsl-dwarfsmultiple-starsinfrared-astronomyspectroscopyvisible-astronomyk-starsinterdisciplinary-astronomystellar-astronomyobservational-astronomyhttps://dc.g-vo.org/rr/q/lp/custom/CDS.VizieR/J/ApJ/923/48http://doi.org/10.26093/cds/vizier.19230048https://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/923/482021ApJ...923...48Fhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/923/48Faherty J.K.Gagne J.Popinchalk M.Vos J.M.Burgasser A.J.,Schumann J.Schneider A.C.Kirkpatrick J.D.Meisner A.M.Kuchner M.J.,Bardalez Gagliuffi D.C.Marocco F.Caselden D.Gonzales E.C.,Rothermich A.Casewell S.L.Debes J.H.Aganze C.Ayala A.Hsu C.-C.,Cooper W.J.Smart R.L.Gerasimov R.Theissen C.A.,The Backyard Worlds: Planet 9 CollaborationCDS2023https://cds.unistra.fr/vizier-org/licences_vizier.htmlCDS support team <cds-question@unistra.fr>DatasetAstroObjectsastronomy