%AWu, Ya-Lin%ABowler, Brendan%ASheehan, Patrick%AClose, Laird%AEisner, Joshua%ABest, William%AWard-Duong, Kimberly%AZhu, Zhaohuan%AKraus, Adam%BJournal Name: The Astrophysical Journal Letters; Journal Volume: 930; Journal Issue: 1 %D2022%I %JJournal Name: The Astrophysical Journal Letters; Journal Volume: 930; Journal Issue: 1 %K %MOSTI ID: 10339654 %PMedium: X %TALMA Discovery of a Disk around the Planetary-mass Companion SR 12 c %XAbstract We report an Atacama Large Millimeter/submillimeter Array 0.88 mm (Band 7) continuum detection of the accretion disk around SR 12 c, an ∼11 M Jup planetary-mass companion (PMC) orbiting its host binary at 980 au. This is the first submillimeter detection of a circumplanetary disk around a wide PMC. The disk has a flux density of 127 ± 14 μ Jy and is not resolved by the ∼0.″1 beam, so the dust disk radius is likely less than 5 au and can be much smaller if the dust continuum is optically thick. If, however, the dust emission is optically thin, then the SR 12 c disk has a comparable dust mass to the circumplanetary disk around PDS 70 c but is about five times lower than that of the ∼12 M Jup free-floating OTS 44. This suggests that disks around bound and unbound planetary-mass objects can span a wide range of masses. The gas mass estimated with an accretion rate of 10 −11 M ☉ yr −1 implies a gas-to-dust ratio higher than 100. If cloud absorption is not significant, a nondetection of 12 CO(3–2) implies a compact gas disk around SR 12 c. Future sensitive observations may detect more PMC disks at 0.88 mm flux densities of ≲100 μ Jy. %0Journal Article