We present Atacama Large Millimeter/submillimeter Array ( ALMA ) observations of GSC 6214-210 A and B , a solar-mass member of the 5–10 Myr Upper Scorpius association with a 15 \pm 2 M _ { \mathrm { Jup } } companion orbiting at \approx 330 AU ( 2 \farcs 2 ) .
Previous photometry and spectroscopy spanning 0.3–5 \mu m revealed optical and thermal excess as well as strong H \alpha and Pa \beta emission originating from a circum-substellar accretion disk around GSC 6214-210 B , making it the lowest mass companion with unambiguous evidence of a subdisk .
Despite ALMA ’ s unprecedented sensitivity and angular resolution , neither component was detected in our 880 \mu m ( 341 GHz ) continuum observations down to a 3- \sigma limit of 0.22 mJy/beam .
The corresponding constraints on the dust mass and total mass are < 0.15 M _ { \earth } and < 0.05 M _ { \mathrm { Jup } } , respectively , or < 0.003 % and < 0.3 % of the mass of GSC 6214-210 B itself assuming a 100:1 gas-to-dust ratio and characteristic dust temperature of 10–20 K. If the host star possesses a putative circum-stellar disk then at most it is a meager 0.0015 % of the primary mass , implying that giant planet formation has certainly ceased in this system .
Considering these limits and its current accretion rate , GSC 6214-210 B appears to be at the end stages of assembly and is not expected to gain any appreciable mass over the next few Myr .