We used the Magellan adaptive optics system to image the 11 Myr substellar companion 1RXS 1609 B at the bluest wavelengths to date ( z ^ { \prime } and Y _ { s } ) .
Comparison with synthetic spectra yields a higher temperature than previous studies of T _ { \mathrm { eff } } = 2000 \pm 100 ~ { } \mathrm { K } and significant dust extinction of A _ { V } = 4.5 ^ { +0.5 } _ { -0.7 } mag .
Mass estimates based on the DUSTY tracks gives 0.012–0.015 M _ { \sun } , making the companion likely a low-mass brown dwarf surrounded by a dusty disk .
Our study suggests that 1RXS 1609 B is one of the \sim 25 % of Upper Scorpius low-mass members harboring disks , and it may have formed like a star and not a planet out at \sim 320 AU .