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tokens: converged when the emcee walkers had reached a steady state with measured best-fit values changing minimally over a large number of steps. 3. Results Figure 1 shows the 1.3 mm dust continuum, the 12 CO (2–1) integrated intensity map (moment 0), and the intensity-weighted velocity map (moment 1) of the FW Tau C disk. Similar to Kraus et al. ( 2015 ) and Caceres et al. ( 2015 ), no signal is found from the close binary FW Tau AB, and the 3 σ upper limit for a unresolved source suggests a dust mass ≲0.07 M ⊕ . It is known that close binaries can shorten disk lifetimes (e.g., Cieza et al. 2009 ), so the disk around FW Tau AB may be depleted already. For the companion FW Tau C, its dust disk is compact and likely unresolved; in contrast, the gas disk is more extended and clearly shows a Keplerian rotation. Figure 2 is the position–velocity diagram constructed along the major axis of the gas disk. On top of the PV diagram we also plot the Keplerian rotation curves for 10 M Jup and 0.1 M objects. It is clear that the velocity profile of the FW Tau C disk is incompatible with the 10 M Jup rotation curve, but more consistent with that of a 0.1 M star. Our disk modeling (see Figure 3 and Table 2 ) also indicates that FW Tau C’s mass is ∼0.1 M , about 10 times higher than the 10 M Jup suggested by Kraus et al. ( 2014 ). Hence, FW Tau C is not a planetary-mass object, but is rather a low-mass star with an inclined disk, as suggested by Bowler et al. ( 2014 ). The high mass of FW Tau C is also in agreement with some features in its spectrum that closely resemble T Tauri stars (Bowler et al. 2014 ). Our observations therefore suggest that FW Tau is a young triple system in which each of the stars has a mass of ∼0.1 M . Figure 2. Position–velocity diagram constructed along the major axis of the FW Tau C disk. Keplerian rotation curves for a 0.01 M (∼10 M Jup ) planet and a 0.1 M star are also plotted. FW Tau C is more consistent with a 0.1 M star. Figure 3. We show our CO (2–1) channel maps (top) as well as the best-fit Keplerian disk model synthetic channel maps (center) and the residual channel maps (bottom). The model channel maps are made by sampling the model at the same baselines as the data and Fourier transforming to produce images. The residual channel maps are produced by subtracting the model visibilities from the visibility data and Fourier transforming to produce maps. The contours start at 3 σ = 13.5 mJy beam −1 and are at intervals of 3 σ . Table 2 FW Tau C Disk Properties Searches for accretion disks in millimeter around directly imaged planet-mass companions have not yielded positive results (e.g., Isella et al. 2014 ; Bowler et al. 2015 ; MacGregor et al. 2017 ; Ricci et al. 2017 ; Wolff et al. 2017 ; Wu et al. 2017 ), although the disk around the free-floating planet OTS 44 has recently been imaged (Bayo et al. 2017 ). Current flux upper limits imply that these wide companion disks might have 0.1 M ⊕ of dust, which in turn could imply a