We present a detailed and unique mass budget for the high-surface-brightness galaxy UGC 463 , showing it is dominated by dark matter ( DM ) at radii beyond one scale length ( h _ { R } ) and has a baryonic-to-DM mass ratio of approximately 1:3 within 4.2 h _ { R } .
Assuming a constant scale height ( h _ { z } , calculated via an empirical oblateness relation ) , we calculate dynamical disk mass surface densities from stellar kinematics , which provide vertical velocity dispersions after correcting for the shape of the stellar velocity ellipsoid ( measured to have \sigma _ { \theta } / \sigma _ { R } = 1.04 \pm 0.22 and \sigma _ { z } / \sigma _ { R } = 0.48 \pm 0.09 ) .
We isolate the stellar mass surface density by accounting for all gas mass components and find an average K -band mass-to-light ratio of 0.22 \pm 0.09 ( ran ) ~ { } ^ { +0.16 } _ { -0.15 } ( sys ) ~ { } \mathcal { M } _ { \odot } / \mathcal { L } _ { % \odot } ^ { K } ; Zibetti et al . and Bell et al . predict , respectively , 0.56 and 3.6 times our dynamical value based on stellar-population-synthesis modeling .
The baryonic matter is submaximal by a factor of \sim 3 in mass and the baryonic-to-total circular-speed ratio is 0.61 ^ { +0.07 } _ { -0.09 } ( ran ) ~ { } ^ { +0.12 } _ { -0.18 } ( sys ) at 2.2 h _ { R } ; however , the disk is globally stable with a multi-component stability that decreases asymptotically with radius to Q \sim 2 .
We directly calculate the circular speed of the DM halo by subtracting the baryonic contribution to the total circular speed ; the result is equally well described by either a Navarro-Frenk-White halo or a pseudo-isothermal sphere .
The volume density is dominated by DM at heights of |z| \gtrsim 1.6 h _ { z } for radii of R \gtrsim h _ { R } .
As is shown in follow-up papers , UGC 463 is just one example among nearly all galaxies we have observed that contradict the hypothesis that high-surface-brightness spiral galaxies have maximal disks .