Revisiting the Full Sets of Orbital Parameters for the XO-3 System: No Evidence for Temporal Variation of the Spin-Orbit Angle

We present 12 new transit light curves and 16 new out-of-transit radial-velocity measurements for the XO-3 system. By modeling our newly collected measurements together with archival photometric and Doppler velocimetric data, we confirmed the unusual configuration of the XO-3 system, which contains a massive planet (M-P = 11.92(-0.63)(+0.59) M-J) on a relatively eccentric (e = 0.2853(-0.0026)(+0.0027)) and short-period (3.19152 +/- 0.00145 day) orbit around a massive star (M-* = 1.219(-0.095)(+0.090) M-circle dot). Furthermore, we find no strong evidence for a temporal change of either V sin i(*) (and by extension, the stellar spin vector of XO-3), or the transit profile (and thus orbital angular momentum vector of XO-3b). We conclude that the discrepancy in previous Rossiter-McLaughlin measurements (70.0 degrees +/- 15.0 degrees; Hebrard et al. 2008; 37.3 degrees +/- 3.7 degrees; Winn et al. 2009; 37.3 degrees +/- 3.0 degrees; Hirano et al. 2011) may have stemmed from systematic noise sources.