On the Spin-Orbit Misalignment of the XO-3 Exoplanetary System

Understand

We present photometric and spectroscopic observations of the 2009 Feb.

• 2 transit of the exoplanet XO-3b.
• The new data show that the planetary orbital axis and stellar rotation axis are misaligned, as reported earlier by Hebrard and coworkers.
• We find the angle between the sky projections of the two axes to be 37.3 +/- 3.7 deg, as compared to the previously reported value of 70 +/- 15 deg.