We present new spectroscopic and photometric observations of the transiting exoplanetary system WASP-3 .
Spectra obtained during two separate transits exhibit the Rossiter-McLaughlin ( RM ) effect and allow us to estimate the sky-projected angle between the planetary orbital axis and the stellar rotation axis , \lambda = 3.3 ^ { +2.5 } _ { -4.4 } degrees .
This alignment between the axes suggests that WASP-3b has a low orbital inclination relative to the equatorial plane of its parent star .
During our first night of spectroscopic measurements , we observed an unexpected redshift briefly exceeding the expected sum of the orbital and RM velocities by 140 m s ^ { -1 } .
This anomaly could represent the occultation of material erupting from the stellar photosphere , although it is more likely to be an artifact caused by moonlight scattered into the spectrograph .