Observational study of sunspot oscillations in Stokes I, Q, U, and V

Time series of 2-dimensional spectro-polarmetric data were obtained with th e intent of studying the temporal behavior of velocity, magnetic flux, and characteristics of the Stokes V profile in a small region of a larger sunsp ot. Full Stokes profiles in I, Q, U, and V were obtained. Velocity oscillat ions were found at frequencies of 3.3 mHz in each of the profiles. Acoustic power maps indicate that locations of highest power correspond to areas in which the polarization signal was greatest, therefore no conclusion about the type of wave mode participating in the oscillations can be made. Veloci ty amplitudes were I: 71 m s(-1), Q: 47 m s(-1), U: 65 m s(-1) and V: 86 m s(-1). Oscillatory behavior was also detected in longitudinal field strengt h, with an r.m.s. amplitude of 22 G, at 2.6 and 3.3 mHz. The power was loca lized at the umbral/penumbral boundary. A phase analysis indicates a -130 d egrees phase difference with Stokes V velocity oscillations at 3.3 mHz and a 75 degrees difference at 2.6 mHz. Results are consistent with magnetic fi eld lines swaying in response to a p-mode driver. No oscillatory behavior w as seen in Stokes V asymmetry or amplitude splitting.