Propagating low-frequency waves in coronal streamers observed by STEREO COR1

Compressional and transverse propagating waves high above the solar surface may play an important role in heating and accelerating the solar wind. Waves with periods of about an hour were detected in streamers in the past using SOHO/LASCO observations. STEREO COR1 provides us with the coronagraph (~4 solar radius) with high temporal resolution (5 min time cadence) so that it allows us to study low frequency waves systematically and address line-of-sight ambiguity. We present a method to detect the periodic oscillations along coronal streamers observed by STEREO COR1 and to determine the wavelength, period and phase speed with wavelet analysis. Further, we discuss physical implications of our results and the possible origin of the waves we found.