Signatures of very long period waves in the polar coronal holes

D. Banerjee, E. O'Shea, J. G. Doyle, M. Goossens
2001 Astronomy and Astrophysics  
We examine long spectral time series of a coronal hole observed on the 7th March 2000 with the Coronal Diagnostic Spectrometer (CDS) on-board SoHO. The observations were obtained in the chromospheric He i, and a series of higher temperature oxygen lines. In this letter we report on the presence of long period oscillations in a polar coronal hole region on the disk. Our observations indicate the presence of compressional waves with periods of 20-30 min or longer.
doi:10.1051/0004-6361:20011548 fatcat:mufsyx7eangc3eqceywmr5ovqy