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New technique for measuring solar rotation

Journal Article · · Astrophys. J.; (United States)
DOI:https://doi.org/10.1086/156773· OSTI ID:6271708
A new technique for measuring solar photospheric and subphotospheric rotation rates is described. The technique utilizes the standing-wave nature of the nonradial p-mode oscillations of the whole Sun. Specifically, the technique is based upon the observed concentration of p-mode oscillatory power into well defined ridges in two-dimensional wavenumber-frequency (K/sub h/, ..omega..) power spectra. The frequencies of the ridges in the eastward- and westward-traveling portions of an individual spectrum are systematically shifted in opposite directions by a drift of the standing-wave pattern across the observing field of view. The magnitudes of these frequency shifts are related to the drift velocity and to the horizontal wavenumber as follows: vertical-bar..delta omega..vertical-bar=vertical-bar..nu..vertical-barK/sub h/. Thus, measurement of the observed frequency shifts in a spectrum yields the drift velocity field at disk center, the observed drift velocity obtained in this way is exactly the rotational velocity of the solar p-mode pattern, and of the solar gas itself.
Research Organization:
George W. Downs Laboratory of Physics, California Institute of Technology
OSTI ID:
6271708
Journal Information:
Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 227:2; ISSN ASJOA
Country of Publication:
United States
Language:
English