Here we report the first measure in radio emission of differential rotation as a function of height in the solar corona. This is derived from the disk-integrated simultaneous daily measurements of solar flux at 11 radio frequencies in the range of 275-2800 MHz. Based on the model calculations, these radio emissions originate from the solar corona in the estimated average height range of ∼ km above the photosphere. The 4 (6-15) # 10 investigations indicate that the sidereal rotation period at the highest frequency (2800 MHz), which originates from the lower corona around km, is ∼24.1 days. The sidereal rotation period decreases with height to 4 6 # 10 ∼23.7 days at the lower frequency (405 MHz), which originates at ∼ km. It is difficult to identify clearly 4 13 # 10 the rotational modulation at 275 MHz, perhaps because these emissions are significantly affected by the turbulence in the intervening medium. Since these investigations are based on disk-integrated solar flux at radio frequencies, it is difficult to say whether these systematic variations in sidereal rotation period are partly due to the latitudinal differential rotation of the solar corona. It will be interesting to investigate this possibility in the future.
In present work we have performed autocorrelation analysis of time series of disc integrated solar flux at 2800 MHz and daily observations of Interplanetary magnetic field (IMF) for the period of 1987 to 2010 to infer rotation period. The analysis presents a comparison between rotation periods obtained from radio emissions, a coronal feature and interplanetary magnetic field. The results show a correlation between two which indicates that IMF seems to emanate from regions of low latitudes while it is expected to originate from polar regions.
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