Periodicity in the rotation of solar transition region and sunspot numbers

Abstract

Abstract The long term study on the temporal variation of the rotation period of the solar photosphere, chromosphere and corona has been widely known. To date it is unclear whether the temporal variation of rotation period of the solar transition region has a systematic periodicity. In this paper we perform a first study on the temporal variation of the rotation period of the solar transition region. For this purpose, we used Lyman – α line emission at wavelength 121.56 nm corresponding to the solar transition region from the years 1965 to 2019. Autocorrelation analysis depicts that the average sidereal rotation period of transition region (from 1965 to 2019) is 24.8 days. Furthermore we found that a significant periodicity of about 12 years exist in the temporal variation of sidereal rotation period of solar transition region. The results indicate that this periodicity is nearly linked to the 11 year Schwabe cycle. Cross-correlation analysis between the time series of sidereal rotation period and sunspot numbers (as a function of lag in years) exhibits a strong correlation between these aforementioned parameters. From this we can state that sidereal rotation period of solar transition region leads the solar activity by about six months. This strong correlation again approves the periodicity of about 11 years in the rotation period of transition region which is nearly linked to the 11 year Schwabe cycle. From this long term study it seems that solar activity is largely derived by solar rotation.