Magnetic rotation of the solar photosphere

TLDR

Magnetograms from Mt. Wilson Observatory (1967–1982) were cross‑correlated in 34 latitude strips at 1–4‑day intervals, and the rotation of magnetic features was derived by averaging correlations and locating the displacement of the maximum, with the method’s validity examined. The rotation rate shows no significant temporal or field‑dependent variation, following ω(φ)=2.902+0.464 sin²φ–0.328 sin⁴φ µrad s⁻¹, matching Doppler measurements near the poles and Newton–Nunn sunspot results, though Doppler values are ~30 m s⁻¹ slower at sunspot latitudes.

Abstract

view Abstract Citations (348) References (28) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Magnetic rotation of the solar photosphere Snodgrass, H. B. Abstract Magnetograms made at Mt. Wilson Observatory from January 1967 to May 1982 are crosscorrelated in 34 latitude strips at 1-4-day increments to determine the rotation of magnetic features in the solar photosphere. The data are smoothed by averaging corresponding correlations and calculating rotation from the displacement of the averaged-correlation maximum; the usefulness and validity of this procedure are discussed. No significant time variation or field dependence is found for the period of the observations, at least to the accuracy of the calculated means (variance of from about 2 m/sec at low latitudes to about 10 m/sec near the poles). The rotation function omega at solar latitude phi is shown to be 2.902 0.464 sin sq phi - 0.328 sin to the 4th phi microrad/sec, in agreement with the Mt. Wilson Doppler profile near the poles and with the sunspot determination of Newton and Nunn (1951) at sunspot latitudes, where the Doppler estimate is about 30 m/sec slower. Publication: The Astrophysical Journal Pub Date: July 1983 DOI: 10.1086/161121 Bibcode: 1983ApJ...270..288S Keywords: Photosphere; Solar Magnetic Field; Solar Rotation; Cross Correlation; Magnetic Signatures; Sunspots; Solar Physics full text sources ADS |