On the solar magnetic ‘monopole’

✍ Scribed by M. Stix; E. Wiehr

• Publisher: Springer
• Year: 1974
• Tongue: English
• Weight: 184 KB
• Volume: 37
• Category: Article
• ISSN: 0038-0938
• DOI: 10.1007/bf00152509

✦ Synopsis

A superposed epoch analysis shows that the Sun's spurious magnetic monopote varies like the solar declination. This indicates that the monopole is caused by instrumental effects, Wilcox (1972) has asked the puzzling question "Why does the Sun sometimes look like a magnetic monopole?" He points out that the Mt. Wilson magnetic charts (Howard et aL, 1967) indicate that for several consecutive months in 1965 the solar field was predominantly directed out of the Sun. He also gives arguments that the higher solar latitudes which are not included into the charts probably did not account for the missing opposite magnetic flux. As far as instrumental errors are concerned, Wilcox argues that these are unlikely because of the good agreement between magnetic field measurements made at the Crimea and Mt Wilson and because of the additional validation of the 'magnetic monopole' by spacecraft observations. Notwithstanding these arguments it is the purpose of the present note to investigate whether instrumental effects might be influential. For this purpose we made a superposed epoch analysis of the Legendre coefficients 9 o for the period August 1959 to January 1973. These coefficients were obtained as a by-product of the expansion of the digitized Mt. Wilson data into spherical harmonics (Altschuler and Newkirk, 1969) and were kindly made available to us by Altschuler. When more than one 9 o value was available within one month, a monthly mean was first computed. Then the averages of all January means, February means, and so on, were calculated. These are shown in Figure 1 (solid curve). We see that the averaged monthly monopole