Temporal variations of the magnetic field in sunspots

✍ Scribed by R. B. Schultz; O. R. White

• Publisher: Springer
• Year: 1974
• Tongue: English
• Weight: 749 KB
• Volume: 35
• Category: Article
• ISSN: 0038-0938
• DOI: 10.1007/bf00151951

✦ Synopsis

We obtained simultaneous spectra with a spatial resolution of 89 and a temporal resolution of 15 s in Hc~, Can-K, Car1 8542 A, and three FeI lines of the sunspot group responsible for the large flares of August, 1972 (McMath No. 11976). A time series taken 1972, August 3 in the Fe16173 A. Zeeman sensitive line was analyzed for oscillations of field strength and the angle between the field and the line of sight, and for changes of the field associated with the Can-K umbral flashes discovered by Beckers and Tallant (1969). The power spectra show no significant peaks, conflicting with the results of Mogilevskii et al. (1972) who reported oscillations in the longitudinal component of the field strength with periods of 56, 90, and 150 s. Changes in the field were not observed to be correlated with the occurrence of umbral flashes. These results place restrictions on magnetic modes of energy transport between the photospheric layers and the chromospheric layers where the umbral flashes are observed.

2. Observations

We observed the sunspot group McMath No.