The Sun's Magnetic Field, 1952-1954.

view Abstract Citations (453) References (14) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Sun's Magnetic Field, 1952-1954. Babcock, Horace W. ; Babcock, Harold D. Abstract More than 450 magnetograms, showing the distribution, intensity, and polarity of weak magnetic fields (> 0.3 gauss) on the sun have been obtained with the solar magnetograph over a two-year period. This interval includes the recent minimum of solar magnetic activity. The records show a pattern with a fluctuating fine structure and certain large-scale regularities. General magnetic fietd.-Consistent evidence is found for a general field, predominantly dipolar, with polarity opposite to that of the earth. The mean intensity is of the order of 1 gauss. The general field is usually limited to heliographic latitudes greater than about t 550; it has a varying fine structure and shows remarkable random fluctuations in effective intensity and extent. There seems to be no prevailing obliquity between the magnetic and rotational axes. The total flux is estimated to be nearly 10 maxwells. Bipolar magnetic (BM) regions.-In the lower latitndes the stronger magnetic effects appear as contiguous areas of opposite magnetic polarity, as if loops of a submerged toroidal field were occasionally brought to the surface by rising material. The BM regions obey Hale's laws of sunspot polarity, but spots are comparatively rare, occurring, when at all, within the BM regions while they are young. Ca ii plages are observed where the field intensity is greater than about 2 gauss. Hydrogen filaments occur around the borders of BM regions or, alternatively, seem to divide the region into parts of opposite polarity. As the regions age, they generally expand, showing a decrease in field intensity, and disintegrate until lost in the background of irregular weak fields. There is much diversity in total magnetic flux, duration, area, and course of development. Unipolar magnetic (UM) regions.-Occasional extended magnetic areas of only one outstanding polarity were recognized. The most prominent UM region of 1953 had an intensity 3 gauss and a duration of many months; it may well have been related to a prominent sequence of 27-day-recurrent terrestrial magnetic storms. UM regions may be remnants of disintegrating BM regions. We suggest that UM regions may be identified as the heretofore hypothetical "M" regions of Bartels. Repeated tracings of the same area of the sun at intervals of a few minutes show changes of the order of 1 gauss in the fine structure of the magnetic pattern within a half-hour. The observations provide objective evidence for the heretofore inferential hypothesis that magnetic fields are fundamental to sunspots, plages, prominences, chromospheric fine structure, bright coronal emissions, and, probably, regions of strong radio emission. Several solar phenomena can be synthesized on the proposition that neutral but ionized corpuscular streams are continually being ejected from all turbulent regions of the surface characterized by coherent magnetic fields of average intensity gauss or more. A hydromagnetic model, based on chromospheric spicules, is proposed for such ejection. Publication: The Astrophysical Journal Pub Date: March 1955 DOI: 10.1086/145994 Bibcode: 1955ApJ...121..349B full text sources ADS |