Solar Cosmic Rays of February, 1956 and Their Propagation through Interplanetary Space

Meyer, P., E. N. Parker, and J. A. Simpson, Solar Cosmic Rays of February, 1956 and Their Propagation through Interplanetary Space, Physical Review, 104, 768-783 (1956) (ADS)

The cartoon

(click on the image for a larger version)

An early speculation about the magnetic structure of the heliosphere, responding to the epochal flare/CME/GLE event SOL1956-02-23. At this remote point in time it did not seem necessary to invoke the Parker spiral, although the suggestion of an organized interplanetary field already existed, and a cartoon soon appeared. Instead, to explain the properties of the solar cosmic rays, the paper argued for an essentially field-free region inside 1.4 AU, beyond which a turbulent barrier separated us from the interstellar field of some 10 μG. Remarkably the direct sampling of the interstellar field by the Voyager spacecraft actually matched this estimate quite well.

      Nowadays we think that the field-free region has field in it, and there are the Cane, Masson and other interpretations of SEPs propagation now available.

Date: 2019 December 17