1937/04/01 by N. U. Mayall · 2 citations
Physics and Astronomy · #Astro and Planetary Science #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Biology #Crab Nebula #Lithium (medication) #Nebula #Physics #Pulsar #Spectrum (functional analysis) #Spectrum analysis #Stars #Stellar, planetary, and galactic studies
paper · pdf · doi:10.1086/124777
openalex publication_date 1937/04/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
The spectrum of the Crab Nebula (NGC 1952, Ml) was first photographed by V. M. Slipher 1 in 1913-15.He described it briefly as follows : "The chief nebular bright lines seem to be split into two components suggesting the Stark electric field analysis for hydrogen, helium, and lithium.A few years later R. F. Sanford 2 obtained a spectrogram exposed a total of 48 hours, but it was "disappointingly weak/' Despite this fact, he noted that "the spectrum is continuous, crossed by bright lines," and he was able to measure the wave-lengths of a number of these lines.The six strongest were correctly identified on the basis of several assumptions, but the results did not provide a satisfactory explanation of the nature of the spectrum of the nebula as a whole.Shortly after these spectrographic observations were published, C. O. Lampland 8 discovered that certain changes had occurred in the nebula.However, he restricted his report to a qualitative description of the observed changes, without giving any measures of the sizes or directions of the angular displacements.The actual measurement of the displacements was at