Physical Processes in Gaseous Nebulae. XVII. Fluorescence in High-Excitation Planetaries.

Abstract

view Abstract Citations (6) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Physical Processes in Gaseous Nebulae. XVII. Fluorescence in High-Excitation Planetaries. Menzel, Donald H. ; Aller, Lawrence H. Abstract Some years ago Bowen attributed the appearance of "fractional multiplets" of 0 iii in the spectra of high-excitation planetaries to absorption by 0 m atoms in the 2p2 3~2 level of the X 303.80 "Lyman alpha" radiation of helium. The subsequent cascading of these atoms from 2p3d 3D2 of 0 m back to the ground level via the 2p3p and 2~3S configurations are supposed to produce the observed lines. We have attempted to put this theory on a quantitative basis by setting up the appropriate equations of sta- tistical equilibrium for the excited levels and predicting the relative intensities of the observed ultraviolet lines. A comparison of observed relative intensities with predicted relative intensities yields a con- sistency check on the theory. The populations of the excited levels are found to be 10 4~IoI6 atoms cm3. The intensity of the radiation in the 0 m 303.80 line is from ~ to ~ times greater than that radiated by the nuclear star, which illustrates why permitted lines of 0 rn other than those originating by cascade from 3d~P2, are not observed. The excess is attributed to the concentration of radiation in these lines, by cyclic processes resulting from ionization of He+. We have also shown that theoretically the images of the Bowen lines shoiild be about 5 per cent larger than those of the He ii lines, which is in rough agreement with the observational data. The paper contains tables of the relevant f's and A's computed from approximate wave functions based on Slater's rules Publication: The Astrophysical Journal Pub Date: November 1941 DOI: 10.1086/144350 Bibcode: 1941ApJ....94..436M full text sources ADS | data products SIMBAD (2) Related Materials (17) Part 1: 1937ApJ....85..330M Part 2: 1937ApJ....86...70M Part 3: 1938ApJ....88...52B Part 4: 1938ApJ....88..313M Part 5: 1938ApJ....88..422B Part 6: 1939ApJ....89..587A Part 7: 1939ApJ....90..271B Part 8: 1939ApJ....90..601A Part 9: 1940ApJ....91..307S Part 10: 1940ApJ....92..408H Part 11: 1941ApJ....93..178S Part 12: 1941ApJ....93..195M Part 13: 1941ApJ....93..230M Part 14: 1941ApJ....93..236A Part 15: 1941ApJ....93..244G Part 16: 1941ApJ....94...30M Part 18: 1945ApJ...102..239A