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Further identifications of hydrogen in Grw +70/sup 0/8247

Journal Article · · Astrophys. J., Lett. Ed.; (United States)
DOI:https://doi.org/10.1086/184427· OSTI ID:5923645
Numerous spectra of the magnetic white dwarf Grw +70/sup 0/8247 were obtained with the double CCD spectrograph at Palomar with signal-to-noise ratio above 100. Five weak absorptions in the blue and four in the red are produced by hydrogen in a strong magnetic field. We compute new, precise, multiparameter, variatioal energy levels yielding intensity and wavelength, from 100 to 600 MG. We search for those Zeeman components with wavelengths nearly constant with field. Two such, which are relatively sharp and strong ..pi.. transitions, explain the Minkowski band, 4137 A (known since 1938), as the 2s0-4f0 and the 5855 A band as the 2s0-3p0. Both have minimum wavelengths at Broughly-equal300 MG. Their absorptions resemble band heads degraded to the red, as observed. The mixed nature of the 4f0 level rsults in an intensity ratio (2s0-4f0)/(2s0-3p0) = 0.58 at 280 MG, high for a line forbidden at zero field. Profiles computed for a pole-on dipole, near logB/sub p/ = 8.5, fit the two observed lines. Other hydrogen transitions (including the core of Ly..cap alpha..) are consistent with that field strength. Six models with a variety of B/sub p/ and inclination are illustrated to show the quality of fit to the observations.
Research Organization:
California Institute of Technology (CalTech), Pasadena, CA (United States)
Contributing Organization:
California Institute of Technology, Palomar Observatory
OSTI ID:
5923645
Journal Information:
Astrophys. J., Lett. Ed.; (United States), Journal Name: Astrophys. J., Lett. Ed.; (United States) Vol. 289:2; ISSN AJLEA
Country of Publication:
United States
Language:
English