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A Spectrographic Study of HD 193576.

1950; IOP Publishing; Volume: 112; Linguagem: Inglês

10.1086/145341

1538-4357

Guido Münch,

Geophysics and Gravity Measurements

view Abstract Citations (99) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Spectrographic Study of HD 193576. Münch, Guido Abstract A series of 93 spectrograms of the eclipsing system HI) 193576, obtained during the summer of 1949, has been used to study the variations in radial velocity and intensity of various spectral features. The velocity-curve of the 0 component was determined from measures of H8, H9, and H10, which give = +10 km/sec and K = 120 km/sec. The radial-velocity-curves for the WR spectrum have an amplitude K = 305 km/sec, but the -axis of the N v lines is shifted 60 km/sec to the red with respect to the systematic velocity of the H lines, while the -axis for N w X 4058 is shifted to the blue by 50 km/sec. The observations provide new evidence confirming the plausibility of explaining the shifts of emission lines as a result of self-absorption processes in the WR envelope. The absorption lines of the 0 star, during primary minimum, have been observed to become shallower and broader than at other phases. This variation has been accounted for in terms of the noncoherent scattering of the 0-star radiation by free electrons in the WR envelope and in the outer layers of the 0 star itself. The problem of the illumination of the envelope by radiation of the 0 star is briefly considered. It is shown that, at conjunctions, the light of the 0 star, scattered in the line of sight by the envelope, amounts to at least 10 per cent of the continuous radiation attributed to the WR component. In the last section of the paper an attempt is made to analyze the general characteristics of the WR spectrum. It is shown how some of the observed features can be interpreted in terms of an envelope with radially decelerated motions. In this model the kinetic energy of mass motion at the lower base of the envelope, supplied by a hypothetical impulsive mechanism from the parent-nucleus, is partly used to support the matter against gravity of the core and partly dissipated into heat of atomic motion, as matter moves outward. It is also suggested that the radiation of the 0 star in the far ultraviolet is an important factor in determining the physical and dynamical state of the matter in the outer parts of the observed envelope. There seems to be some observational evidence indicating that the state of ionization of the envelope is higher in the hemisphere facing the 0 star, but no conclusive test of the hypothesis is provided by the available observations. Publication: The Astrophysical Journal Pub Date: September 1950 DOI: 10.1086/145341 Bibcode: 1950ApJ...112..266M full text sources ADS | data products SIMBAD (10)