THE EFFECT OF LINE BLOCKING ON THE LIGHT CURVES OF THE Ap STAR HR 5355 (HD 125248)

Line-blocking coefficients were measured from coudé spectrograms covering the blue and green parts of the spectra, throughout the 9ḍ3 cycle of HR 5355. The coefficient for the v band of the uvby photometry is found to vary through a range of 0ṃ06 of the continuum in a double wave, with maxima corres...

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Bibliographic Details
Published in:Publications of the Astronomical Society of the Pacific 1975-04, Vol.87 (516), p.221-229
Main Authors: PILACHOWSKI, CATHERINE A., BONSACK, WALTER K.
Format: Article
Language:English
Subjects:
Ap stars
Astronomical photometry
Chromium
Extremely high frequencies
Hydrogen
Light
Light curves
Spectrograms
Stellar spectral lines
Wavelengths
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Summary:Line-blocking coefficients were measured from coudé spectrograms covering the blue and green parts of the spectra, throughout the 9ḍ3 cycle of HR 5355. The coefficient for the v band of the uvby photometry is found to vary through a range of 0ṃ06 of the continuum in a double wave, with maxima corresponding to the maxima of both the Eu II and the Cr spectrum variation, which occur in antiphase. This line blocking cannot account for the strong single-wave light variation in the t; band, which has a minimum at rare-earth maximum, but may be responsible, by redistribution of flux, for the double-wave character of the b-and y-band light variations. There is little variation of line blocking in the b and y bands. Line blocking varies significantly with wavelength and with phase in the vicinity of 5200 Å, and is partially responsible for the minimum in the apparent continuum found by photometric observers. It does not appear to be possible to interpret the basic light variations of HR 5355 by the mechanisms recently proposed for this and other Ap stars.
ISSN:0004-6280
1538-3873
DOI:10.1086/129747