HD 15144, A MAGNETIC Ap STAR WITH A POSSIBLE INTRINSIC PERIODIC VARIATION OF THE MAGNETIC FIELD

HD 15144 (HR 710) is a single-line spectroscopic binary Ap star with a period of 3.d00, which has a variable magnetic field but no obvious variations in line strengths or light. New spectrograms are combined with previous observations by Babcock to derive a probable magnetic period of 15.d9. An appa...

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Bibliographic Details
Published in:Publications of the Astronomical Society of the Pacific 1981-12, Vol.93 (556), p.756-764
Main Author: BONSACK, W. K.
Format: Article
Language:English
Subjects:
Ap stars
Error rates
Line spectra
Magnetic fields
Rotation
Rotational spectra
Spectrograms
Stellar rotation
Stellar spectra
Wavelengths
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Summary:HD 15144 (HR 710) is a single-line spectroscopic binary Ap star with a period of 3.d00, which has a variable magnetic field but no obvious variations in line strengths or light. New spectrograms are combined with previous observations by Babcock to derive a probable magnetic period of 15.d9. An apparent rotational velocity of 7.7 km s⁻¹ is obtained and combined with elements of the orbit to estimate the mass of the secondary. The spectrum of the secondary cannot be detected between 3800 Å and 6700 Å. The most plausible model for the system appears to be one in which the rotation period of the Ap star is 3.d00, the system is seen nearly pole-on, the secondary is a subluminous star of approximately 1.2 solar masses, and the magnetic variation is due to intrinsic changes of the field strength or geometry. An alternative model assumes that the rotation period of the Ap star is 15.d9 days, the system is seen edge-on, the mass of the secondary is 0.2 solar mass, and the magnetic variation is due to rotation with a fixed, but very asymmetric, magnetic field geometry.
ISSN:0004-6280
1538-3873
DOI:10.1086/130922