A Study of the Spectrum and Magnetic Variable Star HD 125248

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Abstract
The relationship between variability in line intensity, radial velocity, magnetic field, and luminosity of HD 125248 is examined. Using the period 9.295 days given by Deutsch for the spectrum changes, the radial velocity measurements made by Morgan in 1931 are analysed. These measurements suggest a radial velocity variation of approximate amplitude 13 km./sec. with zero velocity when the Eu II lines have their maximum intensity. Thus the velocity zeros occur when the magnetic field variation discovered by Babcock has its extreme values. Photometric measurements leading to the light curve of the star are described. An harmonic analysis shows the light variation to be symmetrical about the maximum, the first and second harmonics being the principal terms. The elements of the light variation are Light maximum=JD 2433 103.95+9.295 E , the maximum occurring when the Cr II lines have their greatest intensity. The light maximum occurs when the magnetic intensity of the polar field is –6500 gauss, and the minimum: when the field is +7800 gauss. The amplitude of the light variation at the effective wave-length 4000 A. is consistent with a colour temperature change from maximum to minimum light of about 250 deg. K., corresponding to a gradient change of about 0.01. No change in colour has so far been detected.

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