According to the Oblique Rotator Model, proposed by Babcock (1949) and Stibbs (1950), a magnetic Chemically Peculiar (CP) star consists of: a mainly dipolar magnetic field, whose axis is tilted with respect to the rotational one; non solar chemical abundances; and a non homogeneous distribution of elements on the stellar surface. In such a picture, the period of the observed magnetic, photometric and spectral variability is the stellar rotational period.
Fornacis (= HD 12767= HR 612= HIP 9677) was classified as an A0 silicon star by Bidelman & Böhm (1955), its photometric variability was discovered by Renson & Manfroid (1978) and the presence of a magnetic field suggested by Babcock (1958). Measurements of the effective magnetic field were obtained by Borra & Landstreet (1980).
In the previous picture of a CP star, For is also expected to present spectral variations. With the aim to determine their behaviour and relate spectral, light and magnetic variability, we have obtained time resolved spectra of For.
© European Southern Observatory (ESO) 2000
Online publication: July 7, 2000