A significant fraction of all A-type and late B-type stars have strong, globally ordered magnetic fields. However, models of the surface magnetic field configuration exist for only a handful of these objects. Because these magnetic fields convey information about the formation and pre-main sequence history of these stars (e.g. Moss 1989), offer a means to probe the structure and dynamics of the stellar interior (e.g. Moss 1990), and strongly influence other important physical processes occurring in the stellar envelope (e.g. Babel & Michaud 1991; Babel 1992; Landstreet et al. 1998), a much broader understanding of their magnetic characteristics is required. In this paper, as part of a continuing programme aimed at constructing magnetic field models for stars throughout the F0-B2 temperature range, we report magnetic field geometry models and basic physical properties of two stars: the A2p CrSi star HD 12288 and the B9p CrEuSi star HD 14437.
Magnetically split lines were first observed in the spectrum of the A2p CrSi star HD 12288 (=BD+68 144=HIP 9604; ) by Preston (1971). Mathys et al. (1997) obtained 20 measurements of the mean magnetic field modulus (also known as the surface field) of this star within the context of a broad survey of magnetic fields in sharp lined Ap stars. They also discovered that this object is a spectroscopic binary (SB1), with a radial velocity amplitude of at least 16 km s-1 and an orbital period of at least 4 years. Leroy (1995) noted a strong interstellar polarisation toward this star, and was unable to measure the broadband linear polarisation variation. Both the trigonometric parallax and photometric variation of HD 12288 were obtained by the HIPPARCOS satellite.
Magnetically split lines were reported in the spectrum of the B9p CrEuSi star HD 14437 (=BD+42 502=HIP 10951; ) by Mathys et al. (1993). Mathys et al. (1997) reported 17 measurements of , but were unable to determine a unique rotational period. The trigonometric parallax and photometric variation of HD 14437 were also obtained by the HIPPARCOS satellite.
© European Southern Observatory (ESO) 2000
Online publication: March 21, 2000