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Astron. Astrophys. 359, 635-638 (2000)


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A spectroscopic study of the magnetic chemically peculiar star [FORMULA] Fornacis

F. Leone *  1, G. Catanzaro 2 and S. Malaroda  **  3

1 Osservatorio Astrofisico di Catania, Città Universitaria, 95125 Catania, Italy (fleone@sunct.ct.astro.it)
2 Center for Astrophysical Sciences, The Johns Hopkins University, Department of Physics and Astronomy, Bloomberg Center, 3400 N. Charles str., Baltimore, MD 21218, USA
3 Complejo Astronómico El Leoncito, Casilla de Correo 467, 5400 San Juan, Argentina

Received 3 April 2000 / Accepted 10 May 2000

Abstract

The magnetic chemically peculiar star [FORMULA] Fornacis is known to be a periodic magnetic and luminosity variable. In the framework of the Oblique Rotator Model, [FORMULA] For presents a mainly dipolar magnetic field, whose symmetry axis is tilted with respect to the rotational axis, non solar abundances and a non homogeneous distribution of elements on the stellar surface. The variability period is the stellar rotational period. Thus, spectral variabilities are also expected for this star.

By analysing the Hipparcos photometry and data from the literature, the luminosity period of [FORMULA] For has been found equal to 1.89232 days. This value also represents the variability of the effective magnetic field measurements available in the literature.

To investigate the, up to now unknown, spectroscopic behaviour of [FORMULA] For, we have performed time-resolved spectroscopy of this star in the 400-600 nm range. The equivalent widths are found to be also variable with the previous period and have been used to derive abundances.

Phase relations, between light, spectral and magnetic variabilities have been established. According to the hypothesis that light variations are due to a non-homogeneous distribution of elements on the stellar surface and high metallicity regions are responsible for blocking of ultraviolet flux and its redistribution towards the visible wavelengths, iron is the main origin of the light variability.

Key words: stars: abundances – stars: chemically peculiar – stars: individual: HD 12767 – stars: magnetic fields

* Visiting astronomer, Complejo Astrónomico El Leoncito, operated under agreement between the Consejo Nacional de Investigationes Cientifícas y Técnicas (CONICET) and the National Universities of La Plata, Córdoba and San Juan
** Member of the Carrera del Investigador de la Comision de Investigaciones Cientifícas y Técnicas de la Provincia de Buenos Aires, Argentina

Send offprint requests to: F. Leone (fleone@sunct.ct.astro.it)

© European Southern Observatory (ESO) 2000

Online publication: July 7, 2000

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