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

3. Abundances

Leone & Manfrè (1996) have determined the effective temperature and gravity of For by spectrum synthesis analysis of the region taking into account the effect of the enhanced metallicity. The ATLAS9 (Kurucz 1993) model atmosphere, whose line profile matches the observations, has: = 13400 K, g = 3.85 and a metal opacity scale equal to ten times the solar value.

With this model atmosphere, we have identified the lines in our spectra by using SYNTHE (Kurucz & Avrett 1981) and the atomic line list given by Kurucz (1993). Equivalent widths have been converted to abundances by using WIDTH9 (Kurucz & Avrett 1981) with the exception of the HeI 587.6 and MgII 448.1 nm lines which have been analysed according to Leone & Lanzafame (1998) and Leone et al. (1997) respectively.

Microturbulent velocity measured by forcing the unblended iron lines to give a single abundance value is equal to 2.9 km s^-1 with a 0.8 km s^-1 standard deviation. This value is slightly larger than the microturbulent velocity measured by Leone & Manfrè (1996) (2.1 km s^-1) and coincident with the value measured by Leone et al. (1997). The large value of the standard deviation is probably due to the line desaturation induced by the variable magnetic field.

Average derived abundances and associated standard deviations are listed in Table 1.

Table 1. Logarithm of the average abundances () and logarithm of the relative standard deviations of For. The standard deviations take into account the periodic variability of the abundances. When possible, abundances are compared with the values for B main sequence stars derived by Adelman (1986) and Gies & Lambert (1992) and with solar abundances (Kurucz priv. comm.).

By comparing the derived abundances of For with the values of main sequence A and B-type stars given by Adelman (1986) and Gies & Lambert (1992), within errors: helium, carbon and magnesium are under-abundant; silicon, calcium and chromium abundances are not peculiar and the other considered elements are over-abundant.

The derived abundances for silicon and iron are close to the values given by Leone & Manfrè (1996): and .

© European Southern Observatory (ESO) 2000

Online publication: July 7, 2000
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