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Astron. Astrophys. 356, 665-675 (2000)

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2. Observations

Optical spectra of LB 3459 were obtained during several observation campaigns in the last years. In Table 1 we summarize these observations. The given resolution is measured from the He-Ar and Th-Ar comparison spectra.

We retrieved the three available high-resolution SWP spectra of LB 3459 from the IUE Final Archive (Table 2). Since LB 3459 is a binary, we used H I  [FORMULA]Å , He II  [FORMULA]Å , C IV  [FORMULA]Å , N IV  [FORMULA]Å , N V [FORMULA] [FORMULA], and Si IV  [FORMULA]Å in order to determine the average shifts from their rest wavelengths (Table 2). All these lines show the same deviations and are thus clearly of photospheric origin while e.g. Si III  [FORMULA]Å (Fig. 5) appears at its rest wavelength in all spectra and hence, is dominated by interstellar absorption. The spectra are shifted then by these amounts and co-added (equally-weighted due to their similar S/N ratio). The influence of the orbital motion of LB 3459 is discussed in (Sect. 3.1).


Table 2. Observation log of the optical spectra of LB 3459 taken at ESO

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© European Southern Observatory (ESO) 2000

Online publication: April 10, 2000