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Astron. Astrophys. 359, 299-305 (2000)

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2. Observations

One hundred and seven high-resolution spectra of HD 200775 (51 in H[FORMULA], 16 in H[FORMULA], and 40 near the He I 5876 Å and Na I D lines) were obtained at three observatories between August, 1994 and December, 1999. At the Crimean Astrophysical Observatory (CrAO, Ukraine) the 2.6 m Shajn telescope with a CCD detector (SDS-9000 "Photometric GmbH") in the first camera of the coudé-spectrograph was used, providing a wavelength coverage of about 65 Å and yielding a spectral resolving power [FORMULA] 30 000. Data reduction followed standard procedures and was done with the SPE code developed by S. G. Sergeev. The internal uncertainties of the spectral line parameters in the CrAO data estimated by comparison of those measured in two halves of the star's spectrum, whose image in the CCD is usually 10-20 pixels wide. The mean accuracy of the radial velocity calibration is better than 1 km s-1.

At Ritter Observatory (USA) a 1 m telescope equipped with a Wright Instruments Ltd.CCD camera in a fiberfed échelle spectrograph was used. The spectra from 5285 to 6597 Å consisted of nine non-overlapping [FORMULA] 70 Å wide orders, with spectral resolving power R [FORMULA] 26 000. The Ritter data were reduced with IRAF version 2.10.3[FORMULA] 1. Further details about the observation and reduction procedures are given in Morrison et al. (1997).

Our study also employed observations obtained by Corporon & Lagrange (1999) at the Observatoire de Haute Provence (OHP, France) with the fiberfed échelle spectrograph ÉLODIE located at the 1.93 m telescope (R = 42 000). Each exposure includes the entire spectrum between 3906 and 6811 Å. The data acquisition and reduction are described in Corporon & Lagrange (1999).

The continuum signal-to-noise ratio in the OHP and CrAO spectra varied between 50 and 100 depending on the weather conditions, while it was between 30 and 50 in the Ritter data.

We used the narrow interstellar (IS) components of the Na I [FORMULA] lines for the definition of the radial velocity rest frame connected with the star. According to Finkenzeller & Jankovics (1985), these IS lines can provide us with an estimate of the stellar radial velocity with an uncertainty of [FORMULA] 5 km s-1 for the majority of Herbig Ae/Be stars. All the velocity values presented in this paper are given with respect to the rest frame of the star so defined, which was determined to have a heliocentric velocity of [FORMULA] km s-1. The log of all the observations and the results of the equivalent width (EW) and radial velocity measurements are presented in Table 1. The accuracy of radial velocities is [FORMULA] 3-5 km s-1, while that of the equivalent widths is better than 1 Å.


Table 1. Summary of the spectroscopic observations of HD 200775


Table 1. (continued)
The observation date is listed in column 1, the heliocentric Julian date of the exposure start in column 2, EWs of the lines are given in Å (columns 3 and 6), radial velocities of the absorption components (columns 4 and 7) as well as that of the He I line core (column 9) are given in km s-1 with respect to the rest frame of the star.
To measure the EW(H[FORMULA]) we took into account only the emission component above the underlying continuum. To account for the photospheric contribution, 3 Å was added to the measured values.
EW(H[FORMULA]) was calculated with the photospheric profile for [FORMULA]=19000 K and log g=4.0 from Kurucz (1979) taken into account.
If several absorption features are seen in the profile they were placed in the same column one below another.
The intensities of the emission peaks are not presented in the table (nevertheless, this information exists for both the H[FORMULA] and H[FORMULA]).

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© European Southern Observatory (ESO) 2000

Online publication: June 30, 2000