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Astron. Astrophys. 364, 674-682 (2000)

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2. Observations and data reduction

Two sets of spectra were obtained: for 10 stars the wavelength coverage permits a detailed analysis, whereas for the other 6 stars only an estimation of parameters and Li abundance can be given. The program stars are listed in Table 1.


[TABLE]

Table 1. List of program stars: IRAS name, spectral type (when available), and the equivalent width of the Li I 670.782 nm doublet (in mÅ). Last columns indicate the Observatory where the data were obtained, and the reference of LRG identification.
Notes:
(*) IRAS name; "GCSS" is used to identify an object in the General Catalogue of S stars (Stephenson 1976). Refs.: 1 - Brown et al. (1989); 2 - Castilho et al. (1998); 3 - Fekel & Balachandran (1993); 4 - Gratton & D'Antona (1989); 5 - Gregorio-Hetem et al. (1992); 6 - Luck (1994); 7 - Pilachowski et al. (1990)


Spectra for 10 sample giants were obtained in 1996, December at the 1.4m ESO CAT telescope, using the CES (Coudé Echelle Spectrometer) with the long camera and the Loral CCD ESO # 38 of 2688[FORMULA]512 pixels, with pixel size 15[FORMULA]15µm. For each star eleven spectral regions between 534.8 nm and 806.6 nm were observed. These spectra have a resolving power of R [FORMULA] 58,000 over four pixels, and dispersion of about 0.03[FORMULA]/pixel. Most of them were obtained with S/N [FORMULA] 100, and only for one object (HD 19745) of this set, the spectra have S/N [FORMULA] 50 - 80.

For the other 6 stars, spectra corresponding to one order were obtained at the Laboratório Nacional de Astrofísica (LNA, Brazil), and the Observatoire de Haute Provence (OHP-France). For this set of observations only one spectral range is available, with S/N [FORMULA] 30-95.

The LNA observations, carried out in 1993 March, 1993 November, and 1994 March were obtained at the coudé focus of the 1.6m telescope using a GEC CCD of 1152[FORMULA]770 pixels with 22µm[FORMULA]22µm pixel size, and a grating of 1800 l/mm yielding a resolution over two pixels of [FORMULA] 25,000 covering the wavelength range [FORMULA] 663-677 nm.

The OHP observations were carried out in 1994 July, and 1995 July, with the AURELIE spectrometer at the Coudé focus of the 1.52m telescope (Gillet et al. 1994), with a resolving power R [FORMULA] 11,000 in the range 530-730 nm.

The spectra of hot stars observed during the runs were inspected for telluric lines and bad CCD columns. The spectra of the 6 stars observed at the LNA and OHP are available in FITS format (Castilho et al. 1997).

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© European Southern Observatory (ESO) 2000

Online publication: January 29, 2001
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