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Astron. Astrophys. 320, 74-78 (1997)

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2. Observations

2.1. The sample

The present sample contains 107 stars from Artjukhina & Kalinina's (1970) table 4 that were not already contained in the sample discussed in paper I, which is based on the list of van Leeuwen et al. (1986). In two cases (AK Ib-148 and IV-793), two stars were found at the given position and both were observed. The two stars are identified by 'a' and 'b' respectively in Tables 1 and 2. After each star received a first radial velocity observation, the most probable members, taking also into account possible binaries, were observed photometrically, because no data, except the AK photographic magnitudes or those given in the GSC, were previously known for these stars. The AK identification and the coordinates for epoch 2000 from the GSC are given in Tables 1 (member stars) and Table 3 (non members). Pels identifications are given for a few stars. They correspond to the numbering system used by van Leeuwen et al. (1986). For stars without other sources of photometric data the magnitude from the GSC is quoted. Table 3 is available only in electronic form at the CDS via anonymous ftp. Identification charts for the stars observed can be obtained from the first author (JCM).


Table 4. Orbital elements of two spectroscopic binaries


Table 3. Observational data for stars with contradictory membership criteria

2.2. Coravel observations

The observations were obtained with the CORAVEL radial-velocity scanner (Baranne et al. 1979) installed on the Swiss 1-m telescope at the Haute-Provence Observatory (OHP). The radial velocities were corrected for zero-point difference to place them in the system defined by the southern CORAVEL. Between September 1991 and Decembre 1994, as a rule two to three observations per star were obtained. In total, 288 radial-velocity measurements of 93 stars were made. AK Ib-590, III-153, III-909 and V-151 have spectral types earlier than F5 and could therefore not be observed with CORAVEL; AK III-158 and III-419 have not been observed and ten stars were tested but did not produce any correlation dip. These 10 stars are identified by the remark "no dip". Four double-lined and six single-lined spectroscopic binaries were discovered. Two of them appeared to have short periods and were more intensively monitored until orbital elements could be determined.

The mean radial velocities and errors in km s-1 and number of measurements are displayed separately for the members and non-members in Tables 1 and  3. As mentionned above, Table 3 is available only in electronic form.

2.3. Photometric observations

Photometric observations were obtained by (PB) with a CCD camera and Geneva filters (Bratschi & Blecha 1996) mounted on the 70-cm Swiss telescope at La Silla (Chile). Most observations were obtained in a single run in November 1994, although some measurements were already obtained in October 1992. Ten stars in common between both periods show a good agreement in their magnitudes. A second observation of 8 stars has been made in January 1996 to check their identifications and magnitudes. The V magnitudes and Geneva [B-V] colour indices are given in Tables 1 and  3. [FORMULA] indices in the Johnson system have been computed with the relation given by Meylan & Hauck (1981): [FORMULA]. For four stars (AK Ib-683, Ib-770, V-019 and V-437) the V magnitudes and Johnson [FORMULA] colours given have been computed from the observations in the Walraven system published by van Leeuwen et al. (1986) and no Geneva [ [FORMULA] ] are given.

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© European Southern Observatory (ESO) 1997

Online publication: July 3, 1998