COMMISSIONS 27 AND 42 OF THE IAU INFORMATION BULLETIN ON VARIABLE STARS Number 3715 Konkoly Observatory Budapest 23 April 1992 HU ISSN 0374 - 0676 HD 13654: a new spectroscopic and eclipsing double-line binary of large RV_lsr HD 13654 (alpha_2000 = 2h 15m 11.8s, delta_2000 =+59d 20' 50") belongs to the field of the open cluster Stock 2, but it is not a cluster member according to its spectroscopic parallax (230 pc) and radial velocity (=44 km sec^-1) (Munari 1992a). HD 13654 has captured little attention in the past. Some photometry and spectral classification on objective prism plates can be found in a number of papers dealing with Stock 2 (Stock 1956, Brodskaya & Shajn 1958, Krzeminski 8Z Serkowski 1967, Martini 1971, McCuskey 1974), which give for HD 13654 =9.86 and an early A spectral type. HD 13654 has been extensively observed with the Boller & Chivens + CCD spectrograph at the 1.8 m telescope of the Asiago Astrophysical Observatory during a long term spectroscopic investigation of the Stock 2 cluster (Munari 1992a). 10 spectra have been recorded at resolution of 1 and 2 A/pixel (40 and 80 A/mm) over the period February 1990 - December 1991. A journal of the observations is given in Table 1. Following the procedure described in detail by Munari (1992b), each spectrum was classified by comparison with a library of reference spectra of MKK standards observed with the same instrument and dispersion, and their RVs were determined by cross-correlation techniques. As template stars we used the Stock 2 cluster non-binary members HD 13518, HD 13688, HD 13909, HD 14025 and HD 14161, with their RVs taken from Pesch & McCuskey (1974). The measured RVs are reported in Table 1. It can be seen that HD 13654 presents a large RV variation, indicative of binarity and large orbital inclination. No obvious orbital period has been found from a Fourier analysis the data, which are probably too few to this aim. Nine of the ten HD 13654 spectra we recorded turned out to be very similar, giving a spectral classification of A2.6(+/-0.1) V (see Figure 2a). The spectrum secured on 28.09.1990 showed instead a G9 star continuum (see Figure 2b). The sudden change was immediately recognized during preliminary on-line analysis of the data at the telescope and the star identification was carefully controlled, so the change in spectral type has been real. Table 1: Journal of observations Date grating scale range RV JD In mm^-1 (A/pixel) (lambdalambda A) (km/sec) 2440000+ 18.02.90 1200 1 3850-4400 +33 7941.311 28.09.90 600 2 3790-4910 8163.390 14.10.90 600 2 3790-4910 +51 8179.370 08.01.91 600 2 3790-4910 +1 8265.243 25.01.91 600 2 3790-4910 +141 8282.259 26.01.91 600 2 3790-4910 +75 8283.241 20.10.91 1200 1 3850-4400 +21 8551.455 17.12.91 1200 1 3850-4400 +25 8608.386 18.12.91 1200 1 3850-4400 +10 8609.379 19.12.91 1200 1 3850-4400 +34 8610.246 Table 2: UBV and RGU magnitudes of comparison data Star UBV RGU V U B R G U A 8.74 9.53 9.18 9.40 8.83 9.83 B 8.93 11.46 10.31 9.96 8.49 11.46 C 9.29 11.24 10.30 9.98 9.01 11.31 D^* 9.94 12.37 11.31 10.85 9.43 12.31 E 10.66 11.70 11.24 11.20 10.38 11.80 F^\ddag 11.94 12.72 12.76 12.48 11.32 12.63 G 12.81 14.45 13.82 H^* 14.18 16.74 15.66 I^* 14.70 16.03 15.62 [FIGURE 1] Figure 1. Identification chart for HD 13654 and comparison stars in Table 2. [FIGURE 2] Figure 2. Spectra of HD 13654: top = outside eclipse; bottom = in eclipse The large RV variation and the spectrum change recorded on 28.09.1990 suggest that HD 13654 is an eclipsing spectroscopic binary. A test spectrum secured out of eclipse in the 7000-9000 A region with the equipment above described, showed absorption lines assignable to the G9 companion. Being an eclipsing system, the determination of the orbits of the two components would immediately give their masses. What makes HD 13654 still more interesting is its relatively large RV in the Local Standard of Rest: RV_lsr=+48 km sec^-1, much more than expected from A type stars belonging to the young thin-Disk of the Galaxy (Freeman 1987). Clearly, HD 13654 is worth of a detailed investigation. It is relatively bright and lies at only 2deg from the h and chi double cluster in Perseus. This makes it a worth object to search in plate archive and to be observed by amateur astronomers. For this reason a finding chart (Figure 1) and a photometric comparison sequence (Table 2) are given here. The UBV photometry is the mean of the values reported by Krzeminski & Serkowski (1967) and Martini (1971) and it should be accurate to 0.017 mag (0.024 for stars marked by * which were not observed by Martini 1971). The RGU photometry is from Stock (1956). Star F has anomalous colors but no record of variability. ULISSE MUNARI Asiago Astrophysical Observatory, I-36012 Asiago (VI), Italy, 39035::MUNARI Visiting Astronomer, SAAO-South African Astronomical Observatory References: Brodskaya, E.S. and Shajn, P.F. 1958 Izv. Crimean Ap. Obs. 20, 299 Freeman, K.C. 1987 Ann. Rev. Astron. Ap. 25, 603 [BIBCODE 1987ARA&A..25..603F ] Krzeminski, W. and Serkowski, K. 1967 Astrophys. J. 147, 988 [BIBCODE 1967ApJ...147..988K ] Martini, A. 1971 Mem. SAIt 42, 523 [BIBCODE 1971MmSAI..42..523M ] McCuskey, S.W. 1974 Astron. J. 79,107 [BIBCODE 1974AJ.....79..107M ] Munari, U. 1992a Astron. Astrophys., to be submitted Munari, U. 1992b in "Star Cluster and Stellar Evolution", ed. E. Brocato, F.R. Ferraro, G. Piotto, Mem. SAIt, in press Pesch, P. and McCuskey, S.W. 1974 Astron. J. 79, 116 [BIBCODE 1974AJ.....79..116P ] Stock, J. 1956 Astrophys. J. 123, 258 [BIBCODE 1956ApJ...123..258S ]