COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 3545 Konkoly Observatory Budapest 28 November 1990 HU ISSN 0374 - 0676 NO "CHROMOSPHERIC ACTIVITY" SEEN IN ETA And The double-lined spectroscopic binary eta And (HD 5516) is listed as star #9 in the Catalog of Chromospherically Active Binary Stars (CABS; Strassmeier et al. 1988) as having weak Ca II H and K emission lines according to Wilson's intensity class 3 (Wilson 1976). Because of the overexposure of Wilson's plates in order to bring out even very weak emission and the fact that only one 10 Angström/mm plate was used, his intensity class I_K=3 might be an upper limit for the K-line strength. As demonstrated in the CABS catalog, if one uses high-revolution spectra to detect H and K emission, the resulting intensity class is generally higher than that of Wilson by one subclass. In this paper we report a nondetection of H and K emission in eta And from high-resolution Echelle-Reticon spectra. Halpha appears as a normal (double) absorption feature. We thus reject this star from the CABS catalog as being not chromospherically active. The observations were obtained at the Leopold-Figl Observatorium für Astrophysik (FOA) of the University of Vienna with the 1.5m telescope in October 1990. The Echelle spectrograph (Weiss et al 1981) was used in 57th order (lambda_c=3938 Angström) and in 34th order (lambda_c=6602 Angström) at dispersions of 0.08 Angström/px and 0.15 Angström/px, respectively. The observations utilized a 1872-pixel Reticon array (Weiss, Schalk, Ogris 1987) and had an effective wavelength resolution of 0.2 Angström in the blue and 0.3 Angström in the red region. The blue spectra have S/N ratios of around 30:1 and the red spectra approximately 100:1. Fig. 1 shows parts of our spectra centered at, from top to bottom, Ca II H and K, Ha, and LiI lambda6707 Angström. No obvious H and K emission is present and attempts to measure an absolute emission line flux by identifying the H_1 and K_1 points failed. The lower panel in Fig. 1 shows the 6700 Angs. region where the position of the Lithium blends is indicated. No obvious LiI absorption is present. The Halpha line in the second panel is a composite from both components but the narrower photospheric lines appear clearly doubled. From these we derive v sin i for both components of 5+-2 km sE-1. These values supersede the <15 km s^-1 values of Herbig and Spalding (1955) which were derived from blue spectra (lambda_c ~4500 Angström) where blending is much more severe. [FIGURE 1] Gordon (1946) found the component with the larger radial-velocity amplitude being also the fainter but assigned identical spectral classifications (G8 III-IV). Petrie (1950) measured a brightness difference between the two components of 0.29+-0.02 mag from 6 FeI and TiII lines at around 4500 Angström. From our red-wavelength spectrum centered at 6600 Angström we find a mean ratio of the line strengths of 0.78+-0.08 from eight FeI and CaI lines corresponding to a magnitude difference of 0.27+-0.08 mag in the same sense than found by Petrie. With equal brightness differences in the red and in the blue, the brighter component must be of (approximately) equal spectral type but slightly larger, and thus slightly more massive which is in agreement with the observed mass ratio of 1.11. If we assume synchronous rotation (i.e., P_rot = P_orb), our v sin i measures translate into minimum radii of 11+-5 R_Sun. Thus, the giant classification seems to be appropriate for both components. Two ultra-violet spectra are available in the IUE archive. SWP26529 was underexposed and shows mostly noise. CIV was not detected to an upper limit of about 5x10^-13 ergs.cm^2.s^-1 (J. Eaton, private communication). LWP4671 shows double, but otherwise normal, Mg II h and k lines (Fig. 2). [FIGURE 2] With an orbital period of 115 days, e=0 (Batten, Fletcher, MacCarthy 1989) and assumed synchronism, eta And would be already an unlikely case of an active binary system of the long-period RS CVn class Another long-period system (4 UMi, P_orb=605 days) originally listed in the CABS catalog as having weak (I_K=3) H and K emission, was recently found to be chromospherically inactive (Strassmeier et al. 1990). There are two more systems in the catalog which need high-resolution Ca II H and K observations to verify (or contradict) Wilson's eye-based estimates: nu^2 Sgr and tau Sgr. K. G. STRASSMEIER J. HRON Institut fur Astronomie Universitat Wien Türkenschanzstrase 17 A-1180 Wien AUSTRIA References: Batten, A.H., Fletcher, J.M., MacCarthy, D.G 1989, EIGHT CATALOG OF THE ORBITAL ELEMENTS OF SPECTROSCOPIC BINARIES, Publ. Dom. Astrophys. Obs., 17, 1. [BIBCODE 1989PDAO...17....1B ] Gordon, K.C. 1946, Ap. J., 103, 13.[BIBCODE 1946ApJ...103...13G ] Herbig, G.H., Spalding, J.F. Jr. 1955, Ap. J., 121, 118. [BIBCODE 1955ApJ...121..118H ] Petrie, 1950, Pub. Dom. Astrophys. Obs., 8, 319. [BIBCODE 1950PDAO....8..319P ] Strassmeier, K.G., Hall, D.S., Zeilik, M., Nelson, E., Eker, Z., Fekel, F.C. 1988, Astr. Ap. Suppl., 72, 291. [BIBCODE 1988A&AS...72..291S ] Strassmeier, K.G., Fekel, F.C., Bopp, B.W., Dempsey, R.C., Henry, G.W. 1990, Ap. J. Suppl., 72, 191. [BIBCODE 1990ApJS...72..191S ] Weiss, W.W., Barylak, M., Hron, J., Schmiedmayer, J. 1981, Pub. A.S.P., 93,787 [BIBCODE 1981PASP...93..787W ] Weiss, W.W., Schalk, A., Ogris, V. 1987, Pub. A.S.P., 99, 303. [BIBCODE 1987PASP...99..303W ] Wilson, O.C. 1976, Ap. J., 205, 823. [BIBCODE 1976ApJ...205..823W ]