COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 1083 Konkoly Observatory Budapest 1976 January 20 CLOSE BINARIES WITH H AND K EMISSION In 1970 a list was published (1) of 22 close binaries showing H and K emission outside eclipse in at least one component and with the primary (hotter) star a main-sequence or subgiant star. Since that time 5 more binaries have been found to belong to this group, and sufficient spectroscopic material, published and unpublished, is on hand to obtain provisional minimum masses for 21 of them. Each of these systems that has been investigated adequately shows irregularities in its light curve. H_alpha emission is absent or weakly present with variable intensity. AR Lac and RS CVn may be considered prototypes of this group of close binaries. The purpose of this Bulletin is to inform interested persons of the present state of knowledge, as it is known to me, of this group of systems. The accompanying Table gives a summary of pertinent data. While most of the entries in the Table (except almost all of the periods) are from my own material, data published by others have been included without bibliographical references. With the exceptions of WW Dra and AR Lac, the provisional minimum masses are based on my spectrographic material obtained at the Mount Wilson and (primarily) Lick Observatories. The minimum masses should approximate the actual values in all cases except UX Ari. The spectrographic observations are continuing, and I expect to obtain minimum masses of moderate accuracy for all the systems listed except WY Cnc, for which no lines of the secondary component have been found. The more recent spectrographic material has been concentrated in the region of the D lines, made accessible with relatively short exposure times by the use of an electrostatically focussed Varo image tube at the focus of the 50 mm camera of the coude spectrograph attached to the 3 m Lick reflector. While all the systems for which provisional radii are available are detached systems, photometry is required to establish the status of the others. UX Ari is a non-eclipsing member of this group. Another bright potential non-eclipsing member, in the southern sky, is HD 155555. UX Ari, AR Lac, and RT Lac have been detected as variable radio emitters. RS CVn is the system best studied photometrically. Light curves at one or two epochs have been published for several other systems, but a great deal more photometry is needed. Unpublished observations obtained at Kitt Peak show that UX Com and LX Per should be added to the list of systems with complete (total and annular) eclipses. It will be noted that, in most of the systems, the more massive component appears to be the more evolved one in the conventional sense, as is expected in detached systems. There are, on the other hand, several exceptions, at least one of which, Z Her, is typical of members of the group in other respects. A suggestion on a possible mode of evolution of these systems has been presented (2). In the framework of this suggestion, TY Pyx, with two equal components, not subgiants, yet somewhat evolved, would be considered a system in transition between its main-sequence phase and the phase of typical members of the group, such as AR Lac and LX Per. D. M. POPPER Department of Astronomy University of California Los Angeles References: 1. D.M. Popper, I.A.U. Colloq. No. 6, 25 2. R.K. Ulrich, D.M. Popper, Bull.Amer.Astron.Soc. 6, 461, 1974 [BIBCODE 1974BAAS....6..461U ] ------------------------------------------------------------------------ Emission Sp. B-V or M_pri.M_sec. R_pri. R_sec. System V_max P pri.or type sp.type >= >= sec. pri. sec. ------------------------------------------------------------------------ UX Ari* 6.5m 6.4d sec G5 0.63 0.71 CQ Aur 9.0 10.6 sec? G0 SS Boo 10.3 7.6 sec G2 +1.01 1.00 1.00 SS Cam 10.0 4.8 sec G2 +1.0 RU Cnc 10.1 10.2 sec F8 +1.01 WY Cnc 9.6 0.83 pri G5 RS CVn 8.4 4.8 sec F4 +0.91 1.35 1.40 1.7: 4.0: AD Cap 9.8 3.0 both G5 0.5: 1.1: UX Com 10.0 3.6 sec G2 +1.04 0.95 1.12 RT CrB 10.2 5.1 sec G0 1.27 1.34 WW Dra 8.8 4.6 sec G2 +1.0 1.4 1.4 2.3: 3.9: RZ Eri 7.7 39.3 sec Am G8 2.2 1.7 Z Her 7.3 4.0 sec F4 +0.91 1.22 1.10 1.6 2.6 AW Her 9.7 8.8 sec G0 K2 1.38 1.36 MM Her 9.5 8.0 sec G2-5 1.20 1.24 1.5: 2.8: PW Her 9.9 2.9 sec G0 1.4 1.6 GK Hya 9.4 3.6 sec G0 +0.81 1.2: 1.3: RT Lac 10.0 5.1 both G8 K1 0.6 1.5 AR Lac 6.9 2.0 both G2 +0.93 1.30 1.30 1.8 3.1 RV Lib 9.0 10.7 both G2-5 2.2 0.4 VV Mon 9.4 6.0 sec G2 LX Per 8.1 8.0 sec G2 +0.93 1.23 1.32 1.6: 2.8: SZ Psc 7.3 4.0 sec F8 K1 1.33 1.65 1.6: 4.0: UV Psc 9.1 0.86 both G2 +0.91 1.2 0.9 TY Pyx 6.9 3.2 both G2-5 +0.69 1.20 1.22 1.6: 1.6: RW UMa 10.2 7.3 sec F8 +1.08 1.50 1.45 2.0: 3.8: RS UMi 10.1 6.2 sec F8 ---------------------------------------------------------------------- * Not eclipsing [From IBVS 1090] CORRECTION TO IBVS No.1083 In the Table for the note on "Close Binaries with H and K Emission" there is an error in the magnitude of RT Lac. It should be 9.0 rather than 10.0. D.M. POPPER