J/A+AS/116/497 Radial velocities of 4 Cepheids (Imbert, 1996) ================================================================================ Cepheids and binarity. II. Radial velocities and spectroscopic orbits of four galactic cepheids: RX Camelopardis, MW Cygni, Z Lacertae and U Vulpeculae Imbert M. =1996A&AS..116..497I (SIMBAD/NED BibCode) ================================================================================ ADC_Keywords: Binaries, spectroscopic ; Stars, variable Keywords: stars: individual: RX Cam, MW Cyg, Z Lac, U vul - cepheids - binaries: spectroscopic Description: Continued radial velocity observations over several years, have allowed to discover four spectroscopic binary systems among our sample of twenty five galactic Cepheids. Each system is composed by the Cepheid and an invisible probably hot dwarf star. A spectroscopic orbit has been determined for each system. The orbital periods for RX Cam, MW Cyg, Z Lac and U Vul are 1113, 439, 383 and 2510 days, respectively. For the pulsation motion, radial velocity versus phase diagram have been fitted by an analytic relation, formally similar to a Kepler motion. The stellar radius variation of each cepheid has been derived by integration of this relation over the whole pulsating period. Objects: ---------------------------------------------------------------------- RA (2000) DE Name ---------------------------------------------------------------------- 04 04 58.4 +58 39 35 RX Cam = HD 25361 20 12 22 +32 52.5 MW Cyg = HD 331970 22 40 52.1 +56 49 46 Z Lac = HD 214975 09 33 13.2 -45 30 55 U Vel = HD 82850 ---------------------------------------------------------------------- File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table2 75 401 Observed and calculated radial velocities table5 63 194 Pulsation component of the radial velocity (Coravel measures) -------------------------------------------------------------------------------- Byte-by-byte Description of file: table2 -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 6 A6 --- Name Star name 8- 18 F11.4 --- OBSdate UT date of observation (ddmmyy.hhmm). 22- 33 F12.4 d HJD Heliocentric Julian date 36- 41 F6.2 km/s Vobs Observed velocity 44- 49 F6.2 km/s Vcal Calculated velocity (1) 52- 57 F6.2 km/s Vobs-Vcal Observed - calculated radial velocity 60 I1 --- Ref Source references (2) -------------------------------------------------------------------------------- Note (1): Calculated velocity by superposition of the pulsation and orbital motion following: Vcal(t)=Vo+KP[eP(coswP)+cos(vP(t)+wP)]+Kb[eb(coswb)+cos(vb(t)+wb)] +KG[eG(coswG)+cos(vG(t)+wG)] Note (2): References are: (1) Coravel (2) Barnes et al. 1988 (1988ApJS...66...43B) (3) Evans & Welch 1993 (1993PASP..105..836E) (4) Gieren 1989 (1989PASP..101..160G) (5) Gorynya et al. 1992a (1992PAZh...18..777G) (6) Gorynya et al. 1992b (1992IBVS.3776....1G) (7) Joy 1937 (8) Sanford 1951 (1951ApJ...114..331S) (9) Struve 1945 -------------------------------------------------------------------------------- Byte-by-byte Description of file: table5 -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 6 A6 --- Name Star name 8- 18 F11.4 --- OBSdate Observation date (ddmmyy.hhmm) 22- 33 F12.4 d HJD Heliocentric Julian date 40- 45 F6.4 --- Phase [0/1[ Phase 48- 53 F6.2 km/s RVpul Pulsation component of the radial velocity -------------------------------------------------------------------------------- References: Barnes III T.G. et al., 1988, ApJS 66,43 Evans N.R. & Welch D.L., 1993, PASP 105, 836 Gieren W.P., 1989, PASP 101, 160 Gorynya N.A. et al., 1992a, Pis'ma Astron. Zh. 18, 777 Gorynya N.A. et al. 1992b, IBVS 3776 Joy A.H., 1937, ApJ 86, 263 Sanford R.F., 1951, ApJ 114, 331 Struve O., 1945, ApJ 102, 132 ================================================================================ (End) Patricia Bauer [CDS] 15-Mar-1996