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Radial Velocity Studies of Close Binary Stars. XIII
Radial velocity (RV) measurements and sine-curve fits to the orbital RVvariations are presented for ten close binary systems: EG Cep, V1191Cyg, V1003 Her, BD+7°3142, V357 Peg, V407 Peg, V1123 Tau, V1128 Tau,HH UMa, and PY Vir. While most of the studied eclipsing systems arecontact binaries, EG Cep is a detached or a semidetached double-linedbinary and V1003 Her is a close binary of an uncertain type seen at avery low inclination angle. We discovered two previously unknown triplesystems, BD+7°3142 and PY Vir, both with late spectral-type (K2V)binaries. Of interest is the low mass-ratio (q = 0.106) close binaryV1191 Cyg showing an extremely fast period increase; the system has avery short period for its spectral type and shows a W-type light curve,a feature rather unexpected for such a low mass-ratio system.Based on the data obtained at the David Dunlap Observatory, Universityof Toronto.
| UBVRI Analysis of the Eclipsing Binary V1128 Tauri
Not Available
| Radial Velocities of Population II Binary Stars. Ii.
Here we publish the second list of radial velocities for 91 Hipparcosstars, mostly high transverse velocity binaries without previous radialvelocity measurements. The measurements of radial velocities are donewith a CORAVEL-type radial velocity spectrometer with an accuracy betterthan 1 km/s. We also present the information on eight new radialvelocity variables -- HD 29696, HD 117466 AB, BD +28 4035 AB, BD +302129 A, BD +39 1828 AB, BD +69 230 A, BD +82 565 A and TYC 2267-1300-1-- found from our measurements. Two stars (HD 27961 AB and HD 75632 AB)are suspected as possible radial velocity variables.
| Ground-based photometry of the contact binary V1128 Tauri
V1128 Tau is a short period W UMa type eclipsing binary which has avisual companion with a separation of 14arcsec and a difference inbrightness of about 1 mag. We observed the system in B and V filtersduring two observing seasons using three different telescopes anddetectors. We obtained a total of 6063 observational points in eachcolour. The light curve reveals that V1128 Tau has a totality in theprimary eclipse, which lasts about 16 min. The shape of the light curveindicates that V1128 Tauri is a W-type W UMa binary. We subtracted thevisual component's light contribution to the total light of the system.We used the latest version of the Wilson-Devinney code for the analysisof the light curves and determined for the first time the geometric andphysical parameters of the system. We found that the system consists oflate G and early K type components. The more massive, larger componentis cooler by about 300 K than its companion. The system has a circularorbit with an inclination of 85degr . The light curves show a typicalO'Connell effect, maximum I being brighter than maximum II. Thisdifference may arise from a cool or hot region on either componentand/or an accretion process between the components. Since the componentsappear to be later than G2, we assumed a cool spot or group of spots onthe cooler component. Therefore, the light curves were also analyzedusing the spot hypothesis and the results were compared with thoseobtained with the no-spot model.
| New Times of Minima of Eclipsing Binary Systems
We present several photoelectric minima observations of 7 eclipsingbinaries.
| Search for young low-mass stars in a ROSAT selected sample south of the Taurus-Auriga molecular clouds
We present results of intermediate resolution spectroscopy of 131optical counterparts to 115 ROSAT All-Sky Survey X-ray sources south ofthe Taurus-Auriga dark cloud complex. These objects have been selectedas candidate young stars from a total of 1084 ROSAT sources in a ~300square degree area. We identify 30 objects as low-mass PMS stars on thebasis of the Li i, lambda 6708 Angstroms doublet in their spectrum, asignature of their young age. All these stars have a spectral type laterthan F7 and show spectral characteristics typical of weak-line andpost-T Tauri stars. The presence of young objects several parsecs awayfrom the regions of ongoing star formation is discussed in the light ofthe current models of T Tauri dispersal. Based on observations made withthe Isaac Newton Telescope operated on the island of La Palma by theRoyal Greenwich Observatory in the Spanish Observatorio del Roque de losMuchachos of the Instituto de Astrofisica de Canarias and with the ESO1.52m telescope on La Silla, Chile, operated by the European SouthernObservatory. Tables 1,2,3,4 are also available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
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