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.
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B.R.N.O. Contributions #34
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The N2K Consortium. VII. Atmospheric Parameters of 1907 Metal-rich Stars: Finding Planet-Search Targets
We report high-precision atmospheric parameters for 1907 stars in theN2K low-resolution spectroscopic survey, designed to identify metal-richFGK dwarfs likely to harbor detectable planets. Of these stars, 284 arein the ideal temperature range for planet searches,Teff<=6000 K, and have a 10% or greater probability ofhosting planets based on their metallicities. The stars in thelow-resolution spectroscopic survey should eventually yield >60 newplanets, including 8-9 hot Jupiters. Short-period planets have alreadybeen discovered orbiting the survey targets HIP 14810 and HD 149143.
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Photoelectric Minima of Selected Eclipsing Binaries and Maxima of Pulsating Stars
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Photoelectric Minima of Selected Eclipsing Binaries and Maxima of Pulsating Stars
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Contact Binaries with Additional Components. I. The Extant Data
We have attempted to establish observational evidence for the presenceof distant companions that may have acquired and/or absorbed angularmomentum during the evolution of multiple systems, thus facilitating orenabling the formation of contact binaries. In this preliminaryinvestigation we use several techniques (some of themdistance-independent) and mostly disregard the detection biases ofindividual techniques in an attempt to establish a lower limit to thefrequency of triple systems. While the whole sample of 151 contactbinary stars brighter than Vmax=10 mag gives a firm lowerlimit of 42%+/-5%, the corresponding number for the much better observednorthern-sky subsample is 59%+/-8%. These estimates indicate that mostcontact binary stars exist in multiple systems.
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A catalogue of eclipsing variables
A new catalogue of 6330 eclipsing variable stars is presented. Thecatalogue was developed from the General Catalogue of Variable Stars(GCVS) and its textual remarks by including recently publishedinformation about classification of 843 systems and making correspondingcorrections of GCVS data. The catalogue1 represents thelargest list of eclipsing binaries classified from observations.
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CCD Minima for Selected Eclipsing Binaries in 2005
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A Catalog of 1022 Bright Contact Binary Stars
In this work we describe a large new sample of contact binary starsextracted in a uniform manner from sky patrol data taken by the ROTSE-Itelescope. Extensive ROTSE-I light-curve data are combined with J-, H-,and K-band near-infrared data taken from the Two Micron All Sky Surveyto add color information. Contact binary candidates are selected usingthe observed period-color relation. Candidates are confirmed by visualexamination of the light curves. To enhance the utility of this catalog,we derive a new J-H period-color-luminosity relation and use this toestimate distances for the entire catalog. From these distance estimateswe derive an estimated contact binary space density of(1.7+/-0.6)×10-5 pc-3.
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Pre-main sequence star Proper Motion Catalogue
We measured the proper motions of 1250 pre-main sequence (PMS) stars andof 104 PMS candidates spread over all-sky major star-forming regions.This work is the continuation of a previous effort where we obtainedproper motions for 213 PMS stars located in the major southernstar-forming regions. These stars are now included in this present workwith refined astrometry. The major upgrade presented here is theextension of proper motion measurements to other northern and southernstar-forming regions including the well-studied Orion and Taurus-Aurigaregions for objects as faint as V≤16.5. We improve the precision ofthe proper motions which benefited from the inclusion of newobservational material. In the PMS proper motion catalogue presentedhere, we provide for each star the mean position and proper motion aswell as important photometric information when available. We providealso the most common identifier. The rms of proper motions vary from 2to 5 mas/yr depending on the available sources of ancient positions anddepending also on the embedding and binarity of the source. With thiswork, we present the first all-sky catalogue of proper motions of PMSstars.
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UBVRI Analysis of the Eclipsing Binary V1128 Tauri
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Analysis of the eclipsing binary V1128 Tauri
We present a periodicity and preliminary light analysis of V1128 Tauri[HIP 17878, GSC 664 694, α (2000) = 03h 49m 27.8s, δ (2000)= +12° 54' 44"]. The observations were taken from 24 - 27 December2003, by RGS, DRF, and NCH with the Southeastern Association forResearch in Astronomy (SARA) 0.9-m reflector and AP7 CCD at Kitt Peak.Standard UBVRcIc filters were used. Between 70 and 100 observations weretaken in each pass band. Mean epochs of minimum light for two secondaryeclipses, HJD = 2452998.6636(12) and 2453000.8048(7) as well as oneprimary eclipse, 2453000.6524(3) were determined using quadratic fits.We calculated the following ephemeris from all available timings ofminimum light:J.D. Hel Min I = 2453000.6526 (2) + 0.30537315 (6) d*EV1128 Tau is a near contact or shallow contact solar-type binary. Theeclipse depths are slightly unequal; the amplitudes in V are 0.74 magand 0.70 mag. The slight difference in the maxima gives evidence of somespot activity. A Wilson-Devinney code solution is presented.We wish to thank SARA for their allocation of observing time, and thegrant from NASA administered by the American Astronomical Society.
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Up-to-Date Linear Elements of Eclipsing Binaries
About 1800 O-C diagrams of eclipsing binaries were analyzed and up-todate linear elements were computed. The regularly updated ephemerides(as a continuation of SAC) are available only in electronic form at theInternet address: http://www.as.ap.krakow.pl/ephem/.
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Key parameters of W UMa-type contact binaries discovered by HIPPARCOS
A sample of W UMa-type binaries which were discovered by the HIPPARCOSsatellite was constructed with the aid of well defined selectioncriteria described in this work. The selection process showed up thatseveral systems of which the variability types have been assigned as EBin HIPPARCOS catalogue are genuine contact binaries of W UMa-type. Thelight curves of the 64 selected systems based on HIPPARCOS photometrywere analyzed with the aid of light curve synthesis method by Rucinskiand their geometric elements (namely mass ratio q, degree of contact f,and orbital inclination i) were determined. The solutions were obtainedfor the first time for many of the systems in the sample and would be agood source for their future light curve analyses based on more precisefollow-up observations.Based on observations made with the ESA HIPPARCOSastrometry satellite.
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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.
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New Times of Minima of Eclipsing Binary Systems
We present several photoelectric minima observations of 7 eclipsingbinaries.
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Stars with the Largest Hipparcos Photometric Amplitudes
A list of the 2027 stars that have the largest photometric amplitudes inHipparcos Photometry shows that most variable stars are all Miras. Thepercentage of variable types change as a function of amplitude. Thiscompilation should also be of value to photometrists looking forrelatively unstudied, but large amplitude stars.
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The 74th Special Name-list of Variable Stars
We present the Name-list introducing GCVS names for 3153 variable starsdiscovered by the Hipparcos mission.
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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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Optical high-resolution spectroscopy of ROSAT detected late-type stars south of the Taurus molecular clouds.
We study 111 late-type stars found with optical follow-up observationsof ROSAT All-Sky Survey sources south of the Taurus molecular clouds.Some 30 of them have been claimed to be weak-line T Tauri stars,low-mass pre-main sequence (PMS) stars, based mainly on the presence ofstrong lithium 6708Å absorption in intermediate-resolution(~1Å) spectra. We obtained single-order echelle spectra at bluewavelengths for 106 of these stars, in order to measure their radial androtational velocities, and investigate their angular momentum evolutionand kinematic membership to the Taurus clouds. In addition, we obtainedechelle spectra with high (~0.25Å) resolution for seven stars tomeasure precisely the lithium equivalent width Wlambda_(Li).We find that ~1Å resolution is sufficient in order not tooverestimate Wlambda_(Li), e.g. due to blending. Of our 111stars, 19 are located on the λ Ori cloud, nine of which areK-type stars with lithium in excess of the zero-age-main-sequence (ZAMS)level, i.e. are PMS stars. At least 40 of the remaining 92 off-cloudstars display detectable lithium, 24 of which are lithium-excess stars,i.e. show lithium at least as strong as IC 2602 stars with the samespectral types. Of those 24 stars, nine (25% of the off-cloud stars withdetectable lithium) are PMS stars isolated from cloud material; all havespectral type K, and three of them are spectroscopic binaries. 15off-cloud stars have spectral type G and lithium comparable to IC 2602stars, i.e. may have already arrived on the ZAMS just like G-type IC2602 stars. However, all these 24 off-cloud lithium-excess stars areprobably not older than IC 2602 (~3x10^7^yrs). We discuss possible sitesand modes of origin of the isolated PMS stars south of Taurus.
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New proper motions of pre-main sequence stars in Taurus-Auriga
We present proper motions of 72 T Tauri stars located in the centralregion of Taurus-Auriga (Tau-Aur). These proper motions are taken from anew proper motion catalogue called STARNET. Our sample comprises 17classical T Tauri stars (CTTS) and 55 weak-line T Tauri stars (WTTS),most of the latter discovered by ROSAT. 53 stars had no proper motionmeasurement before. Kinematically, 62 of these stars are members of theassociation. A velocity dispersion of less than 2-3km/s is found whichis dominated by the errors of the proper motions. This velocitydispersion correlates with a spread in distances. Furthermore we presentproper motions of 58 stars located in a region just south of the Taurusmolecular clouds and compare the kinematics of the youngest stars inthis sample (younger than 3.5x10^7^yrs) with the kinematics of thepre-main sequence stars (PMS) in the Taurus-Auriga association. From acomparison of the space velocities we find that the stars in the centralregion of Tau-Aur are kinematically different from the stars in thesouthern part. Among the stars with large proper motions far off theTaurus mean motion we find 2 Pleiades candidates and 7 possible Pleiadesrunaway stars.
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INHABITED SKY
