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Contact Binaries with Additional Components. II. A Spectroscopic Search for Faint Tertiaries
It is unclear how very close binary stars form, given that during thepre-main-sequence phase the component stars would have been inside eachother. One hypothesis is that they formed farther apart but were broughtin closer after formation by gravitational interaction with a thirdmember of the system. If so, all close binaries should be members oftriple (or higher order) systems. As a test of this prediction, wepresent a search for the signature of third components in archivalspectra of close binaries. In our sample of 75 objects, 23 show evidencefor the presence of a third component, down to a detection limit oftertiary flux contributions of about 0.8% at 5200 Å (consideringonly contact and semidetached binaries, we find 20 out of 66). In ahomogeneous subset of 59 contact binaries, we are fairly confident thatthe 15 tertiaries we have detected are all tertiaries present with massratios 0.28<~M3/M12<~0.75 and implied outerperiods P<~106 days. We find that if the frequency oftertiaries were the same as that of binary companions to solar-typestars, one would expect to detect about 12 tertiaries. In contrast, ifall contact binaries were in triple systems, one would expect about 20.Thus, our results are not conclusive but are sufficiently suggestive towarrant further studies.
| 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.
| 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.
| CCD Minima for Selected Eclipsing Binaries in 2005
Not Available
| Photoelectric Minima of Eclipsing Binaries
Not Available
| Physical Parameters of Components in Close Binary Systems: IV
The paper presents new geometric, photometric and absolute parameters,derived from combined spectroscopic and photometric solutions, for tencontact binary systems. The analysis shows that three systems (EF Boo,GM Dra and SW Lac) are of W-type with shallow to moderate contact. Sevensystems (V417 Aql, AH Aur, YY CrB, UX Eri, DZ Psc, GR Vir and NN Vir)are of A-type in a deep contact configuration. For six systems (V417Aql, YY CrB, GM Dra, UX Eri, SW Lac and GR Vir) a spot model isintroduced to explain the O'Connell effect in their light curves. Thephotometric and geometric elements of the systems are combined with thespectroscopic data taken at David Dunlap Observatory to yield theabsolute parameters of the components.
| Kinematics of W Ursae Majoris type binaries and evidence of the two types of formation
We study the kinematics of 129 W UMa binaries and we discuss itsimplications on the contact binary evolution. The sample is found to beheterogeneous in the velocity space. That is, kinematically younger andolder contact binaries exist in the sample. A kinematically young (0.5Gyr) subsample (moving group) is formed by selecting the systems thatsatisfy the kinematical criteria of moving groups. After removing thepossible moving group members and the systems that are known to bemembers of open clusters, the rest of the sample is called the fieldcontact binary (FCB) group. The FCB group is further divided into fourgroups according to the orbital period ranges. Then, a correlation isfound in the sense that shorter-period less-massive systems have largervelocity dispersions than the longer-period more-massive systems.Dispersions in the velocity space indicate a 5.47-Gyr kinematical agefor the FCB group. Compared with the field chromospherically activebinaries (CABs), presumably detached binary progenitors of the contactsystems, the FCB group appears to be 1.61 Gyr older. Assuming anequilibrium in the formation and destruction of CAB and W UMa systems inthe Galaxy, this age difference is treated as an empirically deducedlifetime of the contact stage. Because the kinematical ages (3.21, 3.51,7.14 and 8.89 Gyr) of the four subgroups of the FCB group are muchlonger than the 1.61-Gyr lifetime of the contact stage, the pre-contactstages of the FCB group must dominantly be producing the largedispersions. The kinematically young (0.5 Gyr) moving group covers thesame total mass, period and spectral ranges as the FCB group. However,the very young age of this group does not leave enough room forpre-contact stages, and thus it is most likely that these systems wereformed in the beginning of the main sequence or during thepre-main-sequence contraction phase, either by a fission process or mostprobably by fast spiralling in of two components in a common envelope.
| CCD Minima for Selected Eclipsing Binaries in 2004
Not Available
| Photoelectric Minima of Some Eclipsing Binary Stars
Not Available
| Physical Parameters of Components in Close Binary Systems: II
We present the absolute parameters of components for five contact binarysystems: AB And, GZ And, AO Cam, DN Cam and DK Cyg. The results arebased on solutions of new multicolor light curves as well as new radialvelocity curves from the DDO radial velocity program. All five systemshave a contact configuration with low (5-13%) to intermediate (30-33%)overfilling factors.
| 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.
| Physical parameters of components in close binary systems. I
The paper presents combined spectroscopic and photometric orbitalsolutions for four close binary systems: SW Lyn, QW Gem, AP Leo andV2150 Cyg. The photometric data are new, while the spectroscopy has beenrecently obtained within the radial velocity programme at the DavidDunlap Observatory. This paper is the first in the planned series ofinvestigations. We give an extensive description of the motivation forthe series and of the main assumptions made in our solutions. The fourtargets of this investigation span a range of typical configurations andthus present different levels of difficulty for the combinedspectroscopic and photometric orbital solutions.
| 162-nd List of Minima Timings of Eclipsing Binaries by BBSAG Observers
Not Available
| Radial Velocity Studies of Close Binary Stars. VIII.
Radial velocity measurements and sine-curve fits to the orbital velocityvariations are presented for the seventh set of 10 close binary systems:V410 Aur, V523 Cas, QW Gem, V921 Her, V2357 Oph, V1130 Tau, HN UMa, HXUMa, HD 93917, and NSV 223. All systems but three (V523 Cas, HD 93917,NSV 223) were discovered photometrically by the Hipparcos mission. Allsystems are double-lined (SB2) binaries, and all but the detached, veryclose system V1130 Tau are contact binaries. The broadening functionpermitted improvement of the orbital elements for V523 Cas, which wasthe only system observed before for radial velocity variations.Spectroscopic/visual companions were detected for V410 Aur and HX UMa.Several of the studied systems are prime candidates for combined lightand radial velocity synthesis solutions.Based on data obtained at the David Dunlap Observatory, University ofToronto.
| Catalogue of the field contact binary stars
A catalogue of 361 galactic contact binaries is presented. Listedcontact binaries are divided into five groups according to the type andquality of the available observations and parameters. For all systemsthe ephemeris for the primary minimum, minimum and maximum visualbrightness and equatorial coordinates are given. If available,photometric elements, (m1+m2)sin3i,spectral type, parallax and magnitude of the O'Connell effect are alsogiven. Photometric data for several systems are augmented by newobservations. The quality of the available data is assessed and systemsrequiring modern light-curve solutions are selected. Selectedstatistical properties of the collected data are discussed.
| 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.
| 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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Osservazione e dati astrometrici
| Costellazione: | Gemelli |
| Ascensione retta: | 06h50m46.06s |
| Declinazione: | +29°27'11.3" |
| Magnitudine apparente: | 10.791 |
| Moto proprio RA: | 12.9 |
| Moto proprio Dec: | -29.7 |
| B-T magnitude: | 11.404 |
| V-T magnitude: | 10.842 |
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