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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.
| 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.
| Photoelectric Minima of Some Eclipsing Binary Stars
Not Available
| Times of Minima for Some Eclipsing Binaries
Times of minima for a number of some eclipsing binaries are presented.
| Radial Velocity Studies of Close Binary Stars. VI.
Radial velocity measurements and sine-curve fits to the orbital velocityvariations are presented for the sixth set of 10 close binary systems:SV Cam, EE Cet, KR Com, V410 Cyg, GM Dra, V972 Her, ET Leo, FS Leo,V2388 Oph, and II UMa. All systems except FS Leo are double-linedspectroscopic binaries. The type of FS Leo is unknown, while SV Cam is aclose, detached binary; all remaining systems are contact binaries.Eight binaries (all except SV Cam and V401 Cyg) are the recentphotometric discoveries of the Hipparcos satellite project. Fivesystems, EE Cet, KR Com, V401 Cyg, V2388 Oph, and II UMa, are members ofvisual/spectroscopic triple systems. We were able to observe EE Cetseparately from its companion, but in the remaining four triple systemswe could separate the spectral components only through the use of thebroadening-function approach. Several of the studied systems are primecandidates for combined light and radial velocity synthesis solutions.Based on data obtained at the David Dunlap Observatory, University ofToronto.
| 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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