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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
We present 29 minima observations of 11 eclipsing binaries.
| Radial Velocity Studies of Close Binary Stars. II.
Radial velocity measurements and simple sine-curve fits to the orbitalvelocity variations are presented for the second set of 10 contactbinary systems. Eight systems are of the A type: AH Aur, CK Boo, DK Cyg,UZ Leo, XZ Leo, V839 Oph, GR Vir, and NN Vir; V842 Her is the only Wtype, while SV Equ appears to be a semidetached system seen at a loworbital inclination rather than a contact binary. Several of the studiedsystems are prime candidates for complete light and radial velocitysynthesis solutions.
| CCD Photometry of Five Neglected Eclipsing Binary Stars
Differential V-magnitude CCD photometric data are presented for fiveneglected eclipsing binary stars with shallow eclipses. An improvedperiod is derived for SV Equ, past O-C trends are confirmed for AN Andand DL Vir, and an unexpectedly large O-C values are found for BW DELnad CS Lac.
| Near-contact binaries
Not Available
| Statistics of categorized eclipsing binary systems Lightcurve shapes, periods, and spectral types
The statistics of the light curve morphologies, eclipse depths, orbitalperiods, and spectral types of about 1000 eclipsing binary systems areexamined, after attempting to subdivide these binaries into variousbasic evolutionary categories. The applicability of statisticalcriteria, based on light curve morphologies and eclipse depths, for thecategorization of eclipsing binaries has been found more limited thanpreviously believed. In particular, EW-type light curves turn out to begood indicators of contact systems (though not conversely), while EA-and EB-type light curves have little physical significance. Moreover,the study reveals a strong deficit of short-period noncontact systems inthe whole spectral range, together with an underabundance of early-typecontact binaries (compared with the number of late-type contact pairs).Interestingly, the distribution of evolved Algol-type systems isshifted, on average, to periods longer than those of unevolved detachedsystems in the OB and early A spectral range (and to shorter periods inthe F spectral range).
| Violet and ultraviolet continua of W UMa systems on the basis of UVBY photometry observations
New observations of 17 southern WUMa systems are discussed together withprevious uvby data for 44 systems to determine properties of violet andultraviolet spectral distributions and to relate them to theperiod-color relation. The interstellar-reddening-corrected delta(m1)values extend from -0.02 to +0.10, which could be interpreted by aplausible range of metallicities; the most positive values of delta(m1)and largest ultraviolet excesses are observed for systems having theshortest periods at a given spectral type. The reddening-correcteddelta(c1) values are close to zero and are only slightly positive forearlier spectral types - mean delta (cl) = +0.04 for (b-y)O less than0.31 - indicating only very slight evolutionary advancement. Traces of adelta(cl) = -delta(ml) correlation for least evolved systems - smallestdelta(cl) - leave the possibility of intrinsic excesses still open.
| A catalogue of parameters for eclipsing binaries
Not Available
| Contact binaries . III. Early-type systems.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978AJ.....83..288E&db_key=AST
| 57th Name-List of Variable Stars
Not Available
| New Variable Star in Equuleus
Not Available
| Lettera alla Direzione: Nuova variabile in Equuleus
Not Available
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