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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.
| Catalogue of Algol type binary stars
A catalogue of (411) Algol-type (semi-detached) binary stars ispresented in the form of five separate tables of information. Thecatalogue has developed from an earlier version by including more recentinformation and an improved layout. A sixth table lists (1872) candidateAlgols, about which fewer details are known at present. Some issuesrelating to the classification and interpretation of Algol-like binariesare also discussed.Catalogue is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/417/263
| Beobachtungsergebnisse Bundesdeutsche Arbeitsgemeinschaft fur Veranderlichen Serne e.V.
Not Available
| New Times of Minima of Eclipsing Binary Systems
Not Available
| Is the Algol-type Eclipsing Binary RX Geminorum a True Triple System?
An analysis of the times of minimum light for the long-period Algol-typeeclipsing binary RX Gem is presented based on a new linear ephemeris.The O-C curve shows a cyclic oscillation with a period of 55.7 yr and asemiamplitude of 0.0645 day. Assuming the change to be due to thepresence of a ``third body'' revolving around the RX Gem system, theparameters of the third body's orbit are derived. Since the third-bodyassumption is in good agreement with the spectroscopic data from severalauthors and with published photometric solutions (Gaposchkin, Hall,& Walter; Giuricin et al.), RX Gem is likely to be a triple system.In this case, the third body is an A-type star in a circular orbit,which is nearly coplanar to the orbit of the eclipsing pair. However,the recent light-curve analysis by Olson & Etzel does not show anythird light, so the third star (M3>2.41 Msolar)may be an unseen neutron star or black hole. Additional eclipse timingsover the next decade will be important to verify the presence of thethird body.
| 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.
| RX Geminorum: New Multicolor Photometry and Spectroscopy, and Light and Velocity Solutions
We describe results from intermediate-band I(Kron)ybvu photometry andCCD spectroscopy of the long-period Algol eclipsing binary RX Geminorum.The best solution yields a hot-star rotation about 19 times thesynchronous rate and a photometric mass ratio about 0.19. Problems withthe earlier solution of Hall & Walter are resolved: neither acontinuum-emitting 'ring' nor a polar hot spot are required on the hotstar. The hot-star radial velocity curve is distorted so a reliablespectroscopic mass ratio cannot be found. Binary parameters are based onnew observations of the well-defined cool-star velocity curve and thephotometric mass ratio. RX Gem is presently a deeply but partiallyeclipsing semidetached binary and the usual caveats apply to oursolution. There are suggestions that significant orbital change hasoccurred during the 20th century. A possible explanation invokesperturbations by an unseen third body. We found a significant departurefrom circular rotation in accretion disk Hα emission, traceable tostream impact on the disk. Sudden brightenings of one emission lobeoriginate in the stream impact region of the disk. Thus, disk Hαemission variations probably result from mass-transfer bursts. This workwas partially supported by NSF grant AST-9417035.
| A Search for Trojan Extrasolar Planets: Planets in V442 Cas and YZ Aql?
In this project we are exploring the light curves of eclipsing binariesfor the signature of planets that may exist at the L4 and L5 Lagrangepoints of the stellar system. While no binaries are known to exist thatstrictly satisfy the stellar mass ratio constraint for the restrictedthree-body problem, the general solution would allow a planet formed atthe L-point to remain there if there are no major perturbing bodies suchas an additional planet. We have coined such objects "Trojan planets."The advantage of this approach is that the phases of the planetaryeclipses are known. We picked systems with deep primary eclipses, tomaximize the amount of system light eclipsed by the planet when in frontof the hotter star. We also scanned the Finding List for Observers ofInteractive Binary Stars, for G dwarf systems ,but found only a few thatwere high inclination and detached. The target list includes QY Aql, YZAql, V442 Cas, SS Cet, S Cnc, VW Cyg, WW Cyg, RR Dra, RX Gem, RY Gem, VWHya, Y Leo, TV Mon, BN Sct, UW Vir, AC UMa, TX UMa, and GSC 1657. Wehave concentrated on V442 Cas and YZ Aql, based on initial results thatshow anomalies in the light curves near the phases where a Trojan planeteclipse is expected. We present results on these two, as well as initialresults for some of the other systems. We gratefully acknowledge thesupport of the National Science Foundation, through grants AST-9731062and AST-0089248. We also appreciate the support of the Fund forAstrophysical Research. Gregory Shelton and Brenda Corbin, at the U.S.naval Observatory Library, have been indispensable in providingreferences for these binary systems. This research has made use of theSimbad database, operated at CDS, Strasbourg, France
| Is asynchronism in semidetached binary systems real?
We analyze statistical relationships between the parameters ofAlgol-type binaries with asynchronous rotation of the primary componentsand provide observational evidence for denser, more extended gaseousenvelopes in the eclipsing systems of this group. We conclude thatasynchronism of the primary components in such systems is not real. Thelines that are used to determine the rotational velocities of thesecomponents originate mostly in the part of the atmosphere which acquiresan additional angular momentum during the interaction with the gasstream and produces a transient accretion disk near the equatorialplane.
| Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
| UBV Photometry of W Ser Stars
Not Available
| DN Orionis: A Long-Period Mass-Transferring "Slightly Detached" Algol Binary
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995AJ....110.1809E&db_key=AST
| Rapid H-alpha emission variations in accretion disks in long-period ALGOLS
We demonstrate the continuous presence of large variations indouble-peaked H-alpha long period Algol-type binaries, using recentlyobtained CCD spectra. Most fluctuations occur on a time scale less thanor = an orbital period and a steady state in H-alpha emission ia neverreached. In AD Her (P = 10 d), H-alpha emission dropped in strength morethan a factor of five in one seven-day interval. Contemporay O I lambdaobservations showed no significant changes in oxygen absorption strengthor radial velocity during this time. We tentatively suggest that H-alphavariations arise from an inner-disk instability, possibly triggered bysmall modulations in the mass-transfer rate. This behavior isreminiscent of some cataclysmic variables.
| O I lamba 7774 absorption as a tracer of streams and disks in nondegenerate binary stars
We propose a new spectroscopic approach for observing circumstellarmatter in binary stars, based on the neutral oxygen lambda 7774absorption lines. We present oxygen equivalent widths and radialvelocities in 20 nondegenerate eclipsing binaries. We note limitationsand advantages of using this line to trace circumstellar matter inbinary systems, and confirm the presence of streams and rotatingaccretion disks in a number of short- long-period Algol systems. Wediscuss evidence for geometrically thick disks, and describe a smallradial infall superimposed on disk rotation in most long-period systems.We speculate that infall may be related to viscous dissipation in disks.We emphasize the great sensitivity of lambda 7774 in studying thekinematics of circumstellar matter in many nondegenerate binary stars.
| Radio continuum emission from stars: a catalogue update.
An updated version of my catalogue of radio stars is presented. Somestatistics and availability are discussed.
| New rotational velocities for eclipsing binaries, and a comparison of spectroscopic and photometric rotations
Rotational velocities are determined spectroscopically for 38 eclipsingbinaries, including many long-period, nominally semidetached, systems.We note that spectroscopic rotations may differ from rotations derivedfrom light-curve modeling using the Wilson-Devinney program. In'direct-impact' mass-transferring systems, or in most systems withperiods smaller than about 7 days, observations suggest that the tworotations are usually about the same. In cases where the stream missesthe gainer and an accretion disk forms, however, photometric rotationestimates often exceed spectroscopic determinations. The possiblephysical significance of this situation is briefly discussed. Doubt iscast on the likelihood that the rotation of the hot component of U Sgehas changed detectably in the last 30 years.
| Radio observations of peculiar emission-line Algol binary stars
Twelve peculiar emission-line Algol (PELA) binaries were observed at cmwavelengths. Six of these objects, WW And (tentative), KX And, AM Aur,V644 Mon, DN Ori, and AY Per were detected at the 100 to 400 micro-Jylevel, corresponding to luminosity densities of order 10 exp 17erg/s/Hz. These luminosity densities, combined with nearly flat cmspectra and high brightness temperatures, are consistent with thenonthermal gyrosynchrotron radiation model proposed as the result ofobservations from the previous PELA survey. Also, the star V367 Cyg wasreobserved at thirteen different orbital phases; no variability wasfound within the errors. V367 Cyg's lack of variability andwell-determined average spectral index, however, imply the possibilityof a different emission mechanism, thermal bremsstrahlung, although thenonthermal model cannot be entirely ruled out. The characteristicbrightness temperature of thermal bremsstrahlung is only about 10,000 K,which means that the radius of the emission region would have to be muchlarger than previously assumed, about 10 AU. Suggestions for furtherobservations of all previously observed PELAS are presented in order todetermine the correct emission mechanism.
| Radio Emission From Peculiar Emission-Line Algol Binaries
Not Available
| Period changes of ten eclipsing variable stars
The period variations of 10 eclipsing binary stars (WZ And, RX Cas, SXCas, TW Cas, XX Cep, RX Gem, TT Her, TU Mon, RW Per, and TX UMa) areexamined. A physical interpretation of the combined observational resultis given on the basis of a study of each individual star and in view ofthe Biermann-Hall (1973) model.
| Statistical study of semi-detached and near-contact semi-detached binaries
A statistical study was made of 107 semidetached with combined lightcurve solutions. An empirical period-dependent mass-radius relation wasderived, thereby revealing the impossibility of having evolvedsemidetached systems with very short periods. Statistically, thenear-contact semidetached systems have the common properties of nearlyequal mass densities of the components, larger mass-ratios, shorterperiods and smaller specific angular momenta, and their A- F-typesecondaries generally have greater densities than the secondaries ofclassical Algol systems of the same spectral types. A detaileddiscussion is also made in this paper on the evolution of near-contactsemidetached binaries.
| Investigation of statistical data for close binary stars.
Not Available
| Radial velocities in 12 Algol binaries
Radial velocities derived from photometric analysis of the Na D linesfor the cooler components of the 12 Algol systems are discussed. Thenumber of velocities per system at the D lines ranges from 6 to 63, andin each case, the velocities are well represented by circular motion.For a 5-day period, the spectra of the primaries in RY Aqr, TW Dra, TWAnd, and RS Vul appear to be completely photospheric, while the othereight systems, Rx Gem, Ry Gem, AD Her, TT Hya, Au Mon, RW Per, RY Per,and XY Pup, show double H-alpha emission and other evidence ofnonphotospheric material in the hotter spectra. For most of thesesystems of longer period, the velocities are quite well represented bypseudoelliptical motion, with minimum velocities and maximum departuresfrom circular motion near phase 0.4, measured from primary minimum.Provisional masses are given for the stars based on the availablespectroscopic and photometric evidence, much of it of low weight. Thecompanions of the primaries with A-type spectra have masses of 0.75solar mass or less, and temperatures or types in the early K range asobserved in RY Aqr. All the secondaries are larger than main-sequencestars of the corresponding types.
| A summary of the investigations of semi-detached close binaries (1986-1988)
Not Available
| Statistical Study on the Semidetached and Near Contact Semidetached Binary Systems
Not Available
| Gravitational wave spectra from eccentric binaries - A preliminary census
Gravitational waves (GW) from binary stars are promising candidates forGW detection experiments. The spectral distribution of GW bathing theearth from a set of 1048 binary stars has been computed, and the resultsare presented. Orbital eccentricity and all relevant harmonics areincluded.
| A spectrophotometric study of the Algol binary system RX Geminorum
IUE low-dispersion spectra and optical ITS scans of the semidetachedAlgol-type binary system RX Gem have been obtained. The spectral type ofthe primary component was determined to be A0, with good accuracy. Sincethe primary eclipse is only partial, the spectral type of the coolercomponent has been determined with less accuracy as K2 (+ or - 2). Thesystem is only slightly reddened: its color excess is E(B-V) = 0.04 + or- 0.01 mag. Two models of the system are considered, depending on theluminosity class of the hotter star. Optically, the system is a Be star,since it displays Balmer line emission, visible most clearly during theprimary eclipse. The ultraviolet spectrum observed near mideclipse doesnot display the expected 'W Serpentis-type' emission lines. Probably themain reason is that the primary eclipse is only partial.
| Absolute parameters of stars in semidetached eclipsing binary systems
A number of questions concerning the absolute parameters of stars insemidetached binary systems are addressed. Consideration is given to:similarities between Algol-type binaries and unevolved detached binarieswith respect to the mass-luminosity law; and the single-line classicalAlgol candidates with known mass functions and photometric solutions formass ratio. It is shown that the validity of the mass luminosity-lawcannot be verified for individual Algol-type binaries though it doeshold well on average; and (2), the existence of a definite class ofsd-binaries not containing a proportion of significantly undersize typesis apparent. The conclusions are found to be in general agreement withthe observations of Hall and Neff (1979).
| Comparsion Stars for Some Eclipsing Binaries
Not Available
| A Catalogue of Classical Evolved Algol-Type Binary Candidate Stars
Not Available
| Spectrographic material for RS Canum Venaticorum and Algol binaries
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1982PASP...94..945P&db_key=AST
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