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Photoelectric Minima of Selected Eclipsing Binaries and Maxima of Pulsating Stars
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| The connection between the pulsational and orbital periods for eclipsing binary systems
Considering a sample of 20 eclipsing binary systems with δ Scutitype primaries, we discovered that there is a possible relation amongthe pulsation periods of the primaries and the orbital periods of thesystems. According to this empirical relation, the longer the orbitalperiod of a binary, the longer the pulsation period of its pulsatingprimary. Among the sample, the masses of the secondaries and theseparations between the components are known for eight systems for whicha logPpuls versus logF (the gravitational pull exerted pergram of the matter on the surface of the primaries by the secondaries)diagram also verifies such an interrelation between the periods. So, asthe gravitational force applied by the secondary component onto thepulsating primary increases, its pulsation period decreases. Thedetailed physics underlying this empirical relation between the periodsneeds further confirmation, especially theoretically. However, one mustalso consider the fact that the present sample does not contain asufficiently large sample of longer period (P > 5 d) binaries.
| An improved ephemeris for AB Persei
The ephemeris of the eclipsing binary AB Persei given in the GCVSrepresents modern data badly. I review reported observations and offeran improved ephemeris.
| 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.
| Spectroscopic observations of the oEA-type variable AB Per.
We present spectroscopic results of the Algol-type semi-detachedeclipsing binary AB Per. The binary system had shown short-periodiclight variations of about 0.2 day by our previous photometric study\citep{kim2003}. We have obtained high-resolution echelle spectra inorder to investigate the variability source. The spectra show strongemission at Halpha 6563Å, indicating that AB Per hascircumstellar gases around the primary component. We identified spectrallines of the primary and secondary components separated by the Dopplershift, and found that both components do not rotate fast enough tointerpret the short-periodic light variations as a rotation effect. Inconclusion, the short-periodic light variations are originated frompulsation of the primary component and then AB Per is a bona-fide memberof the oscillating EA stars.
| An Algol type binary with a δ Scuti component: RZ Cassiopeiae revisited
We present new BV photometry and spectroscopic observations of RZCassiopeiae. The light and radial velocity curves were formed by the newobservations which have been analyzed simultaneously by using theWilson-Dewinney code. The non-synchronous rotational velocityv1sin i = 76 ± 6 km s-1, deduced for theprimary component from the new spectroscopic observations, was alsoincorporated in the analysis. A time-series analysis of the residuallight curves revealed the multi-periodic pulsations of the primarycomponent of RZ Cas. The main peak in the frequency spectrum wasobserved at about 64.197 c d-1 in both B and V bands. Thepulsational constant was calculated to be 0.0116 days. This valuecorresponds to high overtones (n˜6) of non-radial modeoscillations. We find significant changes in the pulsational amplitudeof the primary component from year to year. The peak-to-peak pulsationalamplitude of the main frequency displays a decrease from 0.013 m in 2000to 0.002 m in 2001 and thereafter we have found an increase again in theamplitude to 0.01 m in the year 2002. We propose the mass transfer fromthe cool secondary to the pulsating primary as a possible explanationfor such remarkable changes in the pulsational behavior of the primarycomponent.
| Development of a 1-m Robotic Telescope System
Korea Astronomy & Space Science Institute (KASI) has installed a 1-mrobotic telescope at Mt. Lemmon, AZ, in collaboration with a company,Astronomical Consultants & Equipment, Inc (ACE). The telescopesystem is totally designed to make fully robotic observations, and canbe operated in both interactive and unattended robotic modes. Thetelescope is newly designed and manufactured regarding both mechanicaland optical parts. The optical system is designed to collect 80% of theincident light within 0.''5 with an f/7.5 Ritchey-Chretien design. Thetelescope mount is an equatorial fork with a friction drive system, andit allows fully programmable tracking speeds with a typical range of15'' s-1 and an accuracy of ±5''hr-1. Themount system includes an integral pointing model to correct formechanical errors and misalignments, and an auto-guide unit is alsoavailable. To gather environmental information a weather station and anall sky camera are installed at the site. In this paper we introduce thesystem design and the performance of the mechanical and optical qualityof the telescope system based on the results of test observations usingsome variable stars.
| Photoelectric Minima of Selected Eclipsing Binaries and Maxima of Pulsating Stars
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| Beobachtungssergebnisse Bundesdeutsche Arbeitsgemeinschaft fuer Veraenderliche Sterne e.V.
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| Frequency spectrum of the rapidly-oscillating mass-accreting component of the Algol-type system AS Eri
The first multisite photometric campaign devoted to the rapidlyoscillating mass-accreting (primary) component of the Algol-typeeclipsing binary system AS Eri has confirmed the presence of rapidpulsations with frequency 59.03116 d-1, and revealed thesecond and third oscillation modes with frequencies 62.5631d-1 and 61.6743 d-1, respectively. These modes arerelated to the 5-6 overtone oscillations and are among the shortestperiods excited in non-magnetic MS A-F stars. The nearly equator-onvisibility of eclipsing binaries help to narrow the range of possiblemode identifications for the detectable modes as radial or(l,m)=(1,±1), (l,m)=(2,±2) and (l,m)=(2,±0). Wechecked the high-order pulsation-to-orbital synchronization (POS) usingthe trial mode identification and the Doppler effect correction forfrequencies of non-radial pulsation. We found that (l,m,n)=(1,1,5) or(2,2,5) and (l,m,n)=(2,-2,6) identifications for f1 andf2 modes respectively satisfied the high-order POS. Thesemode identifications are in agreement with the range of modes visible indisk integrated light of an equator-on visible pulsating component.The wavelength distribution of pulsation amplitudes in AS Eri is largestin the Strömgren u filter and decreases toward longer wavelengths.We place AS Eri and other known mass-accreting pulsating components ofAlgols on HR-diagram. They are located inside the instability strip onthe Main Sequence. We also discuss the peculiar evolutionary status ofprimary components in Algols and stress that they are not normal δScuti stars, but form a separate group of pulsators. Finally, we discussproximity and eclipse effects, and have simulated the effect of primaryminimum data gaps that may produce the 1/Porb alias sidelobesin DFT analysis of eclipsing binary data. Aliases from gaps in primaryminimum observations seem to be the principal limitation on spectralwindow functions in asteroseismic studies of eclipsing binaries.
| 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
| δ Sct-type pulsations in eclipsing binary systems: RZ Cas
We present the results of a three-continent multisite photometriccampaign carried out on the Algol-type eclipsing binary system RZ Cas,in which the primary component has recently been discovered to be aδ Sct-type pulsator. The present observations include, for thefirst time, complete simultaneous Strömgren uvby light curvestogether with a few Crawford Hβ data collected around the orbitalphase of the first quadrature. The new observations confirm thepulsational behaviour of the primary component. A detailed photometricanalysis, based on these observations, is presented for both binarityand pulsation. The results indicate a semidetached system where thesecondary fills its Roche lobe. The appearance of the light curvesreveals the presence of the mass stream from the secondary component anda hotspot where this stream impacts on the surface of the primary star.There are also some indications of chromospheric activity in thesecondary. On the other hand, the pulsational behaviour out-of-primaryeclipse can be well described with only one frequency at 64.1935cd-1 similar to the main peak found by Ohshima et al. Theexistence of multiperiodicity is not confirmed in our data. Concerningthe mode identification, our results indicate non-radial pulsation in ahigh radial order (n= 6), with l= 2, |m|= 1, 2 as the most suitable.However, additional effects must be taken into account in thepredictions. Moreover, the pulsation amplitude in the u band is largerthan in b and v, which is unusual among the δ Sct-type variables.This can be explained as due to pulsation in a high n value and close tothe blue edge of the δ Sct region. On the other hand, the earlydata of Ohshima et al. have also been analysed and similar results arefound concerning the frequency content and pulsational amplitude.Finally, a revision of all the photometric out-of-primary-eclipse datasets available in the literature is made together with some additionalunpublished data leading to interesting findings relative to changestaking place in the pulsation amplitudes and frequencies from season toseason. Furthermore, multiperiodicity is probably present in someepochs.
| The first CCD photometric study of the open cluster NGC 2126
We present the first CCD photometric observations of the northern opencluster NGC 2126. Data were taken on eight nights in February andDecember 2002 with a total time span of ~ 57 hours. Almost 1000individual V-band frames were examined to find short-period variablestars. We discovered six new variable stars, of which one is a promisingcandidate for an eclipsing binary with a pulsating component. Two starswere classified as delta Scuti stars and one as Algol-type eclipsingbinary. Two stars are slow variables with ambiguous classification. Fromabsolute V(RI)C photometry we have estimated the maincharacteristics of the cluster: m-M=11fm0 +/-0fm5 , E(V-I)=0fm4 +/-0fm1, E(V-R)=0fm08 +/-0fm06 (E(B-V)=0fm2 +/-0fm15 ) and d=1.3+/-0.6 kpc.Cluster membership is suggested for three variable stars from theirpositions on the colour-magnitude diagram.
| Search for A-F Spectral type pulsating components in Algol-type eclipsing binary systems
We present the results of a systematic search for pulsating componentsin Algol-type eclipsing binary systems. A total number of 14 eclipsingbinaries with A-F spectral type primary components were observed for 22nights. We confirmed small-amplitude oscillating features of a recentlydetected pulsator TW Dra, which has a pulsating period of 0.053 day anda semi-amplitude of about 5 mmag in B-passband. We discovered newpulsating components in two eclipsing binaries of RX Hya and AB Per. Theprimary component of RX Hya is pulsating with a dominant period of 0.052day and a semi-amplitude of about 7 mmag. AB Per has also a pulsatingcomponent with a period of 0.196 day and a semi-amplitude of about 10mmag in B-passband. We suggest that these two new pulsators are membersof the newly introduced group of mass-accreting pulsating stars insemi-detached Algol-type eclipsing binary systems.Table 4 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/405/231
| Detection of a Pulsating Component in the Eclipsing Binary AB Per
We report detection of a pulsating component in the Algol type eclipsingbinary AB Per
| HD 275525, GSC 02866-01866 and GSC 03429-01645 : Three New Delta Scuti Type Variables
We report photometric results of three new delta Scuti stars, HD 275525,GSC 02866-01866 and GSC 03429-01645
| Einige interessante Bedeckungsveraenderliche.
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| Speckle observations of binary systems measured by Hipparcos
From speckle observations made with the PISCO speckle camera at the Picdu Midi Observatory, we present high angular resolution astrometric datafor 43 binary stars already observed by the Hipparcos satellite. Thissample consists of mainly new Hipparcos eclipsing binaries with a visualcompanion closer than one arcsecond, chosen with the aim to study thedynamical implications of a third component on the observationalparameters of the eclipsing system. In addition, we also included aselection of close visual binaries with few speckle data in order toanalyse possible systematic departures between the speckle and thenon-speckle orbits. The reduction method and the results are presentedin detail. For the close visual binaries we confront our observationswith the ephemerides based on the best known orbits. For the wide visualbinaries the confrontation is made directly with the Hipparcos data. Ourobservations are consistent both with previous speckle data and withmost of the Hipparcos measurements. Based on observations made with theTélescope Bernard Lyot at the Pic du Midi Observatory, France andon data obtained by the Hipparcos astrometry satellite. This work hasalso made use of the Simbad database, operated at CDS, Strasbourg,France.
| 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.
| Speckle Interferometry of New and Problem HIPPARCOS Binaries
The ESA Hipparcos satellite made measurements of over 12,000 doublestars and discovered 3406 new systems. In addition to these, 4706entries in the Hipparcos Catalogue correspond to double star solutionsthat did not provide the classical parameters of separation and positionangle (rho,theta) but were the so-called problem stars, flagged ``G,''``O,'' ``V,'' or ``X'' (field H59 of the main catalog). An additionalsubset of 6981 entries were treated as single objects but classified byHipparcos as ``suspected nonsingle'' (flag ``S'' in field H61), thusyielding a total of 11,687 ``problem stars.'' Of the many ground-basedtechniques for the study of double stars, probably the one with thegreatest potential for exploration of these new and problem Hipparcosbinaries is speckle interferometry. Results are presented from aninspection of 848 new and problem Hipparcos binaries, using botharchival and new speckle observations obtained with the USNO and CHARAspeckle cameras.
| On the nature of the AM phenomenon or on a stabilization and the tidal mixing in binaries. II. Metallicity and pseudo-synchronization.
We reveal sufficient evidences that for Am binaries the metallicitymight depend on their orbital periods, P_orb_, rather than on vsini. Inparticular, δm_1_ index seems to decrease with increasing orbitalperiod up to at least P_orb_=~50d, probably even up to P_orb_=~200d.This gives further support to our "tidal mixing + stabilization"hypothesis formulated in Part I. Moreover, while the most metallic Amstars seem to have rather large periods the slowest rotators are foundto exhibit substantially shorter P_orb_. A questioning eye is thus caston the generally adopted view that Am peculiarity is caused by asuppressed rotationally induced mixing in slowly rotating `single'stars. The observed anticorrelation between rotation and metallicity mayhave also other than the `textbook' explanation, namely being the resultof the correlation between metallicity and orbital period, as themajority of Am binaries are possibly synchronized. We further argue thatthere is a tendency in Am binaries towards pseudo-synchronization up toP_orb_=~35d. This has, however, no serious impact on our conclusionsfrom Part I; on the contrary, they still hold even if this effect istaken into account.
| On the nature of the AM phenomenon or on a stabilization and the tidal mixing in binaries. I. Orbital periods and rotation.
The paper casts a questioning eye on the unique role of the diffusiveparticle transport mechanism in explaining the Am phenomenon and arguesthat the so-called tidal effects might be of great importance incontrolling diffusion processes. A short period cutoff at =~1.2d as wellas a 180-800d gap were found in the orbital period distribution (OPD) ofAm binaries. The existence of the former can be ascribed to the state ofthe primaries with the almost-filled Roche lobes. The latter couldresult from the combined effects of the diffusion, tidal mixing andstabilization processes. Because the tidal mixing might surpassdiffusion in the binaries with the orbital periods P_orb_ less thanseveral hundred days and might thus sustain the He convection zone,which would otherwise disappear, no Am stars should lie below thisboundary. The fact that they are nevertheless seen there implies theexistence of some stabilization mechanism (as, e.g., that recentlyproposed by Tassoul & Tassoul 1992) for the binaries with orbitalperiods less than 180d. Further evidence is given to the fact that theOPD for the Am and the normal binaries with an A4-F1 primary arecomplementary to each other, from which it stems that Am stars are closeto the main sequence. There are, however, indications that they haveslightly larger radii (2.1-3 Rsun_) than expected for theirspectral type. The generally accepted rotational velocity cutoff at=~100km/s is shown to be of little value when applied on Am binaries ashere it is not a single quantity but, in fact, a function of P_orb_whose shape is strikingly similar to that of the curves of constantmetallicity as ascertained from observations. This also leads to thewell known overlap in rotational velocities of the normal and Am starsfor 402.5d.We have exploited this empirical cutoff function to calibrate thecorresponding turbulent diffusion coefficient associated with tidalmixing, having found out that the computed form of the lines of constantturbulence fits qualitatively the empirical shape of the curves ofconstant metallicity. As for larger orbital periods(20d55km/s found by Burkhart(1979) would then be nothing but a manifestation of insufficientlypopulated corresponding area of larger P_orb_.
| 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.
| The Henry Draper Extension Charts: A catalogue of accurate positions, proper motions, magnitudes and spectral types of 86933 stars
The Henry Draper Extension Charts (HDEC), published in the form offinding charts, provide spectral classification for some 87000 starsmostly between 10th and 11th magnitude. This data, being highlyvaluable, as yet was practically unusable for modern computer-basedastronomy. An earlier pilot project (Roeser et al. 1991) demonstrated apossibility to convert this into a star catalogue, using measurements ofcartesian coordinates of stars on the charts and positions of theAstrographic Catalogue (AC) for subsequent identification. We presenthere a final HDEC catalogue comprising accurate positions, propermotions, magnitudes and spectral classes for 86933 stars of the HenryDraper Extension Charts.
| Mesures d'etoiles doubles faites a Nice, etoiles doubles nouvelles (24eme serie) decouvertes a Nice.
Table 1 gives 1182 measurements of 682 binaries observed with the 74 and50 cm refractors. Table 2 lists 26 new binaries discovered with the 50cm refractor.
| Eclipsing binaries, Pegasus to Sagittarius, in 1972-1987
Photoelectric and visual observations of 34 known and suspectedeclipsing binaries are discussed. Revised light elements are derived forDM Per and Beta Per. EL Sge is confirmed to vary with a period ofapproximately 0.333d. Large deviations from the published elements arereported for BG Peg, AB Per, LS Per, SU Psc, SZ Psc and TU Sge. Thecatalogue period of BQ Peg is probably incorrect.
| On the state of subgiant-stars nuclei in eclipsing binary systems.
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| 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.
| 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).
| Measurements of double stars at Nice with 74-cm and 50-cm refractors
A total of 717 measures of 287 binaries made at the 74-cm and 50-cmrefractors are presented. These are mostly very close binariesdiscovered recently, for which a rapid orbital motion is evident forabout 30 percent.
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