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Absolute Properties of the Eclipsing Triple Star CO Andromedae: Constraints on Convective Core Overshooting
Accurate absolute properties have been determined for the eclipsingtriple star CO And (F8+F8) based on extensive differential photometryobtained by three robotic observatories and CfA spectroscopy. Theeclipsing binary star orbit is circular with a period of 3.655 days. Thetriple nature of this system is revealed by more than a century oftimings of minimum light, and by the presence of third light in thephotometric orbits. The masses of the eclipsing pair are 1.289 ±0.007 and 1.264 ± 0.007 solar masses, and the corresponding radiiare 1.727 ± 0.021 and 1.694 ± 0.017 solar radii. Thesestars are synchronously rotating and are near the end of theirmain-sequence phase, at an age of about 3.6 Gyr. The much fainter widelyseparated third body appears to have a mass of about 0.8 solar masses.The distance to the system is 377 ± 25 pc.
| Absolute dimensions of eclipsing binaries. XXVIII. BK Pegasi and other F-type binaries: Prospects for calibration of convective core overshoot
Context. Double-lined, detached eclipsing binaries are our main sourcefor accurate stellar masses and radii. In this paper we focus on the1.15-1.70 M? interval where convective core overshoot isgradually ramped up in theoretical evolutionary models. Aims: Weaim to determine absolute dimensions and abundances for the F-typedetached eclipsing binary BK Peg, and to perform a detailed comparisonwith results from recent stellar evolutionary models, including a sampleof previously studied systems with accurate parameters. Methods:uvby light curves and uvby? standard photometry were obtained withthe Strömgren Automatic Telescope, ESO, La Silla, andhigh-resolution spectra were acquired with the FIES spectrograph at theNordic Optical Telescope, La Palma. Results: The 5 fd 49 periodorbit of BK Peg is slightly eccentric (e = 0.053). The two componentsare quite different with masses and radii of (1.414 ± 0.007M?, 1.988 ± 0.008 Rsun) and (1.257± 0.005 M?, 1.474 ± 0.017Rsun), respectively. The measured rotational velocities are16.6 ± 0.2 (primary) and 13.4 ± 0.2 (secondary) kms-1. For the secondary component this corresponds to(pseudo)synchronous rotation, whereas the primary component seems torotate at a slightly lower rate. We derive an iron abundance of [Fe/H] =-0.12 ± 0.07 and similar abundances for Si, Ca, Sc, Ti, Cr andNi. The stars have evolved to the upper half of the main-sequence band.Yonsei-Yale and Victoria-Regina evolutionary models for the observedmetal abundance reproduce BK Peg at ages of 2.75 and 2.50 Gyr,respectively, but tend to predict a lower age for the more massiveprimary component than for the secondary. We find the same age trend forthree other upper main-sequence systems in a sample of well studiedeclipsing binaries with components in the 1.15-1.70 M?range. We also find that the Yonsei-Yale models systematically predicthigher ages than the Victoria-Regina models. The sample includes BW Aqr,and as a supplement we have determined a [Fe/H] abundance of -0.07± 0.11 for this late F-type binary. Conclusions: Wepropose to use BK Peg, BW Aqr, and other well-studied 1.15-1.70M? eclipsing binaries to fine-tune convective coreovershoot, diffusion, and possibly other ingredients of moderntheoretical evolutionary models.Based on observations carried out at the Strömgren AutomaticTelescope (SAT) and the 1.5m telescope (63.H-0080) at ESO, La Silla, andthe Nordic Optical Telescope at La PalmaTables 13-17 are available inelectronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/516/A42
| Accurate masses and radii of normal stars: modern results and applications
This article presents and discusses a critical compilation of accurate,fundamental determinations of stellar masses and radii. We haveidentified 95 detached binary systems containing 190 stars (94 eclipsingsystems, and ? Centauri) that satisfy our criterion that the massand radius of both stars be known within errors of ±3% accuracyor better. All of them are non-interacting systems, and so the starsshould have evolved as if they were single. This sample more thandoubles that of the earlier similar review by Andersen (Astron AstrophysRev 3:91-126, 1991), extends the mass range at both ends and, forthe first time, includes an extragalactic binary. In every case, we haveexamined the original data and recomputed the stellar parameters with aconsistent set of assumptions and physical constants. To these we addinterstellar reddening, effective temperature, metal abundance,rotational velocity and apsidal motion determinations when available,and we compute a number of other physical parameters, notably luminosityand distance. These accurate physical parameters reveal the effects ofstellar evolution with unprecedented clarity, and we discuss the use ofthe data in observational tests of stellar evolution models in somedetail. Earlier findings of significant structural differences betweenmoderately fast-rotating, mildly active stars and single stars, ascribedto the presence of strong magnetic and spot activity, are confirmedbeyond doubt. We also show how the best data can be used to testprescriptions for the subtle interplay between convection, diffusion,and other non-classical effects in stellar models. The amount andquality of the data also allow us to analyse the tidal evolution of thesystems in considerable depth, testing prescriptions of rotationalsynchronisation and orbital circularisation in greater detail thanpossible before. We show that the formulae for pseudo-synchronisation ofstars in eccentric orbits predict the observed rotations quite well,except for very young and/or widely separated stars. Deviations dooccur, however, especially for stars with convective envelopes. Thesuperior data set finally demonstrates that apsidal motion rates aspredicted from General Relativity plus tidal theory are in goodagreement with the best observational data. No reliable binary dataexist, which challenge General Relativity to any significant extent. Thenew data also enable us to derive empirical calibrations of M and R forsingle (post-) main-sequence stars above {0.6 M_{odot}}. Simple,polynomial functions of T eff, log g and [Fe/H] yield M and Rwithin errors of 6 and 3%, respectively. Excellent agreement is foundwith independent determinations for host stars of transiting extrasolarplanets, and good agreement with determinations of M and R from stellarmodels as constrained by trigonometric parallaxes and spectroscopicvalues of T eff and [Fe/H]. Finally, we list a set of 23interferometric binaries with masses known to be better than 3%, butwithout fundamental radius determinations (except ? Aur). Wediscuss the prospects for improving these and other stellar parametersin the near future.
| Absolute dimensions of eclipsing binaries. XXVII. V1130 Tauri: a metal-weak F-type system, perhaps with preference for Y = 0.23-0.24
Context. Double-lined, detached eclipsing binaries are our main sourcefor accurate stellar masses and radii. This paper is the first in aseries with focus on the upper half of the main-sequence band and testsof 1-2 M? evolutionary models. Aims: We aim todetermine absolute dimensions and abundances for the detached eclipsingbinary V1130 Tau, and to perform a detailed comparison with results fromrecent stellar evolutionary models. Methods: uvby light curvesand uvby? standard photometry have been obtained with theStrömgren Automatic Telescope, and high-resolution spectra havebeen acquired at the FEROS spectrograph; both are ESO, La Sillafacilities. We have applied the Wilson-Devinney model for thephotometric analysis, spectroscopic elements are based on radialvelocities measured via broadening functions, and [Fe/H] abundances havebeen determined from synthetic spectra and uvby calibrations. Results: V1130 Tau is a bright (mV = 6.56), nearby (71± 2 pc) detached system with a circular orbit (P = 0.80d). Thecomponents are deformed with filling factors above 0.9. Their masses andradii have been established to 0.6-0.7%. We derive a [Fe/H] abundance of-0.25 ± 0.10. The measured rotational velocities, 92.4 ±1.1 (primary) and 104.7 ± 2.7 (secondary) km s-1, arein fair agreement with synchronization. The larger 1.39M? secondary component has evolved to the middle of themain-sequence band and is slightly cooler than the 1.31M? primary. Yonsai-Yale, BaSTI, and Granada evolutionarymodels for the observed metal abundance and a “normal” Hecontent of Y = 0.25-0.26, marginally reproduce the components at agesbetween 1.8 and 2.1 Gyr. All such models are, however, systematicallyabout 200 K hotter than observed and predict ages for the more massivecomponent, which are systematically higher than for the less massivecomponent. These trends can not be removed by adjusting the amount ofcore overshoot or envelope convection level, or by including rotation inthe model calculations. They may be due to proximity effects in V1130Tau, but on the other hand, we find excellent agreement for 2.5-2.8 GyrGranada models with a slightly lower Y of 0.23-0.24. Conclusions:V1130 Tau is a valuable addition to the very few well-studied 1-2M? binaries with component(s) in the upper half of themain-sequence band, or beyond. The stars are not evolved enough toprovide new information on the dependence of core overshoot on mass (andabundance), but might - together with a larger sample of well-detachedsystems - be useful for further tuning of the helium enrichment law.Analyses of such systems are in progress.Based on observations carried out at the Strömgren AutomaticTelescope (SAT) and the 1.5 m telescope at ESO, La Silla (62.H-0319,62.L-0284, 63.H-0080, 64.L-0031, 66.D-0178). Table 11 is available inelectronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/510/A91
| Relativistic apsidal motion in eccentric eclipsing binaries
Context. The study of apsidal motion in detached eclipsing binarysystems is known to be an important source of information about stellarinternal structure as well as the possibility of verifying of GeneralRelativity outside the Solar System. Aims: As part of thelong-term Ond?ejov and Ostrava observational projects, we aim tomeasure precise times of minima for eccentric eclipsing binaries, neededfor the accurate determination of apsidal motion, providing a suitabletest of the effects of General Relativity. Methods: About seventynew times of minimum light recorded with photoelectric or CCDphotometers were obtained for ten eccentric-orbit eclipsing binarieswith significant relativistic apsidal motion. Their O-C diagrams wereanalysed using all reliable timings found in the literature, and new orimproved elements of apsidal motion were obtained. Results: Weconfirm very long periods of apsidal motion for all systems. For BF Draand V1094 Tau, we present the first apsidal-motion solution. Therelativistic effects are dominant, representing up to 100% of the totalobservable apsidal-motion rate in several systems. The theoretical andobserved values of the internal structure constant k 2 werecompared for systems with lower relativistic contribution. Using thelight-time effect solution, we predict a faint third component for V1094Tau orbiting with a short period of about 8 years.Partly based on photoelectric observations secured at the HvarObservatory, Faculty of Geodesy, Zagreb, Croatia, in October 2008.
| Apsidal motion elements of three eccentric eclipsing binaries: V397 Cep, V493 Car and BW Aqr
The apsidal motion analysis of the eccentric eclipsing binaries: V397Cep, V493 Car and BW Aqr have been presented. The method described byLacy (1992) [Lacy, C.H S., 1992. AJ 104, 2213] has been used for theapsidal motion analysis. The apsidal motion periods have been found tobe 174.2 ± 1.4, 277.3 ± 21.3 and 7195 ± 174 yearsfor V397 Cep, V493 Car and BW Aqr, respectively.
| Absolute Dimensions of the F-Type Eclipsing Binary Star VZ Cephei
We present new V-band differential photometry and radial velocitymeasurements of the unevolved, 1.18 day period, F+G-type, double-linedeclipsing binary VZ Cep. We determine accurate values for the absolutemasses, radii, and effective temperatures as follows: M A =1.402 ± 0.015 M sun, R A = 1.534 ±0.012 R sun, and T eff = 6690 ± 160 K forthe primary, and M B = 1.1077 ± 0.0083 Msun, R B = 1.042 ± 0.039 R sun,and T eff = 5720 ± 120 K for the secondary. Acomparison with current stellar evolution models suggests an age of 1.4Gyr for a metallicity that is near solar. The temperature differencebetween the stars, which is much better determined than the absolutevalues, is found to be ~ 250 K larger than predicted by theory. If allof this discrepancy is attributed to the secondary (which would then betoo cool compared to models), the effect would be consistent withsimilar differences found for other low-mass stars, generally believedto be associated with chromospheric activity. However, the radius of VZCep B (which unlike the primary, still has a thin convective envelope)appears normal, whereas in other stars affected by activity the radiusis systematically larger than predicted. Thus, VZ Cep poses a challengenot only to standard theory but also to our understanding of thediscrepancies in other low-mass systems.
| Absolute dimensions of eclipsing binaries. XXVI.. Setting a new standard: Masses, radii, and abundances for the F-type systems AD Bootis VZ Hydrae, and WZ Ophiuchi
Context: Accurate mass, radius, and abundance determinations frombinaries provide important information on stellar evolution, fundamentalto central fields in modern astrophysics and cosmology. Aims: Weaim to determine absolute dimensions and abundances for the three F-typemain-sequence detached eclipsing binaries AD Boo, VZ Hya, and WZ Oph andto perform a detailed comparison with results from recent stellarevolutionary models. Methods: uvby light curves and uvby?standard photometry were obtained with the Strömgren AutomaticTelescope at ESO, La Silla, radial velocity observations at CfAfacilities, and supplementary high-resolution spectra with ESO's FEROSspectrograph. State-of-the-art methods were applied for the analyses:the EBOP and Wilson-Devinney binary models, two-dimensionalcross-correlation and disentangling, and the VWA abundance analysistool. Results: Masses and radii that are precise to 0.5-0.7% and0.4-0.9%, respectively, have been established for the components, whichspan the ranges of 1.1 to 1.4 M? and 1.1 to 1.6R?. The [Fe/H] abundances are from -0.27 to +0.10, withuncertainties between 0.07 and 0.15 dex. We find indications of a slight?-element overabundance of [?/Fe] ˜ + 0.1 for WZ Oph.The secondary component of AD Boo and both components of WZ Oph appearto be slightly active. Yale-Yonsai and Victoria-Regina evolutionarymodels fit the components of AD Boo and VZ Hya almost equally well,assuming coeval formation, at ages of about 1.75/1.50 Gyr (AD Boo) and1.25/1.00 Gyr (VZ Hya). BaSTI models, however, predict somewhatdifferent ages for the primary and secondary components. For WZ Oph, themodels from all three grids are significantly hotter than observed. Alow He content, decreased envelope convection coupled with surfaceactivity, and/or higher interstellar absorption would remove thediscrepancy, but its cause has not been definitively identified. Conclusions: We have demonstrated the power of testing and comparingrecent stellar evolutionary models using eclipsing binaries, providedtheir abundances are known. The strongest limitations and challenges areset by T_eff and interstellar absorption determinations, and by theireffects on and correlation with abundance results.Based on observations carried out at the Strömgren AutomaticTelescope (SAT) and the 1.5 m and 2.2 m telescopes at ESO, La Silla,Chile (62.L-0284, 63.H-0080, 71.D-0554); the 1.5 m Wyeth reflector atthe Oak Ridge Observatory, Harvard, Massachusetts, USA; the 1.5-mTillinghast reflector and the Multiple Mirror Telescope at the F.L.?Whipple Observatory, Mt.?Hopkins, Arizona.
| Mass-luminosity relation of intermediate-mass stars
The mass-luminosity relation (MLR) for intermediate-mass stars is basedon data on detached double-lined eclipsing binaries. However, there is anotable difference between the parameters of B0V-G0V components ofeclipsing binaries and those of single stars. Single early-type starsare rapid rotators, whereas tidal forces produce synchronous rotation inclose binaries and all such pairs are synchronized, so components ofclose binaries rotate more slowly. As is well known, stellar rotationchanges stellar evolution and the global parameters of a star.In this work we collect data on fundamental parameters of stars withmasses m > 1.5msolar. They are components of binaries withP > 15 d and consequently are not synchronized with the orbitalperiods and presumably are rapid rotators. These stars are believed toevolve similarly with single stars. Modern data on masses, absolute andbolometric luminosities, radii and temperatures of detachedmain-sequence double-lined eclipsing binary components (i.e. presumablyslow rotators) are also collected.Mass-luminosity, mass-temperature and mass-radius relations of close andwide binaries are presented, as well as their Hertzsprung-Russelldiagram. For the mass range 4.5 < m/msolar < 5.5 (lateB stars) it was found that rapid rotators exhibit slightly higherluminosities and larger radii than predicted by the standard relations,and their main sequence is shifted to the right-hand side with respectto that of the close binary components. The resulting relations forrapidly and slowly rotating A-F and early B stars are not statisticallydifferent.As our estimations show, for the given mass range the effect on theinitial mass function (IMF) is marginal, but there is no way to estimatethe degree to which the effect may be important for higher masses.Available observational data for m > 12msolar are too poorto make definite conclusions. Knowledge of the MLR should come fromdynamical mass determinations of visual binaries combined with spatiallyresolved precise photometry. Then the IMF should be revised for thatmass range.
| A new catalogue of eclipsing binary stars with eccentric orbits
A new catalogue of eclipsing binary stars with eccentric orbits ispresented. The catalogue lists the physical parameters (includingapsidal motion parameters) of 124 eclipsing binaries with eccentricorbits. In addition, the catalogue also contains a list of 150 candidatesystems, about which not much is known at present.Full version of the catalogue is available online (see the SupplementaryMaterial section at the end of this paper) and in electronic form at theCDS via http://cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/MNRAS/(vol)/ (page)E-mail: ibulut@comu.edu.tr
| Effect of tidal evolution in determining the ages of eclipsing-variable early main sequence close binary systems
New Claret evolutionary model-tracks, constructed for the first time forstudying close binary systems (CBS) including tidal evolution constants,are used to determine the age of 112 eclipsing-variable stars in theSvechnikov-Perevozkina catalog by the method of isochrones. There issome interest in comparing the calculated ages with previous estimatesobtained for these same close binary systems using evolutionarymodeltracks for individual stars taking their mass loss into account. Acorrelation of the ages of the principal and secondary components isnoted, which is most marked for massive close binaries with principalcomponents having masses M1 ? 3 M?. Arejuvenating effect is found to occur for the systems studied here ascalculated on the new tracks; it is most distinct for low-mass closebinaries with a total mass M1 + M2 ? 3.5M? and is predicted theoretically in terms of magneticbraking. The calculated broadband grid of isochrones, from zero-agemain-sequence (ZAMS) to the age of the galaxy, can be used forestimating the ages of close binaries from other catalogs. Ages aregiven for the 112 eclipsing-variable close binaries with detachedcomponents lying within the main sequence.
| Proper-motion binaries in the Hipparcos catalogue. Comparison with radial velocity data
Context: .This paper is the last in a series devoted to the analysis ofthe binary content of the Hipparcos Catalogue. Aims: .Thecomparison of the proper motions constructed from positions spanning ashort (Hipparcos) or long time (Tycho-2) makes it possible to uncoverbinaries with periods of the order of or somewhat larger than the shorttime span (in this case, the 3 yr duration of the Hipparcos mission),since the unrecognised orbital motion will then add to the propermotion. Methods: .A list of candidate proper motion binaries isconstructed from a carefully designed χ2 test evaluatingthe statistical significance of the difference between the Tycho-2 andHipparcos proper motions for 103 134 stars in common between the twocatalogues (excluding components of visual systems). Since similar listsof proper-motion binaries have already been constructed, the presentpaper focuses on the evaluation of the detection efficiency ofproper-motion binaries, using different kinds of control data (mostlyradial velocities). The detection rate for entries from the NinthCatalogue of Spectroscopic Binary Orbits (S_B^9) is evaluated, as wellas for stars like barium stars, which are known to be all binaries, andfinally for spectroscopic binaries identified from radial velocity datain the Geneva-Copenhagen survey of F and G dwarfs in the solarneighbourhood. Results: .Proper motion binaries are efficientlydetected for systems with parallaxes in excess of ~20 mas, and periodsin the range 1000-30 000 d. The shortest periods in this range(1000-2000 d, i.e., once to twice the duration of the Hipparcos mission)may appear only as DMSA/G binaries (accelerated proper motion in theHipparcos Double and Multiple System Annex). Proper motion binariesdetected among S_B9 systems having periods shorter than about400 d hint at triple systems, the proper-motion binary involving acomponent with a longer orbital period. A list of 19 candidate triplesystems is provided. Binaries suspected of having low-mass(brown-dwarf-like) companions are listed as well. Among the 37 bariumstars with parallaxes larger than 5 mas, only 7 exhibit no evidence forduplicity whatsoever (be it spectroscopic or astrometric). Finally, thefraction of proper-motion binaries shows no significant variation amongthe various (regular) spectral classes, when due account is taken forthe detection biases.Full Table [see full textsee full text] is only available in electronicform at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5)or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/464/377
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| Tertiary companions to close spectroscopic binaries
We have surveyed a sample of 165 solar-type spectroscopic binaries (SB)with periods from 1 to 30 days for higher-order multiplicity. Asubsample of 62 targets were observed with the NACO adaptive opticssystem and 13 new physical tertiary companions were detected. Anadditional 12 new wide companions (5 still tentative) were found usingthe 2MASS all-sky survey. The binaries belong to 161 stellar systems; ofthese 64 are triple, 11 quadruple and 7 quintuple. After correction forincompleteness, the fraction of SBs with additional companions is foundto be 63% ± 5%. We find that this fraction is a strong functionof the SB period P, reaching 96% for P<3d and dropping to34% for P>12^d. Period distributions of SBs with and withouttertiaries are significantly different, but their mass ratiodistributions are identical. The statistical data on the multiplicity ofclose SBs presented in this paper indicates that the periods and massratios of SBs were established very early, but the periods of SB systemswith triples were further shortened by angular momentum exchange withcompanions.
| 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.
| Automatic classification of eclipsing binaries light curves using neural networks
In this work we present a system for the automatic classification of thelight curves of eclipsing binaries. This system is based on aclassification scheme that aims to separate eclipsing binary systemsaccording to their geometrical configuration in a modified version ofthe traditional classification scheme. The classification is performedby a Bayesian ensemble of neural networks trained with Hipparcos data ofseven different categories including eccentric binary systems and twotypes of pulsating light curve morphologies.
| Astrometric orbits of SB^9 stars
Hipparcos Intermediate Astrometric Data (IAD) have been used to deriveastrometric orbital elements for spectroscopic binaries from the newlyreleased Ninth Catalogue of Spectroscopic Binary Orbits(SB^9). This endeavour is justified by the fact that (i) theastrometric orbital motion is often difficult to detect without theprior knowledge of the spectroscopic orbital elements, and (ii) suchknowledge was not available at the time of the construction of theHipparcos Catalogue for the spectroscopic binaries which were recentlyadded to the SB^9 catalogue. Among the 1374 binaries fromSB^9 which have an HIP entry (excluding binaries with visualcompanions, or DMSA/C in the Double and Multiple Stars Annex), 282 havedetectable orbital astrometric motion (at the 5% significance level).Among those, only 70 have astrometric orbital elements that are reliablydetermined (according to specific statistical tests), and for the firsttime for 20 systems. This represents a 8.5% increase of the number ofastrometric systems with known orbital elements (The Double and MultipleSystems Annex contains 235 of those DMSA/O systems). The detection ofthe astrometric orbital motion when the Hipparcos IAD are supplementedby the spectroscopic orbital elements is close to 100% for binaries withonly one visible component, provided that the period is in the 50-1000 drange and the parallax is >5 mas. This result is an interestingtestbed to guide the choice of algorithms and statistical tests to beused in the search for astrometric binaries during the forthcoming ESAGaia mission. Finally, orbital inclinations provided by the presentanalysis have been used to derive several astrophysical quantities. Forinstance, 29 among the 70 systems with reliable astrometric orbitalelements involve main sequence stars for which the companion mass couldbe derived. Some interesting conclusions may be drawn from this new setof stellar masses, like the enigmatic nature of the companion to theHyades F dwarf HIP 20935. This system has a mass ratio of 0.98 but thecompanion remains elusive.
| Statistical Constraints for Astrometric Binaries with Nonlinear Motion
Useful constraints on the orbits and mass ratios of astrometric binariesin the Hipparcos catalog are derived from the measured proper motiondifferences of Hipparcos and Tycho-2 (Δμ), accelerations ofproper motions (μ˙), and second derivatives of proper motions(μ̈). It is shown how, in some cases, statistical bounds can beestimated for the masses of the secondary components. Two catalogs ofastrometric binaries are generated, one of binaries with significantproper motion differences and the other of binaries with significantaccelerations of their proper motions. Mathematical relations betweenthe astrometric observables Δμ, μ˙, and μ̈ andthe orbital elements are derived in the appendices. We find a remarkabledifference between the distribution of spectral types of stars withlarge accelerations but small proper motion differences and that ofstars with large proper motion differences but insignificantaccelerations. The spectral type distribution for the former sample ofbinaries is the same as the general distribution of all stars in theHipparcos catalog, whereas the latter sample is clearly dominated bysolar-type stars, with an obvious dearth of blue stars. We point outthat the latter set includes mostly binaries with long periods (longerthan about 6 yr).
| SB9: The ninth catalogue of spectroscopic binary orbits
The Ninth Catalogue of Spectroscopic Binary Orbits(http://sb9.astro.ulb.ac.be) continues the series of compilations ofspectroscopic orbits carried out over the past 35 years by Batten andcollaborators. As of 2004 May 1st, the new Catalogue holds orbits for2386 systems. Some essential differences between this catalogue and itspredecessors are outlined and three straightforward applications arepresented: (1) completeness assessment: period distribution of SB1s andSB2s; (2) shortest periods across the H-R diagram; (3)period-eccentricity relation.
| Updated Elements for Southern Eclipsing Binaries
Analysis of ASAS-3 data for 442 southern eclipsing binaries yielded 131stars with incorrect periods listed in the GCVS catalog
| Up-to-Date Linear Elements of Eclipsing Binaries
About 1800 O-C diagrams of eclipsing binaries were analyzed and up-todate linear elements were computed. The regularly updated ephemerides(as a continuation of SAC) are available only in electronic form at theInternet address: http://www.as.ap.krakow.pl/ephem/.
| An Assessment of Dynamical Mass Constraints on Pre-Main-Sequence Evolutionary Tracks
We have assembled a database of stars having both masses determined frommeasured orbital dynamics and sufficient spectral and photometricinformation for their placement on a theoretical H-R diagram. Our sampleconsists of 115 low-mass (M<2.0 Msolar) stars, 27pre-main-sequence and 88 main-sequence. We use a variety of availablepre-main-sequence evolutionary calculations to test the consistency ofpredicted stellar masses with dynamically determined masses. Despitesubstantial improvements in model physics over the past decade, largesystematic discrepancies still exist between empirical and theoreticallyderived masses. For main-sequence stars, all models considered predictmasses consistent with dynamical values above 1.2 Msolar andsome models predict consistent masses at solar or slightly lower masses,but no models predict consistent masses below 0.5 Msolar,with all models systematically underpredicting such low masses by5%-20%. The failure at low masses stems from the poor match of mostmodels to the empirical main sequence below temperatures of 3800 K, atwhich molecules become the dominant source of opacity and convection isthe dominant mode of energy transport. For the pre-main-sequence samplewe find similar trends. There is generally good agreement betweenpredicted and dynamical masses above 1.2 Msolar for allmodels. Below 1.2 Msolar and down to 0.3 Msolar(the lowest mass testable), most evolutionary models systematicallyunderpredict the dynamically determined masses by 10%-30%, on average,with the Lyon group models predicting marginally consistent masses inthe mean, although with large scatter. Over all mass ranges, theusefulness of dynamical mass constraints for pre-main-sequence stars isin many cases limited by the random errors caused by poorly determinedluminosities and especially temperatures of young stars. Adopting awarmer-than-dwarf temperature scale would help reconcile the systematicpre-main-sequence offset at the lowest masses, but the case for this isnot compelling, given the similar warm offset at older ages between mostsets of tracks and the empirical main sequence. Over all age ranges, thesystematic discrepancies between track-predicted and dynamicallydetermined masses appear to be dominated by inaccuracies in thetreatment of convection and in the adopted opacities.
| Detached double-lined eclipsing binaries as critical tests of stellar evolution. Age and metallicity determinations from the HR diagram
Detached, double-lined spectroscopic binaries that are also eclipsingprovide the most accurate determinations of stellar mass, radius,temperature and distance-independent luminosity for each of theirindividual components, and hence constitute a stringent test ofsingle-star stellar evolution theory. We compile a large sample of 60non-interacting, well-detached systems mostly with typical errorssmaller than 2% for mass and radius and smaller than 5% for effectivetemperature, and compare them with the properties predicted by stellarevolutionary tracks from a minimization method. To assess the systematicerrors introduced by a given set of tracks, we compare the resultsobtained using three widely-used independent sets of tracks, computedwith different physical ingredients (the Geneva, Padova and Granadamodels). We also test the hypothesis that the components of thesesystems are coeval and have the same metallicity, and compare thederived ages and metallicities with the ones obtained by fitting asingle isochrone to the system. Overall, there is a good agreement amongthe different determinations, and we provide a comprehensive discussionon the sub-sample of systems which either present problems or haveestimated metallicities. Although within the errors the published trackscan fit most of the systems, a large degeneracy between age andmetallicity remains. The power of the test is thus limited because themetallicities of most of the systems are unknown. The full version ofTable 6 is only available in the electronic form athttp://www.edpsciences.org
| uvbyβ Photometry of Selected Eclipsing Binary Stars
New uvbyβ observations of 51 eclipsing binary stars are presented,and outside-eclipse averages for 45 of them are given. Many of thesebinaries are detached main-sequence pairs that have been discovered tobe double-lined spectroscopic binaries and appear suitable fordeterminations of accurate absolute dimensions and masses. Photometricproperties are recomputed for 14 of the binaries, for which absoluteproperties have been published previously. Intercomparisons are madewith previous photometry, when available, and notes are given for someindividual systems.
| Determination of the Ages of Close Binary Stars on the Main Sequence from Evolutionary Model Stars of Claret and Gimenez
A grid of isochrones, covering a wide range of stellar ages from thezero-age main sequence to 10 billion years, is calculated in the presentwork on the basis of the model stars of Claret and Gimenez withallowance for convective overshoot and mass loss by the components. Theages of 88 eclipsing variables on the main sequence from Andersen'scatalog and 100 chromospherically active stars from Strassmeier'scatalog are calculated with a description of the method of optimuminterpolation. Comparisons with age determinations by other authors aregiven and good agreement is established.
| Apsidal Motion in Detached Binary Stars: Comparison of Theory and Observations
A list of 62 detached binaries having reliable data on the rotation ofthe line of apsides is considered. Theoretical estimates of the rate ofapsidal motion are obtained. These estimates are compared withobservational data. It is shown that cases in which the theoreticalestimate exceeds the observed value are several times more frequent thancases in which the theoretical value is lower than the observed one.This discrepancy increases when systems with more reliable observationaldata are considered.
| New results on the apsidal-motion test to stellar structure and evolution including the effects of dynamic tides
We revised the current status of the apsidal-motion test to stellarstructure and evolution. The observational sample was increased by about50% in comparison to previous studies. Classical and relativisticsystems were analyzed simultaneously and only systems with accurateabsolute dimensions were considered. New interior models incorporatingrecent opacity tables, stellar rotation, mass loss, and moderate coreovershooting were used as theoretical tools to compare the predictedwith the observed shifts of the position of the periastron. The stellarmodels were computed for the precise observed masses and the adoptedchemical compositions are consistent with the corresponding tables ofopacities to avoid the inherent problems of interpolation in mass and in(X, Z). The derived chemical composition for each individual system wasused to infer the primordial helium content as well as a law ofenrichment. The values found are in good agreement with those obtainedfrom various independent sources. For the first time, the effects ofdynamic tides are taken into account systematically to determine thecontribution of the tidal distortion to the predicted apsidal-motionrate. The deviations between the apsidal-motion rates resulting from theclassical formula and those determined by taking into account theeffects of dynamic tides are presented as a function of the level ofsynchronism. For systems close to synchronisation, dynamic tides causedeviations with respect to the classical apsidal-motion formula due tothe effects of the compressibility of the stellar fluid. For systemswith higher rotational angular velocities, additional deviations due toresonances arise when the forcing frequencies of the dynamic tides comeinto the range of the free oscillation modes of the component stars. Theresulting comparison shows a good agreement between the observed andtheoretical apsidal-motion rates. No systematic effects in the sensethat models are less mass concentrated than real stars and nocorrelations with the evolutionary status of the systems were detected.
| Studies of Intermediate-Mass Stellar Models Using Eclipsing Binaries
Evolutionary computations for intermediate-mass stars are analyzed usingobserved parameters for eclipsing SB2 binaries and theoreticalparameters based on evolutionary tracks. Modern observations cannot beused to distinguish between models with and without convectiveovershooting for stars in the vicinity of the main sequence.Statistically significant discrepancies between the observed andcomputed stellar parameters are associated with systematic errors inphotometric effective temperatures. After taking into account systematiceffects, the theoretical computations fit the observational datauniformly well throughout the entire mass interval studied. Empiricaland semiempirical (i.e., reduced to the ZAMS and with solar elementalabundances) formulas for the mass-luminosity, mass-effectivetemperature, and mass-radius relations are proposed.
| Age and Metallicity Estimates for Moderate-Mass Stars in Eclipsing Binaries
We estimate the ages and metallicities for the components of 43 binarysystems using a compilation of accurate observational data on eclipsingbinaries for which lines of both components are visible in theirspectra, together with two independent modern sets of stellar evolutionmodels computed for a wide range of masses and chemical abundances. Theuncertainties of the resulting values are computed, and their stabilityis demonstrated. The ages and metallicity are compared with thosederived in other studies using different methods, as well as withindependent estimates from photometric observations and observations ofclusters. These comparisons con firm the reliability of our ageestimates. The resulting metallicities depend significantly on thechoice of theoretical model. Comparison with independent estimatesfavors the estimates based on the evolutionary tracks of the Genevagroup.
| Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics
The Catalogue, available at the Centre de Données Stellaires deStrasbourg, consists of 13 573 records concerning the results obtainedfrom different methods for 7778 stars, reported in the literature. Thefollowing data are listed for each star: identifications, apparentmagnitude, spectral type, apparent diameter in arcsec, absolute radiusin solar units, method of determination, reference, remarks. Commentsand statistics obtained from CADARS are given. The Catalogue isavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcar?J/A+A/367/521
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Besorolás csoportokba:
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Pozíciós és asztrometriai adatok
| Csillagkép: | Sas |
| Rektaszcenzió: | 22h23m15.93s |
| Deklináció: | -15°19'56.3" |
| Vizuális fényesség: | 10.324 |
| RA sajátmozgás: | -10.3 |
| Dec sajátmozgás: | -17.8 |
| B-T magnitude: | 11.067 |
| V-T magnitude: | 10.386 |
Katalógusok és elnevezések:
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