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The V-band Empirical Mass-luminosity Relation for Main Sequence Stars
Stellar mass is an indispensable parameter in the studies of stellarphysics and stellar dynamics. On the one hand, the most reliable way todetermine the stellar dynamical mass is via orbital determinations ofbinaries. On the other hand, however, most stellar masses have to beestimated by using the mass luminosity relation (MLR). Therefore, it isimportant to obtain the empirical MLR through fitting the data ofstellar dynamical mass and luminosity. The effect of metallicity canmake this relation disperse in the V-band, but studies show that this ismainly limited to the case when the stellar mass is less than0.6M? Recently, many relevant data have been accumulatedfor main sequence stars with larger masses, which make it possible tosignificantly improve the corresponding MLR. Using a fitting methodwhich can reasonably assign weights to the observational data includingtwo quantities with different dimensions, we obtain a V-band MLR basedon the dynamical masses and luminosities of 203 main sequence stars. Incomparison with the previous work, the improved MLR is statisticallysignificant, and the relative error of mass estimation reaches about 5%.Therefore, our MLR is useful not only in the studies of statisticalnature, but also in the studies of concrete stellar systems, such as thelong-term dynamical study and the short-term positioning study of aspecific multiple star system.
| 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.
| Searching for transiting circumbinary planets in CoRoT and ground-based data using CB-BLS
Aims: Already from the initial discoveries of extrasolar planets it wasapparent that their population and environments are far more diversethan initially postulated. Discovering circumbinary (CB) planets willhave many implications, and in this context it will again substantiallydiversify the environments that produce and sustain planets. We searchfor transiting CB planets around eclipsing binaries (EBs). Methods: CB-BLS is a recently-introduced algorithm for the detectionof transiting CB planets around EBs. We describe progress in searchsensitivity, generality and capability of CB-BLS, and detection tests ofCB-BLS on simulated data. We also describe an analytical approach forthe determination of CB-BLS detection limits, and a method for thecorrect detrending of intrinsically-variable stars. Results: Wepresent some blind-tests with simulated planets injected to real CoRoTdata. The presented upgrades to CB-BLS allowed it to detect all theblind tests successfully, and these detections were in line with thedetection limits analysis. We also correctly detrend bright eclipsingbinaries from observations by the TrES planet search, and present someof the first results of applying CB-BLS to multiple real light curvesfrom a wide-field survey. Conclusions: CB-BLS is now matureenough for its application to real data, and the presented processingscheme will serve as the template for our future applications of CB-BLSto data from wide-field surveys such as CoRoT. Being able to putconstraints even on non-detection will help to determine the correctfrequency of CB planets, contributing to the understanding of planetformation in general. Still, searching for transiting CB planets isstill a learning experience, similarly to the state of transitingplanets around single stars only a few years ago. The recent rapidprogress in this front, coupled with the exquisite quality ofspace-based photometry, allows to realistically expect that iftransiting CB planets exist - then they will soon be found.Based on observations obtained with CoRoT, a space project operated bythe French Space Agency, CNES, with participation of the ScienceProgramme of ESA, ESTEC/RSSD, Austria, Belgium, Brazil, Germany andSpain.
| On the apsidal motion of BP Vulpeculae
BP Vulpeculae is a bright eclipsing binary system showing apsidalmotion. It was found in an earlier study that it shows retrogradeapsidal motion which contradicts theory. In this paper we present thefirst BV light curve of the system and its light curve solution as wellas seven new times of the minima from the years 1959 1963. This way wecould expanded the baseline of the investigation to five decades. Basedon this longer baseline we concluded that the apsidal motion is progradeagreeing with the theoretical expectations and its period is about 365years and the determined internal structure constant is close to thetheoretically expected one.
| 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.
| B.R.N.O. Times of minima
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| Artificial Intelligence Approach to the Determination of Physical Properties of Eclipsing Binaries. I. The EBAI Project
Achieving maximum scientific results from the overwhelming volume ofastronomical data to be acquired over the next few decades demandsnovel, fully automatic methods of data analysis. Here we concentrate oneclipsing binary (EB) stars, a prime source of astrophysicalinformation, of which only some hundreds have been rigorously analyzed,but whose numbers will reach millions in a decade. We describe theartificial neural network (ANN) approach which is able to surmount thehuman bottleneck and permit EB-based scientific yield to keep pace withfuture data rates. The ANN, following training on a sample of 33,235model light curves, outputs a set of approximate model parameters[T2/T1, (R1+R2)/a,esinω, ecosω, and sini] for each input light curve data set.The obtained parameters can then be readily passed to sophisticatedmodeling engines. We also describe a novel method polyfit forpreprocessing observational light curves before inputting their data tothe ANN and present the results and analysis of testing the approach onsynthetic data and on real data including 50 binaries from the Catalogand Atlas of Eclipsing Binaries (CALEB) database and 2580 light curvesfrom OGLE survey data. The success rate, defined by less than a 10%error in the network output parameter values, is approximately 90% forthe OGLE sample and close to 100% for the CALEB sample-sufficient for areliable statistical analysis. The code is made available to the public.Our approach is applicable to EB light curves of all classes; this firstpaper in the eclipsing binaries via artificial intelligence (EBAI)series focuses on detached EBs, which is the class most challenging forthis approach.
| 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.
| B.R.N.O. Contributions #34
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| Photoelectric Minima of Selected Eclipsing Binaries and Maxima of Pulsating Stars
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| 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
| New Times of Minima of Some Eclipsing Variables
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| MECI: A Method for Eclipsing Component Identification
We describe an automated method for assigning the most probable physicalparameters to the components of an eclipsing binary, using only itsphotometric light curve and combined colors. With traditional methods,one attempts to optimize a multiparameter model over many iterations, soas to minimize the ?2 value. We suggest an alternativemethod, in which one selects pairs of coeval stars from a set oftheoretical stellar models and compares their simulated light curves andcombined colors with the observations. This approach greatly reduces theparameter space over which one needs to search and allows one toestimate the components' masses, radii, and absolute magnitudes, withoutspectroscopic data. We have implemented this method in an automatedprogram using published theoretical isochrones and limb-darkeningcoefficients. Since it is easy to automate, this method lends itself tosystematic analyses of data sets consisting of photometric time seriesof large numbers of stars, such as those produced by OGLE, MACHO, TrES,HAT, and many others surveys.
| Photoelectric Minima of Selected Eclipsing Binaries and Maxima of Pulsating Stars
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| A catalogue of close binaries located in the δ Scuti region of the Cepheid instability strip
A catalogue of close eclipsing binary systems (detached andsemidetached) with at least one of the components located in the δScuti region of the Cepheid instability strip is presented. Thepositions of the stars in the instability strip are determined by theiraccurate temperatures and luminosities. Observationally detectedbinaries (20 semidetached, four detached and one unclassified) withoscillating components were included in the catalogue as a separatetable. The primaries of the oscillating Algols tend to be located nearthe blue edge of the instability strip. Using reliable luminosities andtemperatures determined by recent photometric and spectroscopic studies,we have found that at least one or two components of 71 detached and 90semidetached systems are located in the δ Scuti region of theCepheid instability strip. In addition, 36 detached or semidetachedsystems discovered by the Hipparcos satellite were also given as aseparate list. One of their components is seen in the δ Scutiregion, according to their spectral type or B - V colours. They arepotential candidate binaries with the δ Scuti-type pulsatingcomponents which need further photometric and spectroscopic studies inbetter precision. This catalogue covers information and literaturereferences for 25 known and 197 candidate binaries with pulsatingcomponents.
| 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.
| New Times of Minima of Some Eclipsing Variables
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| Solutions for 10,000 Eclipsing Binaries in the Bulge Fields of OGLE II Using DEBiL
We have developed a fully automated pipeline for systematicallyidentifying and analyzing eclipsing binaries within large data sets oflight curves. The pipeline is made up of multiple tiers that subject thelight curves to increasing levels of scrutiny. After each tier, lightcurves that did not conform to a given criteria were filtered out of thepipeline, reducing the load on the following, more computationallyintensive tiers. As a central component of the pipeline, we created thefully automated Detached Eclipsing Binary Light curve fitter (DEBiL),which rapidly fits large numbers of light curves to a simple model.Using the results of DEBiL, light curves of interest can be flagged forfollow-up analysis. As a test case, we analyzed the 218,699 light curveswithin the bulge fields of the OGLE II survey and produced 10,862 modelfits. We point out a small number of extreme examples, as well asunexpected structure found in several of the population distributions.We expect this approach to become increasingly important as light-curvedata sets continue growing in both size and number.
| CCD Times of Minima of Selected Eclipsing Binaries
682 CCD minima observations of 259 eclipsing binaries made mainly byauthor are presented. The observed stars were chosen mainly fromcatalogue BRKA of observing programme of BRNO-Variable Star Section ofCAS.
| New Times of Minima of Some Eclipsing Variables
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| 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.
| 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/.
| 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
| Times of Minima of Eclipsing Binary Stars
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| Absolute Properties of the Main-Sequence Eclipsing Binary Star BP Vulpeculae
We present 5236 differential observations in the V filter measured by arobotic telescope, as well as radial velocities from spectroscopicobservations, of the detached, eccentric 1.9 day double-lined eclipsingbinary star BP Vul. Absolute dimensions of the components are determinedwith high precision (better than 1% in the masses and radii) for thepurpose of testing various aspects of theoretical modeling. We obtain1.737+/-0.015 Msolar and 1.852+/-0.014 Rsolar forthe primary, and 1.408+/-0.009 Msolar and 1.489+/-0.014Rsolar for the secondary. The effective temperatures andinterstellar reddening of the stars are accurately determined fromuvbyβ photometry: 7700+/-150 K for the primary, 6800+/-150 K forthe secondary-corresponding to spectral types of A7m and F2m-and 0.022mag for Eb-y. The metallic-lined character of the stars isrevealed by high-resolution spectroscopy and uvbyβ photometry.Spectral line widths give rotational velocities that are synchronouswith the orbital motion for the secondary component, but subsynchronousfor the primary component, in a slightly eccentric orbit (e=0.0345).Apsidal motion based on times of minimum light appears to be negativewith a period of about 75 years based on recent observations of minima,but this result is not confirmed by the radial velocity measurements,and it is indeterminate when older photographic and visual data areincluded. The components of BP Vul are main-sequence stars with an ageof about 1 Gyr according to models.Some of the observations reported here were obtained with the MultipleMirror Telescope, a joint facility of the Smithsonian Institution andthe University of Arizona.
| 162-nd List of Minima Timings of Eclipsing Binaries by BBSAG Observers
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| Times of Minimum for the Eclipsing Binary BP Vul
We report times of minimum light for the eclipsing binary BP Vuldetermined from archival photographic plates at the Harvard CollegeObservatory.
| Times of Minima of Eclipsing Binaries
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| 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.
| Times of Minima of Eclipsing Binaries
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