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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.
| Synchronization and circularization in early-type binaries on main sequence
We showed in a preceding paper based on an analysis of the observedrates of apsidal motion that synchronization in early-type eclipsingbinaries continues on the main sequence, and the observedsynchronization times, tsyn, agree with the Zahn's theory andare inconsistent with the shorter time-scale proposed by Tassoul. Itfollows from this that circularization in early-type binaries must alsoproceed in accordance with the Zahn's theory because the circularizationtimes, tcirc, in both theories are rather tightly related totsyn via relation tcirc ~?tsyn,where ? is the orbital-to-axial momentum ratio.To further investigate this problem, we compile a catalogue of 101eclipsing binaries with early-type main-sequence components(M1,2 > 1.6Msolar). We determine the ages, t,and circularization time-scales, tcirc, for all these systemsin terms of the two competing theories by comparing observational datawith modern models of stellar evolution of Claret and atmospheric modelsof Kurucz. We compute tcirc with the allowance for theevolutionary variations of the physical parameters of the componentsand, for the first time in such studies, also take into account thevariations of the orbital parameters (P, a, e) in the process ofcircularization subject to the conservation of the total angularmomentum.The results of these computations show that the mechanism of orbitalcircularization in early-type close binary systems (CBSs) suggested byTassoul is, like in the case of synchronization, inconsistent withobservational data. At the same time, the Zahn's mechanism, which isbased on the dissipation of the energy of dynamic tides in the upperlayers of the envelopes of CBSs components due to non-adiabaticity ofthese layers, agrees satisfactorily with observations.
| Radii of Rapidly Rotating Stars, with Application to Transiting-Planet Hosts
The currently favored method for estimating radii and other parametersof transiting-planet host stars is to match theoretical models toobservations of the stellar mean density ?*, theeffective temperature T eff, and the composition parameter[Z]. This explicitly model-dependent approach is based on readilyavailable observations, and results in small formal errors. Itsperformance will be central to the reliability of results fromground-based transit surveys such as TrES, HAT, and SuperWASP, as wellas to the space-borne missions MOST, CoRoT, and Kepler. Here, I use twocalibration samples of stars (eclipsing binaries (EBs) and stars forwhich asteroseismic analyses are available) having well-determinedmasses and radii to estimate the accuracy and systematic errors inherentin the ?* method. When matching to the Yonsei-Yalestellar evolution models, I find the most important systematic errorresults from selection bias favoring rapidly rotating (hence probablymagnetically active) stars among the EB sample. If unaccounted for, thisbias leads to a mass-dependent underestimate of stellar radii by as muchas 4% for stars of 0.4 M sun, decreasing to zero for massesabove about 1.4 M sun. Relative errors in estimated stellarmasses are three times larger than those in radii. The asteroseismicsample suggests (albeit with significant uncertainty) that systematicerrors are small for slowly rotating, inactive stars. Systematic errorsarising from failings of the Yonsei-Yale models of inactive starsprobably exist, but are difficult to assess because of the small numberof well-characterized comparison stars having low mass and slowrotation. Poor information about [Z] is an important source of randomerror, and may be a minor source of systematic error as well. Withsuitable corrections for rotation, it is likely that systematic errorsin the ?* method can be comparable to or smaller than therandom errors, yielding radii that are accurate to about 2% for moststars.
| Using binaries containing giants to constrain theories of stellar and tidal evolution
Aims: Investigations of stellar and tidal evolution of binary stars withgiant components are rare. In this paper, we will investigate suchfeatures in three binary systems for which at least one component is agiant star. As some of these giants seem to be in the blue loop, it isan excellent opportunity to investigate the sensitivity of coreovershooting on their location in the HR Diagram. We expect that thesecharacteristics shall serve as an incentive to observers to investigatesuch kinds of binaries, increasing the accuracy of measurements and thenumber of systems to test the evolutionary models. Methods:Prior to performing the study of the circularization and synchronizationlevels, an analysis of the capability of our stellar evolutionary modelsto reproduce the observed masses, radii and effective temperatures iscarried out. Next, the differential equations of tidal evolution areintegrated and the corresponding critical times are compared with theinferred age of the system and with the observed eccentricity androtational velocities (when available). Results: We have foundgood agreement between our stellar models and the astrophysicalproperties of ? And, V2291 Oph and SZ Cen by adopting a moderatecore overshooting amount (?_ov = 0.20). Three mechanisms were usedto try to explain the observed levels of circularization andsynchronization: the hydrodynamical mechanism, turbulent dissipation andradiative damping. In the cases of ? And and SZ Cen, for which therotational velocities are available, by assuming solid body rotation forboth stars of each system we have found that the theoretical ratiobetween the rotational velocities Vrot A/Vrot B atthe inferred ages are in good agreement with the observational ratios.
| New absolute magnitude calibrations for detached binaries
Lutz-Kelker bias corrected absolute magnitude calibrations for thedetached binary systems with main-sequence components are presented. Theabsolute magnitudes of the calibrator stars were derived at intrinsiccolours of Johnson-Cousins and 2MASS (Two Micron All Sky Survey)photometric systems. As for the calibrator stars, 44 detached binarieswere selected from the Hipparcos catalogue, which have relative observedparallax errors smaller than 15% (σπ/π≤0.15).The calibration equations which provide the corrected absolute magnitudefor optical and near-infrared pass bands are valid for wide ranges ofcolours and absolute magnitudes: -0.18<(B-V)0<0.91,-1.6
| Does convective core overshooting depend on stellar mass?. Tests using double-lined eclipsing binaries
Aims.We have selected 13 double-line eclipsing binary systems (DLEBS),strategically positioned in the HR diagram, to infer the mass dependenceof the core overshooting parameter α_ov. Methods: In order tocompare the data from these DLEBS with the theoretical predictions wecomputed four grids of evolutionary stellar models with variable amountsof core overshooting (α_ov = 0.0, 0.2, 0.4, and 0.6) in additionto those previously computed. In some particular cases specific modelswere computed for the precise observed masses. This procedure avoidsinterpolations and extrapolations, and only considers chemicalcompositions within the limits of the usual primordial helium abundanceand enrichment law. Results: We used the ratio TR ≡ Teff2/Teff 1 instead of the effective temperaturesthemselves as we consider it a much better constrained parameter. Thisis because it is directly derived from the analysis of light curves andis independent of calibrations, distances, and model atmospheres. Incontrast to previous studies on the subject, we have found that standardmodels or models with moderate core overshooting (α_ov ≈ 0.2)are able to match the absolute dimensions of key DLEBS such as V380 Cygor V453 Cyg. The resulting log M - α_ov diagram indicates that thedependence of α_ov on mass is more uncertain and less pronouncedthat previously established. This result is also consistent with theanalysis of colour-magnitude diagrams for clusters and with previouscomparisons of stellar models with larger samples of DLEBS.Figures 1-12 are only available in electronic form athttp://www.aanda.org
| 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.
| Four-colour photometry of eclipsing binaries. XL. uvby light curves for the B-type systems DW Carinae, BF Centauri, AC Velorum, and NSV 5783
Aims.In order to increase the limited number of B-stars with accuratelyknown dimensions, and also the number of well studied eclipsing binariesin open clusters, we have undertaken observations and studies of foursouthern double-lined eclipsing B-type binaries; DW Car, BF Cen, AC Vel,and NSV 5783. Methods: .Complete {uvby} light curves were observedbetween January 1982 and April 1991 at the Danish 0.5 m telescope at ESOLa Silla, since 1985 known as the Strömgren Automatic Telescope(SAT). Standard indices for the systems and the comparison stars, aswell as additional minima observations for AC Vel, have been obtainedlater at SAT. For DW Car and AC Vel, high-resolution spectra fordefinitive spectroscopic orbits have also been obtained; they arepresented as part of the detailed analyses of these systems. A fewspectra of NSV 5783 are included in the present paper. Results:.For all four systems, the first modern accurate light curves have beenestablished. DW Car is a detached system consisting of two nearlyidentical components. It is member of the young open cluster Cr228. Adetailed analysis, based on the new light curves and 29 high-resolutionspectra, is published separately. BF Cen is semidetached and is memberof NGC 3766. Modern spectra are needed for a detailed study. AC Vel is adetached system with at least one more star. A full analysis, based onthe new light curves and 18 high-resolution spectra, is publishedseparately. NSV 5783 is discovered to be an eclipsing binary consistingof two well-detached components in an 11-day period eccentric (e = 0.18)orbit. Secondary eclipse is practically total. From the light curves anda few high-resolution spectra, accurate photometric elements andpreliminary absolute dimensions have been determined. The quite similarcomponents have masses of about 5 Mȯ and radii of about3.5 Rȯ, and they seem to have evolved just slightly offthe ZAMS. The measured rotational velocities (≈150 kms-1) are about 6 times those corresponding topseudosynchronization.
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| 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.
| 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.
| 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
| Convective core mixing: A metallicity dependence?
The main purpose of this paper is to investigate the possible existenceof a metallicity dependence of the overshooting from main sequence starturbulent cores. We focus on objects with masses in the range ~ 2.5Msun- ~ 25 Msun. Evolutionary time scale ratiosare compared with star number ratios on the main sequence. Starpopulations are synthesized using grids of evolutionary tracks computedwith various overshooting amounts. Observational material is provided bythe large and homogeneous photometric database of the OGLE 2 project forthe Magellanic clouds. Attention is paid to the study of uncertainties:distance modulus, intergalactic and interstellar reddening, IMF slopeand average binarity rate. Rotation and the chemical compositiongradient are also considered. The result for the overshooting distanceis loverSMC = 0.40+0.12-0.06Hp (Z0=0.004) and loverLMC =0.10+0.17-0.10 Hp (Z0=0.008)suggesting a possible dependence of the extent of the mixed centralregions with metallicity within the considered mass range. Unfortunatelyit is not yet possible to fully disentangle the effects of mass andchemical composition.
| 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.
| 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.
| Absolute Dimensions of the Unevolved B-Type Eclipsing Binary GG Orionis
We present photometric observations in B and V, as well as spectroscopicobservations of the detached, eccentric 6.6 day double-lined eclipsingbinary GG Ori, a member of the Orion OB1 association. Absolutedimensions of the components, which are virtually identical, aredetermined to high accuracy (better than 1% in the masses and betterthan 2% in the radii) for the purpose of testing various aspects oftheoretical modeling. We obtain MA=2.342+/-0.016Msolar and RA=1.852+/-0.025 Rsolar forthe primary, and MB=2.338+/-0.017 Msolar andRB=1.830+/-0.025 Rsolar for the secondary. Theeffective temperature of both stars is 9950+/-200 K, corresponding to aspectral type of B9.5. GG Ori is very close to the zero-age mainsequence, and comparison with current stellar evolution models givesages of 65-82 Myr or 7.7 Myr, depending on whether the system isconsidered to be burning hydrogen on the main sequence or still in thefinal stages of pre-main-sequence contraction. Good agreement is foundin both scenarios for a composition close to solar. We have detectedapsidal motion in the binary at a rate of ω=0.00061d+/-0.00025dcycle-1, corresponding to an apsidal period ofU=10,700+/-4500 yr. A substantial fraction of this (~70%) is due to thecontribution from general relativity, and our measurement is entirelyconsistent with theory. The eccentric orbit of GG Ori is well explainedby tidal evolution models, but both theory and our measurements of therotational velocity of the components are as yet inconclusive as towhether the stars are synchronized with the orbital motion. Some of theobservations reported here were obtained with the Multiple MirrorTelescope, a joint facility of the Smithsonian Institution and theUniversity of Arizona.
| The mass dependence of the overshooting parameter determined from eclipsing binary data
High-precision data on absolute dimensions of evolved eclipsing binarieshave been used for a quantitative evaluation of the significance ofconvective overshoot in the stellar core. Eight detached double-linedeclipsing binaries with components close to or beyond the terminal agemain sequence (TAMS) and masses between 2 and 12Msolar havebeen compared with evolutionary models using different overshootingparameters. The results are robust and indicate a systematic increase ofthe amount of convective overshoot with the stellar mass. Suchdetermination constitutes a fundamental point for stellar structure andevolution theory.
| Chemical composition of eclipsing binaries: a new approach to the helium-to-metal enrichment ratio
The chemical enrichment law Y(Z) is studied by using detacheddouble-lined eclipsing binaries with accurate absolute dimensions andeffective temperatures. A sample of 50 suitable systems was collectedfrom the literature, and their effective temperatures were carefullyre-determined. The chemical composition of each of the systems wasobtained by comparison with stellar evolutionary models, under theassumption that they should fit an isochrone to the observed propertiesof the components. Evolutionary models covering a wide grid in Z and Ywere adopted for our study. An algorithm was developed for searching thebest-fitting chemical composition (and the age) for the systems, basedon the minimization of a χ2 function. The errors (andbiases) of these parameters were estimated by means of Monte Carlosimulations, with special care put on the correlations existing betweenthe errors of both components. In order to check the physicalconsistency of the results, we compared our metallicity values withempirical determinations, obtaining excellent coherence. Theindependently derived Z and Y values yielded a determination of thechemical enrichment law via weighted linear least-squares fit. Our valueof the slope, ΔY/ΔZ=2.2+/-0.8, is in good agreement withrecent results, but it has a smaller formal error and it is free ofsystematic effects. Linear extrapolation of the enrichment law to zerometals leads to an estimation of the primordial helium abundance ofYp=0.225+/-0.013, possibly affected by systematics in theeffective temperature determination.
| Estimating the ages of eclipsing variable DM-stars on the basis of the evolutionary star models by Maeder and Meynet
A set of isochrones covering a wide range of star ages from5\cdot106 to 1010 yr was built on the basis of thestellar models by A. Maeder and G. Meynet with overshooting and massloss for Population I stars with abundances (X, Y, Z) = 0.70, 0.28,0.02. The isochrones were used to compute the ages of 88 eclipsingvariable stars from the catalog by Andersen which lie on the mainsequence. The influence of initial data errors on the rezultes wasinvestigated. The ages derived are in good agreement with the results ofother authors.
| Determination of empirical mass-luminosity and mass-radius relations for main-sequence stars that are the components of eclipsing binary systems
Based on a new catalog of photometric, geometrical, and absoluteelements for 112 eclipsing binary systems with both components on themain sequence and with known photometric and spectroscopic orbitalelements, we redetermined the mass-luminosity and mass-radius relations:M_bol = 4.46 - 9.52 lg M (lg M > -0.4), M_bol = 6.58 - 5.00 lg M (lgM <= -0.4), lg R = 0.096 + 0.652 lg M (lg M > 0.14), lg R = 0.049+ 0.993 lg M (lg M <= 0.14). For most systems, the masses and radiiof the components are determined with an accuracy of 2-3% and 2-4%,respectively. We estimated the parameters of these relations by theleast-squares method using the procedure for correcting the estimatesthus obtained for noise in the argument.
| Convective Overshooting and Mixing in Stellar Evolution
Not Available
| Photometric versus empirical surface gravities of eclipsing binaries.
Systematic differences in photometric stellar surface gravitydetermination are studied by means of the comparison with empiricalvalues derived from detached double-lined eclipsing binaries.Photometric gravities were computed using Moon & Dworetsky(1985MNRAS.217..305M) grids based on Kurucz (1979ApJS...40....1K)atmosphere models, and empirical gravities were taken from Andersen(1991A&ARv...3...91A). Individual Stroemgren colours and βindices of each component of the binary system have to be taken intoaccount to correctly analyze the observed differences. A compilation ofdata on a sample containing 30 detached double-lined eclipsing binarieswith accurate (=~1-2%) determination of mass and radius and availableuvbyHbeta_ photometric data is also presented. Correction ofthe differences in terms of T_eff_ and logg for the range11000K
| Further critical tests of stellar evolution by means of double-lined eclipsing binaries
The most accurately measured stellar masses and radii come fromdetached, double-lined eclipsing binaries, as compiled by Andersen. Wepresent a detailed quantitative comparison of these fundamental datawith evolution models for single stars computed with our evolution code,both with and without the effects of enhanced mixing or overshootingbeyond the convective cores. We use the same prescription forovershooting that Schroder, Pols & Eggleton found to reproduce theproperties of zeta Aurigae binaries. For about 80 per cent of the 49binary systems in the sample, both sets of models provide a good fit toboth stars at a single age and metallicity within the observationaluncertainties. We discuss possible causes for the discrepancies in theother systems. For only one system, AI Hya, do the enhanced-mixingmodels provide a significantly better fit to the data. For two others(WX Cep and TZ For) the fit to the enhanced-mixing models is alsobetter. None of the other systems can individually distinguish betweenthe models with and without enhanced mixing. However, the number ofsystems in a post-main-sequence phase is in much better agreement withthe enhanced-mixing models. This test provides supportive evidence forextended mixing in main-sequence stars in the range 2-3Msolar.
| 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.
| Effective Temperature Bolometric Correction and Mass Calibration of O-F
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1994MNRAS.268..119B&db_key=AST
| The spectroscopic orbit and subsynchronous rotation of the Herbig Ae/Be star TY CrA
High-resolution spectra of the Herbig Ae/Be eclipsing binary TY CrA areobtained and used to measure high-precision radial velocities. We findTY CrA to be a single-lined spectroscopic binary having a circular orbitwith a period of 2.88873 days, supporting a previous photometric periodof 2.888777 days. We also place an upper limit of 15 km/s on the v sin iof the primary. Such a low rotational velocity corresponds to highlysubsynchronous rotation, presuming the stellar rotation axis to have aninclination angle near 90. We argue that this remarkably slow rotationvelocity in a circular orbit cannot be explained in the context ofstellar evolution and tidal interactions alone. Presuming TY CrA to be apre-main-sequence star, the origin of its subsynchronism must lie in abraking mechanism early in the life of the primary. Finally, we notethat the lack of NIR excess emission indicates that no optically thickdisk material is present within a few orbital separations of the binary.
| Catalogue of astrophysical parameters of binary systems
Not Available
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Observation and Astrometry data
| Constellation: | Centaurus |
| Right ascension: | 13h50m35.09s |
| Declination: | -58°29'57.1" |
| Apparent magnitude: | 8.601 |
| Distance: | 262.467 parsecs |
| Proper motion RA: | -10.2 |
| Proper motion Dec: | -12.5 |
| B-T magnitude: | 8.954 |
| V-T magnitude: | 8.631 |
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