Contents
Images
Upload your image
DSS Images Other Images
Related articles
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.
| 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
| Circular Polarization of Starlight
Of the 7500 stars cited in the Catalog of starlight polarization, thosewhich satisfy the condition P obs % and A V 0m.5 are selected. It ispresumed that the selected stars (n=216) have circularly polarizedlight.
| Masses and other parameters of massive binaries
Binary stars provide us with the means to measure stellar mass. Here Ipresent several lists of known O-type stars with reliable mass estimatesthat are members of eclipsing, double-lined spectroscopic binaries. Themasses of young, unevolved stars in binaries are suitable for testingthe predictions of evolutionary codes, and there is good agreementbetween the observed and predicted masses (based upon temperature andluminosity) if the lower temperature scale from line-blanketed modelatmospheres is adopted. A final table lists masses for systems in awide variety of advanced evolutionary stages.
| Tomographic Separation of Composite Spectra. IX. The Massive Close Binary HD 115071
We present the first orbital elements for the massive close binary HD115071, a double-lined spectroscopic binary in a circular orbit with aperiod of 2.73135+/-0.00003 days. The orbital semiamplitudes indicate amass ratio of M2/M1=0.58+/-0.02, and yet the starshave similar luminosities. We used a Doppler tomography algorithm toreconstruct the individual component optical spectra, and we appliedwell-known criteria to arrive at classifications of O9.5 V and B0.2 IIIfor the primary and secondary, respectively. We present models of theHipparcos light curve of the ellipsoidal variations caused by the tidaldistortion of the secondary, and the best-fit model for a Roche-fillingsecondary occurs for an inclination of i=48.7d+/-2.1d. The resultingmasses are 11.6+/-1.1 and 6.7+/-0.7Msolar for the primary andsecondary, respectively, so both stars are very overluminous for theirmass. The system is one of only a few known semidetached, Algol-typebinaries that contain O stars. We suggest that the binary has recentlyemerged from extensive mass transfer (possibly through a delayed contactand common-envelope process).
| Spectroscopy of four early-type eclipsing binaries
New spectroscopic data were obtained for the early-type binariesV337 Aql, V649 Cas, V382Cyg, and V431 Pup. Their radial velocitycurves are presented. These are the first such data for V337Aql and V431 Pup. In the case ofV382 Cyg, our data confirm previously obtainedresults. Especially for V649 Cas our radial velocitycurve yields important new implications for the component masses: thedetection of third body lines, which are blended with the lines of theprimary component, solves the problem of the unacceptably small massesformerly deduced for this binary; now we determine masses closer to thevalues expected for spectral type B 0. V431 Pup is animportant object, because it is a new member of the small group ofearly-type eclipsing binaries with an evolved component. A publishedlight curve of V337 Aql is solved by the MORO code, and systemparameters are derived. The period of V649 Cas isfound to be variable, and a more accurate period is calculated forV431 Pup. Based on observations collected at theEuropean Southern Observatory, La Silla, Chile, and at theGerman-Spanish Astronomical Center (DSAZ), Calar Alto, operated by theMax-Planck-Institut für Astronomie Heidelberg jointly with theSpanish National Commission for Astronomy.
| 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.
| Five-colour photometry of OB-stars in the Southern Hemisphere
Observations of OB-stars, made in 1959 and 1960 at the Leiden SouthernStation near Hartebeespoortdam, South Africa, with the VBLUW photometerattached to the 90 cm light-collector, are given in this paper. They arecompared with photometry obtained by \cite[Graham (1968),]{gra68}\cite[Walraven & Walraven (1977),]{wal77} \cite[Lub & Pel(1977)]{lub77} and \cite[Van Genderen et al. (1984).]{gen84} Formulaefor the transformation of the present observations to those of\cite[Walraven & Walraven (1977)]{wal77} and \cite[Lub & Pel(1977)]{lub77} are given. Table 4 is only available in electronic format the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) orvia http://cdsweb.u-strasbg.fr/Abstract.html
| V606 Centauri: an early-type eclipsing contact binary
We present a spectroscopic and photometric analysis of the early-typeeclipsing binary V606 Cen. Based on new high-resolution CCD spectra thefirst radial velocity curve of this system is given, which allows for anaccurate determination of radial velocity amplitudes (K_1=181.8 km s(-1), K_2=345.2 km s(-1) ) and the spectroscopic mass ratio q_spec=0.527.Moreover, equivalent widths are listed. The line strengths of He i 4922show strong variations with the orbital phase, related to the so-called(and hitherto unexplained) ``Struve-Sahade effect". In this context,some aspects concerning the determination of equivalent widths in closebinary systems are discussed, with special reference to the influence ofthe ellipsoidal light variations. For the first time, photoelectric UBVlight curves of V606 Cen are presented, which were solved with the MOROcode, based on the Wilson-Devinney model. The first set of solutions wasachieved with effective temperatures according to the previous spectralclassification B1-2 Ib/IIb, but the derived absolute dimensions, surfacegravities, as well as an investigation of the equivalent widths led to arevision of the spectral type. We now suggest B0-0.5 V for the primary,and B2-3 V for the secondary component, respectively. Using thecorresponding effective temperatures, another light curve analysis wasperformed, yielding the following absolute dimensions: M_1=14.7 M_sun,M_2=8.0 M_sun, R_1=6.8 R_sun, R_2=5.2 R_sun, log L_1/L_sun=4.48, and logL_2/L_sun=3.74. In all cases, a contact configuration is found. Theevolutionary state of V606 Cen is discussed in the light of modernevolutionary grids. It turns out that this contact system was formedduring the slow phase of case A mass transfer after reversal of its massratio. In this respect it is similar to other early-type contactbinaries such as V382 Cyg, V701 Sco or RZ Pyx. Based on observationscollected at the European Southern Observatory, La Silla, Chile
| Interacting OB star binaries: LZ Cep, SZ Cam and IU AUR
New spectroscopic observations of three O+O binary stars (LZ Cep, SZ Camand IU Aur), obtained over a number of years at the DominionAstrophysical Observatory, are analysed using state-of-the-artcross-correlation techniques to produce radial velocity curves. Theseresults are combined with new (LZ Cep) and published (SZ Cam and IU Aur)photometry to yield masses, temperatures, radii and luminosities. Wefind that LZ Cep is a semi-detached system, in agreement with theresults of Howarth et al., with the secondary star filling its Rochelobe. We find a distance modulus of 9.6+/-0.2, which is slightly smallerthan the distance modulus to Cep OB2 (=9.9).The reddening of LZ Cep isalso at the lower end of the cluster range, suggesting that the binaryis located on the near side of the cluster. SZ Cam is a triple system,and we are able to measure the radial velocities of the three componentsthat are observed in the absorption lines. A light-curve solutionemploying our new mass ratio shows that the short-period binary isdetached. The third body emits about 40 per cent of the radiation fromthe system, and is probably a binary itself. The distance modulus for SZCam (=9.88) is in good agreement with that of its parent cluster NGC1502 (=9.71). IU Aur is another triple system, although we are unable tofind spectroscopic evidence for the tertiary. The close binary issemi-detached, with the secondary filling its Roche lobe. The distancemodulus of the system is 11.0, which is in approximate agreement withthat of the Aur OB1 association (=10.6+/-0.2). We note that the currentmodels for interacting massive binaries all assume case B mass transfer,in which the mass-loser becomes a Wolf-Rayet star. Case A mass-transfermodels (in which the mass-loser fills its Roche lobe while still on themain sequence) are required in order to see whether or not they canexplain the observed properties of these interacting systems.
| UBV beta Database for Case-Hamburg Northern and Southern Luminous Stars
A database of photoelectric UBV beta photometry for stars listed in theCase-Hamburg northern and southern Milky Way luminous stars surveys hasbeen compiled from the original research literature. Consisting of over16,000 observations of some 7300 stars from over 500 sources, thisdatabase constitutes the most complete compilation of such photometryavailable for intrinsically luminous stars around the Galactic plane.Over 5000 stars listed in the Case-Hamburg surveys still lackfundamental photometric data.
| SZ Camelopardalis - an early-type eclipsing binary embedded in a multiple system
We present a spectroscopic and photometric analysis of a complexmultiple system: the early-type eclipsing binary SZ Cam (O9 IV + B0.5 V)is physically bound to a third body, which itself is a close binary;this quadruple system has a visual companion, which shows evidence forduplicity as well. A careful deconvolution of spectral lines in our CCDspectra yields rv curves of the SB2 system (K_1 = 180 km s(-1) , K_2 =261 km s(-1) ; P = 2fd 6984) and of its SB1 companion (K_{1{,T}} = 25 kms(-1) ; P 2fd 7966). UBV light curves of Kitamura & Yamasaki (1970)are reanalyzed and absolute dimensions of the eclipsing pair arederived. Both components of this close detached binary are overluminousfor their masses. The photometric solution suggests third light of ~20-30%, which confirms the spectroscopic and speckle interferometricdetection (Mason 1995) of the third component. The observed light timeeffect encompasses the long period range to ~ 50-60 years. Comparison ofcalculated orbits with the speckle interferometric result yields adistance of 1050 pc, which is ~ 10% larger than the value derived fromthe absolute bolometric magnitude, and ~ 20% above the photometricdistance of the open cluster NGC 1502. The minimum mass of the thirdcomponent is 20-30 M_ȯ, depending on the long orbital period andinclination assumed. This high mass supports the binary nature of thethird body. An analysis of the spectra of the visual companion ADS 2984A confirms its binarity. Based on observations collected at theGerman-Spanish Astronomical Centre, Calar Alto, operated by theMax-Planck-Institut für Astronomie, Heidelberg, jointly with theSpanish National Commission for Astronomy
| A Radial Velocity Database for Stephenson-Sanduleak Southern Luminous Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1997AJ....113..823R&db_key=AST
| Application of the KOREL cross-correlation technique to radial-velocity measurements of early-type close binaries.
Not Available
| A spectroscopic database for Stephenson-Sanduleak Southern Luminous Stars
A database of published spectral classifications for objects in theStepenson-Sanduleak Luminous Stars in the Southern Milky Way catalog hasbeen compiled from the literature. A total of 6182 classifications for2562 stars from 139 sources are incorporated.
| 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.
| Radiation pressure effects in early-type close binaries and implications for the solution of eclipse light curves
A new method is presented to include radiation pressure effects in themodeling of close binaries. The radiative interaction of the binarycomponents increases with Teff exp 4 and the inverse squareof reduced separation, and is of particular importance for hot OB-typebinaries in close configurations. Since no analytical representation ofthe modified potential field exists, a numerical procedure was developedto implement radiation pressure. The radiative forces are parameterizedusing the ratio of radiative relative to gravitational forces asnormalizing factor for the calculation of the radiation pressure actionon the irradiated photospheres. The local incident flux is obtained byan integration over the visible surface parts of the irradiatingcomponent, and the effective radiation pressure action on the irradiatedstar is determined with respect to the local geometrical conditions.Principal effects of radiation pressure on the shape of the stars andthe binary configuration are demonstrated by model calculations. Theseare several important implications for the binary structure: thegeometry of the stellar surfaces is modified; the Lagrangean points areshifted, and the shape and extent of the Roche lobes are changed; thetendency to take up inner contact in L1 is partlycounteracted by radiative forces; outer contact components (withsurfaces incorporating L2 or L3) may be formedabove some critical radiation pressure strength; obvious consequencesfor the evolution of systems with hot and luminous components like WR orX-ray binaries exist. The modified Roche potential is used as animproved model for the calculation of eclipse light curves, based on thegeneral logistics of the Wilson-Devinney method. The inverse problem issolved by applying the nonlinear simplex parameter optimizationalgorithm. The feasibility of the new method is demonstrated byphotometric solutions of the OB systems IU Aur and AB Cru. Theimplementation of radiation pressure effects yields improved solutionscompared with conventional methods. Therefore it appears promising toapply the method to hot O-type systems with non-negligible radiativeeffects, in order to derive more reliable absolute dimensions for thisparticularly important group of stars.
| Light curve solution of early-type binary systems with radiative interaction.
Not Available
| Absolute dimensions of AB Crucis: A semi-detached O-type eclipsing binary
New spectroscopic and photometric results for the eclipsing binary ABCru are presented. The first photoelectric UBV light curves of thisO8-type system were solved with a newly developed light curve modelingcode taking into account radiation pressure effects due to the mutualirradiation of the binary components. The radiative forces exerted onthe irradiated surface layers reach a few percent of the gravitationalattraction of the companion, and have non-negligible influence on thebinary structure. The first radial velocity curve of AB Cru, based onhigh resolution Coude-Echelle spectra, allowed for an accuratedetermination of the spectroscopic mass ratio and the radial velocityamplitudes. For the first time, precise absolute dimensions of AB Crucan be given: the stellar masses for the primary and secondary componentare 19.75 and 6.95 solar mass, the radii 10.54 and 8.85 solar radius,and luminosities 1.64 105 and 3.84 104 solar mass.A semi-detached system configuration was found. The evolutionary stateof AB Cru is discussed; both stellar components are slightly evolved,but still located within the upper main sequence band. Strongindications for case A mass transfer from the secondary towards theprimary are found, suggesting that AB Cru has formerly undergone areversal of its mass ratio.
| The Diffuse Ionized Interstellar Medium: Structures Resulting from Ionization by O Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1993ApJ...417..579M&db_key=AST
| Absolute dimensions of the O-type eclipsing binary AB Cru.
Not Available
| Solution of new UBV light curves of the O-type eclipsing binary AB Cru.
Not Available
| Close binaries observed polarimetrically
Not Available
| Statistical Study of the Rotation of ALGOLS
Not Available
| UBV-beta photometry of luminous early-type stars and emission-line stars in the Southern Coalsack region
A catalog is presented giving UBV-beta photometry for 144 luminous OBstars and UBV photometry for 154 emission-line stars in a 100-sq-degregion around the Southern Coalsack. Total visual absorptions anddistance moduli have been determined for all the stars and aretabulated. Comparisons with previous observations are discussed.
| A uvby, beta photometric survey of southern hemisphere
A uvby, beta photometric study of southern hemisphere eclipsing binarystars has been undertaken at Cerro Tololo Inter-American Observatory.The standardized colors and V magnitudes for 288 binaries at quadratureand/or at minimum are presented, along with an indication of theaccuracy of the standardization and photometry. Discussions of theresolving time of the pulse-counting photometers and of the atmosphericextinction at CTIO are included.
| Massive eclipsing binary candidates
New UBV data are provided for 63 southern OB stars which are eitheridentified in the survey by Garrison, Hiltner, and Schild as havingdouble lines or are known from Wood et al. to be eclipsing binaries.Twenty of the stars are known eclipsing variables. Four stars, notpreviously known as eclipsing, have both spectroscopic evidence ofduplicity and significant photometric variations. Several additionalstars have a marginally significant spread in V magnitude.
| UBV photometry for southern OB stars
New UBV photometry of 1227 OB stars in the southern Milky Way ispresented. For 1113 of these stars, MK spectral types have been reportedpreviously in a comprehensive survey to B = 10.0 mag.
| Statistics of categorized eclipsing binary systems Lightcurve shapes, periods, and spectral types
The statistics of the light curve morphologies, eclipse depths, orbitalperiods, and spectral types of about 1000 eclipsing binary systems areexamined, after attempting to subdivide these binaries into variousbasic evolutionary categories. The applicability of statisticalcriteria, based on light curve morphologies and eclipse depths, for thecategorization of eclipsing binaries has been found more limited thanpreviously believed. In particular, EW-type light curves turn out to begood indicators of contact systems (though not conversely), while EA-and EB-type light curves have little physical significance. Moreover,the study reveals a strong deficit of short-period noncontact systems inthe whole spectral range, together with an underabundance of early-typecontact binaries (compared with the number of late-type contact pairs).Interestingly, the distribution of evolved Algol-type systems isshifted, on average, to periods longer than those of unevolved detachedsystems in the OB and early A spectral range (and to shorter periods inthe F spectral range).
| The initial mass function for massive stars
A machine readable catalog of over 750 galactic O stars with publishedphotometry, spectral types, and luminosity classes has been compiled.The catalog is probably complete to a distance of about 2.5 kpc. Fromthis volume-limited data, the initial mass function (IMF) for stars moremassive than 20 solar masses has been derived. This IMF differs fromthat of Miller and Scalo (1979) and of Lequeux (1979), in havingproportionately more O type stars and not as steep a fall-off in numberof stars with increasing mass. Dividing the sample into stars inside andoutside the solar circle, a substantial difference in the IMF of themost massive stars is found. There are proportionally more toward thegalactic center. This gradient in the IMF may be related to the observedspace density of Wolf-Rayet stars, which are descendants of O typestars.
|
Submit a new article
Related links
Submit a new link
Member of following groups:
|
Observation and Astrometry data
| Constellation: | Croix du Sud |
| Right ascension: | 12h17m37.12s |
| Declination: | -58°09'52.4" |
| Apparent magnitude: | 8.489 |
| Distance: | 2380.952 parsecs |
| Proper motion RA: | -13.5 |
| Proper motion Dec: | 0.7 |
| B-T magnitude: | 8.615 |
| V-T magnitude: | 8.5 |
Catalogs and designations:
|
