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A high-resolution spectroscopy survey of β Cephei pulsations in bright stars
We present a study of absorption line-profile variations in early-B typenear-main-sequence stars without emission lines. We have surveyed atotal of 171 bright stars using the Nordic Optical Telescope (NOTSA),William Herschel Telescope (ING) and Coudé Auxiliary Telescope(ESO). Our sample contains 75% of all O9.5-B2.5 III-V non-emission-linestars brighter than 5.5 mag. We obtained high signal-to-noise,high-resolution spectra of the SiIII λ4560 triplet - for 125stars of our sample we obtained more than one spectrum - and examinedthese for pulsational-like line-profile variations and/or structure. Weconclude that about half of our sample stars show evidence forline-profile variations (LPV). We find evidence for LPV in about 65% ofour sample stars brighter than V=5.5. For stars with rotationalbroadening V sin i 100 km s-1, we find evidence for LPVin about 75% of the cases. We argue that it is likely that these LPV areof pulsational origin, and that hence more than half of thesolar-neighbourhood O9.5-B2.5 III-V stars is pulsating in modes that canbe detected with high-resolution spectroscopy. We detected LPV in 64stars previously unknown to be pulsators, and label these stars as newβ Cep candidates. We conclude that there is no obvious differencein incidence of (pulsational) LPV for early-B type near-main-sequencestars in binaries or in OB associations, with respect to single fieldstars.
| Catalog of Galactic β Cephei Stars
We present an extensive and up-to-date catalog of Galactic β Cepheistars. This catalog is intended to give a comprehensive overview ofobservational characteristics of all known β Cephei stars, coveringinformation until 2004 June. Ninety-three stars could be confirmed to beβ Cephei stars. We use data from more than 250 papers publishedover the last nearly 100 years, and we provide over 45 notes onindividual stars. For some stars we reanalyzed published data orconducted our own analyses. Sixty-one stars were rejected from the finalβ Cephei list, and 77 stars are suspected to be β Cepheistars. A list of critically selected pulsation frequencies for confirmedβ Cephei stars is also presented.We analyze the β Cephei stars as a group, such as the distributionsof their spectral types, projected rotational velocities, radialvelocities, pulsation periods, and Galactic coordinates. We confirm thatthe majority of the β Cephei stars are multiperiodic pulsators. Weshow that, besides two exceptions, the β Cephei stars with highpulsation amplitudes are slow rotators. Those higher amplitude starshave angular rotational velocities in the same range as thehigh-amplitude δ Scuti stars (Prot>~3 days).We construct a theoretical HR diagram that suggests that almost all 93β Cephei stars are main-sequence objects. We discuss theobservational boundaries of β Cephei pulsation and the physicalparameters of the stars. We corroborate that the excited pulsation modesare near to the radial fundamental mode in frequency and we show thatthe mass distribution of the stars peaks at 12 Msolar. Wepoint out that the theoretical instability strip of the β Cepheistars is filled neither at the cool nor at the hot end and attempt toexplain this observation.
| Classification of Spectra from the Infrared Space Observatory PHT-S Database
We have classified over 1500 infrared spectra obtained with the PHT-Sspectrometer aboard the Infrared Space Observatory according to thesystem developed for the Short Wavelength Spectrometer (SWS) spectra byKraemer et al. The majority of these spectra contribute to subclassesthat are either underrepresented in the SWS spectral database or containsources that are too faint, such as M dwarfs, to have been observed byeither the SWS or the Infrared Astronomical Satellite Low ResolutionSpectrometer. There is strong overall agreement about the chemistry ofobjects observed with both instruments. Discrepancies can usually betraced to the different wavelength ranges and sensitivities of theinstruments. Finally, a large subset of the observations (~=250 spectra)exhibit a featureless, red continuum that is consistent with emissionfrom zodiacal dust and suggest directions for further analysis of thisserendipitous measurement of the zodiacal background.Based on observations with the Infrared Space Observatory (ISO), aEuropean Space Agency (ESA) project with instruments funded by ESAMember States (especially the Principle Investigator countries: France,Germany, Netherlands, and United Kingdom) and with the participation ofthe Institute of Space and Astronautical Science (ISAS) and the NationalAeronautics and Space Administration (NASA).
| 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
| Fluorescence in ultraviolet active binaries: the case of FF Aquarii
The eclipsing binary FF Aquarii (FF Aqr) consists of a small hot star ofuncertain type and a red giant. An Hα feature varies fromabsorption during eclipse to maximum emission during hot star transit.We have obtained simultaneous differential photometry in BVRI bands andHα spectroscopy in 1998 that covered an entire orbit with someoverlap. A binary star model was used with our light-curve, radialvelocity and Hα data to refine stellar and orbital parameters. Anew ephemeris indicates that the period has increased or is longer thanpreviously thought. A physically simple algorithm is developed thatgenerates properly blended spectral line profiles of binaries witharbitrary combinations of surface emission and absorption line regions.Although there is no radiative transfer, the algorithm can accommodatemodest geometrical intricacy. For now, all line broadening in the modelis rotational. The algorithm has now been incorporated within thegeneral Wilson-Devinney binary star model, and we used it to model FFAqr's photospheric iron profile. It also is used to generate templatesthat illustrate problems with FF Aqr's strongly time-dependent Hαemission profiles, which appear to be blends of features from thephotosphere and from above the photosphere. The dominant broadeningmechanism should be rotation for individual line components. Absorptionprofiles were generated by the model and fit to the observations toyield a red star radius ~6.9 Rsolar, which then requires i~76°. Our light-curve models have five spots with temperatures ~1000K cooler than the surrounding photosphere. Hα emission wasmodelled on the red star surface, centred at the substellar point tosimulate a fluorescent chromosphere. Additional emission is seen outsideour modelled profiles. The origins of this excess emission may becorotating prominences, winds, or coronal mass ejections, all of whichcould affect the orbit period.
| Photoelectric Minimum Times of Some Eclipsing Binary Stars
We present 15 minimum times of 8 eclipsing binaries observed in theyears from 2001 to 2003 and in 1998 only for V436 Per.
| 162-nd List of Minima Timings of Eclipsing Binaries by BBSAG Observers
Not Available
| Search for forced oscillations in binaries. IV. The eclipsing binary V436 Per revisited
An analysis of new spectroscopic and photoelectric U B V observations,satisfactorily covering the whole orbital period of V436 Per, togetherwith existing data allowed us to improve the knowledge of the basicphysical characteristics of the binary and its components. In severalaspects, our new results differ from the findings of Paper I of thisseries: in particular, we found that it is the star eclipsed in thesecondary minimum which is slightly more massive and larger than theoptical primary. We also conclude that the apsidal advance - if presentat all - is much slower than that estimated in a previous study. Theorbital period might be increasing by 0.28 s per year but also thisfinding is very uncertain and needs verification by future observations.It is encouraging to note that two completely independent sets ofprograms for light-curve solutions lead to identical results. A notablefinding is that both binary components rotate with very similar - if notidentical - rotational periods of 1d.45 and 1d.40,much shorter than what would correspond to a 10d.9 spin-orbitsynchronization period at periastron. Rapid line-profile changesreported earlier could not be confirmed from new, dedicated series ofhigh-resolution and S/N spectra.This research is based on spectra from the Dominion AstrophysicalObservatory (DAO), Ondřejov, and Thuringer Landessternwarte (TLS)Tautenburg.
| Search for duplicity in periodic variable Be stars
Four Be stars, HR 1960, HR 2968,HR 3237 and HR 3642, selectedaccording to their periodic variations in HIPPARCOS and GENEVAphotometries, were monitored from 1998 until 2001 with the CORALIEspectrograph. Among these stars, two are new spectroscopic binaries andone is a new lambda Eri short period variable. HR 1960 is a lowamplitude (K = 3.4 km s-1) SB1 with a period of 395.48 d inagreement with the photometric prediction. HR 3237 is a short period SB1(P = 5.1526 d). HR 3642 presents some interesting variations inphotometry and spectroscopy: indeed, a mid- and a short-term variationis present with periods of 137.99 d (Hp magnitude) and 1.13028 d (radialvelocity) respectively. The short-term variation, characteristic of thelambda Eri stars, probably implies non-radial pulsations orinhomogeneities in the corotating disc. The last star, HR 2968, is anexcellent photometric binary candidate, but no spectroscopic obviousnessof a companion has been found. Based on observations collected at theSwiss 40 cm, 70 cm and 120 cm telescopes at the European SouthernObservatory (La Silla, Chile) and on data from the ESA HIPPARCOSsatellite. The photometric and radial velocity data are only availablein electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/385/488 Table 3 is onlyavailable in electronic form at http://www.edpsciences.org
| Internationale Konferenz uber Veranderlichenforschung N. Kopernikus Observatorium und Planetarium in Brunn November 08-11, 2001.
Not Available
| 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
| On the Variability of O4-B5 Luminosity Class III-V Stars
We investigate the Hipparcos Satellite photometry of O4-B5 luminosityclass III-V stars. Some for which further study is desirable areidentified. These stars in general are more variable than cooler stars
| A HIPPARCOS Census of the Nearby OB Associations
A comprehensive census of the stellar content of the OB associationswithin 1 kpc from the Sun is presented, based on Hipparcos positions,proper motions, and parallaxes. It is a key part of a long-term projectto study the formation, structure, and evolution of nearby young stellargroups and related star-forming regions. OB associations are unbound``moving groups,'' which can be detected kinematically because of theirsmall internal velocity dispersion. The nearby associations have a largeextent on the sky, which traditionally has limited astrometricmembership determination to bright stars (V<~6 mag), with spectraltypes earlier than ~B5. The Hipparcos measurements allow a majorimprovement in this situation. Moving groups are identified in theHipparcos Catalog by combining de Bruijne's refurbished convergent pointmethod with the ``Spaghetti method'' of Hoogerwerf & Aguilar.Astrometric members are listed for 12 young stellar groups, out to adistance of ~650 pc. These are the three subgroups Upper Scorpius, UpperCentaurus Lupus, and Lower Centaurus Crux of Sco OB2, as well as VelOB2, Tr 10, Col 121, Per OB2, alpha Persei (Per OB3), Cas-Tau, Lac OB1,Cep OB2, and a new group in Cepheus, designated as Cep OB6. Theselection procedure corrects the list of previously known astrometricand photometric B- and A-type members in these groups and identifiesmany new members, including a significant number of F stars, as well asevolved stars, e.g., the Wolf-Rayet stars gamma^2 Vel (WR 11) in Vel OB2and EZ CMa (WR 6) in Col 121, and the classical Cepheid delta Cep in CepOB6. Membership probabilities are given for all selected stars. MonteCarlo simulations are used to estimate the expected number of interloperfield stars. In the nearest associations, notably in Sco OB2, thelater-type members include T Tauri objects and other stars in the finalpre-main-sequence phase. This provides a firm link between the classicalhigh-mass stellar content and ongoing low-mass star formation. Detailedstudies of these 12 groups, and their relation to the surroundinginterstellar medium, will be presented elsewhere. Astrometric evidencefor moving groups in the fields of R CrA, CMa OB1, Mon OB1, Ori OB1, CamOB1, Cep OB3, Cep OB4, Cyg OB4, Cyg OB7, and Sct OB2, is inconclusive.OB associations do exist in many of these regions, but they are eitherat distances beyond ~500 pc where the Hipparcos parallaxes are oflimited use, or they have unfavorable kinematics, so that the groupproper motion does not distinguish it from the field stars in theGalactic disk. The mean distances of the well-established groups aresystematically smaller than the pre-Hipparcos photometric estimates.While part of this may be caused by the improved membership lists, arecalibration of the upper main sequence in the Hertzsprung-Russelldiagram may be called for. The mean motions display a systematicpattern, which is discussed in relation to the Gould Belt. Six of the 12detected moving groups do not appear in the classical list of nearby OBassociations. This is sometimes caused by the absence of O stars, but inother cases a previously known open cluster turns out to be (part of) anextended OB association. The number of unbound young stellar groups inthe solar neighborhood may be significantly larger than thoughtpreviously.
| An improved method for the determination of the orbital parameters of a binary system that contains a pulsating component
In this paper we present a method to assign statistical weights toradial-velocity measurements of a binary system of which one of thecomponents is a variable star. The basic idea of the method is toseparate the radial-velocity changes due to the intrinsic variabilityfrom those due to the orbital motion. This can be achieved if part ofthe data set consists of good coverages of the intrinsic variabilitycycle. These full coverages are used to estimate the variability for thenights on which only one or a few spectra were obtained. Our techniqueis applicable when the intrinsic variability has a period that isconsiderably shorter than the orbital period. Once weights have beenassigned, existing methods to derive the orbital parameters can be usedwith better accuracy compared to the case where all data points aretreated as if no intrinsic variability were present (equal weights). Weillustrate our method and compare the orbital solution obtained with andwithout assigning weights for three pulsating stars in a binary system:beta Cru, varepsilon Per, and kappa Sco.
| Search for forced oscillations in binaries. III. Improved elements and the detection of line-profile variability of the B4V + A6V: system AR Cassiopeiae
An analysis of a new and extensive set of spectroscopic observations ofthe early-type binary system {AR Cas} , based also on spectraldisentangling, has led to the discovery of the spectrum of the secondarystar and of line-profile variations of the B4V primary star. A revisedspectroscopic orbit based on these and published data is presented. Wealso present new photometric data, which have allowed us to improve thesolution of the light curve and demonstrate the presence of apsidalmotion. Determination of the basic physical parameters of the binary hasallowed us to conclude that the system combines the main-sequenceprimary with an A6V: secondary, possibly an Am star. The consistency ofour model of {AR Cas} is documented by a comparison of model atmosphereflux profiles with the profiles recovered from the spectraldisentangling. Analysis of the He i 667.8 nm line indicates that lineprofile variability is present, and that these variations may beperiodic.
| 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.
| Long-term visual spectrophotometric behaviour of Be stars
The long-term spectrophotometric variations of 49 Be stars are studiedusing the U and V magnitudes of the UBV system, the total Balmerdiscontinuity D and the visible gradient Phi _rb. BCD spectrophotometricand photometric data in five different photometric systems, obtained inmost cases since 1950 and reduced to the BCD system, were used. The(U,D), (V,D), (Phi _rb,D) and (Phi _rb,V) correlations obtained differfrom star to star and they can be single or double-valued. They differclearly for Be phases or Be-shell phases. Be stars with small Vsin ishowing the ``spectrophotometric shell behaviour'': D > D_*, werefound. This finding implies either that strongly flattened models ofcircumstellar envelopes are in doubt for these stars, or that not all Bestars are rapid rotators. Comparison of observed variations with thosepredicted for model Be stars with spherical circumstellar envelopes ofvariable densities and dimensions implies that spectrophotometricpatterns of Be phases are due to circumstellar envelopes in low opacityregimes, while those of spectrophotometric shell phases are due tocircumstellar envelopes in high opacity regimes. In a given star, theenvelope regions responsible for the observed variations of D and Phi_rbin spectrophotometric shell phases seem to be smaller and denser thanthose producing the observed variations of these parameters inspectrophotometric Be phases. The high positive RV found in strong shellphases might favor the formation of compact circumstellar layers nearthe star. Figure 6 is only available in electronic form at CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| On the nature of the Be phenomenon. I. The case of omega Canis Majoris
The main purpose of this paper is to demonstrate the extreme complexityof the observed variations of Be stars on the example of a well-observedbright Be star omega CMa. A detailed analysis of all published radialvelocities and a representative set of photometric and spectralobservations of this star led to the following firm conclusions:\begin{itemize} At least three and possibly four different time scalesof variability of omega CMa, ranging from 1\D37 to more than 40 years,could be identified. The correct mean period of the RV and line-profilechanges is 1\D371906, not 1\D3667 as derived earlier. The brightness ofthe object and the strength of the Balmer emission vary in an apparentcycle of several thousands of days. The long-term brightness andemission-line changes can be understood as consequences of the formationand gradual dispersal of a gaseous envelope which is flattened and seenmore face-on than equator-on. During each episode, the envelope growsfrom an optically thick pseudophotosphere to a more extended andoptically thin envelope. Existence of much smaller episodes of lightbrightening which can have the same cause (though on a more limitedscale) has clearly been demonstrated. The amplitude of the 1\D37 RVcurve varies on a time scale somewhere between 10 and 300 d. Thefollowing conclusions are less certain and represent possiblealternatives to be tested by future, systematic and homogeneousobservations: \begin{itemize} Some evidence is presented that theamplitude of the 1\D372 RV variations, local mean RV and brightness ofthe object, prewhitened for the long-term changes, all vary on a timescale of about 35 d, possibly with a period of 34\D675. The O-Cdeviations of the local epochs of RV maxima from a linear ephemeris forthe 1\D372 period seem to be undergoing a slow and probably cyclicvariation in time, being shortest at times when the star is brightestand when a new Be envelope begins to grow. However, the same O-Cdeviations can also be reconciled with the 34\D675 period. Whatever thetrue timescale of the O-C deviations is, their behaviour can also besimulated as an interference of several periods, the second mostsignificant period being close to 1\D35. Several reasons are given whythe explanation in terms of one variable period appears more probable.With the help of both, real and artificial data it is demonstrated thatthe slow variation of the 1\D3719 period -- if unrecognized -- may bemisinterpreted for a multiperiodic variation with several close periodsbetween 1\D3 and 1\D45. This constitutes a methodological warning forthe period analyses of data on some \bn, Be and ``slowly pulsating" Bstars. The cause(s) of the variations with the 1\D37 (and 1\D345)period(s) and/or the 35 d cycle remain unexplained. It is obvious,however, that these three periods are not mutually independent. The34\D675 period may be either a real physical period or a beat periodbetween the 1\D372 and 1\D345 periods. In the former case, omega CMacould be a 34\D7 binary in an eccentric orbit and the periods twicelonger than the two periods near 1\D4 would represent the sidereal andsynodic rotational periods of the Be primary. Finally, some speculationsare offered in terms of a hierarchical multiple system of three or evenfour stars.
| Cirrus Color Variations Due to Enhanced Radiation Fields
We have investigated the variations in 12/100, 25/100, 60/100, and 12/25mu m colors for seven main-sequence B stars and three F and Gsupergiants associated with infrared cirrus. All sources displayed anincrease in 60/100 color above the background cirrus color. In two ofthe sources, epsilon Apodis and HR 890, the 12/100 and 25/100 colorsdecline toward the embedded star in a similar fashion to the IR colorsof S264 and the Rosette Nebula. Current grain models composed ofequilibrium-heated submicron grains, transiently heated small grains,and polycyclic aromatic hydrocarbons cannot account for the colorvariations observed around epsilon Aps and HR 890. The supergiantsexhibited 12/100 and 25/100 increases, suggesting that the colordeficits observed for the B stars are due to an enhancement in the softUV component of the radiation field only. A candidate explanation forthe color variations is a conglomerate small grain component, composedof very small grains and/or large molecules, that is fragmented in theenhanced radiation field around epsilon Aps and HR 890.
| Mesures de vitesses radiales. VIII. Accompagnement AU sol DU programme d'observation DU satellite HIPPARCOS
We publish 1879 radial velocities of stars distributed in 105 fields of4^{\circ} \times 4^{\circ}. We continue the PPO series \cite[(Fehrenbachet al. 1987;]{Feh87} \cite[Duflot et al. 1990, 1992 and 1995),]{Du90}using the Fehrenbach objective prism method. Table 1 only available inelectronic form at CDS via to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| Search for forced oscillations in binaries. II. β Scorpii A. New physical parameters and a search for line profile variability.
We present new spectroscopic data and physical parameters for theearly-type binary system β Sco A. Radial velocity measurements ofReticon spectra have been made using both cross-correlation anddisentangling techniques. Spectroscopic orbits, based on the new dataand published radial velocities are presented. The orbital period andapsidal motion rate have been refined using 603 radial velocitiescovering a time interval of 84-years. The anomalistic period is6.828245+/-0.000009-days, and the apsidal motion rate is˙(ω)=0.00131+/-0.00004°/day. The firstvisual-spectroscopic orbit for the system is given here as well, fromwhich we derive a parallax for the system of 0.0070+/-0.0001"corresponding to a distance of 143+/-3pc. This has allowed us to computethe absolute dimensions and mean internal structure constant for thesystem. We find, for the primary and secondary respectively, masses,radii, and effective temperatures of: m_p_/msun_=13.5+/-0.9,m_s_/msun_=9.6+/-0.4, r_p_/rsun_=6.8+/-0.4,r_s_/rsun_=4.2+/-0.3, T_p_=28000+/-2000K, andT_s_=26400+/-2000K. The corresponding spectral types of the componentsare B0.5IV-V and B1.5V. Line photometry produced from the disentanglingsolutions suggests the presence of eclipses in β Sco A, which mustbe verified through systematic photometry. We also present a tentativedetection of possible β Cep -type line profile variability in thesecondary.
| Search for forced oscillations in binaries. I. The eclipsing and spectroscopic binary V436 Persei = 1 Persei.
Outline of a project aimed at testing the presence of rapid line-profilevariations in the atmospheres of hot components of close binaries ispresented and its first results are described. An analysis of newelectronic spectra of the eclipsing binary V436 Per from threeobservatories and of photoelectric observations, obtained earlier byseveral authors, leads to a unique determination of all basic physicalelements of this interesting object. The first practical application ofa new method of spectral disentangling allowed us to obtain, for thefirst time, individual accurate line profiles of both binary componentsand to derive their rotational velocities and orbital radial-velocitycurves. We also detected absorption sub-features travelling from blue tored accross the He I 6678 line profile, in a series of six spectra takenduring one night. At least one of the components of V436 Per is,therefore, a new hot line-profile variable.
| A Catalogue of Correlations Between Eclipsing Binaries and Other Categories of Double Stars
Among the 9110 stars in The Bright Star Catalogue, there are 225eclipsing or ellipsoidal variables. A search has been made for these incatalogues of spectroscopic binaries, visual double or multiple stars,speckle interferometry, occulation binaries, and galatic clusters. Themajority of the photometric binaries are also members of groups ofhigher multiplicity. The variables are in systems ranging from one to 91stars, five on the average. 199 are either spectroscopic binaries (SB)or stars with variable radial velocity, with orbital periods known for160. Photometric periods are lacking for 48 while SB periods areavailable for 23 of these. Observers with photoelectric equipment areencouraged to plan observations to test if the SB periods are consistentwith photometric data. Observers are likewise encouraged to examinethose stars for which the photometric and SB periods appear to beinconsistent. Parallaxes are available for 86 of the stars, 41 of themindicating distances nearer than 50 parsecs.
| The ROSAT all-sky survey catalogue of optically bright OB-type stars.
For the detailed statistical analysis of the X-ray emission of hot starswe selected all stars of spectral type O and B listed in the Yale BrightStar Catalogue and searched for them in the ROSAT All-Sky Survey. Inthis paper we describe the selection and preparation of the data andpresent a compilation of the derived X-ray data for a complete sample ofbright OB stars.
| Eclipsing binaries as IRAS sources.
In a systematic search we looked for coincidences in the positions ofeclipsing binaries and IRAS point sources as evidence of a physicalassociation. In a detailed discussion of the available optical andinfrared data combined with model calculations, we show that 50-75% ofthe coincidences between eclipsing binaries and IRAS sources are real.We discuss a subsample of 44 stars in some detail and surveyed thevicinity of them on POSS and SRC/ESO atlases for possible opticalcounterparts and present identification maps. In the cases of BS Sco andV 718 Sco the infrared radiation may come from an accretion disk.
| Eclipse Monitoring of Eccentric Binary Systems
Not Available
| 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.
| Toward a consistent model of the B0.5IVe + sdO binary φ Persei.
A detailed analysis of a very rich collection of spectroscopic andphotometric observations of the bright Be star φ Per is presented.Earlier reports that φ Per is a double-lined spectroscopic binaryconsisting of two emission-line objects are confirmed. An orbitalsolution based on the emission-wing radial velocities for both stars hasled to a determination of the orbital elements which defines the correctorbital phases. All data since the beginning of this century can bereconciled with a constant orbital period of 126.6731d+/-0.0071d. Thenew orbital solution gives lower masses than those found by earlierinvestigators, namely M_1_sin^3^i=16.35Msun_ andM_2_sin^3^i=1.69Msun_. These masses are in agreement with therecently derived spectral classes B0.5IVe and sdO6: for the primary andsecondary, respectively. Long-term light variations are positivelycorrelated with the emission strength, and in the U-B vs. B-V diagramthe object has changed its apparent photometric type from a B supergianttoward an MS object. Dereddening of the mean seasonal UBV magnitudesfrom recent years (when spectra show the weakest recorded Balmeremission) leads to a photometric spectral type a bit earlier than B1V.An important and exciting finding is that the emission lines of bothstars have been weakening simultaneously in recent years, which seems toindicate some kind of interaction between the binary components. Thepresence of rapid light variability is confirmed, but its more detailedanalysis is postponed for another study. Low-amplitude orbital lightvariations with rather complicated light and color curves are foundafter the removal of long-term and rapid changes. The principal maximaand minima of the orbital light curves can be traced in both old and newphotometry and can probably be attributed to specific circumstellarstructures whose signatures are also seen spectroscopically. Finally,systematic secular changes in the shape and amplitude of the orbitalradial-velocity curve of the Balmer shell lines are found, based on 1024radial velocities spanning nearly a century.
| Improved Mean Positions and Proper Motions for the 995 FK4 Sup Stars not Included in the FK5 Extension
Not Available
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| Yükselim: | +55°08'51.0" |
| Görünürdeki Parlaklýk: | 5.52 |
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