SKY-MAP.ORG
 首页 开始 To Survive in the Universe News@Sky 天文图片 收集 论坛 Blog New! 常见问题 新闻 登录

# ζβ CrB

### 图像

DSS Images   Other Images

### 相关文章

 Generalized SCIDAR Measurements at San Pedro Mártir. II. Wind Profile StatisticsWe present the results of monitoring the speed of optical turbulentlayers in the atmosphere above San Pedro Mártir, Mexico, during15 nights in 2000 May. The data were obtained using the generalizedscintillation detection and ranging technique (generalized SCIDAR),developed at Nice University. This paper constitutes the second in aseries. The first paper presents results concerning measurements ofoptical turbulence strength obtained at the same site and time. Theprincipal results of the present article are as follows: (1) The windprofiles remain stable during each night. (2) No correlation between theturbulence intensity C2N and the speed of theturbulent layers, V, is detected for speeds lower than ~45 ms-1. Above that speed, which was only exceeded in thejet-stream layer on one night, the optical turbulence strength is seento increase. (3) Layers in the first 4 km and higher than 16 km abovesea level are similarly slow, with median speeds of 8.6 and 9.6 ms-1, respectively. (4) Between 9 and 16 km, where the jetstream flows on some of the nights, the median wind speed is 26.0 ms-1. (5) From simultaneous measurements ofC2N(h) and V(h), we compute the temporal coherenceof the turbulence, layer by layer, in 500 m thick layers. This is thefirst time that such data have been published. For a multiconjugateadaptive optics system, our measurements show that the temporalresponses of three deformable mirrors conjugated on the ground and at 6km and 13 km above sea level, each one correcting for the turbulence in500 m thick layers, would need to be 64, 40, and 20 ms. (6) The verticalvariation of V dominates the vertical variation of the coherence time.(7) For the first time, we compare wind velocity profiles obtained fromthree different sources: generalized SCIDAR, NCEP/NCAR (National Centersfor Environmental Prediction/National Center for Atmospheric Research)reanalysis data, and meteorological research balloons. The comparisonshows excellent agreement in both the modulus and the direction of thewind velocity. Evolution of interacting binaries with a B type primary at birthWe revisited the analytical expression for the mass ratio distributionfor non-evolved binaries with a B type primary. Selection effectsgoverning the observations were taken into account in order to comparetheory with observations. Theory was optimized so as to fit best withthe observed q-distribution of SB1s and SB2s. The accuracy of thistheoretical mass ratio distribution function is severely hindered by theuncertainties on the observations. We present a library of evolutionarycomputations for binaries with a B type primary at birth. Some liberalcomputations including loss of mass and angular momentum during binaryevolution are added to an extensive grid of conservative calculations.Our computations are compared statistically to the observeddistributions of orbital periods and mass ratios of Algols. ConservativeRoche Lobe Over Flow (RLOF) reproduces the observed distribution oforbital periods but fails to explain the observed mass ratios in therange q in [0.4-1]. In order to obtain a better fit the binaries have tolose a significant amount of matter, without losing much angularmomentum. Observed Orbital EccentricitiesFor 391 spectroscopic and visual binaries with known orbital elementsand having B0-F0 IV or V primaries, we collected the derivedeccentricities. As has been found by others, those binaries with periodsof a few days have been circularized. However, those with periods up toabout 1000 or more days show reduced eccentricities that asymptoticallyapproach a mean value of 0.5 for the longest periods. For those binarieswith periods greater than 1000 days their distribution of eccentricitiesis flat from 0 to nearly 1, indicating that in the formation of binariesthere is no preferential eccentricity. The binaries with intermediateperiods (10-100 days) lack highly eccentric orbits. The fundamental parameters of the Algol binary AI Draconis revisited We present the results of an analysis of our infrared light curves ofthe Algol-type binary AI Draconis in the J, H and K bands, and ofpublished light curves in the B, V and Strömgren uvby bands,together with spectra obtained by us. The analysis of the light curveswas carried out using a code based on ATLAS model atmospheres and Rochegeometry.The small contribution of the secondary cool component to the totallight of the system in the visible, producing light curves with veryshallow secondary eclipses, makes the stellar and orbital parametersderived from light-curve analysis in the visible spectral rangeuncertain. The larger contribution of the secondary star to the infraredfluxes makes this range particularly well suited to the derivation ofprecise orbital and stellar parameters in binaries of Algol type. Fromthe simultaneous solution of the infrared JHK light curves, we derivethe following absolute orbital and stellar parameters for the twocomponents: = 10160 +/- 160 K,Req,1= 2.12 +/- 0.04 Rsolar,log()1= 4.23; = 5586 +/-110 K, Req,2= 2.36 +/- 0.04 Rsolar,log()2= 3.76; M1= 2.86 +/- 0.09Msolar, q=M2/M1= 0.44 +/- 0.03; a= 7.62+/- 0.09 Rsolar, i= 76.53°+/- 0.3°, e~= 0.0. Here, and log() indicate average surfacevalues, Req is the equivalent radius of the deformed star anda is the orbital size.In our light-curve solutions, the secondary star of AI Dra fills itsRoche lobe (as also indicated by the spectroscopy), thus discountingclaims, based on UBV light curves, that both components of the binaryare located within their Roche lobes. The visible and infraredphotometry show no evidence of any significant infrared excess in thesystem, and the distance of AI Dra is estimated as d= 169 +/- 17 pc.Based on the spectra of AI Dra and template stars in the ranges8210-9060, 6250-7130 and 4040-4920 Å, we classify the stellarcomponents of AI Dra and find that the most probable spectral types areA0V (or perhaps A1V) for the primary and F9.5V for the secondary(although it could reach as far as G4V), respectively. From ourspectroscopic observations, the spectral evolution of AI Dra withorbital phase is also presented. Furthermore, we obtain the projectedrotational velocity of the secondary, whose value turns out to becompatible with the star filling its Roche lobe. Tidal Effects in Binaries of Various PeriodsWe found in the published literature the rotational velocities for 162B0-B9.5, 152 A0-A5, and 86 A6-F0 stars, all of luminosity classes V orIV, that are in spectroscopic or visual binaries with known orbitalelements. The data show that stars in binaries with periods of less thanabout 4 days have synchronized rotational and orbital motions. Stars inbinaries with periods of more than about 500 days have the samerotational velocities as single stars. However, the primaries inbinaries with periods of between 4 and 500 days have substantiallysmaller rotational velocities than single stars, implying that they havelost one-third to two-thirds of their angular momentum, presumablybecause of tidal interactions. The angular momentum losses increase withdecreasing binary separations or periods and increase with increasingage or decreasing mass. Optical-Turbulence and Wind Profiles at San Pedro MártirResults of monitoring optical-turbulence profiles and velocity of theturbulence layers at San Pedro Mártir, Mexico, are presented. Thedata were collected during 11 nights in April-May 1997 and 16 nights inMay 2000 using the Generalized Scidar of Nice University installed onthe 1.5-m and 2.1-m telescopes. The statistical analysis of the 6414turbulence profiles obtained shows that the seeing produced by theturbulence in the first 1.2 km, not including dome seeing, at the 1.5-mand the 2.1-m telescopes have median values of 0 to z 0. hss'' 63 and0 to z 0. hss'' 44, respectively. The dome seeing at those telescopeshave median values of 0 to z 0. hss'' 64 and 0 to z 0. hss'' 31. Theturbulence above 1.2 km and in the whole atmosphere produces seeing withmedian values of 0 to z 0. hss'' 38 and 0 to z 0. hss'' 71. Thetemporal correlation of the turbulence strength drops to 50% in timelags of 2 and 0.5 hours, approximately, for altitudes below and above 16km above sea level, respectively. The turbulence above  9 kmremained notably calm during 9 consecutive nights, which is encouragingfor adaptive optics observations at the site. The 3016 profiles of theturbulent-layer velocity that are analyzed show that the fastest layersare found between 10 and 17 km, where the tropopause and the jet streamare located, with median speed of 24.4 m s-1. In the first 2.2 km andabove 17 km, the turbulent layers move relatively slowly, with medianspeeds of 2.3 and 9.2 m s-1. The median of the wavefront coherence-timeis 6.5 ms, in the visible. The results obtained here places San PedroMártir among the best suited sites for installing next generationoptical telescopes. Rotational Velocities of B StarsWe measured the projected rotational velocities of 1092 northern B starslisted in the Bright Star Catalogue (BSC) and calibrated them againstthe 1975 Slettebak et al. system. We found that the published values ofB dwarfs in the BSC average 27% higher than those standards. Only 0.3%of the stars have rotational velocities in excess of two-thirds of thebreakup velocities, and the mean velocity is only 25% of breakup,implying that impending breakup is not a significant factor in reducingrotational velocities. For the B8-B9.5 III-V stars the bimodaldistribution in V can be explained by a set of slowly rotating Ap starsand a set of rapidly rotating normal stars. For the B0-B5 III-V starsthat include very few peculiar stars, the distributions in V are notbimodal. Are the low rotational velocities of B stars due to theoccurrence of frequent low-mass companions, planets, or disks? Therotational velocities of giants originating from late B dwarfs areconsistent with their conservation of angular momentum in shells.However, we are puzzled by why the giants that originate from the earlyB dwarfs, despite having 3 times greater radii, have nearly the samerotational velocities. We find that all B-type primaries in binarieswith periods less than 2.4 days have synchronized rotational and orbitalmotions; those with periods between 2.4 and 5.0 days are rotating withina factor 2 of synchronization or are nearly synchronized.'' Thecorresponding period ranges for A-type stars are 4.9 and 10.5 days, ortwice as large. We found that the rotational velocities of the primariesare synchronized earlier than their orbits are circularized. The maximumorbital period for circularized B binaries is 1.5 days and for Abinaries is 2.5 days. For stars of various ages from 107.5 to1010.2 yr the maximum circularized periods are a smoothexponential function of age. First evidence of the finite horizontal extent of the optical turbulence layers. Implications for new adaptive optics techniquesIt was recently shown (Masciadri et al. \cite{mas00}; Masciadri\cite{mas01a}), using a numerical simulation (Meso-Nh model), thatconsidering horizontally uniform CN2 can havesevere consequences. For example, the integration of theCN2 along lines of sight different from the zenithgives variations that can be larger than 0.50arcsec . In this paper wetry to validate this result following two approaches. (a) numericalapproach: we compare measured and simulated CN2profiles. The first ones were obtained with a Generalized Scidar (GS)and the latter are simulated with the Meso-Nh model at the same azimuthand elevation as those of the observations. Further measurements (DIMM,mast and balloons) are considered in order to support the comparison.(b) experimental approach: we compare CN2 profilesmeasured (almost simultaneously) by a GS along different lines of sight.The results of this study show that (1) the horizontal size of theturbulent layers can be finite, (2) the simulations and the measurementsare well correlated and (3) for the first time, we show that the modelcan reproduce observed seeing values that vary as much as 0.50arcsecduring the same night. This definitely shows that the numericalsimulations are a useful tool in the context of the turbulencecharacterization for astronomical applications. Finally, we discuss theimplications that a finite horizontal size of the turbulent layers couldhave on new adaptive optics techniques, particularly in applications tothe extremely large size telescopes. Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statisticsThe 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 The Equilibrium Tide Model for Tidal FrictionWe derive from first principles the equations governing (a) thequadrupole tensor of a star distorted both by rotation and by thepresence of a companion in a possibly eccentric orbit; (b) a functionalform for the dissipative force of tidal friction, based on the conceptthat the rate of energy loss from a time-dependent tide should be apositive-definite function of the rate of change of the quadrupoletensor as seen in the frame that rotates with the star; and (c) theequations governing the rates of change of the magnitude and thedirection of the stellar rotation, the orbital period and eccentricity,based on the concept of the Laplace-Runge-Lenz vector. Our analysisleads relatively simply to a closed set of equations, valid forarbitrary inclination of the stellar spin to the orbit. The results areequivalent to classical results based on the rather less clear principlethat the tidal bulge lags behind the line of centers by some timedetermined by the rate of dissipation. Our analysis gives the effectivelag time as a function of the dissipation rate and the quadrupolemoment. We discuss briefly some possible applications of theformulation. Zeta$^2$ Coronae Borealis, A Spectroscopic Triple System Including an Asynchronous Close BinaryUsing the 1-m telescope at Ritter Observatory, we took 36 observationsof \zeta$^2$ Coronae Borealis with a fiber-fed echelle spectrograph.From these observations, \zeta$^2$ CrB was found to be a triple systemand a new spectroscopic orbit was calculated. This orbit has twoperiods, a 1.72357 day period for the inner binary composed of \zeta$^2$CrB A $&$ B and a 251 day period for the outer binary compsed of\zeta$^2$ CrB AB $&$ C. The inner binary is a double-linedspectroscopic binary composed of two B7 V stars. The inner binary`scenter of mass (\zeta$^2$ CrB AB) describes a long-period single-linedvariation identified with the outer binary. The inner binary period issignificantly shorter than the 12.5842 day period previously calculatedby Abhyankar $&$ Sarma (1966). The inner binary possesses anessentially circular orbit $(e = 0.48)$. From the widths of their Si II6371 \AA lines, the \upsilon sin $i$'s were calculated to be 46 \pm 7 kms$^-1$ for \zeta$^2$ CrB A and 7.5 \pm 2 km s$^-1$ for \zeta$^2$ CrB B.As \zeta$^2$ CrB A $&$ B have similar masses, their differentrotational velocities make this system a sensitive test ofsynchronization theories. (SECTION: Stars) MSC - a catalogue of physical multiple starsThe MSC catalogue contains data on 612 physical multiple stars ofmultiplicity 3 to 7 which are hierarchical with few exceptions. Orbitalperiods, angular separations and mass ratios are estimated for eachsub-system. Orbital elements are given when available. The catalogue canbe accessed through CDS (Strasbourg). Half of the systems are within 100pc from the Sun. The comparison of the periods of close and widesub-systems reveals that there is no preferred period ratio and allpossible combinations of periods are found. The distribution of thelogarithms of short periods is bimodal, probably due to observationalselection. In 82\% of triple stars the close sub-system is related tothe primary of a wide pair. However, the analysis of mass ratiodistribution gives some support to the idea that component masses areindependently selected from the Salpeter mass function. Orbits of wideand close sub-systems are not always coplanar, although thecorresponding orbital angular momentum vectors do show a weak tendencyof alignment. Some observational programs based on the MSC aresuggested. Tables 2 and 3 are only available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html Observations of Ubiquitous Small-Scale Structure in the Diffuse Interstellar MediumWe present results of a study of the Na I D interstellar absorptiontoward 17 binary and/or common proper-motion systems (including twotriples). The stars range in spectral type from O6 to A5, lie atdistances between 85 and 1200 pc, and have stellar separations between480 and 29,000 AU. We compare the Na I absorption present in each of thetwo (or three) lines of sight and find that the line strength and/orprofile varies for all 17 of the systems examined. We infer thatsmall-scale structure in clouds containing Na I is ubiquitous anddiscuss the implications of that conclusion. 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. Speckle observations of visual and spectroscopic binaries. VI.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. Radio continuum emission from stars: a catalogue update.An updated version of my catalogue of radio stars is presented. Somestatistics and availability are discussed. Corrections to the right ascension to be applied to the apparent places of 1217 stars given in "The Chinese Astronomical Almanach" for the year 1984 to 1992.Not Available Speckle observations of visual and spectroscopic binaries. IIIThis is the third paper of this series giving results of speckleobservations carried out for seven visual and 119 spectroscopic binariesat seven nights from May 20 to May 27, 1989, and for 30 visual and 272spectroscopic binaries at 12 nights from June 11 to June 15, and fromAugust 28 to September 3, 1990, using the 212-cm telescope at San PedroMartir Observatory in Mexico. Fringes in the lower spectrum of 31 visualand spectroscopic binaries with angular separation larger than 21 arcsecare obtained. Additionally to two spectroscopic binaries, HD41116 andHD206901, named in the second paper of this series, six spectroscopicbinaries are found each of which has the third component starsurrounding two stars of spectroscopic binary having periodic variationof radial velocity. Observations of double stars and new pairs. XIVResults of a continuing survey of visual double stars are presented,including 4880 measurements made from February 1987 to November 1989.The positions in WDS format and Durchmusterung numbers are given for 194pairs first reported here. Micrometer measurements of 1142 doubles madewith the Swarthmore 61 cm refractor are presented. Magnitudes areestimated for some of the objects. Plate measurements, plateorientations, position angles, number of nights, and measured exposuresare given. Visual observations of 342 pairs obtained in May 1989 atCerro Tololo, mostly with the 1.0 m reflector, are reported. Precise Radial Velocity Measurements of Visual Binary StarsNot Available Photographic astrometry of binary and proper-motion stars. IVParallax data are given for 62 binary and proper motion stars based onobservations obtained between May 1987 and March 1988. The datapresented in tabular form include reference positions, identifiers (BDand GC numbers, if any), visual magnitudes, and spectral types. Massratio results for eight binary stars are also presented. Notes areprovided which indicate the inclusion or replacement of previousmeasurements and which reductions have been applied. ICCD speckle observations of binary stars. I - A survey for duplicity among the bright starsA survey of a sample of 672 stars from the Yale Bright Star Catalog(Hoffleit, 1982) has been carried out using speckle interferometry onthe 3.6-cm Canada-France-Hawaii Telescope in order to establish thebinary star frequency within the sample. This effort was motivated bythe need for a more observationally determined basis for predicting thefrequency of failure of the Hubble Space Telescope (HST) fine-guidancesensors to achieve guide-star lock due to duplicity. This survey of 426dwarfs and 246 evolved stars yielded measurements of 52 newly discoveredbinaries and 60 previously known binary systems. It is shown that thefrequency of close visual binaries in the separation range 0.04-0.25arcsec is 11 percent, or nearly 3.5 times that previously known. Distribution of mass ratios in spectroscopic binariesA total of 205 main-sequence spectroscopic binaries were selected inorder to derive the distribution of mass ratios of unevolved closebinaries. In the case of single-line binaries, the parameter Y, definedas the mass function divided by the mass of the primary component, wasused. The derivation of the distribution of mass ratios was tackled byusing three different methods: (1) the use of a mean value for sin cubedi in the mass function, (2) the search for a discrete distribution ofmass ratios, and (3) a sampling experiment. These methods were appliedto double-line binaries in order to check their efficiency. It was foundthat method (1) gives erroneous results but provides valuable bins foran histogram of Y; method (2) may be used to obtain a crudeapproximation, and method (3) is the most valuable, but the scatter inthe mass-spectral type relation must be taken into account. A search for the H-alpha emission in spectroscopic binaries of the spectral types B0-B9The H-alpha emission is searched for 67 spectroscopic binaries of thespectral types B0-B9 and of the orbital period 1-1000 days. Among themthe H-alpha emission is detected in 13 stars with various intensity. Theresults of this inspection are presented. When combined with theprevious data, the results show that the Be-star frequency inspectroscopic binaries along the orbital periods exhibits a sharpmaximum in the period range 100-300 days, and that the stars of strongH-alpha emission concentrate in the same period range. Photographic observations of bright stars in the declination zone from +40 to +90 deg with a normal astrograph and 26-arcsec refractor at PulkovoNot Available Catalogue of the energy distribution data in spectra of stars in the uniform spectrophotometric system.Not Available Binary stars unresolved by speckle interferometry. IIIThe KPNO's 4-m telescope was used in 1975-1981 to determine the epochsof 1164 speckle observations for 469 unresolved, known or suspectedbinary stars. The data, presented in tabular form, encompass visualbinaries with eccentric orbits, occultation binaries, astrometricbinaries, Hyades stars of known or suspected duplicity, and many longperiod spectroscopic binaries. The period distribution of unevolved close binary systemsPeriod distributions have been examined for various spectral types ofabout 600 (eclipsing and spectroscopic) close binaries, which are likelyto be substantially unevolved. The comparison with the previouscorresponding analyses of extensive (but heterogeneous) binary samplesallows a clarification of the extent of the evolutionary andobservational selection effects. Remarkably, this analysis reveals agreat deficiency of short period binaries (with periods corresponding tocase A mass transfer) in the whole spectral range. For the late spectraltypes, this result may be connected with postformation angular momentumloss caused by stellar wind magnetic braking; at least for the late Band A spectral range, a ready interpretation of this finding is thatclose binaries of corresponding periods and spectral types are rarelyformed. Four-colour photometry of B stars north of B = + 45 deg and comparison with the southFour-color photometry of 33 Henry Draper B stars north of b = + 45 degis presented. Most are little-reddened B or intermediate-A stars. A newAm star is discovered. The new measures essentially complete uvbyphotometry of all HD B stars within 45 deg of either galactic pole. Thenorthern and southern cones of HD B stars are compared, and selectioneffects deduced. Far from the galactic plane, it appears that B starsmay be equally distributed north and south of the plane; closer to thesun, an asymmetry associated with Gould's Belt is evident.

• - 没有找到链接 -

### 下列团体成员

#### 观测天体数据

 星座: 劍魚座 右阿森松: 15h39m22.70s 赤纬: +36Â°38'09.0" 视星: 5.07 右阿森松适当运动: 0 赤纬适当运动: 0 B-T magnitude: 4.847 V-T magnitude: 4.962

 适当名称 (Edit) Bayer ζβ CrB Flamsteed 7 CrB HD 1989 HD 139892 TYCHO-2 2000 TYC 2577-1754-1 USNO-A2.0 USNO-A2 1200-07612599 BSC 1991 HR 5834 HIP HIP 76669 → 要求更多目录从vizier