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
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Sixth Catalogue of Fundamental Stars (FK6). Part III. Additional fundamental stars with direct solutions
The FK6 is a suitable combination of the results of the HIPPARCOSastrometry satellite with ground-based data, measured over a longinterval of time and summarized mainly in the FK5. Part III of the FK6(abbreviated FK6(III)) contains additional fundamental stars with directsolutions. Such direct solutions are appropriate for single stars or forobjects which can be treated like single stars. Part III of the FK6contains in total 3272 stars. Their ground-based data stem from thebright extension of the FK5 (735 stars), from the catalogue of remainingSup stars (RSup, 732 stars), and from the faint extension of the FK5(1805 stars). From the 3272 stars in Part III, we have selected 1928objects as "astrometrically excellent stars", since their instantaneousproper motions and their mean (time-averaged) ones do not differsignificantly. Hence most of the astrometrically excellent stars arewell-behaving "single-star candidates" with good astrometric data. Thesestars are most suited for high-precision astrometry. On the other hand,354 of the stars in Part III are Δμ binaries in the sense ofWielen et al. (1999). Many of them are newly discovered probablebinaries with no other hitherto known indication of binarity. The FK6gives, besides the classical "single-star mode" solutions (SI mode),other solutions which take into account the fact that hidden astrometricbinaries among "apparently single-stars" introduce sizable "cosmicerrors" into the quasi-instantaneously measured HIPPARCOS proper motionsand positions. The FK6 gives, in addition to the SI mode, the "long-termprediction (LTP) mode" and the "short-term prediction (STP) mode". TheseLTP and STP modes are on average the most precise solutions forapparently single stars, depending on the epoch difference with respectto the HIPPARCOS epoch of about 1991. The typical mean error of anFK6(III) proper motion in the single-star mode is 0.59 mas/year. This isa factor of 1.34 better than the typical HIPPARCOS errors for thesestars of 0.79 mas/year. In the long-term prediction mode, in whichcosmic errors are taken into account, the FK6(III) proper motions have atypical mean error of 0.93 mas/year, which is by a factor of about 2better than the corresponding error for the HIPPARCOS values of 1.83mas/year (cosmic errors included).
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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
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An extensive Delta a-photometric survey of southern B and A type bright stars
Photoelectric photometry of 803 southern BS objects in the Deltaa-system as detection tool for magnetic chemically peculiar (=CP2) starshas been carried out and compared to published spectral types. Thestatistical yield of such objects detected by both techniques ispractically the same. We show that there are several factors whichcontaminate the search for these stars, but this contamination is onlyof the order of 10% in both techniques. We find a smooth transition fromnormal to peculiar stars. Our sample exhibits the largest fraction ofCP2 stars at their bluest colour interval, i.e. 10% of all stars in thecolour range -0.19 <= B-V < -0.10 or -0.10 <= b-y < -0.05.No peculiar stars based on the Delta a-criterion were found at bluercolours. Towards the red side the fraction of CP2 stars drops to about3% for positive values of B-V or b-y with red limits roughlycorresponding to normal stars of spectral type A5. The photometricbehaviour of other peculiar stars: Am, HgMn, delta Del, lambda Boo, Heabnormal stars, as well as Be/shell stars and supergiants shows someslight, but definite deviations from normal stars. Spectroscopic andvisual binaries are not distinguished from normal stars in their Delta abehaviour. The results of this work justify larger statistical work(e.g. in open clusters) employing more time-saving photometric methods(CCD). \newpage Based on observations obtained at the European SouthernObservatory, La Silla, Chile. This research has made use of the Simbaddatabase, operated at CDS, Strasbourg, France. Table 2 is only availablein electronic form via anonymous ftp 130.79.128.5 orhttp://cdsweb.u-strasbg.fr/Abstract.html
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Investigation of the variability of bright Be stars using HIPPARCOS photometry
The high accuracy and the homogeneity of Hipparcos data for bright starshave allowed us to quantify the degree of variability of Be stars. Thisdegree has been found to be highly dependent on the temperature of thestar. Rapid variability is the main feature of the 86% of early Be andless than 20% of late Be stars taking into account the limit ofdetection considered. In addition to Be stars reported in the Hipparcoscatalogue (ESA 1997) as short-period variables, we have been able toenlarge the number of detections as well as to confirm periodspreviously determined. Be stars that show larger amplitude rapidvariations are proposed as candidates for a search of multiperiodicityi.e. as non-radial pulsators. We have also searched for the presence ofoutbursts and fading events in the Hipparcos data. Outbursts have beenfrequently and preferentially detected in early Be stars with rather lowto moderate v sini while fading events seem to be more conspicuous instars with higher v sini. Mid-term and long-term variations have alsobeen investigated. Several stars have shown some evidence of temporaryquasi-periodic oscillations ranging between 10 and 200 days. Finallyinformation concerning long-term variations is reported. Cycles shorterthan or equal to the Hipparcos mission have mainly been detected instars earlier than B6. Long-term time scales of late Be stars areconfirmed to be longer by far. Tables 1 and 2 are only available inelectronic form at CDS via ftp to cdsarc.u-strasbg.fr (130.79.128.5) orvia http://cdsweb.u-strasbg.fr/Abstract.html
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Nova V351 Puppis 1991: a multiwavelength study of the nebular phase
We combine ground-based optical and IUE spectrophotometry to study thephysical conditions in the shell of Nova V351 Puppis 1991. The structureand the evolution of the shell during the early nebular (i.e. opticallythin) phase are discussed in this paper. The reddening, derived fromrecombination lines, is E(B-V)=0.72+/-0.10. The optical/UV light curvesimply a distance of 3.0+/-0.5 kpc. These values are found to beconsistent with a study of the reddening in the stellar field near thenova. Abundances from the emission-line spectra yield enhancementswithin the predictions of thermonuclear runaway models for classicalnovae. Relative to solar by number, they are: He/H=1.7, C/H=3.5,N/H=130, O/H=38, Ne/H=120, Al/Si=28. The shell shows a low ejected mass(M_ej~10^-7 M_solar), implying a high-mass white dwarf. The opticalspectra reveal a strong red excess, which we tentatively attribute tothe red companion. The strength of this continuum suggests that thecompanion is either a giant or an irradiated main-sequence star.
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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.
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The position corrections of 1400 stars observed with PA II in San Juan.
Not Available
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Intensive photometry of southern Be variables. II - Summer objects
Results are presented of photometric campaign on some bright southern Bestars to search for periodic light variations. In order to obtain goodphase coverage, many observations were conducted from two sites withdifferent longitudes: ESO and SAAO. A large fraction of early-Be starsare found to be variable with periods close to or equal to theirrotational periods. Particular attention is devoted to the late-Bestars. Unlike the hotter members of this class, the late-Be stars do notseem to have detectable periodic light variations except for one or twostars of very small amplitude.
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Fifth fundamental catalogue. Part 2: The FK5 extension - new fundamental stars
The mean positions and proper motions for 3117 new fundamental starsessentially in the magnitude range about 4.5 to 9.5 are given in thisFK5 extension. Mean apparent visual magnitude is 7.2 and is on average2.5 magnitudes fainter then the basic FK5 which has a mean magnitude of4.7. (The basic FK5 gives the mean positions and proper motions for theclassical 1535 fundamental stars). The following are discussed: theobservational material, reduction of observations, star selection, andthe system for the FK5 extension. An explanation and description of thecatalog are given. The catalog of 3117 fundamental stars for the equinoxand epoch J2000.0 and B1950.0 is presented. The parallaxes and radialvelocities for 22 extension stars with large forecasting effects aregiven. Catalogs used in the compilation of the FK5 fundamental catalogare listed.
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Merged log of IUE observations.
Not Available
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A photometric survey of the bright southern Be stars
Repeated UBV photometric measurements were made of the 86 bright Bestars south of declination -20 deg, and a network of comparison starswas set up. From a statistical study of the differential photometry itwas found that short- or intermediate-term variability seems to beoccurring in about half of the Be stars, and to be more evident in thestars of earlier spectral type. It was also possible to identify 11individual short- or intermediate-term variables. Four of these (all ofearly B spectral type) appear to exhibit significant variability on atime-scale of a day or less. More intensive observations of one of thesestars, 28 Omega CMA, indicate short-term variations consistent with thepublished spectroscopic period of 1.37 day.
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IRAS observations of Be stars. I - Statistical study of the IR excess of 101 Be stars
IRAS observations at 12, 25, and 60 microns are reported for 101 Bestars from the Bright Star Catalog of Hoffleit (1982). The data arepresented in extensive tables and graphs and analyzed. Normal-starcolor-color relations are used to derive the IR excesses, and theposition of the Be stars on the (12-60) versus (12-25) diagram is shownto correspond to free-free emission from a star surrounded by ionizedgas with density inversely proportional to r exp 2.5-3. An apparentupper limit on the degree of optical polarization and a link betweenlarge polarization and large IR excess are found.
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HR 3562 and 3600 - Two short-period B-type variables
Fron intensive photometric observations of the early B stars HR 3562 andHR 3600, it is shown that they are both singly periodic variables. Themultiple periods previously proposed are not confirmed, and anexplanation in terms of nonradial oscillations need not be invoked. Itis suggested that they be classified as ellipsoidal variables ratherthan 53 Per stars. One of the comparison stars, HR 3527, is an eclipsingbinary.
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Radial velocities of bright southern stars. I - 139 B-type HR and FK stars
Radial velocity determinations for 139 southern B stars in the BrightStar, FK4, and FK4 Supplement catalogues and for 53 bright southernlate-type stars are presented, based on coudespectrograms taken with theESO 1.5 m telescope at La Silla. The programs, observations,measurements, and reductions are described. Among the data presented arethe visual magnitude, spectral class, mean error, E/T variabilityparameter, velocity of interstellar lines, and rotation class.
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Near infrared excesses in Be stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1981PASP...93..110F&db_key=AST
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Interstellar gas in the GUM Nebula
A survey of the interstellar gas near the Gum Nebula by opticalobservation of 67 stars at Ca II, 42 stars at Na I, and 14 stars in theUV with the Copernicus satellite provided radial velocities and columndensities for all resolved absorption components. Velocity dispersionsfor gas in the Gum Nebula are not significantly larger than in thegeneral interstellar medium; the ionization structure is predominantlythat of an H II region with moderately high ionization. Denser, morehighly ionized clouds are concentrated toward the Gum Nebula; theseclouds do not show the anomalously high ionization observed in the Velaremnant clouds.
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A model of light variations of Be stars
The following model of Be star is proposed: a star rotating rigidly witha 'break up' velocity is surrounded with a flat, geometrically thin,optically thick gaseous disk rotating with a Keplerian velocity. Thedisk absorbs and reemits stellar light. Viscous heat dissipation in thedisk is neglected. The emerging spectrum of the system is calculated inblack body approximation with temperature being a function of a positionon the star and on the disk. Variation of the inner and outer disk radiimay give rise to monochromatic light variations of the whole system inthe range of 0.1-0.7 magnitudes. The light variations observed in Bestars are in the same range.
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64th Name-List of Variable Stars
Not Available
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The photometric behavior of Be Stars
Photometric data are presented for 76 Be stars observed in UBV and inthe Balmer lines H-alpha, H-beta, and H-gamma. An ultraviolet excess,derived from the Q value, appears as a common feature for nearly all thestars. From a statistical study of the data, the percentages ofvariability are: 77 percent in V, 48 percent in B-V, and 68 percent inU-B. The amounts of emission in the alpha and beta indices are computed.It is demonstrated that both emission indices are very well correlatedwith the spectroscopic emission features, their equivalent widths, andpossibly also the ultraviolet excess. The correlation of the standarddeviation of the V magnitude with the projected rotational velocity isin agreement with a model in which the Balmer line emission is due to agaseous ring. The observed beta values corrected for the emissionindices become good indicators of the absolute magnitudes, as isconfirmed by a sample of Be stars known to be members of clusters andassociations. Some properties of the galactic distribution of the Bestars are derived.
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Be stars with large magnitude changes.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975PASP...87..603F&db_key=AST
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Behavior of lambda 2800 Mg II in stellar spectra
The results of measurements of the equivalent widths of the resonancedoublet of ionized magnesium lambda 2800 Mg II in the spectra of 51relatively faint stars, up to 10m, of the spectral classes B1-K5 arepresented. The observed material has been obtained by means of the spaceobservatory 'Orion 2'. Some regularities in the behavior of lambda 2800Mg II in stellar spectra have been revealed: wide and deep depression ofthe continuous spectra at 2800 A in F-G type stars; the presence of thedoublet lambda 2800 Mg II in the form of weak emission in the spectra ofcold stars (K2-K5); the presence both of the multiplet lambda 3080 Ti IIand the doublet lambda 2800 Mg II simultaneously either in emission - inthe late-type stars - or in absorption in earlier types; the existenceof combined profiles of lambda 2800 Mg II, i.e., a wide absorption linewith a weak emission in the center, in stars of the transitional class(G5-K0), etc. A well-defined empirical relationship between theequivalent width of lambda 2800 Mg II and the spectral class of the starhas been established.
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Photoelectric measures of the hydrogen lines in early-type stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974MNRAS.169..171F&db_key=AST
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New kinematical data for bright southern OB-stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972A&AS....5..129L&db_key=AST
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Four-color and H-beta photometry for bright B-type stars in the southern hemisphere.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971AJ.....76..621C&db_key=AST
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MK Spectral Types for Bright Southern OB Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1969ApJ...157..313H&db_key=AST
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A Survey of Southern Be Stars. II. Photometric data
Not Available
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Photoelectric magnitudes and colours of southern stars, II
Not Available
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A Survey of Southern Be Stars
Not Available
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NEWS@SKY (Science&Space News)
