Rotational Velocities of B Stars
We 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.
|
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
|
Absolute declinations with the photoelectric astrolabe at Calern Observatory (OCA)
A regular observational programme with a photoelectric astrolabe havebeen performed at ``Observatoire du Calern" (Observatoire de laCôte d'Azur, OCA, phi = +43() o44′55.011″; lambda =-0() h27() m42.44() s, Calern, Caussols, France) for the last twentyyears. It has been almost fully automatized between 1984 and 1987. Since1988 the photoelectric astrolabe was used without any modification. Inaddition to determining the daily orientation of the local vertical, theyearly analysis of the residuals permits to derive corrections to theused star catalogue \cite[(Vigouroux et al. 1992)]{vig92}. A globalreduction method was applied for the ASPHO observations. The new form ofthe equations \cite[(Martin & Leister 1997)]{mar97} give us thepossibility of using the entire set of the observing program using datataken at two zenith distances (30() o and 45() o). The program containsabout 41648 stars' transits of 269 different stars taken at``Observatoire du Calern" (OCA). The reduction was based on theHIPPARCOS system. We discuss the possibility of computing absolutedeclinations through stars belonging simultaneously to the 30() o and45() o zenith distances programmes. The absolute declination correctionswere determined for 185 stars with precision of 0.027arcsec and thevalue of the determined equator correction is -0.018arcsec +/-0.005arcsec . The instrumental effects were also determined. The meanepoch is 1995.29. Catalogue only available at CDS in electronic from viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
|
Rotational Velocity Determinations for 164 Be and B Stars
Rotational velocities, v sin i, have been obtained for 96 Be and 68normal B stars by measurements of the FWHM of the He I lambda-4471 line(for spectral types B0-B4.5) and Mg II lambda-4481 (for types B5-B9.5).The consistency of various published sources is examined. (SECTION:Stars)
|
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.
|
The photoelectric astrolabe catalogue of Yunnan Observatory (YPAC).
The positions of 53 FK5, 70 FK5 Extension and 486 GC stars are given forthe equator and equinox J2000.0 and for the mean observation epoch ofeach star. They are determined with the photoelectric astrolabe ofYunnan Observatory. The internal mean errors in right ascension anddeclination are +/- 0.046" and +/- 0.059", respectively. The meanobservation epoch is 1989.51.
|
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.
|
Photometric variability in early B stars I. 53 ARIETIS
Not Available
|
Observation of fine structure in the cold phase of the local interstellar medium using K I absorption
The K I 7699-A resonance absorption line was used to observe a group of18 early-type stars within a 200-pc radius of the sun with asignal-to-noise ratio of 50-250. The interstellar absorptions provide away to 'tag' a cloud via its radial velocity to within +/-1.5 km/s.Based on the hypothesis of pressure confinement, the temperatures of theclouds are estimated at 100 K or less. The mass fraction of the localinterstellar medium (LISM) is found to be high in these clouds, at least80 percent of the total, whereas the filling factor is low, well below10 percent of the total LISM volume. One cloud with high densities andlower temperatures was detected which is thought to be on the edge ofatomic-molecular equilibrium.
|
High-resolution observations of interstellar NA I and K I absorptions towards giants within 200 PC from the sun
The first results of a program of observations designed to probe thestructure and kinematics of the Local Interstellar Medium (LISM) usingthe Queen's University of Belfast Echelle Spectrograph (QUBES) on the4.2 m William Herschel Telescope are reported. The observations show thepotential of the instrument for measuring small column densities and forprecise velocity structure analysis.
|
Third preliminary catalogue of stars observed with the photoelectric astrolabe of the Beijing Astronomical Observatory.
Not Available
|
The local system of early type stars - Spatial extent and kinematics
Published uvby and H-beta photometric data and proper motions arecompiled and analyzed to characterize the structure and kinematics ofthe bright early-type O-A0 stars in the solar vicinity, with a focus onthe Gould belt. The selection and calibration techniques are explained,and the data are presented in extensive tables and graphs and discussedin detail. The Gould belt stars of age less than 20 Myr are shown togive belt inclination 19 deg to the Galactic plane and node-lineorientation in the direction of Galactic rotation, while the symmetricaldistribution about the Galactic plane and kinematic properties (purecircular differential rotation) of the belt stars over 60 Myr oldresemble those of fainter nonbelt stars of all ages. The unresolveddiscrepancy between the expansion observed in the youngest nearby starsand the predictions of simple models of expansion from a point isattributed to the inhomogeneous distribution of interstellar matter.
|
The galactic reddening law - The evidence from uvby-beta photometry of B stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1985A&A...142..189T&db_key=AST
|
Binary stars unresolved by speckle interferometry. III
The 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.
|
Geneva photometric boxes. II - The reddening towards the galactic poles
It is noted that photometric boxes allow a very accurate estimation ofindividual reddenings for B- and early A-type stars. A catalog of 129stars with galactic latitudes higher than 30 deg is given. A small butsignificant reddening is seen in the direction of both the northern andsouthern galactic poles: E(B-V) approximately 0.04.
|
Uvby-Beta Photometry of Equatorial and Southern Bright Stars - Part Two
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1980A&AS...42..311H&db_key=AST
|
Late B-type stars - Rotation and the incidence of HgMn stars
High-dispersion spectrograms for an unbiased sample of 256 late B-typestars are examined in an attempt to determine whether slow rotation isnecessary and sufficient for the appearance of HgMn anomalies innonmagnetic stars. The peculiar stars in the sample are identified,values of v sin i are derived for all the stars observed, and theradial-velocity variations of the identified HgMn stars are analyzed.The distribution of rotational velocities for late B-type stars isobtained, and the role of rotation in producing extended envelopes isevaluated. The binary frequency and mass-ratio distribution are derivedfor systems containing HgMn components, the effect of duplicity on thedistribution of rotational velocities is estimated, and the role of suchfactors as rotation, age, and binary characteristics in determiningwhether HgMn anomalies are present is investigated. The results clearlyshow that HgMn stars occur only within a limited temperature range, thatall such stars rotate slowly, but that rotation, effective temperature,age, surface gravity, and binary properties do not serve to determinewhether a star will exhibit abundance anomalies.
|
Is star formation bimodal ? II. The nearest early-type stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977PASP...89..187E&db_key=AST
|
Catalogue of early-type stars measured in a narrow-band photometric system
A compilation of the photoelectric measurements in the Barbier-Morguleffsystem is presented. The catalogue includes data for 773 stars ofspectral type 08 to F6. 706 stars have been measured at least twice.
|
The manganese stars
Ultraviolet spectrograms of 194 middle and late B-type stars wereobtained in a search for Mn stars. The 24 Mn stars found in this searchlay within the limited temperature range from 0.33 to 0.48. Theirobserved rate of incidence and rotational velocity distributionsubstantiate the hypothesis that the Mn stars constitute a considerablefraction of the slowly rotating stars in this temperature range. If theatmospheres of these stars are sufficiently stable for diffusionprocesses to be effective, then it also becomes possible to account forthe temperature range in which the Mn overabundance occurs.
|
Four-color and H beta photometry for the bright B8 and B9 type stars north of declination -10 degre.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973AJ.....78..738C&db_key=AST
|
Intermediate-band photometry of RR LYR variables. I. Definition and characteristics of the system.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971MNRAS.154...79J&db_key=AST
|
Observations of occultations made at the University observatory at Brno in the years 1961-1962
Not Available
|
U, b, v, and Hβ Photometry for the Bright B8- and B9-TYPE Stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1963ApJ...137..530C&db_key=AST
|
INHABITED SKY
