|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 (22.214.171.124) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcar?J/A+A/367/521
|Observations of BN and AN stars: New Be stars|
From a survey of spectra of Bn/An stars, we have detected seven new Bestars: HR 1056 (A0Vn), 1544 (A1Vn), 2191 (A0Vnn), 2300 (B8Vn), 3134(B9.5 Vn), 3878 (B0.5 IIIn) and 4552 (B9IIIpSi). H_alpha profiles ofthese stars are presented. Measured values of equivalent widths, fullwidths at half intensity maximum, and the peak-separations of theH_alpha emission profiles are also tabulated in this paper. We have alsocomputed the radii of emission disks of the newly detected Be stars.
|Ultrafine Structure in the lambda 5797 Diffuse Interstellar Absorption Band|
High-resolution and high-S/N observations of the strong and relativelynarrow lambda 5797 diffuse interstellar absorption band, recorded withthe Ultra-High-Resolution Facility at the 3.9 m Anglo-AustralianTelescope and the 0.9 m coude feed of the Kitt Peak NationalObservatory, are reported. For selected lines of sight and usingresolving powers of up to 600,000, a remarkable degree of intrinsicultrafine structure is found within the band. There exists an almostexact correspondence between the structure in the spectra recordedtoward mu Sgr, zeta Per, and zeta Oph, including one particularly narrowcomponent with a width that is comparable to the widths of atomic andmolecular absorption lines along these lines of sight. The resultsprovide a new and extremely exacting test against which theoretical orlaboratory candidates can be assessed, and they point to a new approachto studies of diffuse band carrier distributions through their velocitysignatures.
|The Pulkovo Spectrophotometric Catalog of Bright Stars in the Range from 320 TO 1080 NM|
A spectrophotometric catalog is presented, combining results of numerousobservations made by Pulkovo astronomers at different observing sites.The catalog consists of three parts: the first contains the data for 602stars in the spectral range of 320--735 nm with a resolution of 5 nm,the second one contains 285 stars in the spectral range of 500--1080 nmwith a resolution of 10 nm and the third one contains 278 stars combinedfrom the preceding catalogs in the spectral range of 320--1080 nm with aresolution of 10 nm. The data are presented in absolute energy unitsW/m(2) m, with a step of 2.5 nm and with an accuracy not lower than1.5--2.0%.
|On the normal energy distribution in stellar spectra: Main-sequence B 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.
|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.
|The determination of T_eff_ of B, A and F main sequence stars from the continuum between 3200 A and 3600 A.|
A method of determination of the effective temperature of B, A and Fmain sequence stars is proposed, using the slope of the continuumbetween 3200A and 3600A. The effective temperature calibration is basedon a sample of stars with energy distributions known from UV to the red.We have determined the Balmer jump and the effective temperatures for235 main sequence stars. The temperatures found have been compared withthose derived by Underhill et al. (1979), Kontizas & Theodossiou(1980), Theodossiou (1985), Morossi & Malagnini (1985). Thecomparison showed good agreement for most of the stars in common. On theother hand, the temperatures derived from the reddening-free colourfactor QUV, from the colour index (m1965-V) and from (B-V), given inGulati et al. (1989), are systematically lower than our temperatures,however the differences are within one-sigma error.
|The local distribution of NA I interstellar gas|
We present high-resolution absorption measurements (lambda/Delta lambdaapproximately 75,000) of the interstellar Na I D lines at 5890 A toward80 southern hemisphere early-type stars located in the localinterstellar medium (LISM). Combining these results with other sodiummeasurements taken from the literature, we produce galactic maps of thedistribution of neutral sodium column density for a total of 293 starsgenerally lying within approximately 250 pc of the Sun. These mapsreveal the approximate shape of the mid-plane contours of the rarefiedregion of interstellar space termed the Local Bubble. Its shape is seenas highly asymmetric, with a radius ranging from 30 to 300 pc, and withan average radius of 60 pc. Similar plots of the Galactic mid-planedistribution of sources emitting extreme ultraviolet radiation show thatthey also trace out similar contours of the Local Bubble derived from NaI absorption measurements. We conclude that the Local Bubble absorptioninterface can be represented by a hydrogen column density,NuETA = 2 x 1019 cm-2, which explainsboth the local distribution of Na I absorption and the observed galacticdistribution of extreme ultraviolet sources. The derived mid-planecontours of the Bubble generally reproduce the large-scale featurescarved out in the interstellar medium by several nearby galactic shellstructures.
|The stellar temperature scale for stars of spectral types from O8 to F6 and the standard deviation of the MK spectral classification|
Empirical effective temperature of 211 early-type stars found in aprevious investigation (Kontizas and Theodossiou, 1980; Theodossiou,1985) are combined with the effective temperatures of 313 early-typestars from the literature. From these effective temperatures of a totalnumber of 524 early-type stars of spectral types from O8 to F6 a newstellar temperature scale is developed along with the standard deviationof the MK spectral classification.
|Stellar integrated fluxes in the wavelength range 380 NM - 900 NM derived from Johnson 13-colour photometry|
Petford et al. (1988) have reported measured integrated fluxes for 216stars with a wide spread of spectral type and luminosity, and mentionedthat a cubic-spline integration over the relevant Johnson 13-colormagnitudes, converted to fluxes using Johnson's calibration, is inexcellent agreement with those measurements. In this paper a list of thefluxes derived in this way, corrected for a small dependence on B-V, isgiven for all the 1215 stars in Johnson's 1975 catalog with completeentries.
|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.
|Far ultraviolet colors of B and Be stars|
A far-UV color index, G, which is free of interstellar reddening effectsis applied to TD-1 satellite observations of B and Be stars listed inthe catalogs of Jamar et al. (1976) and Macau-Hercot et al. (1978). Theexpressions defining G(in terms of the wavelengths 146, 235, and 274 nm)and the S70 index of spectral type are set forth. Tables of mean andindividual-star G and S70 indices and plots of G versus S70, Delta-Gversus spectral type, Delta-G versus H-alpha and H-beta intensity, and Gversus V(sin i) are presented and discussed. The Be stars are classifiedas strong if they show strong Balmer emission, some Paschen and Fe IIemission, and IR excess; otherwise they are 'weak'. Weak Be stars arefound to have G similar to that of B stars, while G in strong Be starsis either much more negative or much less negative than in the B stars.No correlation is found between G and V(sin i) for either B or Be stars.
|Standard Stars for Hα Photometry|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1981A&AS...44..337S&db_key=AST
|Effective temperatures, angular diameters, distances and linear radii for 160 O and B stars|
This paper discusses effective temperatures, angular diameters,distances, and linear diameters that have been determined for 160 O andB stars on the basis of published UV spectrophotometry, visible andnear-IR intermediate-band photometry, and model-atmosphere fluxes. Theresults are compared with previous measurements and calculations formain-sequence and giant O and B stars. It is found that: (1) the fluxeffective temperatures of O and B supergiants are systematically lowerthan those of main-sequence and giant stars of the same subtype; (2) theeffective temperatures and radii of Beta Cep stars are the same as thoseof nonvariable stars of the same spectral type; (3) Be stars that do nothave two Balmer jumps have effective temperatures very similar to thoseof normal B stars of the same subtype; (4) O and B stars increase insize from the main sequence to supergiants; and (5) late B supergiantsare approximately twice as large as O9 supergiants.
|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
|Spectral classification from the ultraviolet line features of S2/68 spectra. II - Late B-type stars|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977A&AS...30...71C&db_key=AST
|Rotational Velocities of a0 Stars|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974ApJS...28..101D&db_key=AST
|NGC 2287 and the Pleiades group.|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974ApJ...188...59E&db_key=AST
|Feasibility of UV astronomy by balloon-borne observations. II. Stellar gradients in the near ultraviolet.|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973A&A....22..371N&db_key=AST
|Feasibility of UV astronomy by balloon-borne observations 1 Stellar spectrophotometry.|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973A&A....22..361N&db_key=AST
|Four-colour and H BET photometry of some bright southern stars- II.|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972MNRAS.160..155S&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
|Four-colour and H-beta photometry for bright stars in the southern hemisphere.|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970AJ.....75..624C&db_key=AST
|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
|Stellar groups, VI. Space motions of the dwarf A-type and giant M-type stars in the solar neighbourhood|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1960MNRAS.120..448E&db_key=AST
|Photoelectric determination of the colors of 286 stars south of declination -15 degrees.|