The total-to-selective extinction ratio determined from near IR photometry of OB stars
The paper presents an extensive list of the total to selectiveextinction ratios R calculated from the infrared magnitudes of 597 O andB stars using the extrapolation method. The IR magnitudes of these starswere taken from the literature. The IR colour excesses are determinedwith the aid of "artificial standards" - Wegner (1994). The individualand mean values of total to selective extinction ratios R differ in mostcases from the average value R=3.10 +/-0.05 - Wegner (1993) in differentOB associations. The relation between total to selective extinctionratios R determined in this paper and those calculated using the "methodof variable extinction" and the Cardelli et al. (1989) formulae isdiscussed. The R values presented in this paper can be used to determineindividual absolute magnitudes of reddened OB stars with knowntrigonometric parallaxes.
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The Carina Spiral Feature: Strömgren-Hβ photometry approach. I. The photometric data-base
A data-base collating all uvbybeta photometry available at present forO-B9 stars brighter than 10th visual magnitude in the field of theCarina Spiral Feature is presented. The completeness and homogeneity ofthe data-base are discussed.Based on CDS data.Table 1 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/410/523
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Long-term spectroscopic monitoring of the Luminous Blue Variable HD 160529
We have spectroscopically monitored the galactic Luminous Blue VariableHD 160529 and obtained an extensive high-resolution data set that coversthe years 1991 to 2002. During this period, the star evolved from anextended photometric minimum phase towards a new visual maximum. Inseveral observing seasons, we covered up to four months with almostdaily spectra. Our spectra typically cover most of the visual spectralrange with a high spectral resolution (lambda /Delta lambda ~ 20 000 ormore). This allows us to investigate the variability in many lines andon many time scales from days to years. We find a correlation betweenthe photospheric HeI lines and the brightness of the star, both on atime scale of months and on a time scale of years. The short-termvariations are smaller and do not follow the long-term trend, stronglysuggesting different physical mechanisms. Metal lines also show bothshort-term and long-term variations in strength and also a long-termtrend in radial velocity. Most of the line-profile variations can beattributed to changing strengths of lines. Propagating features in theline profiles are rarely observed. We find that the mass-loss rate of HD160529 is almost independent of temperature, i.e. visual brightness.Based on observations collected at the European Southern Observatory atLa Silla, Chile (proposals 69.D-0378, 269.D-5038).
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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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Light variations of massive stars (alpha Cyg variables). XV. The LMC supergiants R99 (LBV), R103, R123 (LBV) and R128
VBLUW photometry (Walraven system) of the four variable LMC supergiantsR99, R103, R123 and R128 is analysed, searched for periods anddiscussed. Based on former and present photometry we conclude that twoof the three emission-line objects are undoubtedly active LBVs (R99 andR123), although not so spectacular. R123, like AG Car near minimumbrightness, shows a low amplitude S Dor activity with superimposed alphaCyg-type variations. Based on observations obtained at the EuropeanSouthern Observatory at La Silla, Chile
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The inhomogeneous circumstellar envelope of Rigel (beta Orionis A)
We report on time series Hα profiles of the late B-type supergiantRigel (beta Orionis A). Our observations indicate the presence ofvariable and asymmetric outflows and infalls of matter. We have recordeda blueshifted high-velocity absorption component in Hα almostsimultaneously with Kaufer et al. The final part of this extraordinaryevent has been observed. We have found that blueshifted high-velocityabsorption completely disappeared in one month, and, during another,redshifted strong absorption appeared at 50kms^-1. Based on ourobservations and those reported in the literature, we propose extendedrotating magnetic structures (closed loops) in the mantle of Rigel. Thefundamental parameters of the star are discussed.
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Long-term spectroscopic monitoring of BA-type supergiants. III. Variability of photospheric lines.
We obtained time series of spectra with high S/N and high resolution inwavelength and time of early-type A and late-type B supergiants (cf.Kaufer et al. 1996A&A...305..887K, Paper I, and Kaufer et al.1996A&A...314..599K, Paper II for the analysis of the variability ofthe stellar envelopes). In this work we inspect the time variations ofthe numerous photospheric line profiles in the optical spectrum. We findcomplex cyclical variations of the radial velocities with a typicalvelocity dispersion of σ=~3km/s. The correspondingequivalent-width variations are less than 1% of their mean if we assumea common modulation mechanism for both radial velocities and equivalentwidth. We do not find any depth dependence of the velocity fields in themetallic lines. For αCyg the Balmer lines show an increase of theradial velocity from H27 to H8 by 3km/s, which is identified with theonset of the radially accelerating velocity field of the stellar wind.The Cleaned periodograms of the radial-velocity curves show thesimultaneous excitation of multiple pulsation modes with periods longerand shorter than the estimated radial fundamental periods of theobjects, which might indicate the excitation of non-radial and radialovertones, respectively. The analysis of the line-profile variations(LPV) of the photospheric line spectrum reveals prograde travellingfeatures in the dynamical spectra. The travelling times of thesefeatures are in contradiction to the possible rotation periods of theseextended, slowly rotating objects. Therefore, we suggest that thesefeatures should be identified with non-radial pulsation modes, possiblyg-modes, of low order (l=|m|<~5).
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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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Long-term spectroscopic monitoring of BA-type supergiants. II. High-velocity absorptions in βOri and HD96919.
During our extended monitoring campaigns on late B and early A-typesupergiants (Kaufer et al. 1996A&A...305..887K, Paper I) we haveobserved extraordinarily deep and highly blue-shifted absorption eventsin the Hα line. In this work, new time-series observations showingthe most extreme cases of such events observed so far are presented fortwo objects, βOri (B8Ia) and HD96919 (B9Ia). The development ofthese high-velocity absorption (HVA) events in velocity and time arediscussed: the HVAs show no signs of spherically symmetric mass-lossevents with subsequent accelerated propagation into the wind. Theabsence of unshifted line emission in connection with the HVAs isespecially indicative of the non-sphericity of the active circumstellarregions. Simultaneously with the blue-shifted absorption, red-shiftedabsorption is found in Balmer and metallic lines, primarily during theonset of the developing event, which clearly reveals the complexstructure of the involved velocity fields. Mass outflow and mass infallare present in the envelope. As a picture for the circumstellarstructures that cause the sudden appearance of the HVAs over a largevelocity range, localized regions of enhanced mass loss on the stellarsurface, which build up extended, rotating streak lines in theequatorial plane are suggested. Finally, the role of a criticalionization structure in the condensed structures is discussed.
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Long-term spectroscopic monitoring of BA-type supergiants. I. Halpha_ line-profile variability.
We have obtained time series of spectra in the wavelength range4000-6800 A over several months with high S/N and high resolution inwavelength (λ/{DELTA}λ=~20000) and time ({DELTA}t=~1d) ofthe late-type B and early-type A supergiants HD91619 (B7Ia), βOri(B8Ia), HD96919 (B9Ia), HD92207 (A0Ia), HD100262 (A2Ia) and αCyg(A2Ia). Halpha_ is found to show broad emission extended toabout +/-1200km/s for all objects except αCyg. Due to the lack ofstrong line-emission in Halpha_ the electron-scatteredphotons are expected to originate in deep atmospheric layers. In all ofthe objects the Halpha_-line profiles are found to be highlyvariable on different time scales reaching from days to months. Patternsof variation in Halpha_ are found to be quite symmetric aboutthe systemic velocity and are mainly due to variable blue andred-shifted emission superimposed on almost constant photospheric and/orwind profiles. These V/R variations are interpreted in terms of axialsymmetry of the envelopes of these objects. Time-series analyses of thevariations reveal Halpha_ time scales up to a factor of 6longer than expected radial fundamental pulsation periods but consistentwith rotational periods. Therefore, rotational modulation as a possiblesource of variability is concluded. Corotating weak magnetic surfacestructures are suggested as the source for a rotationally modulatedlower wind region. Suddenly appearing deep and highly blue-shiftedabsorptions in Halpha_ are ascribed to instabilities of theionization structure of the wind. Outwards propagating discreteabsorption components have been observed only once in HD92207.
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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.
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Spectroscopic monitoring of BA-type supergiants.
Not Available
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Second astrolabe catalogue of Santiago.
Positions for 350 FK5 and 164 FK5 Extension stars as determined with theDanjon astrolabe of Santiago and differences astrolabe-catalogue aregiven for Equinox J2000.0 and for the mean observation epoch of eachstar. The average mean error in alpha is +/-0.005s and +/-0.07" indelta. The mean epoch of observation of the catalogue is J1979.96.
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Improved Mean Positions and Proper Motions for the 995 FK4 Sup Stars not Included in the FK5 Extension
Not Available
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The maximum amplitude of the optical micro-variations of massive O-F type stars (or Alpha Cygni variables, including LBV's or S DOR variables) across the HR diagram
The maximum light amplitude (MLA) of the microvariations of nearly 100massive stars with spectral type O 3-F8 are collected from theliterature and unpublished material. These variables, called the AlphaCygni variables, also include the LBVs or S Dor type variables. The SDor type variables must be in a quiescent stage to detect theirintrinsic variations properly. The log T(eff)/MLA diagram exhibits aclear separation between S Dor type variables and the normal Alpha Cygnivariables (the majority). The results suggest that the outer layers ofboth types of stars where gravity waves presumably occur, differphysically from each other.
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Non-canonical insights into the evolution of stars. II - Are variable supergiants indeed pulsating?
It is shown that the interpretation of the observed semiperiodicluminosity or radial-velocity variations of supergiants in terms ofnonradial pulsations is not as straightforward as often believed. Theobserved semiperiodic luminosity-light dependence can also be derivedunder the assumption of rotational modulation or orbital motion in abinary system. Consideration is also given to the hypothesis that atleast some of the variable supergiants are actually contacts ornear-contacts of the more massive components of unrecognized binarysystems with a low mass-ratio.
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Small Magellanic Cloud: H-gamma-line equivalent widths and luminosity classes of the brightest blue star members
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1987A&AS...69..421A&db_key=AST
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High-resolution spectroscopy of the unique eclipsing binary system - Epsilon Aurigae
H-alpha and Na D line profiles of the Epsilon Aur system acquired duringthe eclipse of 1982-84 are presented. As in previous eclipses, theH-alpha absorption core shows striking, systematic changes in width andradial velocity. H-alpha also exhibits time-varying blueshifted andredshifted emission in the line wings. It is suggested that the H-alphaemission-wing variability is due solely to ongoing processes in theextended atmosphere of the supergiant primary. As the eclipseprogresses, the Na D absorption lines deepen and widen, then decrease insize as their weak emission components strengthen. The time-developmentof the Na D line profiles over the duration of the eclipse is consistentwith the eclipsing object being a massive, cool, rotating, gaseous disk.The observed Na D line velocities combined with derived values for themass and spatial extent of the secondary suggest that the disk is losingmaterial.
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First Stellar Catalog in Rio-Grande
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1985RMxAA..10..377M&db_key=AST
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The ultraviolet variability of early-type supergiants
Four early-type supergiants - HD 79186 (B5 Ia), HD 96919 (B9 Ia), HD105056 (ON9.7 Iae), and HD 148379 (B2 Iae) - have been observed with thelow-resolution spectrographs of IUE in the large aperture on 14 days.The behavior of the ultraviolet fluxes with time is studied. The lightfrom all four stars seems to vary. Typically the dispersion about themean magnitude at any wavelength corresponds to + or - 0.085, + or -0.080, + or - 0.101, and + or - 0.106 mag, respectively. Theseamplitudes exceed the typical uncertainty in an IUE measurement of fluxby about a factor of 3; they are somewhat larger than the variationsknown in the visible wavelength range. There are insufficient data toinvestigate periodicity in the observed light changes. The effectivetemperatures and angular diameters of the stars have been estimatedusing the present ultraviolet photometry, published UBV and uvbyphotometry, and the model-atmosphere fluxes reported by Kurucz in 1979.The program stars have dimensions typical for their spectral types. Abrief discussion is given of possible causes of the variability of hotsupergiants.
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New UBVRI photometry for 900 supergiants
A description is presented of the results obtained in connection with asystematic program of supergiant photometry on the Johnson UBVRI system.During the eight years after the start of the program, almost 1000 starshave been observed, about 400 three or more times each. The originalselection of stars used the spectral type catalog of Jaschek et al.(1964) to choose supergiants. Since observations were possible from bothChile and Canada, no declination limits were imposed, and no particularselection criteria were imposed other than to eliminate carbon stars.These are so red as to require enormous extrapolations of thetransformation equations.
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Variable stars in the General Catalogue of Trigonometric Parallaxes
Not Available
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Refined Data for Parallax Stars
Not Available
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Infrared photometry of southern early-type stars
The paper presents infrared photometry tied to the JHKL (1.2-3.5microns) broadband photometric system for 229 southern early-type stars.To determine data for stars of low reddening intrinsic visual-IR colorindices were used; the E(V-K)/E(B-V) diagram was applied to evaluate theratio of total selective extinction. A mean value of R = 3.12 plus orminus 0.05 was found for stars close to the galactic plane, but a highervalue of R (about 4.0) applies to the Orion and Sco-Oph regions.Infrared two-color diagrams were used to investigate the occurrence ofinfrared excess emission in different classes of shell star; no excesseswere found for supergiants or Of stars. It is concluded that theanomalous position HD 164740 in the two-color diagrams is produced bystrong infrared excess and not by a peculiar extinction law.
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Supergiant variability - Amplitudes and pulsation constants in relation with mass loss and convection
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1980A&A....90..311M&db_key=AST
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64th Name-List of Variable Stars
Not Available
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SKYMAP : a new catalog of stellar data.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978ApJS...38..287G&db_key=AST
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The semi-period-luminosity-color relation for supergiant stars
The semi-period-luminosity-color relation for 32 B- to G-typesupergiants is determined using bolometric corrections and evolutionarytracks for massive stars. Empirical calibrations based on the HR diagramgive semi-periods from 5-100 days. The pulsation quantity is determinedfor each star, which is found to vary within a range comparable to thatof M-type stars. An oscillatory mechanism is proposed as the drivingforce behind the supergiant variability.
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Light variations of extreme galactic B- and A supergiants
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977A&A....57..361S&db_key=AST
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NEWS@SKY (Science&Space News)
