Interferometric observations of the supergiant stars α Orionis and α Herculis with FLUOR at IOTA
We report the observations in the K band of the red supergiant starα Orionis and of the bright giant star α Herculis with theFLUOR beamcombiner at the IOTA interferometer. The high quality of thedata allows us to estimate limb-darkening and derive precise diametersin the K band which combined with bolometric fluxes yield effectivetemperatures. In the case of Betelgeuse, data collected at high spatialfrequency although sparse are compatible with circular symmetry andthere is no clear evidence for departure from circular symmetry. We havecombined the K band data with interferometric measurements in the L bandand at 11.15 μm. The full set of data can be explained if a 2055 Klayer with optical depths τK=0.060±0.003,τL=0.026±0.002 and τ11.15 μm=2.33±0.23 is added 0.33 R* above the photosphereproviding a first consistent view of the star in this range ofwavelengths. This layer provides a consistent explanation for at leastthree otherwise puzzling observations: the wavelength variation ofapparent diameter, the dramatic difference in limb darkening between thetwo supergiant stars, and the previously noted reduced effectivetemperature of supergiants with respect to giants of the same spectraltype. Each of these may be simply understood as an artifact due to notaccounting for the presence of the upper layer in the data analysis.This consistent picture can be considered strong support for thepresence of a sphere of warm water vapor, proposed by \cite{tsuji2000}when interpreting the spectra of strong molecular lines.Based on observations collected at the IOTA interferometer, WhippleObservatory, Mount Hopkins, Arizona.
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Spectral Classification of the Hot Components of a Large Sample of Stars with Composite Spectra, and Implication for the Absolute Magnitudes of the Cool Supergiant Components.
A sample of 135 stars with composite spectra has been observed in thenear-UV spectral region with the Aurélie spectrograph at theObservatoire de Haute-Provence. Using the spectral classifications ofthe cool components previously determined with near infrared spectra, weobtained reliable spectral types of the hot components of the samplesystems. The hot components were isolated by the subtraction methodusing MK standards as surrogates of the cool components. We also derivedthe visual magnitude differences between the components usingWillstrop's normalized stellar flux ratios. We propose a photometricmodel for each of these systems on the basis of our spectroscopic dataand the Hipparcos data. We bring to light a discrepancy for the Gsupergiant primaries between the visual absolute magnitudes deduced fromHipparcos parallaxes and those tabulated by Schmidt-Kaler for the GIbstars: we propose a scale of Mv-values for these stars incomposite systems. By way of statistics, about 75% of the hot componentsare dwarf or subgiant stars, and 25% should be giants. The distributionin spectral types is as follows: 41% of B-type components, 57% of typeA, and 2% of type F; 68% of the hot components have a spectral type inthe range B7 to A2. The distribution of the ΔMv-valuesshows a maximum near 0.75 mag.
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Rotation and Activity in the Solar-Metallicity Open Cluster NGC 2516
We report new measures of radial velocities and rotation rates (vsini)for 51 F and early G stars in the open cluster NGC 2516 and combinethese with previously published data. From high signal-to-noise ratiospectra of two stars, we show that NGC 2516 has a relative ironabundance with respect to the Pleiades of Δ[Fe/H]=+0.04+/-0.07 atthe canonical reddening of E(B-V)=0.12, in contrast to previousphotometric studies that placed the cluster 0.2-0.4 dex below solar. Weconstruct a color-magnitude diagram based on radial velocity members andexplore the sensitivity of photometric determinations of the metallicityand distance to assumed values of the reddening. For a metal abundancenear solar, the Hipparcos distance to NGC 2516 is probablyunderestimated. Finally, we show that the distribution of rotation ratesand X-ray emission does not differ greatly from that of the Pleiades,when allowance is made for the somewhat older age of NGC 2516. Based onobservations obtained at the Anglo-Australian Telescope and onobservations obtained at the Cerro Tololo Inter-American Observatory,NOAO, which is operated by the Associated Universities for Research inAstronomy (AURA), Inc., under cooperative agreement with the NationalScience Foundation.
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Radial velocities of giant M stars near the ecliptic
A search dedicated to the identification of new, dwarf and cold starsclose to the Sun has allowed us to measure the radial velocities of aset of stars of late spectral type. The stars selected were M-type starspresent in the Hipparcos Input Catalogue located in a strip of+/-20° around the Ecliptic and observables from La Silla. Our inalset contains 22 M-type stars whose radial velocities Vr havebeen measured with an accuracy of ~ 0.5 km s-1 during asingle observing run. From their velocities, parallaxes and magnitudeswe deduce that all the stars observed are red giants, with spacevelocities relative to the Sun mostly lower than 100 km s-1.Based on observations collected at the CAT telescope, European SouthernObservatory, La Silla, Chile.
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Dating Ptolemy's star catalogue through proper motions : the Hipparchan epoch.
Not Available
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CCD Speckle Observations of Binary Stars from the Southern Hemisphere. II. Measures from the Lowell-Tololo Telescope during 1999
Speckle observations of 145 double stars and suspected double stars arepresented and discussed. On the basis of multiple observations, a totalof 280 position angle and separation measures are determined, as well as23 high-quality nondetections. All observations were taken with the(unintensified) Rochester Institute of Technology fast-readout CCDcamera mounted on the Lowell-Tololo 61 cm telescope at the Cerro TololoInter-American Observatory during 1999 October. We find that themeasures, when judged as a whole against ephemeris positions of binarieswith very well-known orbits, have root mean square deviations of1.8d+/-0.3d in position angle and 13+/-2 mas in separation. Elevendouble stars discovered by Hipparcos were also successfully observed,and the change in position angle and/or separation since the Hipparcosobservations was substantial in three cases.
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A catalog of rotational and radial velocities for evolved stars
Rotational and radial velocities have been measured for about 2000evolved stars of luminosity classes IV, III, II and Ib covering thespectral region F, G and K. The survey was carried out with the CORAVELspectrometer. The precision for the radial velocities is better than0.30 km s-1, whereas for the rotational velocity measurementsthe uncertainties are typically 1.0 km s-1 for subgiants andgiants and 2.0 km s-1 for class II giants and Ib supergiants.These data will add constraints to studies of the rotational behaviourof evolved stars as well as solid informations concerning the presenceof external rotational brakes, tidal interactions in evolved binarysystems and on the link between rotation, chemical abundance and stellaractivity. In this paper we present the rotational velocity v sin i andthe mean radial velocity for the stars of luminosity classes IV, III andII. Based on observations collected at the Haute--Provence Observatory,Saint--Michel, France and at the European Southern Observatory, LaSilla, Chile. Table \ref{tab5} also available in electronic form at CDSvia anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
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Ultraviolet and Optical Studies of Binaries with Luminous Cool Primaries and Hot Companions. V. The Entire IUE Sample
We have obtained or retrieved IUE spectra for over 100 middle- andlate-type giant and supergiant stars whose spectra indicate the presenceof a hot component earlier than type F2. The hot companions areclassified accurately by temperature class from their far-UV spectra.The interstellar extinction of each system and the relative luminositiesof the components are derived from analysis of the UV and opticalfluxes, using a grid of UV intrinsic colors for hot dwarfs. We find thatthere is fair agreement in general between current UV spectralclassification and ground-based hot component types, in spite of thedifficulties of assigning the latter. There are a few cases in which thecool component optical classifications disagree considerably with thetemperature classes inferred from our analysis of UV and opticalphotometry. The extinction parameter agrees moderately well with otherdeterminations of B-V color excess. Many systems are worthy of furtherstudy especially to establish their spectroscopic orbits. Further workis planned to estimate luminosities of the cool components from the dataherein; in many cases, these luminosities' accuracies should becomparable to or exceed those of the Hipparcos parallaxes.
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Spectral classifications in the near infrared of stars with composite spectra. II. Study of a sample of 180 stars
A sample of 180 supposedly composite-spectrum stars has been studied onthe basis of spectra obtained in the near infrared (8370-8780 Angstroms)at a dispersion of 33 Anstroms/mm. The objective was to study the coolercomponents of the systems. Of our sample, 120 are true compositespectra, 35 are hot spectra of types B, F and 25 are Am stars. We find astrong concentration of the cooler components of the composite spectraaround G8III. In view of the difficulty of classifying compositespectra, because of the super position of an early type dwarf and a latetype giant or supergiant spectrum, we have made several tests to controlthe classification based upon the infrared region. Since all tests gavepositive results, we conclude that our classifications can be consideredas being both reliable and homogeneous. Table \ref{tab1} is alsoavailable electronically at the CDS via anonymous ftp 130.79.128.5 orhttp://cdsweb.u-strasbg.fr/Abstracts.html} Based upon observationscarried out at Observatoire de Haute-Provence (CNRS).
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On the reflection effect in three sdOB binary stars.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996MNRAS.279.1380H&db_key=AST
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H-alpha measurements for cool giants
The H-alpha line in a cool star is usually an indication of theconditions in its chromosphere. I have collected H-alpha spectra of manynorthern G-M stars, which show how the strength and shape of the H-alphaline change with spectral type. These observations detect surprisinglittle variation in absoption-line depth (Rc approximately0.23 +/- 0.08), linewidth (FWHD approximately 1.44 +/- 0.22 A), orequivalent width (EW approximately 1.12 +/- 0.17 A) among G5-M5 IIIgiants. Lines in the more luminous stars tend to be broader and strongerby 30%-40% than in the Class III giants, while the H-alpha absorptiontends to weaken among the cooler M giants. Velocities of H-alpha andnearby photospheric lines are the same to within 1.4 +/- 4.4 km/s forthe whole group. To interpret these observations, I have calculatedH-alpha profiles, Ly-alpha strengths, and (C II) strengths for a seriesof model chromospheres representing a cool giant star like alpha Tau.Results are sensitive to the mass of the chromosphere, to chromospherictemperature, to clumping of the gas, and to the assumed physics of lineformation. The ubiquitous nature of H-alpha in cool giants and the greatdepth of observed lines argue that chromospheres of giants cover theirstellar disks uniformly and are homogeneous on a large scale. This isquite different from conditions on a small scale: To obtain a highenough electron density with the theoretical models, both to explain theexitation of hydrogen and possibly also to give the observed C IImultiplet ratios, the gas is probably clumped. The 6540-6580 A spectraof 240 stars are plotted in an Appendix, which identifies the date ofobservation and marks positions of strong telluric lines on eachspectrum. I assess the effects of telluric lines and estimates that thestrength of scattered light is approximately 5% of the continuum inthese spectra. I give the measurements of H-alpha as well as equivalentwidths of two prominent photospheric lines, Fe I lambda 6546 and Ca Ilambda 6572, which strengthen with advancing spectral type.
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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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Lucifers, a photoelectric radial-velocity spectrometer
A spectrometer dedicated to the measurement of stellar radial velocitieshas been developed at the University of Canterbury and the Mt JohnUniversity Observatory. The spectrometer scans a spectrum from theObservatory's 1-meter McLellan reflecting telescope and fiber-fedechelle with an oscillating mask having 2447 rectangular slotsrepresenting absorption lines in the spectrum of the star Alpha CentauriA covered by the wavelength range 397 to 570 nm in orders 40 to 58 ofthe spectrograph and measures the light passing through the mask as afunction of mask position. A dedicated computer constructs across-correlation function to which a Gaussian distribution function isfitted. The difference between the radial velocities of a star and azero-velocity reference spectrum provided by a hollow-cathode ironemission lamp is calculated from the Gaussian parameters. The sources ofrandom error in the system are discussed and its magnitude for stars ofspectral types F0 to M3.5 is estimated. Systematic errors in the systemare also discussed.
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Rotational Velocities of G and K Giants
Not Available
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Large and kinematically unbiased samples of G- and K-type stars. II - Observations of evolved stars in the Bright Star sample. III - Evolved young disk stars in the Bright Star sample
Four color and RI observations were obtained for a large sample ofG-type and K-type stars in the Bright Star Catalogue. Data are firstpresented for 110 evolved stars. Photometry of evolved young diskpopulation stars have then been calibrated for luminosity, reddening,and metallicity on the basis of results for members of the Hyades andSirius superclusters. New DDO results are given for 120 stars.
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An extended galaxy redshift survey. I - The catalogue
Redshifts and blue magnitudes are presented for a sample of 264 'field'galaxies virtually complete to a limiting magnitude of 16.80 mag. Thegalaxies were selected by sampling one galaxy in every three in order ofapparent magnitude on each of nine high-latitude UK Schmidt (UKST)fields. The spectral data came from observations with the 1.9-mtelescope at the South African Astronomical Observatory (SAAO), and theresulting radial velocities have a precision of 130 + or - km/s. Thissurvey augments substantially the Durham/AAT redshift survey. Theobservational techniques and reduction procedures are discussed.
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On the (B-V) colors of the bright stars
The possible causes of the dispersion of (B-V) colors of nearby stars inthe Bright Star Catalog are investigated. The distribution of (B-V)colors is presented for the entire range of spectral classes.Explanations for the dispersion in terms of a nonuniform distribution ofinterstellar absorbing material and a variability of metallicity areaddressed. A new statistical model for reddening by interstellar dustclouds is developed. It is concluded that extinction by nonuniforminterstellar matter is an important contribution to the reddening ofnearby stars, and that a part of the dispersion of (B-V) colors of Kand, possibly, M giants may be due to some unidentified variableproperty of those stars.
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Radial velocities of bright southern stars. VI - Standard and reference stars 1983-1986
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1987A&AS...68..347A&db_key=AST
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E. W. Fick Observatory stellar radial velocity measurements. I - 1976-1984
Stellar radial velocity observations made with the large vacuumhigh-dispersion photoelectric radial velocity spectrometer at FickObservatory are reported. This includes nearly 2000 late-type starsobserved during 585 nights. Gradual modifications to this instrumentover its first eight years of operation have reduced the observationalerror for high-quality dip observations to + or - 0.8 km/s.
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An analysis of the radial-velocity performance of the image-tube spectrograph on the CTIO 1-meter telescope
An analysis of the radial-velocity performance of the 120 A/mmconfiguration of the image-tube spectrograph on the CTIO/Yale 1-metertelescope is presented. The instrument is found to be stable within agiven run but to be susceptible to small changes from run to run. Theremay be systematic changes in velocity residual with declination; noneare found with zenith angle or hour angle. A typical precision of plusor minus 10 km/sec for a single spectrum of a Population I star isachieved for the spectrograph configuration. Rest wavelengths derivedfor F0-K4 Population I stars observed with this spectrograph/image-tubeconfiguration are presented. A table of radial velocities and residualsfor IAU radial-velocity standard stars, as well as some other brightstars, is also presented.
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Catalogue of the energy distribution data in spectra of stars in the uniform spectrophotometric system.
Not Available
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Radial velocities for 28 southern young open clusters
Radial velocities for 83 OB-stars in 28 southern young open clusters arepresented. The internal and external accuracy of the data is in goodagreement with results obtained by Ardeberg and Maurice (1977) with thesame equipment. From a comparison with radial velocities existing in theliterature no systematic radial-velocity differences for stars in commonare found.
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Photographic observations of visual double stars
Photographic observations of 238 pairs of visual binaries obtained on770 plates using the 60-cm visual refractor of Bosscha Observatory(Lembang, Java) during 1976-1979 are reported, continuing the catalog ofvan Albada-van Dien (1983). The data-reduction procedures are brieflydescribed, and the data are presented in a table.
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On the accuracy of the wavelength calibration and of the flat-fielding of the CCD CASPEC spectra
Results of an analysis of the spectral data reduced by the CASPECinstrument are reported. In the wavelength calibration performed byCASPEC calibration lines are identified according to a detectioncriterion which is based on line-width and the intensity above thebackground. In the commissioning phase nine spectra of 4 velocitystandard stars are reduced using the standard procedure in the MunichImage Data Analysis System (MIDAS) of the ESO. The procedures followedby CASPEC for reducing a flat-field CCD image is described. As anexample, two extracted orders from a 25 min. exposure of the 12.1 visualmagnitude star LTT 3864 are presented.
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Observations of Standard Velocity Stars
Not Available
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Standard Velocity Stars
Not Available
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Radial velocities of bright southern stars. III - Late-type standard stars at 12 A/mm
An analysis is conducted of radial velocities measured on 51spectrograms of 14 late type standard stars at a dispersion of 12.4A/mm. A list of 15 suitable lines and wavelengths for radial velocitydetermination in late type spectra is established, by means of which theinternal and external standard errors for a single plate are found to be0.25 and 0.66 km/sec. The present velocity system is in good agreementwith the standard system, but the results obtained for HD 51250 agreebetter with the revised velocity proposed by Batten (1982). Thevariability of the former IAU standard stars HD 35410 and HD 80170 isconfirmed.
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Radial velocities of IAU standard stars
Radial velocities of 52 IAU Radial Velocity Standard stars, obtainedfrom 358 spectra of 12 and 20 A/mm dispersion during the 1970-1978period, are presented. Some discrepancies between the present resultsand those of the IAU are discussed.
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Photometric differences of magnitude in southern double stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1980A&A....84..108F&db_key=AST
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On the spectrographic and photometric data for the brightest stars in the Small Magellanic Cloud
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1979A&A....77..269A&db_key=AST
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INHABITED SKY
