Visual Star Colours from Instrumental Photometry
In order to display graphically the visual colours of stars and otherastronomical objects, photometric broadband R, V, B colours are used toproxy for the r, g, b colours of the three visual sensors of the eye.From photometric Johnson B-V and V-R colour indices, R, V, and Bmagnitudes (V = 0) are calculated, and from these the respectivebrightnesses (r, v = 1 = g, and b) are calculated. After suitablenormalization these are then placed in a ternary diagram having r, g,and b as the vertices. All B-V and V-R are adjusted so that the Sunfalls in the same place as a blackbody at 5800 K. The resulting ternaryplot shows all of its objects (stars, planets) in their visual coloursat their relative positions in the ternary diagram. The star coloursdisplayed on a computer monitor screen or as a print with a colourprinter are more vivid than the usual visual impressions of isolatedstars, undoubtedly because of properties of the dark-adapted eye, butdouble-star pairs with contrasting colours correspond nicely totelescopic visual impressions.
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Observational constraints for lithium depletion before the RGB
Precise Li abundances are determined for 54 giant stars mostly evolvingacross the Hertzsprung gap. We combine these data with rotationalvelocity and with information related to the deepening of the convectivezone of the stars to analyse their link to Li dilution in the referredspectral region. A sudden decline in Li abundance paralleling the onealready established in rotation is quite clear. Following similarresults for other stellar luminosity classes and spectral regions, thereis no linear relation between Li abundance and rotation, in spite of thefact that most of the fast rotators present high Li content. The effectsof convection in driving the Li dilution is also quite clear. Stars withhigh Li content are mostly those with an undeveloped convective zone,whereas stars with a developed convective zone present clear sign of Lidilution.Based on observations collected at ESO, La Silla, Chile, and at theObservatoire de Haute Provence, France, operated by the Centre Nationalde la Recherche Scientifique (CNRS).
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Circularization of binary orbits.
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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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The ROSAT all-sky survey catalogue of optically bright late-type giants and supergiants
We present X-ray data for all late-type (A, F, G, K, M) giants andsupergiants (luminosity classes I to III-IV) listed in the Bright StarCatalogue that have been detected in the ROSAT all-sky survey.Altogether, our catalogue contains 450 entries of X-ray emitting evolvedlate-type stars, which corresponds to an average detection rate of about11.7 percent. The selection of the sample stars, the data analysis, thecriteria for an accepted match between star and X-ray source, and thedetermination of X-ray fluxes are described. Catalogue only available atCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
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Photoelectric Photometry of TX Psc, Alpha Her A, Omicron Cet, and RT Cyg
Photoelectric observations at 5500A have been conducted on the Lb carbonstar TX Psc as part of the AAVSO Small Amplitude Red Variable program;the observed light curve from 1990 through 1995 indicates a semiregularvariation with a cycle length of approximately 220 days, rather thancomplete irregularity. Photoelectric (V) observations were also made onthe SRc variable alpha Her A; a beat period of 277 days with anamplitude of 0.8 magnitude was found. The Mira-type variables o Cet andRT Cyg have recently been observed in V and three narrow-band filters inthe near infrared. Results from the first two months of observations areshown.
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Photoelectric Photometry of the Red Supergiant alpha1 Her
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Speckle observations of visual and spectroscopic binaries. VI.
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Formation Rate of Triple Stars relative to Double Stars
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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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Ultraviolet Observations of the Circumstellar Envelope of ALPHA-1-HERCULIS in the Line-Of of ALPHA-2-HERCULIS
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1993A&A...274..838T&db_key=AST
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Statistical Analysis of a Sample of Spectroscopic Binaries Containing Late Type Giants
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1993A&A...271..125B&db_key=AST
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Speckle observations of visual and spectroscopic binaries. IV
This is the fourth paper of this series giving results of speckleobservations for 22 visual and 161 spectroscopic binaries. Theobservation was carried out by using the 212 cm telescope of San PedroMartir Observatory in Mexico on 7 nights from July 20 to July 26, 1991.We obtained fringes in power spectra of 19 visual and 11 spectroscopicbinaries (6 newly resolved ones) with angular separation larger than0.06 arcsec. We introduced a new ICCD TV camera in this observation, andwere able to achieve the diffraction-limit resolution of the 212 cmtelescope.
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Speckle observations of visual and spectroscopic binaries. III
This is the third paper of this series giving results of speckleobservations carried out for seven visual and 119 spectroscopic binariesat seven nights from May 20 to May 27, 1989, and for 30 visual and 272spectroscopic binaries at 12 nights from June 11 to June 15, and fromAugust 28 to September 3, 1990, using the 212-cm telescope at San PedroMartir Observatory in Mexico. Fringes in the lower spectrum of 31 visualand spectroscopic binaries with angular separation larger than 21 arcsecare obtained. Additionally to two spectroscopic binaries, HD41116 andHD206901, named in the second paper of this series, six spectroscopicbinaries are found each of which has the third component starsurrounding two stars of spectroscopic binary having periodic variationof radial velocity.
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Speckle observations of spectroscopic binaries
Results from speckle observations of binary stars carried out between1987 and 1990 using a 212-cm telescope at the San Pedro MartirObservatory, Mexico, are presented. Fringe patterns for 21 of the 76reduced spectroscopic binaries in the Fourier domain were detected. Thespeckle observations and the astrometric observations are consistent forthe stars HD41116, HD202275, and HD206901.
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The infrared angular diameter of Alpha Herculis measured with a Michelson interferometer
The first infrared angular diameter measurements of Alpha Her, a brightcool supergiant are presented. The measurements are the firstastronomical scientific results from the infrared Michelson array, aprototype near-infrared, broadband, two-telescope interferometer.Visibilities obtained with telescope separations of 4.8, 8.0, and 12.0 mare reported. The data were fit with both uniform disk and limb darkenedmodels. It is found that the uniform disk angular diameter of Alpha Herat 2.2 microns is 32.2 +/-0.8 marcsec. By using the limb darkeningmodels of Sholz and Takeda (1987) and the present angular diametermeasurement, a stellar physical angular diameter of 34 +/-0.8 marcsec isderived. From this determined stellar angular diameter and a compilationof flux measurements from the literature, it is further determined thatthe effective temperature of Alpha Her is 3210 +/-40 K.
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Speckle observations of visual and spectroscopic binaries.
Speckle observations performed for 16 visual and 79 spectroscopicbinaries with the 212-cm telescope at San Pedro Martir Observatory arepresented. The data were collected over a period of 20 nights, from June15 to July 11, 1987. Examples are given of the power spectra of starswith differing angular separations.
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Merged log of IUE observations.
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Search for wide binaries in the Yale Bright Star Catalogue
A specific scheme for identifying wide binary candidates in the YaleBright Star Catalogue is presented. The choice of criteria for selectingcandidates is discussed, and the final criteria are used to compile apreliminary list of candidates which is presented and discussed. Thestatistics of the candidate list are characterized, and the list is usedto compute upper bounds on the wide binary density using a simpletheoretical model.
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Evidence for mass loss in visual binary stars
The present status of the observational evidence about mass loss invisual binary and multiple systems is reviewed. Particular emphasis isplaced on the importance of mass-loss rates measures in these stars, asa systematic study would provide useful constraints in two fields.First, as mass-outflows processes are not modified by the interaction ofthe two stars, and distances, masses, and evolutionary stages areusually fairly well known, an absolute stellar scale for mass loss canmore easily and accurately be derived for these systems. Second, massloss rates are essential to study the detailed orbital evolution of widepairs, providing clues to their origin. Detailed numerical simulationsincluding mass loss have been carried out. It is suggested that massloss may explain in part the recent statistics on separation of widevisual binaries as a function of spectral type and age.
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Are tides responsible for enhanced MG II emission in late-type binaries?
Mg II h and k fluxes are measured for a homogeneous sample of 30 G IIIand K III binaries. The spectra have been obtained from the IUE archiveand calibrated in absolute units (erg/sq cm sec). Contrary to thegenerally accepted view that the rate of rotation is responsible for theenhanced chromospheric activity, the Mg II h and k fluxes correlate muchbetter with parameters containing the separation of components in binarysystems. It is suggested that the enhanced chromospheric emission inlate-type giant binary systems is due to tides rather than to rotationalvelocities.
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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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ICCD speckle observations of binary stars. I - A survey for duplicity among the bright stars
A survey of a sample of 672 stars from the Yale Bright Star Catalog(Hoffleit, 1982) has been carried out using speckle interferometry onthe 3.6-cm Canada-France-Hawaii Telescope in order to establish thebinary star frequency within the sample. This effort was motivated bythe need for a more observationally determined basis for predicting thefrequency of failure of the Hubble Space Telescope (HST) fine-guidancesensors to achieve guide-star lock due to duplicity. This survey of 426dwarfs and 246 evolved stars yielded measurements of 52 newly discoveredbinaries and 60 previously known binary systems. It is shown that thefrequency of close visual binaries in the separation range 0.04-0.25arcsec is 11 percent, or nearly 3.5 times that previously known.
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Photometric Data for the Bright Stars
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Photographic observations of bright stars in the declination zone from +40 to +90 deg with a normal astrograph and 26-arcsec refractor at Pulkovo
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A progress report on the analysis of long exposure SWP high resolution spectra of cool stars
The IUE is the first experiment with sufficient sensitivity to obtainhigh resolution spectra (lambda/delta lambda is approximately 10,000) ofmany cool stars in the vitally important 1200 to 2000 A spectral region.These data provide qualitatively new information with which tounderstand the properties of and structures in the outer atmospheres ofthese stars. Also, these cool star spectra will be extremely useful inplanning for the Space Telescope High Resolution Spectrograph, whichwill be 1000 times more sensitive than IUE but will be hampered bylimited observing time and limited spectral bandwidth in each exposure.Very long exposure, high disperson SWP spectra of many stars locatedthroughout the cool half of the HR diagram were obtained. These 12 to 21hour exposures were obtained by combining NASA and Vilspa shifts so asto obtain the longest possible exposures at times of low background.Included are dwarf stars of spectral type G0 V to M2 V, G9.5 III to M5II giants, G2 Ib to M2 Iab supergiants, a number of RS CVn-type systems,and Barium stars.
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First detection of winds in red giants by microwave continuum techniques
Eight red giants and supergiants have been observed at 4885 MHz (6 cm)with the Very Large Array in an attempt to detect continuum emission.The bright giant Alpha-1 Her (M5 II) was detected at an average fluxdensity of 0.9 + or - 0.13 mJy. Since the likely source of this emissionis an ionized, optically thick component of a stellar wind, thisdetection implies a mass loss rate of 2 x 10 to the -9th solar massesper yr for the ionized gas. The fraction of the outflow in Alpha-1 Herthat is ionized (0.002-0.02) seems to be similar to that previouslyfound for Alpha Ori and Alpha Sco A. Alpha Boo (K2 IIIp) and Beta Gem(K0 III) are probable and definite detections, respectively. The derivedionized mass loss rates for these two stars are about 1 x 10 to the-10th solar masses per yr, implying in the case of Alpha Boo that thewind is largely ionized.
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List of Estimated Angular Separations of Spectroscopic Binaries
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1981A&AS...44...47H&db_key=AST
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NEWS@SKY (Science&Space News)
