HIPPARCOS photometry of 24 variable massive stars (alpha Cygni variables)
The photometric variability of 24 alpha Cyg variables, i.e. variablesuper-and hypergiants, observed by the Hipparcos satellite is described.Three of the selected stars are situated in the SMC, 12 in the LMC andthe remaining 9 in the Galactic plane. Four of them are hot S Dor-typevariables, or LBVs (luminous blue variables) and two are possiblemembers of this class. Light curves are presented for all stars. Forfive stars, among which one LBV, the variability was discovered from theHipparcos photometric data. Results of period searches are presentedand, when relevant, folded light curves are shown. The linear ephemerisof two variables was revised. For most of the program stars theHipparcos magnitude scale (Hp) differs from the V of the UBV system byla 0fm1 . For all variables temperatures and M_bol are given. Galacticforeground reddening for the objects in the Magellanic Clouds are givenbased on IRAS maps.
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The HIPPARCOS proper motion of the Magellanic Clouds
The proper motion of the Large (LMC) and Small (SMC) Magellanic Cloudusing data acquired with the Hipparcos satellite is presented. Hipparcosmeasured 36 stars in the LMC and 11 stars in the SMC. A correctlyweighted mean of the data yields the presently available most accuratevalues, mu_alpha cos(delta) = 1.94 +/- 0.29 mas/yr, mu_delta = - 0.14+/- 0.36 mas/yr for the LMC. For the SMC, mu_alpha cos(delta) = 1.23 +/-0.84 mas/yr, mu_delta = - 1.21 +/- 0.75 mas/yr is obtained, whereby careis taken to exclude likely tidal motions induced by the LMC. Bothgalaxies are moving approximately parallel to each other on the sky,with the Magellanic Stream trailing behind. The Hipparcos proper motionsare in agreement with previous measurements using PPM catalogue data byKroupa et al. (1994), and by Jones et al. (1994) using backgroundgalaxies in a far-outlying field of the LMC. For the LMC the Hipparcosdata suggest a weak rotation signal in a clockwise direction on the sky.Comparison of the Hipparcos proper motion with the proper motion of thefield used by Jones et al. (1994), which is about 7.3 kpc distant fromthe center of the LMC, also suggests clockwise rotation. Combining thethree independent measurements of the proper motion of the LMC and thetwo independent measurements of the proper motion of the SMC improvesthe estimate of the proper motion of the LMC and SMC. The correspondinggalactocentric space motion vectors are computed. Within theuncertainties, the LMC and SMC are found to be on parallel trajectories.Recent theoretical work concerning the origin of the Magellanic Systemis briefly reviewed, but a unique model of the Magellanic Stream, forthe origin of the Magellanic Clouds, and for the mass distribution inthe Galaxy cannot yet be decided upon. Future astrometric space missionsare necessary to significantly improve our present knowledge of thespace motion of the two most conspicuous galactic neighbours of theMilky Way.
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CCD photometry of the young association NGC 1962-65-66-70 in the Large Magellanic Cloud.
We present CCD data in the Johnson passbands B and V of the youngassociation NGC 1962-65-66-70 in the Large Magellanic Cloud. We find theassociation to show an age spread in the range 4 to 9Myr. Some signs fora propagation of star formation from the south-eastern to the northernpart of the region can be found, but they are based on very few stars.The slope of the luminosity function is γ=0.27+/-0.02 for stars ofthe magnitude range -8
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The OB association LH 58 in the Large Magellanic Cloud
We present charge coupled device (CCD) photometry and spectroscopy forstars in Lucke-Hodge 58, an isolated OB association in the LargeMagellanic Cloud (LMC) northwest of 30 Doradus. The photometric catalogcontains 839 stars with UBV magnitudes complete to V approximately = 19.We have obtained spectra and classified 35 stars; combined with previouspublished spectral types, we find 22 O-type stars. The earliest type isO3-4 V, and there are three Wolf-Rayet (WR) stars in the association.The slope of the initial mass function, Gamma = -1.7 +/- 0.3, is in goodagreement with other LMC associations. The presence of several evolvedsupergiants with masses about 15-25 solar mass suggests that some starformation took place as early as 10 million years ago, but the majorityof stars formed coevally within the past few million years.
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Photometric variability study of Wolf-Rayet binaries in the Magellanic Clouds
Photometry in different photometric systems is presented for 14Wolf-Rayet (WR) stars in the Large Magellanic Cloud and 4 Wolf-Rayetstars in the Small Magellanic Cloud. All but two stars are spectroscopicbinaries. Nine of the 16 binaries show phase-dependent variations due towind transparency effects or, in one case, eclipses of the stars. In theformer case, the shape of the light curve of 5 stars is used to derivethe orbital inclination and the WR star mass loss rate.
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Are luminous asymptotic giant branch stars all of spectral type MS? - Evidence from spectroscopic and photometric observations of LMC stars
A sample of stars that included luminous supergiants and AGB stars wasexamined for spectral differences between these two star types; thespectra include those of 49 LMC stars previously classified as M stars,eight red stars in NGC 2100, and one known LMC S star. A closeexamination of image-dissector-scanner spectra revealed a great numberof stars with enhanced ZrO bands, which were classified as MS. A totalof nine AGB stars more luminous than M(bol) = -6 were found, the mostluminous at M(bol) = -6.6. In the region of M(bol) between -5 and -6.6,no star was found showing a normal M-type spectrum; this region isoccupied by MS, S, and C stars. The luminous stars of the M(bol) lessthan -5.5, are from their brightness and pure M-type spectra massivesupergiants; all NGC 2100 stars belong to this group.
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Astrometry of SN 1987A and SK -69.202 deg
Two sets of astrometric plates (epochs 1987.2 and 1973.0) and asecondary reference system comprised of LMC members were used todetermine the position of SN 1987A relative to about 30 Perth 70 stars.The positional coincidence of the SN and Star 1 of Sanduleak -69 deg 202is confirmed to within an uncertainty of + or - 0.13 arcsec in eachcoordinate. The relative brightness of the two major components of Sk-69 deg 202 was assessed by fitting the density profiles of the blendedimages.
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Photometric Studies of Magellanic Cloud Supergiants. II. Variability
Abstract image available at:http://adsabs.harvard.edu/abs/1986ApJS...62..451G
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Photometric studies of Magellanic Cloud supergiants. I - Mean magnitudes and reddenings. II - Variability
In the first part of this paper, a combination of spectral types for 81LMC and 46 SMC supergiants from the literature with new BVRI photometryyields reddenings and intrinsic colors for these stars. While reddeningsup to E(B-V) of 0.3 are found for the LMC sample, the figure for the SMCappears to be no more than 0.2. The dust/gas ratio in both galaxies isfound to be lower than in the Milky Way. In the second part, individualBVRI photoelectric observations for 88 LMC and 46 SMC intermediatespectral type supergiants are analyzed for variability. It is noted that45 percent of the stars exhibit significant variations, with theincidence of variability decreasing with decreasing luminosity.
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Interstellar dust in the Large Magellanic Cloud
The results of observations from the IUE satellite and Las Campanas60-cm telescope of the physical characteristics of interstellar dust inthe Large Magellanic Cloud (LMC) are presented. Extinction andpolarization analysis of 12 reddened stars in the LMC showed dustcharacteristics in the optical and infrared regions similar to those ofGalactic dust. The derived wavelength dependences of polarization andpolarization efficiency were found to be comparable to Galactic values.The dust-to-gas ratios of the NH and CNO in the LMC were several timeslower than Galactic values. The relationship between the ultravioletextinction properties and heavy element abundances in the Galaxy, LMC,and the Small Magellanic Cloud (SMC) are discussed.
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Radial velocities from objective-prism plates in the direction of the Large Magellanic Cloud
A catalog is presented of 711 Large Magellanic Cloud (LMC) stars, withattention to the radial velocities of 418 of these. Also given are theradial velocities of 1127 galactic stars in the direction of the LMC, aswell as discussions of the precision of these measurements and of radialvelocity dispersion in different fields.
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Supergiant and Giant M-Type Stars in the Large Magellanic Cloud
Abstract image available at:http://adsabs.harvard.edu/abs/1981A&AS...43..267W
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A catalogue of A- and F-type supergiants in the Large Magellanic Cloud
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976A&AS...24...35S&db_key=AST
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UBV photometry for supergiants of the Large Magellanic Cloud
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975A&A....43..345B&db_key=AST
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Radial velocities from objective-prism plates in the direction of the Large Magellanic Cloud. List of 398 stars, LMC members. List of 1434 galactic stars, in the LMC direction
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974A&AS...13..173F&db_key=AST
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Rotation et masse DU grand nuage de Magellan.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973A&A....28..165P&db_key=AST
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Spectrographic and photometric observations of supergiants and foreground stars in the direction of the Large Magellanic Cloud
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972A&AS....6..249A&db_key=AST
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La mesure des vitesses radiales AU spectrographe coude DU telescope de 152 CM de l'Observatoire de Hte Provence.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972A&A....19..427F&db_key=AST
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A deep objective-prism survey for Large Magellanic Cloud members
Not Available
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Grand Nuage de Magellan. Liste des etoiles membres DU Grand Nuage de Magellan et liste d'etoiles galactiques
Not Available
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Mesures de vitesses radiales dans la direction du Grand Nuage de Magellan
Not Available
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Vitesses radiales dans la direction du Grand Nuage de Magellan
Not Available
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