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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Large Magellanic Cloud Wolf-Rayet Stars in the HD and HDE Catalogues - a Brief Census
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The properties of OB supergiants in the Large Magellanic Cloud. II - Spectral types and intrinsic colors
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1988ApJ...335..703F&db_key=AST
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Mass loss in A and B supergiants and the extragalactic distance scale
Samples of B5 and A0 stars in the Large Magellanic Cloud (LMC)demonstrate the existence of tight correlations between luminosity andequivalent widths in the H-alpha and H-beta lines. The H-alpha line isin emission for stars brighter than M(v) = -7, and this easilyidentifiable feature should be detectable at the distances of nearbygroups of galaxies. The correlations imply that mass loss in A and Bsupergiants is strongly dependent on luminosity and therefore on stellarmass. Similar samples of stars in the Small Magellanic Cloud (SMC) showssystematically smaller H-alpha emission and more scatter in therelationships between luminosity and H-alpha line strengths than werefound for the LMC stars. There is independent evidence that mass-lossrates are smaller in the SMC than in the LMC, and this fact probablyaccounts for the lower emission at H-alpha in the SMC stars. Thedifferences between the samples in the two clouds may be caused bydifferences in stellar chemical composition.
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On the photometric differences between luminous OBA type stars in the LMC with and without P Cygni characteristics
A comparison is presented of the photometric characteristics of O to A0stars of high luminosity in the Large Magellanic Cloud which exhibit ordo not exhibit P Cygni characteristics. VBLUW observations were made of29 OBA stars and 15 OBA stars with P Cygni characteristics (OBA/PC/stars). Examination of the three two-color diagrams in the systemindicates that the OBA(PC) stars are slightly bluer than the OBA stars,which may be explained by a higher luminosity for the OBA(PC) stars at agiven temperature. Computations of the free-free emission from theextended envelopes of OBA(PC) stars show the contribution of suchemission to the spectral energy distribution to be negligible in theabsence of extreme conditions in the shell. Comparison of observed withtheoretical colors reveals the reddening in OBA(PC) stars to be on theaverage 0.07 magnitudes greater than in OBA stars. Results suggest thatOBA supergiants start to exhibit P Cygni characteristics when the massloss rate becomes greater than or equal to 2 x 10 to the -6th solarmass/year.
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Infrared interstellar extinction in the LMC
J(1.25 micron), H(1.65 micron) and K(2.20 microns) magnitudes arepresented for early-type supergiants in the Large Magellanic Cloud, theobservations being obtained with the AAO Infrared Photometer on the3.9-m Anglo-Australian telescope. A value of 3.21 + or - 0.13 for theratio of total to selective extinction is derived for the LMC from thecolor excess ratio. This value is the same as the mean value of theextinction ratio for the Galaxy within the errors of observations. Theemission line stars show infrared excesses which are consistent withemission from electrons in shells around the stars.
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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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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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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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BVRI-Photometry of the Brightest Stars in the Magellanic Clouds
We have made photometric observations in the BVRI system of 100 objectsthat belong to the Magellanic Clouds. The observational data indicate atleast two remarkable differences between some of the Magellanic Cloudobjects and the supergiant stars in the Galaxy, namely, the former aremore luminous than the most luminous galactic supergiants and they alsohave a color excess in V-R unexplained by interstellar extinction alone.Two possible explanations are likely for the additional color excess;either the presence of a circumstellar dust envelope or a differentchemical atmospheric composition from galactic supergiant stars, orperhaps both of them.
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Five-colour photometry of supergiants and the dust-to-gas ratio in the Large Magellanic Cloud.
Abstract image available at:http://adsabs.harvard.edu/abs/1970A&A.....7...49V
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A deep objective-prism survey for Large Magellanic Cloud members
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Grand Nuage de Magellan. Liste des etoiles membres DU Grand Nuage de Magellan et liste d'etoiles galactiques
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Equivalent widths of Hγ in stellar spectra of the Magellanic Clouds
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1966MNRAS.132..433H&db_key=AST
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Vitesses radiales dans la direction du Grand Nuage de Magellan
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The brightest stars in the Magellanic Clouds
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1960MNRAS.121..337F&db_key=AST
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INHABITED SKY
